Attachment 357975 Details for Bug 192355 – Patch

[patch] Patch

patch.txt (text/plain), 115.77 KB, created by Myles C. Maxfield on 2018-12-21 13:41:01 PST

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Creator: Myles C. Maxfield

Created: 2018-12-21 13:41:01 PST

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patch

obsolete

>commit d4aeeec5a966741da03729fe962bef4e65606776
>Author: Myles C. Maxfield <mmaxfield@apple.com>
>Date:   Fri Dec 21 13:39:33 2018 -0800
>
>    Parser
>
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index 1ce1a8daf8e..63f9fd93546 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,102 @@
>+2018-12-21  Myles C. Maxfield  <mmaxfield@apple.com>
>+
>+        [WHLSL] Add a handwritten parser
>+        https://bugs.webkit.org/show_bug.cgi?id=192355
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        The parser is a mechanical representation of WHLSL's ANTLR grammar at
>+        https://github.com/gpuweb/WHLSL/blob/master/Spec/WHLSL.g4. The parser
>+        uses Expected<> to return an appropriate Error string when parsing fails.
>+
>+        This patch doesn't include the AST nodes themselves - those are in
>+        https://bugs.webkit.org/show_bug.cgi?id=192991. I split up the patch to
>+        aid easier reviewing.
>+
>+        No new tests because the parser isn't hooked up yet.
>+
>+        * Modules/webgpu/WHLSL/WHLSLParser.cpp:
>+        (WebCore::WHLSL::Parser::Parser):
>+        (WebCore::WHLSL::Parser::parse):
>+        (WebCore::WHLSL::Parser::fail):
>+        (WebCore::WHLSL::Parser::peek):
>+        (WebCore::WHLSL::Parser::tryType):
>+        (WebCore::WHLSL::Parser::tryTypes):
>+        (WebCore::WHLSL::Parser::consumeType):
>+        (WebCore::WHLSL::Parser::consumeTypes):
>+        (WebCore::WHLSL::digitValue):
>+        (WebCore::WHLSL::intLiteralToInt):
>+        (WebCore::WHLSL::uintLiteralToUint):
>+        (WebCore::WHLSL::floatLiteralToFloat):
>+        (WebCore::WHLSL::Parser::consumeIntegralLiteral):
>+        (WebCore::WHLSL::Parser::consumeNonNegativeIntegralLiteral):
>+        (WebCore::WHLSL::recognizeSimpleUnsignedInteger):
>+        (WebCore::WHLSL::Parser::parseConstantExpression):
>+        (WebCore::WHLSL::Parser::parseTypeArgument):
>+        (WebCore::WHLSL::Parser::parseTypeArguments):
>+        (WebCore::WHLSL::Parser::parseTypeSuffixAbbreviated):
>+        (WebCore::WHLSL::Parser::parseTypeSuffixNonAbbreviated):
>+        (WebCore::WHLSL::Parser::parseAddressSpaceType):
>+        (WebCore::WHLSL::Parser::parseNonAddressSpaceType):
>+        (WebCore::WHLSL::Parser::parseType):
>+        (WebCore::WHLSL::Parser::parseTypeDefinition):
>+        (WebCore::WHLSL::Parser::parseBuiltInSemantic):
>+        (WebCore::WHLSL::Parser::parseResourceSemantic):
>+        (WebCore::WHLSL::Parser::parseSpecializationConstantSemantic):
>+        (WebCore::WHLSL::Parser::parseStageInOutSemantic):
>+        (WebCore::WHLSL::Parser::parseSemantic):
>+        (WebCore::WHLSL::Parser::parseQualifiers):
>+        (WebCore::WHLSL::Parser::parseStructureElement):
>+        (WebCore::WHLSL::Parser::parseStructureDefinition):
>+        (WebCore::WHLSL::Parser::parseEnumerationDefinition):
>+        (WebCore::WHLSL::Parser::parseEnumerationMember):
>+        (WebCore::WHLSL::Parser::parseNativeTypeDeclaration):
>+        (WebCore::WHLSL::Parser::parseNumThreadsFunctionAttribute):
>+        (WebCore::WHLSL::Parser::parseAttributeBlock):
>+        (WebCore::WHLSL::Parser::parseParameter):
>+        (WebCore::WHLSL::Parser::parseParameters):
>+        (WebCore::WHLSL::Parser::parseFunctionDefinition):
>+        (WebCore::WHLSL::Parser::parseEntryPointFunctionDeclaration):
>+        (WebCore::WHLSL::Parser::parseRegularFunctionDeclaration):
>+        (WebCore::WHLSL::Parser::parseOperatorFunctionDeclaration):
>+        (WebCore::WHLSL::Parser::parseFunctionDeclaration):
>+        (WebCore::WHLSL::Parser::parseNativeFunctionDeclaration):
>+        (WebCore::WHLSL::Parser::parseBlock):
>+        (WebCore::WHLSL::Parser::parseBlockBody):
>+        (WebCore::WHLSL::Parser::parseIfStatement):
>+        (WebCore::WHLSL::Parser::parseSwitchStatement):
>+        (WebCore::WHLSL::Parser::parseSwitchCase):
>+        (WebCore::WHLSL::Parser::parseForLoop):
>+        (WebCore::WHLSL::Parser::parseWhileLoop):
>+        (WebCore::WHLSL::Parser::parseDoWhileLoop):
>+        (WebCore::WHLSL::Parser::parseVariableDeclaration):
>+        (WebCore::WHLSL::Parser::parseVariableDeclarations):
>+        (WebCore::WHLSL::Parser::parseStatement):
>+        (WebCore::WHLSL::Parser::parseEffectfulExpression):
>+        (WebCore::WHLSL::Parser::parseEffectfulAssignment):
>+        (WebCore::WHLSL::Parser::parseEffectfulPrefix):
>+        (WebCore::WHLSL::Parser::parseEffectfulSuffix):
>+        (WebCore::WHLSL::Parser::parseLimitedSuffixOperator):
>+        (WebCore::WHLSL::Parser::parseSuffixOperator):
>+        (WebCore::WHLSL::Parser::parseExpression):
>+        (WebCore::WHLSL::Parser::parseTernaryConditional):
>+        (WebCore::WHLSL::Parser::parseAssignment):
>+        (WebCore::WHLSL::Parser::parsePossibleTernaryConditional):
>+        (WebCore::WHLSL::Parser::parsePossibleLogicalBinaryOperation):
>+        (WebCore::WHLSL::Parser::parsePossibleRelationalBinaryOperation):
>+        (WebCore::WHLSL::Parser::parsePossibleShift):
>+        (WebCore::WHLSL::Parser::parsePossibleAdd):
>+        (WebCore::WHLSL::Parser::parsePossibleMultiply):
>+        (WebCore::WHLSL::Parser::parsePossiblePrefix):
>+        (WebCore::WHLSL::Parser::parsePossibleSuffix):
>+        (WebCore::WHLSL::Parser::parseCallExpression):
>+        (WebCore::WHLSL::Parser::parseTerm):
>+        * Modules/webgpu/WHLSL/WHLSLParser.h:
>+        (WebCore::WHLSL::Parser::Error::Error):
>+        (WebCore::WHLSL::Parser::backtrackingScope):
>+        (WebCore::WHLSL::Parser::SuffixExpression::SuffixExpression):
>+        (WebCore::WHLSL::Parser::SuffixExpression::operator bool const):
>+
> 2018-12-21  Myles C. Maxfield  <mmaxfield@apple.com>
> 
>         [WHLSL] Implement parser AST nodes
>diff --git a/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.cpp b/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.cpp
>index 016c692e2d8..bbc9e160e48 100644
>--- a/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.cpp
>+++ b/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.cpp
>@@ -34,6 +34,2485 @@ namespace WebCore {
> 
> namespace WHLSL {
> 
>+Parser::Parser()
>+{
>+}
>+
>+auto Parser::parse(Program& result, StringView stringView, Mode mode) -> Optional<Error>
>+{
>+    m_lexer = Lexer(stringView);
>+    m_mode = mode;
>+
>+    while (!m_lexer.isFullyConsumed()) {
>+        if (tryType(Lexer::Token::Type::Semicolon)) {
>+            m_lexer.consumeToken();
>+            continue;
>+        }
>+
>+        {
>+            auto typeDefinition = backtrackingScope<Expected<AST::TypeDefinition, Error>>([&]() {
>+                return parseTypeDefinition();
>+            });
>+            if (typeDefinition) {
>+                result.append(WTFMove(*typeDefinition));
>+                continue;
>+            }
>+        }
>+
>+        {
>+            auto structureDefinition = backtrackingScope<Expected<AST::StructureDefinition, Error>>([&]() {
>+                return parseStructureDefinition();
>+            });
>+            if (structureDefinition) {
>+                result.append(WTFMove(*structureDefinition));
>+                continue;
>+            }
>+        }
>+
>+        {
>+            auto enumerationDefinition = backtrackingScope<Expected<AST::EnumerationDefinition, Error>>([&]() {
>+                return parseEnumerationDefinition();
>+            });
>+            if (enumerationDefinition) {
>+                result.append(WTFMove(*enumerationDefinition));
>+                continue;
>+            }
>+        }
>+
>+        Optional<Error> error;
>+        {
>+            auto functionDefinition = backtrackingScope<Expected<AST::FunctionDefinition, Error>>([&]() {
>+                return parseFunctionDefinition();
>+            });
>+            if (functionDefinition) {
>+                result.append(WTFMove(*functionDefinition));
>+                continue;
>+            }
>+            error = functionDefinition.error();
>+        }
>+
>+        if (m_mode == Mode::StandardLibrary) {
>+            auto nativeFunctionDeclaration = backtrackingScope<Expected<AST::NativeFunctionDeclaration, Error>>([&]() {
>+                return parseNativeFunctionDeclaration();
>+            });
>+            if (nativeFunctionDeclaration) {
>+                result.append(WTFMove(*nativeFunctionDeclaration));
>+                continue;
>+            }
>+        }
>+
>+        if (m_mode == Mode::StandardLibrary) {
>+            auto nativeTypeDeclaration = backtrackingScope<Expected<AST::NativeTypeDeclaration, Error>>([&]() {
>+                return parseNativeTypeDeclaration();
>+            });
>+            if (nativeTypeDeclaration) {
>+                result.append(WTFMove(*nativeTypeDeclaration));
>+                continue;
>+            }
>+        }
>+
>+        WTFLogAlways("%s", error->error.utf8().data());
>+        return WTFMove(*error);
>+    }
>+    return WTF::nullopt;
>+}
>+
>+auto Parser::fail(const String& message) -> Unexpected<Error> {
>+    if (auto nextToken = peek())
>+        return Unexpected<Error>(Error(m_lexer.errorString(*nextToken, message)));
>+    return Unexpected<Error>(Error(String::format("Cannot lex: %s", message.utf8().data())));
>+}
>+
>+auto Parser::peek() -> Expected<Lexer::Token, Error> {
>+    if (auto token = m_lexer.consumeToken()) {
>+        m_lexer.unconsumeToken(Lexer::Token(*token));
>+        return *token;
>+    }
>+    return fail(String("Cannot consume token", String::ConstructFromLiteral));
>+}
>+
>+Optional<Lexer::Token> Parser::tryType(Lexer::Token::Type type)
>+{
>+    if (auto token = m_lexer.consumeToken()) {
>+        if (token->type == type)
>+            return token;
>+        m_lexer.unconsumeToken(Lexer::Token(*token));
>+    }
>+    return WTF::nullopt;
>+}
>+
>+Optional<Lexer::Token> Parser::tryTypes(Vector<Lexer::Token::Type> types)
>+{
>+    if (auto token = m_lexer.consumeToken()) {
>+        if (std::find(types.begin(), types.end(), token->type) != types.end())
>+            return token;
>+        m_lexer.unconsumeToken(Lexer::Token(*token));
>+    }
>+    return WTF::nullopt;
>+}
>+
>+auto Parser::consumeType(Lexer::Token::Type type) -> Expected<Lexer::Token, Error> {
>+    if (auto token = m_lexer.consumeToken()) {
>+        if (token->type == type)
>+            return *token;
>+        return fail(String::format("Unexpected token (expected %s got %s)", Lexer::Token::typeName(type), Lexer::Token::typeName(token->type)));
>+    }
>+    return fail(String::format("Cannot consume token (expected %s)", Lexer::Token::typeName(type)));
>+}
>+
>+auto Parser::consumeTypes(Vector<Lexer::Token::Type> types) -> Expected<Lexer::Token, Error> {
>+    auto buildExpectedString = [&]() -> String {
>+        StringBuilder builder;
>+        builder.append("[");
>+        for (unsigned i = 0; i < types.size(); ++i) {
>+            if (i > 0)
>+                builder.append(", ");
>+            builder.append(Lexer::Token::typeName(types[i]));
>+        }
>+        builder.append("]");
>+        return builder.toString();
>+    };
>+
>+    if (auto token = m_lexer.consumeToken()) {
>+        if (std::find(types.begin(), types.end(), token->type) != types.end())
>+            return *token;
>+        return fail(String::format("Unexpected token (expected one of %s got %s)", buildExpectedString().utf8().data(), Lexer::Token::typeName(token->type)));
>+    }
>+    return fail(String::format("Cannot consume token (expected %s)", buildExpectedString().utf8().data()));
>+}
>+
>+static int digitValue(UChar character)
>+{
>+    if (character >= '0' && character <= '9')
>+        return character - '0';
>+    if (character >= 'a' && character <= 'f')
>+        return character - 'a' + 10;
>+    return character - 'A' + 10;
>+}
>+
>+static Expected<int, Parser::Error> intLiteralToInt(StringView text)
>+{
>+    bool negate = false;
>+    if (text.startsWith(String("-", String::ConstructFromLiteral))) {
>+        negate = true;
>+        text = text.substring(1);
>+    }
>+    int base = 10;
>+    if (text.startsWith(String("0x", String::ConstructFromLiteral))) {
>+        text = text.substring(2);
>+        base = 16;
>+    }
>+
>+    int result = 0;
>+    for (unsigned i = 0; i < text.length(); ++i) {
>+        int digit = digitValue(text[i]);
>+        auto previous = result;
>+        result = result * base + digit;
>+        if (result < previous) // FIXME: overflow on signed integers is undefined
>+            return Unexpected<Parser::Error>(Parser::Error(String::format("int literal %s is out of bounds", text.utf8().data())));
>+    }
>+    if (negate)
>+        result *= -1;
>+    // FIXME: This algorithm makes it impossible to represent 0x800000 (the most negative representable value)
>+    return { result };
>+}
>+
>+static Expected<unsigned, Parser::Error> uintLiteralToUint(StringView text)
>+{
>+    unsigned base = 10;
>+    if (text.startsWith(String("0x", String::ConstructFromLiteral))) {
>+        text = text.substring(2);
>+        base = 16;
>+    }
>+    ASSERT(text.substring(text.length() - 1) == "u");
>+    text = text.substring(0, text.length() - 1);
>+    unsigned result = 0;
>+    for (unsigned i = 0; i < text.length(); ++i) {
>+        unsigned digit = digitValue(text[i]);
>+        auto previous = result;
>+        result = result * base + digit;
>+        if (result < previous)
>+            return Unexpected<Parser::Error>(Parser::Error(String::format("uint literal %s is out of bounds", text.utf8().data())));
>+    }
>+    return { result };
>+}
>+
>+static Expected<float, Parser::Error> floatLiteralToFloat(StringView text)
>+{
>+    bool negate = false;
>+    if (text.length() > 0 && text[0] == '-') {
>+        negate = true;
>+        text = text.substring(1);
>+    }
>+    if (text.length() > 0 && text[text.length() - 1] == 'f')
>+        text = text.substring(0, text.length() - 1);
>+    float result;
>+    unsigned index = 0;
>+    for (index = 0; index < text.length() && text[index] != '.'; ++index) {
>+        ASSERT(text[index] >= '0' && text[index] <= '9');
>+        result = result * 10 + (text[index] - '0');
>+    }
>+    ASSERT(index < text.length());
>+    ASSERT(text[index] == '.');
>+    float decimal = 1.0f / 10.0f;
>+    for (++index; index < text.length(); ++index) {
>+        ASSERT(text[index] >= '0' && text[index] <= '9');
>+        result += decimal * (text[index] - '0');
>+        decimal /= 10.0f;
>+    }
>+    if (negate)
>+        result *= -1;
>+    return result;
>+}
>+
>+auto Parser::consumeIntegralLiteral() -> Expected<Variant<int, unsigned>, Error> {
>+    auto integralLiteralToken = consumeTypes({ Lexer::Token::Type::IntLiteral, Lexer::Token::Type::UintLiteral });
>+    if (!integralLiteralToken)
>+        return Unexpected<Error>(integralLiteralToken.error());
>+
>+    switch (integralLiteralToken->type) {
>+    case Lexer::Token::Type::IntLiteral: {
>+        auto result = intLiteralToInt(integralLiteralToken->stringView);
>+        if (result)
>+            return {{ *result }};
>+        return Unexpected<Error>(result.error());
>+    }
>+    case Lexer::Token::Type::UintLiteral: {
>+        auto result = uintLiteralToUint(integralLiteralToken->stringView);
>+        if (result)
>+            return {{ *result }};
>+        return Unexpected<Error>(result.error());
>+    }
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+    }
>+}
>+
>+auto Parser::consumeNonNegativeIntegralLiteral() -> Expected<unsigned, Error> {
>+    auto integralLiteral = consumeIntegralLiteral();
>+    if (!integralLiteral)
>+        return Unexpected<Error>(integralLiteral.error());
>+    auto result = WTF::visit(WTF::makeVisitor([](int x) -> Optional<unsigned> {
>+        if (x < 0)
>+            return WTF::nullopt;
>+        return x;
>+    }, [](unsigned x) -> Optional<unsigned> {
>+        return x;
>+    }), *integralLiteral);
>+    if (result)
>+        return *result;
>+    return fail(String("int literal is negative", String::ConstructFromLiteral));
>+}
>+
>+static Expected<unsigned, Parser::Error> recognizeSimpleUnsignedInteger(StringView stringView)
>+{
>+    unsigned result = 0;
>+    if (stringView.length() < 1)
>+        return Unexpected<Parser::Error>(Parser::Error(String::format("Simple unsigned literal %s is too short", stringView.utf8().data())));
>+    for (unsigned i = 0; i < stringView.length(); ++i) {
>+        if (stringView[i] < '0' || stringView[i] > '9')
>+            return Unexpected<Parser::Error>(Parser::Error(String::format("Simple unsigned literal %s isn't of the form [0-9]+", stringView.utf8().data())));
>+        auto previous = result;
>+        result = result * 10 + (stringView[i] - '0');
>+        if (result < previous)
>+            return Unexpected<Parser::Error>(Parser::Error(String::format("Simple unsigned literal %s is out of bounds", stringView.utf8().data())));
>+    }
>+    return result;
>+}
>+
>+auto Parser::parseConstantExpression() -> Expected<AST::ConstantExpression, Error> {
>+    auto type = consumeTypes({
>+        Lexer::Token::Type::IntLiteral,
>+        Lexer::Token::Type::UintLiteral,
>+        Lexer::Token::Type::FloatLiteral,
>+        Lexer::Token::Type::Null,
>+        Lexer::Token::Type::True,
>+        Lexer::Token::Type::False,
>+        Lexer::Token::Type::Identifier,
>+    });
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    switch (type->type) {
>+    case Lexer::Token::Type::IntLiteral: {
>+        auto value = intLiteralToInt(type->stringView);
>+        if (!value)
>+            return Unexpected<Error>(value.error());
>+        return {{ AST::IntegerLiteral(WTFMove(*type), *value) }};
>+    }
>+    case Lexer::Token::Type::UintLiteral: {
>+        auto value = uintLiteralToUint(type->stringView);
>+        if (!value)
>+            return Unexpected<Error>(value.error());
>+        return {{ AST::UnsignedIntegerLiteral(WTFMove(*type), *value) }};
>+    }
>+    case Lexer::Token::Type::FloatLiteral: {
>+        auto value = floatLiteralToFloat(type->stringView);
>+        if (!value)
>+            return Unexpected<Error>(value.error());
>+        return {{ AST::FloatLiteral(WTFMove(*type), *value) }};
>+    }
>+    case Lexer::Token::Type::Null:
>+        return { AST::NullLiteral(WTFMove(*type)) };
>+    case Lexer::Token::Type::True:
>+        return { AST::BooleanLiteral(WTFMove(*type), true) };
>+    case Lexer::Token::Type::False:
>+        return { AST::BooleanLiteral(WTFMove(*type), false) };
>+    case Lexer::Token::Type::Identifier: {
>+        auto origin = consumeType(Lexer::Token::Type::FullStop);
>+        if (!origin)
>+            return Unexpected<Error>(origin.error());
>+        auto next = consumeType(Lexer::Token::Type::Identifier);
>+        if (!next)
>+            return Unexpected<Error>(next.error());
>+        return { AST::ConstantExpressionEnumerationMemberReference(WTFMove(*origin), type->stringView.toString(), next->stringView.toString()) };
>+    }
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+    }
>+}
>+
>+auto Parser::parseTypeArgument() -> Expected<AST::TypeArgument, Error> {
>+    auto constantExpression = backtrackingScope<Expected<AST::ConstantExpression, Error>>([&]() {
>+        return parseConstantExpression();
>+    });
>+    if (constantExpression)
>+        return AST::TypeArgument(WTFMove(*constantExpression));
>+    auto result = consumeType(Lexer::Token::Type::Identifier);
>+    if (!result)
>+        return Unexpected<Error>(result.error());
>+    return AST::TypeArgument(result->stringView.toString());
>+}
>+
>+auto Parser::parseTypeArguments() -> Expected<AST::TypeArguments, Error> {
>+    auto typeArguments = backtrackingScope<Optional<AST::TypeArguments>>([&]() -> Optional<AST::TypeArguments> {
>+        auto lessThanSign = consumeType(Lexer::Token::Type::LessThanSign);
>+        if (!lessThanSign)
>+            return WTF::nullopt;
>+        AST::TypeArguments typeArguments;
>+        auto typeArgument = parseTypeArgument();
>+        if (!typeArgument)
>+            return WTF::nullopt;
>+        typeArguments.append(WTFMove(*typeArgument));
>+        while (tryType(Lexer::Token::Type::Comma)) {
>+            auto typeArgument = parseTypeArgument();
>+            if (!typeArgument)
>+                return WTF::nullopt;
>+            typeArguments.append(WTFMove(*typeArgument));
>+        }
>+        auto greaterThanSign = consumeType(Lexer::Token::Type::GreaterThanSign);
>+        if (!greaterThanSign)
>+            return WTF::nullopt;
>+        return typeArguments;
>+    });
>+    if (typeArguments)
>+        return WTFMove(*typeArguments);
>+
>+    typeArguments = backtrackingScope<Optional<AST::TypeArguments>>([&]() -> Optional<AST::TypeArguments> {
>+        auto lessThanSign = consumeType(Lexer::Token::Type::LessThanSign);
>+        if (!lessThanSign)
>+            return WTF::nullopt;
>+        auto greaterThanSign = consumeType(Lexer::Token::Type::GreaterThanSign);
>+        if (!greaterThanSign)
>+            return WTF::nullopt;
>+        return {{ }};
>+    });
>+    if (typeArguments)
>+        return WTFMove(*typeArguments);
>+
>+    return AST::TypeArguments();
>+}
>+
>+auto Parser::parseTypeSuffixAbbreviated() -> Expected<TypeSuffixAbbreviated, Error> {
>+    auto token = consumeTypes({ Lexer::Token::Type::Star, Lexer::Token::Type::SquareBracketPair, Lexer::Token::Type::LeftSquareBracket });
>+    if (!token)
>+        return Unexpected<Error>(token.error());
>+    if (token->type == Lexer::Token::Type::LeftSquareBracket) {
>+        auto numElements = consumeNonNegativeIntegralLiteral();
>+        if (!numElements)
>+            return Unexpected<Error>(numElements.error());
>+        auto rightSquareBracket = consumeType(Lexer::Token::Type::RightSquareBracket);
>+        if (!rightSquareBracket)
>+            return Unexpected<Error>(rightSquareBracket.error());
>+        return {{ *token, *numElements }};
>+    }
>+    return {{ *token, WTF::nullopt }};
>+}
>+
>+auto Parser::parseTypeSuffixNonAbbreviated() -> Expected<TypeSuffixNonAbbreviated, Error> {
>+    auto token = consumeTypes({ Lexer::Token::Type::Star, Lexer::Token::Type::SquareBracketPair, Lexer::Token::Type::LeftSquareBracket });
>+    if (!token)
>+        return Unexpected<Error>(token.error());
>+    if (token->type == Lexer::Token::Type::LeftSquareBracket) {
>+        auto numElements = consumeNonNegativeIntegralLiteral();
>+        if (!numElements)
>+            return Unexpected<Error>(numElements.error());
>+        auto rightSquareBracket = consumeType(Lexer::Token::Type::RightSquareBracket);
>+        if (!rightSquareBracket)
>+            return Unexpected<Error>(rightSquareBracket.error());
>+        return {{ *token, WTF::nullopt, *numElements }};
>+    }
>+    auto addressSpace = consumeTypes({ Lexer::Token::Type::Constant, Lexer::Token::Type::Device, Lexer::Token::Type::Threadgroup, Lexer::Token::Type::Thread});
>+    if (!addressSpace)
>+        return Unexpected<Error>(addressSpace.error());
>+    return {{ *token, { *addressSpace }, WTF::nullopt }};
>+}
>+
>+auto Parser::parseAddressSpaceType() -> Expected<std::unique_ptr<AST::Type>, Error> {
>+    auto addressSpace = consumeTypes({ Lexer::Token::Type::Constant, Lexer::Token::Type::Device, Lexer::Token::Type::Threadgroup, Lexer::Token::Type::Thread});
>+    if (!addressSpace)
>+        return Unexpected<Error>(addressSpace.error());
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+    auto typeArguments = parseTypeArguments();
>+    if (!typeArguments)
>+        return Unexpected<Error>(typeArguments.error());
>+
>+    auto constructTypeFromSuffixAbbreviated = [&](const TypeSuffixAbbreviated& typeSuffixAbbreviated, std::unique_ptr<AST::Type>&& previous) -> std::unique_ptr<AST::Type> {
>+        switch (typeSuffixAbbreviated.token.type) {
>+        case Lexer::Token::Type::Star:
>+            return std::make_unique<AST::PointerType>(Lexer::Token(typeSuffixAbbreviated.token), addressSpace->stringView.toString(), WTFMove(previous));
>+        case Lexer::Token::Type::SquareBracketPair:
>+            return std::make_unique<AST::ArrayReferenceType>(Lexer::Token(typeSuffixAbbreviated.token), addressSpace->stringView.toString(), WTFMove(previous));
>+        case Lexer::Token::Type::LeftSquareBracket:
>+            return std::make_unique<AST::ArrayType>(Lexer::Token(typeSuffixAbbreviated.token), WTFMove(previous), *typeSuffixAbbreviated.numElements);
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return nullptr;
>+        }
>+    };
>+
>+    auto firstTypeSuffixAbbreviated = parseTypeSuffixAbbreviated();
>+    if (!firstTypeSuffixAbbreviated)
>+        return Unexpected<Error>(firstTypeSuffixAbbreviated.error());
>+    std::unique_ptr<AST::Type> result = std::make_unique<AST::TypeReference>(Lexer::Token(*addressSpace), name->stringView.toString(), WTFMove(*typeArguments));
>+    result = constructTypeFromSuffixAbbreviated(*firstTypeSuffixAbbreviated, WTFMove(result));
>+    while (true) {
>+        auto typeSuffixAbbreviated = backtrackingScope<Expected<TypeSuffixAbbreviated, Error>>([&]() {
>+            return parseTypeSuffixAbbreviated();
>+        });
>+        if (!typeSuffixAbbreviated)
>+            break;
>+        // FIXME: The nesting here might be in the wrong order.
>+        result = constructTypeFromSuffixAbbreviated(*typeSuffixAbbreviated, WTFMove(result));
>+    }
>+
>+    return WTFMove(result);
>+}
>+
>+auto Parser::parseNonAddressSpaceType() -> Expected<std::unique_ptr<AST::Type>, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+    auto typeArguments = parseTypeArguments();
>+    if (!typeArguments)
>+        return Unexpected<Error>(typeArguments.error());
>+
>+    auto constructTypeFromSuffixNonAbbreviated = [&](const TypeSuffixNonAbbreviated& typeSuffixNonAbbreviated, std::unique_ptr<AST::Type>&& previous) -> std::unique_ptr<AST::Type> {
>+        switch (typeSuffixNonAbbreviated.token.type) {
>+        case Lexer::Token::Type::Star:
>+            return std::make_unique<AST::PointerType>(Lexer::Token(typeSuffixNonAbbreviated.token), typeSuffixNonAbbreviated.addressSpace->stringView.toString(), WTFMove(previous));
>+        case Lexer::Token::Type::SquareBracketPair:
>+            return std::make_unique<AST::ArrayReferenceType>(Lexer::Token(typeSuffixNonAbbreviated.token), typeSuffixNonAbbreviated.addressSpace->stringView.toString(), WTFMove(previous));
>+        case Lexer::Token::Type::LeftSquareBracket:
>+            return std::make_unique<AST::ArrayType>(Lexer::Token(typeSuffixNonAbbreviated.token), WTFMove(previous), *typeSuffixNonAbbreviated.numElements);
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return nullptr;
>+        }
>+    };
>+
>+    std::unique_ptr<AST::Type> result = std::make_unique<AST::TypeReference>(WTFMove(*origin), name->stringView.toString(), WTFMove(*typeArguments));
>+    while (true) {
>+        auto typeSuffixNonAbbreviated = backtrackingScope<Expected<TypeSuffixNonAbbreviated, Error>>([&]() {
>+            return parseTypeSuffixNonAbbreviated();
>+        });
>+        if (!typeSuffixNonAbbreviated)
>+            break;
>+        // FIXME: The nesting here might be in the wrong order.
>+        result = constructTypeFromSuffixNonAbbreviated(*typeSuffixNonAbbreviated, WTFMove(result));
>+    }
>+
>+    return WTFMove(result);
>+}
>+
>+auto Parser::parseType() -> Expected<std::unique_ptr<AST::Type>, Error> {
>+    auto type = backtrackingScope<Expected<std::unique_ptr<AST::Type>, Error>>([&]() {
>+        return parseAddressSpaceType();
>+    });
>+    if (type)
>+        return type;
>+
>+    type = backtrackingScope<Expected<std::unique_ptr<AST::Type>, Error>>([&]() {
>+        return parseNonAddressSpaceType();
>+    });
>+    if (type)
>+        return type;
>+
>+    return Unexpected<Error>(type.error());
>+}
>+
>+auto Parser::parseTypeDefinition() -> Expected<AST::TypeDefinition, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Typedef);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+    auto equals = consumeType(Lexer::Token::Type::EqualsSign);
>+    if (!equals)
>+        return Unexpected<Error>(equals.error());
>+    auto type = parseType();
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+    auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+    if (!semicolon)
>+        return Unexpected<Error>(semicolon.error());
>+    return AST::TypeDefinition(WTFMove(*origin), name->stringView.toString(), WTFMove(*type));
>+}
>+
>+auto Parser::parseBuiltInSemantic() -> Expected<AST::BuiltInSemantic, Error> {
>+    auto origin = consumeTypes({
>+        Lexer::Token::Type::SVInstanceID,
>+        Lexer::Token::Type::SVVertexID,
>+        Lexer::Token::Type::PSize,
>+        Lexer::Token::Type::SVPosition,
>+        Lexer::Token::Type::SVIsFrontFace,
>+        Lexer::Token::Type::SVSampleIndex,
>+        Lexer::Token::Type::SVInnerCoverage,
>+        Lexer::Token::Type::SVTarget,
>+        Lexer::Token::Type::SVDepth,
>+        Lexer::Token::Type::SVCoverage,
>+        Lexer::Token::Type::SVDispatchThreadID,
>+        Lexer::Token::Type::SVGroupID,
>+        Lexer::Token::Type::SVGroupIndex,
>+        Lexer::Token::Type::SVGroupThreadID});
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    switch (origin->type) {
>+    case Lexer::Token::Type::SVInstanceID:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVInstanceID);
>+    case Lexer::Token::Type::SVVertexID:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVVertexID);
>+    case Lexer::Token::Type::PSize:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::PSize);
>+    case Lexer::Token::Type::SVPosition:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVPosition);
>+    case Lexer::Token::Type::SVIsFrontFace:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVIsFrontFace);
>+    case Lexer::Token::Type::SVSampleIndex:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVSampleIndex);
>+    case Lexer::Token::Type::SVInnerCoverage:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVInnerCoverage);
>+    case Lexer::Token::Type::SVTarget: {
>+        auto target = consumeNonNegativeIntegralLiteral();
>+        if (!target)
>+            return Unexpected<Error>(target.error());
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVTarget, *target);
>+    }
>+    case Lexer::Token::Type::SVDepth:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVDepth);
>+    case Lexer::Token::Type::SVCoverage:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVCoverage);
>+    case Lexer::Token::Type::SVDispatchThreadID:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVDispatchThreadID);
>+    case Lexer::Token::Type::SVGroupID:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVGroupID);
>+    case Lexer::Token::Type::SVGroupIndex:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVGroupIndex);
>+    case Lexer::Token::Type::SVGroupThreadID:
>+        return AST::BuiltInSemantic(WTFMove(*origin), AST::BuiltInSemantic::Variable::SVGroupThreadID);
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+    }
>+}
>+
>+auto Parser::parseResourceSemantic() -> Expected<AST::ResourceSemantic, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Register);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto info = consumeType(Lexer::Token::Type::Identifier);
>+    if (!info)
>+        return Unexpected<Error>(info.error());
>+    if (info->stringView.length() < 2 || (info->stringView[0] != 'u'
>+        && info->stringView[0] != 't'
>+        && info->stringView[0] != 'b'
>+        && info->stringView[0] != 's'))
>+        return Unexpected<Error>(Error(String::format("%c is not a known resource type ('u', 't', 'b', or 's')", info->stringView[0])));
>+
>+    AST::ResourceSemantic::Mode mode;
>+    switch (info->stringView[0]) {
>+    case 'u':
>+        mode = AST::ResourceSemantic::Mode::UnorderedAccessView;
>+        break;
>+    case 't':
>+        mode = AST::ResourceSemantic::Mode::Texture;
>+        break;
>+    case 'b':
>+        mode = AST::ResourceSemantic::Mode::Buffer;
>+        break;
>+    case 's':
>+        mode = AST::ResourceSemantic::Mode::Sampler;
>+        break;
>+    }
>+
>+    auto index = recognizeSimpleUnsignedInteger(info->stringView.substring(1));
>+    if (!index)
>+        return Unexpected<Error>(index.error());
>+
>+    unsigned space = 0;
>+    if (tryType(Lexer::Token::Type::Comma)) {
>+        auto spaceToken = consumeType(Lexer::Token::Type::Identifier);
>+        if (!spaceToken)
>+            return Unexpected<Error>(spaceToken.error());
>+        auto prefix = String("space", String::ConstructFromLiteral);
>+        if (!spaceToken->stringView.startsWith(StringView(prefix)))
>+            return Unexpected<Error>(Error(String::format("Second argument to resource semantic %s needs be of the form 'space0'", spaceToken->stringView.utf8().data())));
>+        if (spaceToken->stringView.length() <= prefix.length())
>+            return Unexpected<Error>(Error(String::format("Second argument to resource semantic %s needs be of the form 'space0'", spaceToken->stringView.utf8().data())));
>+        auto spaceValue = recognizeSimpleUnsignedInteger(spaceToken->stringView.substring(prefix.length()));
>+        if (!spaceValue)
>+            return Unexpected<Error>(spaceValue.error());
>+        space = *spaceValue;
>+    }
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    return AST::ResourceSemantic(WTFMove(*origin), mode, *index, space);
>+}
>+
>+auto Parser::parseSpecializationConstantSemantic() -> Expected<AST::SpecializationConstantSemantic, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Specialized);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+    return AST::SpecializationConstantSemantic(WTFMove(*origin));
>+}
>+
>+auto Parser::parseStageInOutSemantic() -> Expected<AST::StageInOutSemantic, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Attribute);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto index = consumeNonNegativeIntegralLiteral();
>+    if (!index)
>+        return Unexpected<Error>(index.error());
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    return AST::StageInOutSemantic(WTFMove(*origin), *index);
>+}
>+
>+auto Parser::parseSemantic() -> Expected<AST::Semantic, Error> {
>+    auto builtInSemantic = backtrackingScope<Expected<AST::BuiltInSemantic, Error>>([&]() {
>+        return parseBuiltInSemantic();
>+    });
>+    if (builtInSemantic)
>+        return AST::Semantic(WTFMove(*builtInSemantic));
>+
>+    auto resourceSemantic = backtrackingScope<Expected<AST::ResourceSemantic, Error>>([&]() {
>+        return parseResourceSemantic();
>+    });
>+    if (resourceSemantic)
>+        return AST::Semantic(WTFMove(*resourceSemantic));
>+
>+    auto specializationConstantSemantic = backtrackingScope<Expected<AST::SpecializationConstantSemantic, Error>>([&]() {
>+        return parseSpecializationConstantSemantic();
>+    });
>+    if (specializationConstantSemantic)
>+        return AST::Semantic(WTFMove(*specializationConstantSemantic));
>+
>+    auto stageInOutSemantic = backtrackingScope<Expected<AST::StageInOutSemantic, Error>>([&]() {
>+        return parseStageInOutSemantic();
>+    });
>+    if (stageInOutSemantic)
>+        return AST::Semantic(WTFMove(*stageInOutSemantic));
>+
>+    return Unexpected<Error>(stageInOutSemantic.error());
>+}
>+AST::Qualifiers Parser::parseQualifiers()
>+{
>+    AST::Qualifiers qualifiers;
>+    while (true) {
>+        if (auto next = tryType(Lexer::Token::Type::Qualifier)) {
>+            if ("nointerpolation" == next->stringView)
>+                qualifiers.append(AST::Qualifier::Nointerpolation);
>+            else if ("noperspective" == next->stringView)
>+                qualifiers.append(AST::Qualifier::Noperspective);
>+            else if ("uniform" == next->stringView)
>+                qualifiers.append(AST::Qualifier::Uniform);
>+            else if ("centroid" == next->stringView)
>+                qualifiers.append(AST::Qualifier::Centroid);
>+            else if ("sample" == next->stringView)
>+                qualifiers.append(AST::Qualifier::Sample);
>+            else
>+                ASSERT_NOT_REACHED();
>+        } else
>+            break;
>+    }
>+    return qualifiers;
>+}
>+
>+auto Parser::parseStructureElement() -> Expected<AST::StructureElement, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    AST::Qualifiers qualifiers = parseQualifiers();
>+
>+    auto type = parseType();
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+
>+    if (tryType(Lexer::Token::Type::Colon)) {
>+        auto semantic = parseSemantic();
>+        if (!semantic)
>+            return Unexpected<Error>(semantic.error());
>+
>+        auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+        if (!semicolon)
>+            return Unexpected<Error>(semicolon.error());
>+
>+        return AST::StructureElement(WTFMove(*origin), WTFMove(qualifiers), WTFMove(*type), name->stringView.toString(), WTFMove(*semantic));
>+    }
>+
>+    auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+    if (!semicolon)
>+        return Unexpected<Error>(semicolon.error());
>+
>+    return AST::StructureElement(WTFMove(*origin), WTFMove(qualifiers), WTFMove(*type), name->stringView.toString(), WTF::nullopt);
>+}
>+
>+auto Parser::parseStructureDefinition() -> Expected<AST::StructureDefinition, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Struct);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+
>+    auto leftCurlyBracket = consumeType(Lexer::Token::Type::LeftCurlyBracket);
>+    if (!leftCurlyBracket)
>+        return Unexpected<Error>(leftCurlyBracket.error());
>+
>+    AST::StructureElements structureElements;
>+    while (true) {
>+        auto structureElement = backtrackingScope<Expected<AST::StructureElement, Error>>([&]() {
>+            return parseStructureElement();
>+        });
>+        if (structureElement)
>+            structureElements.append(WTFMove(*structureElement));
>+        else
>+            break;
>+    }
>+
>+    auto rightCurlyBracket = consumeType(Lexer::Token::Type::RightCurlyBracket);
>+    if (!rightCurlyBracket)
>+        return Unexpected<Error>(rightCurlyBracket.error());
>+
>+    return AST::StructureDefinition(WTFMove(*origin), name->stringView.toString(), WTFMove(structureElements));
>+}
>+
>+auto Parser::parseEnumerationDefinition() -> Expected<AST::EnumerationDefinition, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Enum);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+
>+    std::unique_ptr<AST::Type> type;
>+    if (tryType(Lexer::Token::Type::Colon)) {
>+        auto parsedType = parseType();
>+        if (!parsedType)
>+            return Unexpected<Error>(parsedType.error());
>+        type = WTFMove(*parsedType);
>+    }
>+
>+    auto leftCurlyBracket = consumeType(Lexer::Token::Type::LeftCurlyBracket);
>+    if (!leftCurlyBracket)
>+        return Unexpected<Error>(leftCurlyBracket.error());
>+
>+    auto firstEnumerationMember = parseEnumerationMember();
>+    if (!firstEnumerationMember)
>+        return Unexpected<Error>(firstEnumerationMember.error());
>+
>+    Vector<AST::EnumerationMember> members;
>+    members.append(WTFMove(*firstEnumerationMember));
>+
>+    while (tryType(Lexer::Token::Type::Comma)) {
>+        auto member = parseEnumerationMember();
>+        if (!member)
>+            return Unexpected<Error>(member.error());
>+        members.append(WTFMove(*member));
>+    }
>+
>+    auto rightCurlyBracket = consumeType(Lexer::Token::Type::RightCurlyBracket);
>+    if (!rightCurlyBracket)
>+        return Unexpected<Error>(rightCurlyBracket.error());
>+
>+    return AST::EnumerationDefinition(WTFMove(*origin), name->stringView.toString(), WTFMove(type), WTFMove(members));
>+}
>+
>+auto Parser::parseEnumerationMember() -> Expected<AST::EnumerationMember, Error> {
>+    auto identifier = consumeType(Lexer::Token::Type::Identifier);
>+    if (!identifier)
>+        return Unexpected<Error>(identifier.error());
>+    auto name = identifier->stringView.toString();
>+
>+    if (tryType(Lexer::Token::Type::EqualsSign)) {
>+        auto constantExpression = parseConstantExpression();
>+        if (!constantExpression)
>+            return Unexpected<Error>(constantExpression.error());
>+        return AST::EnumerationMember(Lexer::Token(*identifier), WTFMove(name), WTFMove(*constantExpression));
>+    }
>+    return AST::EnumerationMember(Lexer::Token(*identifier), WTFMove(name));
>+}
>+
>+auto Parser::parseNativeTypeDeclaration() -> Expected<AST::NativeTypeDeclaration, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Native);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto parsedTypedef = consumeType(Lexer::Token::Type::Typedef);
>+    if (!parsedTypedef)
>+        return Unexpected<Error>(parsedTypedef.error());
>+
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+
>+    auto typeArguments = parseTypeArguments();
>+    if (!typeArguments)
>+        return Unexpected<Error>(typeArguments.error());
>+
>+    auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+    if (!semicolon)
>+        return Unexpected<Error>(semicolon.error());
>+
>+    return AST::NativeTypeDeclaration(WTFMove(*origin), name->stringView.toString(), WTFMove(*typeArguments));
>+}
>+
>+auto Parser::parseNumThreadsFunctionAttribute() -> Expected<AST::NumThreadsFunctionAttribute, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::NumThreads);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto width = consumeNonNegativeIntegralLiteral();
>+    if (!width)
>+        return Unexpected<Error>(width.error());
>+
>+    auto comma = consumeType(Lexer::Token::Type::Comma);
>+    if (!comma)
>+        return Unexpected<Error>(comma.error());
>+
>+    auto height = consumeNonNegativeIntegralLiteral();
>+    if (!height)
>+        return Unexpected<Error>(height.error());
>+
>+    comma = consumeType(Lexer::Token::Type::Comma);
>+    if (!comma)
>+        return Unexpected<Error>(comma.error());
>+
>+    auto depth = consumeNonNegativeIntegralLiteral();
>+    if (!depth)
>+        return Unexpected<Error>(depth.error());
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    return AST::NumThreadsFunctionAttribute(WTFMove(*origin), *width, *height, *depth);
>+}
>+
>+auto Parser::parseAttributeBlock() -> Expected<AST::AttributeBlock, Error> {
>+    auto leftSquareBracket = consumeType(Lexer::Token::Type::LeftSquareBracket);
>+    if (!leftSquareBracket)
>+        return Unexpected<Error>(leftSquareBracket.error());
>+
>+    AST::AttributeBlock result;
>+
>+    while (true) {
>+        auto numThreadsFunctionAttribute = backtrackingScope<Expected<AST::NumThreadsFunctionAttribute, Error>>([&]() {
>+            return parseNumThreadsFunctionAttribute();
>+        });
>+        if (numThreadsFunctionAttribute) {
>+            result.append(WTFMove(*numThreadsFunctionAttribute));
>+            continue;
>+        }
>+
>+        break;
>+    }
>+
>+    auto rightSquareBracket = consumeType(Lexer::Token::Type::RightSquareBracket);
>+    if (!rightSquareBracket)
>+        return Unexpected<Error>(rightSquareBracket.error());
>+
>+    return WTFMove(result);
>+}
>+
>+auto Parser::parseParameter() -> Expected<AST::Parameter, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    AST::Qualifiers qualifiers = parseQualifiers();
>+
>+    auto type = parseType();
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    Optional<String> name;
>+    if (auto token = tryType(Lexer::Token::Type::Identifier))
>+        name = token->stringView.toString();
>+
>+    if (tryType(Lexer::Token::Type::Colon)) {
>+        auto semantic = parseSemantic();
>+        if (!semantic)
>+            return Unexpected<Error>(semantic.error());
>+        return AST::Parameter(WTFMove(*origin), WTFMove(qualifiers), WTFMove(*type), WTFMove(name), WTFMove(*semantic));
>+    }
>+
>+    return AST::Parameter(WTFMove(*origin), WTFMove(qualifiers), WTFMove(*type), WTFMove(name), WTF::nullopt);
>+}
>+
>+auto Parser::parseParameters() -> Expected<AST::Parameters, Error> {
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    AST::Parameters parameters;
>+    if (tryType(Lexer::Token::Type::RightParenthesis))
>+        return WTFMove(parameters);
>+
>+    auto firstParameter = parseParameter();
>+    if (!firstParameter)
>+        return Unexpected<Error>(firstParameter.error());
>+    parameters.append(WTFMove(*firstParameter));
>+
>+    while (tryType(Lexer::Token::Type::Comma)) {
>+        auto parameter = parseParameter();
>+        if (!parameter)
>+            return Unexpected<Error>(parameter.error());
>+        parameters.append(WTFMove(*parameter));
>+    }
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    return WTFMove(parameters);
>+}
>+
>+auto Parser::parseFunctionDefinition() -> Expected<AST::FunctionDefinition, Error> {
>+    bool restricted = static_cast<bool>(tryType(Lexer::Token::Type::Restricted));
>+
>+    auto functionDeclaration = parseFunctionDeclaration();
>+    if (!functionDeclaration)
>+        return Unexpected<Error>(functionDeclaration.error());
>+
>+    auto block = parseBlock();
>+    if (!block)
>+        return Unexpected<Error>(block.error());
>+
>+    return AST::FunctionDefinition(WTFMove(*functionDeclaration), WTFMove(*block), restricted);
>+}
>+
>+auto Parser::parseEntryPointFunctionDeclaration() -> Expected<AST::FunctionDeclaration, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    AST::AttributeBlock attributeBlock;
>+    AST::FunctionDeclaration::EntryPointType entryPointType;
>+
>+    auto parsedAttributeBlock = backtrackingScope<Expected<AST::AttributeBlock, Error>>([&]() {
>+        return parseAttributeBlock();
>+    });
>+    if (parsedAttributeBlock) {
>+        auto compute = consumeType(Lexer::Token::Type::Compute);
>+        if (!compute)
>+            return Unexpected<Error>(compute.error());
>+        attributeBlock = WTFMove(*parsedAttributeBlock);
>+        entryPointType = AST::FunctionDeclaration::EntryPointType::Compute;
>+    } else {
>+        auto type = consumeTypes({ Lexer::Token::Type::Vertex, Lexer::Token::Type::Fragment });
>+        if (!type)
>+            return Unexpected<Error>(type.error());
>+
>+        switch (origin->type) {
>+        case Lexer::Token::Type::Vertex:
>+            entryPointType = AST::FunctionDeclaration::EntryPointType::Vertex;
>+            break;
>+        case Lexer::Token::Type::Fragment:
>+            entryPointType = AST::FunctionDeclaration::EntryPointType::Fragment;
>+            break;
>+        default:
>+            ASSERT_NOT_REACHED();
>+            entryPointType = AST::FunctionDeclaration::EntryPointType::Vertex;
>+        }
>+    }
>+
>+    auto type = parseType();
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+
>+    auto parameters = parseParameters();
>+    if (!parameters)
>+        return Unexpected<Error>(parameters.error());
>+
>+    if (tryType(Lexer::Token::Type::Colon)) {
>+        auto semantic = parseSemantic();
>+        if (!semantic)
>+            return Unexpected<Error>(semantic.error());
>+        return AST::FunctionDeclaration(WTFMove(*origin), WTFMove(attributeBlock), entryPointType, WTFMove(*type), name->stringView.toString(), WTFMove(*parameters), WTFMove(*semantic));
>+    }
>+
>+    return AST::FunctionDeclaration(WTFMove(*origin), WTFMove(attributeBlock), entryPointType, WTFMove(*type), name->stringView.toString(), WTFMove(*parameters), WTF::nullopt);
>+}
>+
>+auto Parser::parseRegularFunctionDeclaration() -> Expected<AST::FunctionDeclaration, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto type = parseType();
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    auto name = consumeTypes({ Lexer::Token::Type::Identifier, Lexer::Token::Type::OperatorName });
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+
>+    auto parameters = parseParameters();
>+    if (!parameters)
>+        return Unexpected<Error>(parameters.error());
>+
>+    if (tryType(Lexer::Token::Type::Colon)) {
>+        auto semantic = parseSemantic();
>+        if (!semantic)
>+            return Unexpected<Error>(semantic.error());
>+        return AST::FunctionDeclaration(WTFMove(*origin), { }, WTF::nullopt, WTFMove(*type), name->stringView.toString(), WTFMove(*parameters), WTFMove(*semantic));
>+    }
>+
>+    return AST::FunctionDeclaration(WTFMove(*origin), { }, WTF::nullopt, WTFMove(*type), name->stringView.toString(), WTFMove(*parameters), WTF::nullopt);
>+}
>+
>+auto Parser::parseOperatorFunctionDeclaration() -> Expected<AST::FunctionDeclaration, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Operator);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto type = parseType();
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    auto parameters = parseParameters();
>+    if (!parameters)
>+        return Unexpected<Error>(parameters.error());
>+
>+    if (tryType(Lexer::Token::Type::Colon)) {
>+        auto semantic = parseSemantic();
>+        if (!semantic)
>+            return Unexpected<Error>(semantic.error());
>+        return AST::FunctionDeclaration(WTFMove(*origin), { }, WTF::nullopt, WTFMove(*type), String("Operator Cast", String::ConstructFromLiteral), WTFMove(*parameters), WTFMove(*semantic));
>+    }
>+
>+    return AST::FunctionDeclaration(WTFMove(*origin), { }, WTF::nullopt, WTFMove(*type), String("Operator Cast", String::ConstructFromLiteral), WTFMove(*parameters), WTF::nullopt);
>+}
>+
>+auto Parser::parseFunctionDeclaration() -> Expected<AST::FunctionDeclaration, Error> {
>+    auto entryPointFunctionDeclaration = backtrackingScope<Expected<AST::FunctionDeclaration, Error>>([&]() {
>+        return parseEntryPointFunctionDeclaration();
>+    });
>+    if (entryPointFunctionDeclaration)
>+        return WTFMove(*entryPointFunctionDeclaration);
>+
>+    auto regularFunctionDeclaration = backtrackingScope<Expected<AST::FunctionDeclaration, Error>>([&]() {
>+        return parseRegularFunctionDeclaration();
>+    });
>+    if (regularFunctionDeclaration)
>+        return WTFMove(*regularFunctionDeclaration);
>+
>+    auto operatorFunctionDeclaration = backtrackingScope<Expected<AST::FunctionDeclaration, Error>>([&]() {
>+        return parseOperatorFunctionDeclaration();
>+    });
>+    if (operatorFunctionDeclaration)
>+        return WTFMove(*operatorFunctionDeclaration);
>+
>+    return Unexpected<Error>(operatorFunctionDeclaration.error());
>+}
>+
>+auto Parser::parseNativeFunctionDeclaration() -> Expected<AST::NativeFunctionDeclaration, Error> {
>+    Optional<Lexer::Token> origin;
>+
>+    bool restricted = false;
>+    if (auto restrictedValue = tryType(Lexer::Token::Type::Restricted)) {
>+        origin = *restrictedValue;
>+        restricted = true;
>+    }
>+
>+    auto native = consumeType(Lexer::Token::Type::Native);
>+    if (!native)
>+        return Unexpected<Error>(native.error());
>+    if (!origin)
>+        origin = *native;
>+
>+    auto functionDeclaration = parseFunctionDeclaration();
>+    if (!functionDeclaration)
>+        return Unexpected<Error>(functionDeclaration.error());
>+
>+    auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+    if (!semicolon)
>+        return Unexpected<Error>(semicolon.error());
>+
>+    return AST::NativeFunctionDeclaration(functionDeclaration->takeOrigin(), functionDeclaration->takeAttributeBlock(), functionDeclaration->takeEntryPointType(), functionDeclaration->takeType(), functionDeclaration->takeName(), functionDeclaration->takeParameters(), functionDeclaration->takeSemantic(), restricted);
>+}
>+
>+auto Parser::parseBlock() -> Expected<AST::Block, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::LeftCurlyBracket);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto result = parseBlockBody(WTFMove(*origin));
>+
>+    auto rightCurlyBracket = consumeType(Lexer::Token::Type::RightCurlyBracket);
>+    if (!rightCurlyBracket)
>+        return Unexpected<Error>(rightCurlyBracket.error());
>+
>+    return WTFMove(result);
>+}
>+
>+AST::Block Parser::parseBlockBody(Lexer::Token&& origin)
>+{
>+    Vector<std::unique_ptr<AST::Statement>> statements;
>+    while (true) {
>+        auto statement = backtrackingScope<Expected<std::unique_ptr<AST::Statement>, Error>>([&]() {
>+            return parseStatement();
>+        });
>+        if (statement)
>+            statements.append(WTFMove(*statement));
>+        else
>+            break;
>+    }
>+    return AST::Block(WTFMove(origin), WTFMove(statements));
>+}
>+
>+auto Parser::parseIfStatement() -> Expected<AST::IfStatement, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::If);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto conditional = parseExpression();
>+    if (!conditional)
>+        return Unexpected<Error>(conditional.error());
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    auto body = parseStatement();
>+    if (!body)
>+        return Unexpected<Error>(body.error());
>+
>+    std::unique_ptr<AST::Statement> elseBody;
>+    if (tryType(Lexer::Token::Type::Else)) {
>+        auto parsedElseBody = parseStatement();
>+        if (!parsedElseBody)
>+            return Unexpected<Error>(parsedElseBody.error());
>+        elseBody = WTFMove(*parsedElseBody);
>+    }
>+
>+    return AST::IfStatement(WTFMove(*origin), WTFMove(*conditional), WTFMove(*body), WTFMove(elseBody));
>+}
>+
>+auto Parser::parseSwitchStatement() -> Expected<AST::SwitchStatement, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Switch);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto value = parseExpression();
>+    if (!value)
>+        return Unexpected<Error>(value.error());
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    auto leftCurlyBracket = consumeType(Lexer::Token::Type::LeftCurlyBracket);
>+    if (!leftCurlyBracket)
>+        return Unexpected<Error>(leftCurlyBracket.error());
>+
>+    Vector<AST::SwitchCase> switchCases;
>+    while (true) {
>+        auto switchCase = backtrackingScope<Expected<AST::SwitchCase, Error>>([&]() {
>+            return parseSwitchCase();
>+        });
>+        if (switchCase)
>+            switchCases.append(WTFMove(*switchCase));
>+        else
>+            break;
>+    }
>+
>+    auto rightCurlyBracket = consumeType(Lexer::Token::Type::RightCurlyBracket);
>+    if (!rightCurlyBracket)
>+        return Unexpected<Error>(rightCurlyBracket.error());
>+
>+    return AST::SwitchStatement(WTFMove(*origin), WTFMove(*value), WTFMove(switchCases));
>+}
>+
>+auto Parser::parseSwitchCase() -> Expected<AST::SwitchCase, Error> {
>+    auto origin = consumeTypes({ Lexer::Token::Type::Case, Lexer::Token::Type::Default });
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    switch (origin->type) {
>+    case Lexer::Token::Type::Case: {
>+        auto value = parseConstantExpression();
>+        if (!value)
>+            return Unexpected<Error>(value.error());
>+
>+        auto origin = consumeType(Lexer::Token::Type::Colon);
>+        if (!origin)
>+            return Unexpected<Error>(origin.error());
>+
>+        auto block = parseBlockBody(Lexer::Token(*origin));
>+
>+        return AST::SwitchCase(WTFMove(*origin), WTFMove(*value), WTFMove(block));
>+    }
>+    case Lexer::Token::Type::Default: {
>+        auto origin = consumeType(Lexer::Token::Type::Colon);
>+        if (!origin)
>+            return Unexpected<Error>(origin.error());
>+
>+        auto block = parseBlockBody(Lexer::Token(*origin));
>+
>+        return AST::SwitchCase(WTFMove(*origin), WTF::nullopt, WTFMove(block));
>+    }
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+    }
>+}
>+
>+auto Parser::parseForLoop() -> Expected<AST::ForLoop, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::For);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto parseRemainder = [&](Variant<AST::VariableDeclarationsStatement, std::unique_ptr<AST::Expression>>&& initialization) -> Expected<AST::ForLoop, Error> {
>+        auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+        if (!semicolon)
>+            return Unexpected<Error>(semicolon.error());
>+
>+        auto condition = backtrackingScope<std::unique_ptr<AST::Expression>>([&]() -> std::unique_ptr<AST::Expression> {
>+            if (auto expression = parseExpression())
>+                return WTFMove(*expression);
>+            return nullptr;
>+        });
>+
>+        semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+        if (!semicolon)
>+            return Unexpected<Error>(semicolon.error());
>+
>+        auto increment = backtrackingScope<std::unique_ptr<AST::Expression>>([&]() -> std::unique_ptr<AST::Expression> {
>+            if (auto expression = parseExpression())
>+                return WTFMove(*expression);
>+            return nullptr;
>+        });
>+
>+        auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+        if (!rightParenthesis)
>+            return Unexpected<Error>(rightParenthesis.error());
>+
>+        auto body = parseStatement();
>+        if (!body)
>+            return Unexpected<Error>(body.error());
>+
>+        return AST::ForLoop(WTFMove(*origin), WTFMove(initialization), WTFMove(condition), WTFMove(increment), WTFMove(*body));
>+    };
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto variableDeclarations = backtrackingScope<Expected<AST::VariableDeclarationsStatement, Error>>([&]() {
>+        return parseVariableDeclarations();
>+    });
>+    if (variableDeclarations)
>+        return parseRemainder(WTFMove(*variableDeclarations));
>+
>+    auto effectfulExpression = parseEffectfulExpression();
>+    if (!effectfulExpression)
>+        return Unexpected<Error>(effectfulExpression.error());
>+
>+    return parseRemainder(WTFMove(*effectfulExpression));
>+}
>+
>+auto Parser::parseWhileLoop() -> Expected<AST::WhileLoop, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::While);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto conditional = parseExpression();
>+    if (!conditional)
>+        return Unexpected<Error>(conditional.error());
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    auto body = parseStatement();
>+    if (!body)
>+        return Unexpected<Error>(body.error());
>+
>+    return AST::WhileLoop(WTFMove(*origin), WTFMove(*conditional), WTFMove(*body));
>+}
>+
>+auto Parser::parseDoWhileLoop() -> Expected<AST::DoWhileLoop, Error> {
>+    auto origin = consumeType(Lexer::Token::Type::Do);
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto body = parseStatement();
>+    if (!body)
>+        return Unexpected<Error>(body.error());
>+
>+    auto whileKeyword = consumeType(Lexer::Token::Type::While);
>+    if (!whileKeyword)
>+        return Unexpected<Error>(whileKeyword.error());
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    auto conditional = parseExpression();
>+    if (!conditional)
>+        return Unexpected<Error>(conditional.error());
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    return AST::DoWhileLoop(WTFMove(*origin), WTFMove(*body), WTFMove(*conditional));
>+}
>+
>+auto Parser::parseVariableDeclaration(std::unique_ptr<AST::Type>&& type) -> Expected<AST::VariableDeclaration, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto qualifiers = parseQualifiers();
>+
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+
>+    if (tryType(Lexer::Token::Type::Colon)) {
>+        auto semantic = parseSemantic();
>+        if (!semantic)
>+            return Unexpected<Error>(semantic.error());
>+
>+        if (tryType(Lexer::Token::Type::EqualsSign)) {
>+            auto initializer = parseExpression();
>+            if (!initializer)
>+                return Unexpected<Error>(initializer.error());
>+            return AST::VariableDeclaration(WTFMove(*origin), WTFMove(qualifiers), WTFMove(type), name->stringView.toString(), WTFMove(*semantic), WTFMove(*initializer));
>+        }
>+
>+        return AST::VariableDeclaration(WTFMove(*origin), WTFMove(qualifiers), WTFMove(type), name->stringView.toString(), WTFMove(*semantic), nullptr);
>+    }
>+
>+    if (tryType(Lexer::Token::Type::EqualsSign)) {
>+        auto initializer = parseExpression();
>+        if (!initializer)
>+            return Unexpected<Error>(initializer.error());
>+        return AST::VariableDeclaration(WTFMove(*origin), WTFMove(qualifiers), WTFMove(type), name->stringView.toString(), WTF::nullopt, WTFMove(*initializer));
>+    }
>+
>+    return AST::VariableDeclaration(WTFMove(*origin), WTFMove(qualifiers), WTFMove(type), name->stringView.toString(), WTF::nullopt, nullptr);
>+}
>+
>+auto Parser::parseVariableDeclarations() -> Expected<AST::VariableDeclarationsStatement, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto type = parseType();
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    auto firstVariableDeclaration = parseVariableDeclaration(std::unique_ptr<AST::Type>((*type)->clone()));
>+    if (!firstVariableDeclaration)
>+        return Unexpected<Error>(firstVariableDeclaration.error());
>+
>+    Vector<AST::VariableDeclaration> result;
>+    result.append(WTFMove(*firstVariableDeclaration));
>+
>+    while (tryType(Lexer::Token::Type::Comma)) {
>+        auto variableDeclaration = parseVariableDeclaration(std::unique_ptr<AST::Type>((*type)->clone()));
>+        if (!variableDeclaration)
>+            return Unexpected<Error>(variableDeclaration.error());
>+        result.append(WTFMove(*variableDeclaration));
>+    }
>+
>+    return AST::VariableDeclarationsStatement(WTFMove(*origin), WTFMove(result));
>+}
>+
>+auto Parser::parseStatement() -> Expected<std::unique_ptr<AST::Statement>, Error> {
>+    {
>+        auto block = backtrackingScope<Expected<AST::Block, Error>>([&]() {
>+            return parseBlock();
>+        });
>+        if (block)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::Block>(WTFMove(*block)));
>+    }
>+
>+    {
>+        auto ifStatement = backtrackingScope<Expected<AST::IfStatement, Error>>([&]() {
>+            return parseIfStatement();
>+        });
>+        if (ifStatement)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::IfStatement>(WTFMove(*ifStatement)));
>+    }
>+
>+    {
>+        auto switchStatement = backtrackingScope<Expected<AST::SwitchStatement, Error>>([&]() {
>+            return parseSwitchStatement();
>+        });
>+        if (switchStatement)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::SwitchStatement>(WTFMove(*switchStatement)));
>+    }
>+
>+    {
>+        auto forLoop = backtrackingScope<Expected<AST::ForLoop, Error>>([&]() {
>+            return parseForLoop();
>+        });
>+        if (forLoop)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::ForLoop>(WTFMove(*forLoop)));
>+    }
>+
>+    {
>+        auto whileLoop = backtrackingScope<Expected<AST::WhileLoop, Error>>([&]() {
>+            return parseWhileLoop();
>+        });
>+        if (whileLoop)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::WhileLoop>(WTFMove(*whileLoop)));
>+    }
>+
>+    {
>+        auto doWhileLoop = backtrackingScope<Expected<AST::DoWhileLoop, Error>>([&]() -> Expected<AST::DoWhileLoop, Error> {
>+            auto result = parseDoWhileLoop();
>+            if (!result)
>+                return Unexpected<Error>(result.error());
>+
>+            auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+            if (!semicolon)
>+                return Unexpected<Error>(semicolon.error());
>+
>+            return result;
>+        });
>+        if (doWhileLoop)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::DoWhileLoop>(WTFMove(*doWhileLoop)));
>+    }
>+
>+    {
>+        auto breakObject = backtrackingScope<Expected<AST::Break, Error>>([&]() -> Expected<AST::Break, Error> {
>+            auto origin = consumeType(Lexer::Token::Type::Break);
>+            if (!origin)
>+                return Unexpected<Error>(origin.error());
>+
>+            auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+            if (!semicolon)
>+                return Unexpected<Error>(semicolon.error());
>+
>+            return AST::Break(WTFMove(*origin));
>+        });
>+        if (breakObject)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::Break>(WTFMove(*breakObject)));
>+    }
>+
>+    {
>+        auto continueObject = backtrackingScope<Expected<AST::Continue, Error>>([&]() -> Expected<AST::Continue, Error> {
>+            auto origin = consumeType(Lexer::Token::Type::Continue);
>+            if (!origin)
>+                return Unexpected<Error>(origin.error());
>+
>+            auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+            if (!semicolon)
>+                return Unexpected<Error>(semicolon.error());
>+
>+            return AST::Continue(WTFMove(*origin));
>+        });
>+        if (continueObject)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::Continue>(WTFMove(*continueObject)));
>+    }
>+
>+    {
>+        auto fallthroughObject = backtrackingScope<Expected<AST::Fallthrough, Error>>([&]() -> Expected<AST::Fallthrough, Error> {
>+            auto origin = consumeType(Lexer::Token::Type::Fallthrough);
>+            if (!origin)
>+                return Unexpected<Error>(origin.error());
>+
>+            auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+            if (!semicolon)
>+                return Unexpected<Error>(semicolon.error());
>+
>+            return AST::Fallthrough(WTFMove(*origin));
>+        });
>+        if (fallthroughObject)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::Fallthrough>(WTFMove(*fallthroughObject)));
>+    }
>+
>+    {
>+        auto trapObject = backtrackingScope<Expected<AST::Trap, Error>>([&]() -> Expected<AST::Trap, Error> {
>+            auto origin = consumeType(Lexer::Token::Type::Trap);
>+            if (!origin)
>+                return Unexpected<Error>(origin.error());
>+
>+            auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+            if (!semicolon)
>+                return Unexpected<Error>(semicolon.error());
>+
>+            return AST::Trap(WTFMove(*origin));
>+        });
>+        if (trapObject)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::Trap>(WTFMove(*trapObject)));
>+    }
>+
>+    {
>+        auto returnObject = backtrackingScope<Expected<AST::Return, Error>>([&]() -> Expected<AST::Return, Error> {
>+            auto origin = consumeType(Lexer::Token::Type::Return);
>+            if (!origin)
>+                return Unexpected<Error>(origin.error());
>+
>+            if (auto semicolon = tryType(Lexer::Token::Type::Semicolon))
>+                return AST::Return(WTFMove(*origin), nullptr);
>+
>+            auto expression = parseExpression();
>+            if (!expression)
>+                return Unexpected<Error>(expression.error());
>+
>+            auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+            if (!semicolon)
>+                return Unexpected<Error>(semicolon.error());
>+
>+            return AST::Return(WTFMove(*origin), WTFMove(*expression));
>+        });
>+        if (returnObject)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::Return>(WTFMove(*returnObject)));
>+    }
>+
>+    {
>+        auto variableDeclarations = backtrackingScope<Expected<AST::VariableDeclarationsStatement, Error>>([&]() -> Expected<AST::VariableDeclarationsStatement, Error> {
>+            auto result = parseVariableDeclarations();
>+            if (!result)
>+                return Unexpected<Error>(result.error());
>+
>+            auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+            if (!semicolon)
>+                return Unexpected<Error>(semicolon.error());
>+
>+            return result;
>+        });
>+        if (variableDeclarations)
>+            return std::unique_ptr<AST::Statement>(std::make_unique<AST::VariableDeclarationsStatement>(WTFMove(*variableDeclarations)));
>+    }
>+
>+    auto effectfulExpression = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+        auto result = parseEffectfulExpression();
>+        if (!result)
>+            return Unexpected<Error>(result.error());
>+
>+        auto semicolon = consumeType(Lexer::Token::Type::Semicolon);
>+        if (!semicolon)
>+            return Unexpected<Error>(semicolon.error());
>+
>+        return result;
>+    });
>+    if (effectfulExpression)
>+        return std::unique_ptr<AST::Statement>(std::make_unique<AST::EffectfulExpressionStatement>(WTFMove(*effectfulExpression)));
>+
>+    return Unexpected<Error>(effectfulExpression.error());
>+}
>+
>+auto Parser::parseEffectfulExpression() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    Vector<std::unique_ptr<AST::Expression>> expressions;
>+
>+    auto first = backtrackingScope<std::unique_ptr<AST::Expression>>([&]() -> std::unique_ptr<AST::Expression> {
>+        auto effectfulExpression = parseEffectfulAssignment();
>+        if (!effectfulExpression)
>+            return nullptr;
>+        return WTFMove(*effectfulExpression);
>+    });
>+    if (!first)
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::CommaExpression>(WTFMove(*origin), WTFMove(expressions)));
>+
>+    expressions.append(WTFMove(first));
>+
>+    while (tryType(Lexer::Token::Type::Comma)) {
>+        auto expression = parseEffectfulAssignment();
>+        if (!expression)
>+            return Unexpected<Error>(expression.error());
>+        expressions.append(WTFMove(*expression));
>+    }
>+
>+    if (expressions.size() == 1)
>+        return WTFMove(expressions[0]);
>+    return std::unique_ptr<AST::Expression>(std::make_unique<AST::CommaExpression>(WTFMove(*origin), WTFMove(expressions)));
>+}
>+
>+auto Parser::parseEffectfulAssignment() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto assignment = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() {
>+        return parseAssignment();
>+    });
>+    if (assignment)
>+        return assignment;
>+
>+    assignment = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() {
>+        return parseEffectfulPrefix();
>+    });
>+    if (assignment)
>+        return assignment;
>+
>+    assignment = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() {
>+        return parseCallExpression();
>+    });
>+    if (assignment)
>+        return assignment;
>+
>+    return Unexpected<Error>(assignment.error());
>+}
>+
>+auto Parser::parseEffectfulPrefix() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto prefix = consumeTypes({ Lexer::Token::Type::PlusPlus, Lexer::Token::Type::MinusMinus });
>+    if (!prefix)
>+        return Unexpected<Error>(prefix.error());
>+
>+    auto previous = parsePossiblePrefix();
>+    if (!previous)
>+        return Unexpected<Error>(previous.error());
>+
>+    switch (prefix->type) {
>+    case Lexer::Token::Type::PlusPlus: {
>+        auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*prefix), WTFMove(*previous));
>+        Vector<std::unique_ptr<AST::Expression>> callArguments;
>+        callArguments.append(result->oldVariableReference());
>+        result->setNewValueExpression(std::make_unique<AST::CallExpression>(WTFMove(*prefix), String("operator++", String::ConstructFromLiteral), WTFMove(callArguments)));
>+        result->setResultExpression(result->newVariableReference());
>+        return std::unique_ptr<AST::Expression>(WTFMove(result));
>+    }
>+    case Lexer::Token::Type::MinusMinus: {
>+        auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*prefix), WTFMove(*previous));
>+        Vector<std::unique_ptr<AST::Expression>> callArguments;
>+        callArguments.append(result->oldVariableReference());
>+        result->setNewValueExpression(std::make_unique<AST::CallExpression>(WTFMove(*prefix), String("operator--", String::ConstructFromLiteral), WTFMove(callArguments)));
>+        result->setResultExpression(result->newVariableReference());
>+        return std::unique_ptr<AST::Expression>(WTFMove(result));
>+    }
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+    }
>+}
>+
>+auto Parser::parseEffectfulSuffix() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto effectfulSuffix = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+        auto previous = parsePossibleSuffix();
>+        if (!previous)
>+            return Unexpected<Error>(previous.error());
>+
>+        auto suffix = consumeTypes({ Lexer::Token::Type::PlusPlus, Lexer::Token::Type::MinusMinus });
>+        if (!suffix)
>+            return Unexpected<Error>(suffix.error());
>+
>+        switch (suffix->type) {
>+        case Lexer::Token::Type::PlusPlus: {
>+            auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*suffix), WTFMove(*previous));
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(result->oldVariableReference());
>+            result->setNewValueExpression(std::make_unique<AST::CallExpression>(WTFMove(*suffix), String("operator++", String::ConstructFromLiteral), WTFMove(callArguments)));
>+            result->setResultExpression(result->oldVariableReference());
>+            return std::unique_ptr<AST::Expression>(WTFMove(result));
>+        }
>+        case Lexer::Token::Type::MinusMinus: {
>+            auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*suffix), WTFMove(*previous));
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(result->oldVariableReference());
>+            result->setNewValueExpression(std::make_unique<AST::CallExpression>(WTFMove(*suffix), String("operator--", String::ConstructFromLiteral), WTFMove(callArguments)));
>+            result->setResultExpression(result->oldVariableReference());
>+            return std::unique_ptr<AST::Expression>(WTFMove(result));
>+        }
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+        }
>+    });
>+    if (effectfulSuffix)
>+        return effectfulSuffix;
>+
>+    effectfulSuffix = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() {
>+        return parseCallExpression();
>+    });
>+    if (effectfulSuffix)
>+        return effectfulSuffix;
>+
>+    effectfulSuffix = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+        auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+        if (!leftParenthesis)
>+            return Unexpected<Error>(leftParenthesis.error());
>+
>+        auto expression = parseExpression();
>+        if (!expression)
>+            return Unexpected<Error>(expression.error());
>+
>+        auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+        if (!rightParenthesis)
>+            return Unexpected<Error>(rightParenthesis.error());
>+
>+        return std::unique_ptr<AST::Expression>(WTFMove(*expression));
>+    });
>+    if (effectfulSuffix)
>+        return effectfulSuffix;
>+
>+    return Unexpected<Error>(effectfulSuffix.error());
>+}
>+
>+auto Parser::parseLimitedSuffixOperator(std::unique_ptr<AST::Expression>&& previous) -> SuffixExpression
>+{
>+    auto type = consumeTypes({ Lexer::Token::Type::FullStop, Lexer::Token::Type::Arrow, Lexer::Token::Type::LeftSquareBracket });
>+    if (!type)
>+        return SuffixExpression(WTFMove(previous), false);
>+
>+    switch (type->type) {
>+    case Lexer::Token::Type::FullStop: {
>+        auto identifier = consumeType(Lexer::Token::Type::Identifier);
>+        if (!identifier)
>+            return SuffixExpression(WTFMove(previous), false);
>+        return SuffixExpression(std::make_unique<AST::DotExpression>(WTFMove(*type), WTFMove(previous), identifier->stringView.toString()), true);
>+    }
>+    case Lexer::Token::Type::Arrow: {
>+        auto identifier = consumeType(Lexer::Token::Type::Identifier);
>+        if (!identifier)
>+            return SuffixExpression(WTFMove(previous), false);
>+        return SuffixExpression(std::make_unique<AST::DotExpression>(Lexer::Token(*type), std::make_unique<AST::DereferenceExpression>(WTFMove(*type), WTFMove(previous)), identifier->stringView.toString()), true);
>+    }
>+    case Lexer::Token::Type::LeftSquareBracket: {
>+        auto expression = parseExpression();
>+        if (!expression)
>+            return SuffixExpression(WTFMove(previous), false);
>+        if (!consumeType(Lexer::Token::Type::RightSquareBracket))
>+            return SuffixExpression(WTFMove(previous), false);
>+        return SuffixExpression(std::make_unique<AST::IndexExpression>(WTFMove(*type), WTFMove(previous), WTFMove(*expression)), true);
>+    }
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return SuffixExpression(WTFMove(previous), false);
>+    }
>+}
>+
>+auto Parser::parseSuffixOperator(std::unique_ptr<AST::Expression>&& previous) -> SuffixExpression
>+{
>+    auto suffix = consumeTypes({ Lexer::Token::Type::FullStop, Lexer::Token::Type::Arrow, Lexer::Token::Type::LeftSquareBracket, Lexer::Token::Type::PlusPlus, Lexer::Token::Type::MinusMinus });
>+    if (!suffix)
>+        return SuffixExpression(WTFMove(previous), false);
>+
>+    switch (suffix->type) {
>+    case Lexer::Token::Type::FullStop: {
>+        auto identifier = consumeType(Lexer::Token::Type::Identifier);
>+        if (!identifier)
>+            return SuffixExpression(WTFMove(previous), false);
>+        return SuffixExpression(std::make_unique<AST::DotExpression>(WTFMove(*suffix), WTFMove(previous), identifier->stringView.toString()), true);
>+    }
>+    case Lexer::Token::Type::Arrow: {
>+        auto identifier = consumeType(Lexer::Token::Type::Identifier);
>+        if (!identifier)
>+            return SuffixExpression(WTFMove(previous), false);
>+        return SuffixExpression(std::make_unique<AST::DotExpression>(Lexer::Token(*suffix), std::make_unique<AST::DereferenceExpression>(WTFMove(*suffix), WTFMove(previous)), identifier->stringView.toString()), true);
>+    }
>+    case Lexer::Token::Type::LeftSquareBracket: {
>+        auto expression = parseExpression();
>+        if (!expression)
>+            return SuffixExpression(WTFMove(previous), false);
>+        if (!consumeType(Lexer::Token::Type::RightSquareBracket))
>+            return SuffixExpression(WTFMove(previous), false);
>+        return SuffixExpression(std::make_unique<AST::IndexExpression>(WTFMove(*suffix), WTFMove(previous), WTFMove(*expression)), true);
>+    }
>+    case Lexer::Token::Type::PlusPlus: {
>+        auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*suffix), WTFMove(previous));
>+        Vector<std::unique_ptr<AST::Expression>> callArguments;
>+        callArguments.append(result->oldVariableReference());
>+        result->setNewValueExpression(std::make_unique<AST::CallExpression>(WTFMove(*suffix), String("operator++", String::ConstructFromLiteral), WTFMove(callArguments)));
>+        result->setResultExpression(result->oldVariableReference());
>+        return SuffixExpression(WTFMove(result), true);
>+    }
>+    case Lexer::Token::Type::MinusMinus: {
>+        auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*suffix), WTFMove(previous));
>+        Vector<std::unique_ptr<AST::Expression>> callArguments;
>+        callArguments.append(result->oldVariableReference());
>+        result->setNewValueExpression(std::make_unique<AST::CallExpression>(WTFMove(*suffix), String("operator--", String::ConstructFromLiteral), WTFMove(callArguments)));
>+        result->setResultExpression(result->oldVariableReference());
>+        return SuffixExpression(WTFMove(result), true);
>+    }
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return SuffixExpression(WTFMove(previous), false);
>+    }
>+}
>+
>+auto Parser::parseExpression() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto first = parsePossibleTernaryConditional();
>+    if (!first)
>+        return Unexpected<Error>(first.error());
>+
>+    Vector<std::unique_ptr<AST::Expression>> expressions;
>+    expressions.append(WTFMove(*first));
>+
>+    while (tryType(Lexer::Token::Type::Comma)) {
>+        auto expression = parsePossibleTernaryConditional();
>+        if (!expression)
>+            return Unexpected<Error>(expression.error());
>+        expressions.append(WTFMove(*expression));
>+    }
>+
>+    if (expressions.size() == 1)
>+        return WTFMove(expressions[0]);
>+    return std::unique_ptr<AST::Expression>(std::make_unique<AST::CommaExpression>(WTFMove(*origin), WTFMove(expressions)));
>+}
>+
>+auto Parser::parseTernaryConditional() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto predicate = parsePossibleLogicalBinaryOperation();
>+    if (!predicate)
>+        return Unexpected<Error>(predicate.error());
>+
>+    auto questionMark = consumeType(Lexer::Token::Type::QuestionMark);
>+    if (!questionMark)
>+        return Unexpected<Error>(questionMark.error());
>+
>+    auto bodyExpression = parseExpression();
>+    if (!bodyExpression)
>+        return Unexpected<Error>(bodyExpression.error());
>+
>+    auto colon = consumeType(Lexer::Token::Type::Colon);
>+    if (!colon)
>+        return Unexpected<Error>(colon.error());
>+
>+    auto elseExpression = parsePossibleTernaryConditional();
>+    if (!elseExpression)
>+        return Unexpected<Error>(elseExpression.error());
>+
>+    // FIXME: Cast the predicate to a bool.
>+    return std::unique_ptr<AST::Expression>(std::make_unique<AST::TernaryExpression>(WTFMove(*origin), WTFMove(*predicate), WTFMove(*bodyExpression), WTFMove(*elseExpression)));
>+}
>+
>+auto Parser::parseAssignment() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto origin = peek();
>+    if (!origin)
>+        return Unexpected<Error>(origin.error());
>+
>+    auto left = parsePossiblePrefix();
>+    if (!left)
>+        return Unexpected<Error>(left.error());
>+
>+    auto assignmentOperator = consumeTypes({
>+        Lexer::Token::Type::EqualsSign,
>+        Lexer::Token::Type::PlusEquals,
>+        Lexer::Token::Type::MinusEquals,
>+        Lexer::Token::Type::TimesEquals,
>+        Lexer::Token::Type::DivideEquals,
>+        Lexer::Token::Type::ModEquals,
>+        Lexer::Token::Type::XorEquals,
>+        Lexer::Token::Type::AndEquals,
>+        Lexer::Token::Type::OrEquals,
>+        Lexer::Token::Type::RightShiftEquals,
>+        Lexer::Token::Type::LeftShiftEquals
>+    });
>+    if (!assignmentOperator)
>+        return Unexpected<Error>(assignmentOperator.error());
>+
>+    auto right = parsePossibleTernaryConditional();
>+    if (!right)
>+        return Unexpected<Error>(right.error());
>+
>+    if (assignmentOperator->type == Lexer::Token::Type::EqualsSign)
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::AssignmentExpression>(WTFMove(*origin), WTFMove(*left), WTFMove(*right)));
>+
>+    String name;
>+    switch (assignmentOperator->type) {
>+    case Lexer::Token::Type::PlusEquals:
>+        name = String("operator+", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::MinusEquals:
>+        name = String("operator-", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::TimesEquals:
>+        name = String("operator*", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::DivideEquals:
>+        name = String("operator/", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::ModEquals:
>+        name = String("operator%", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::XorEquals:
>+        name = String("operator^", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::AndEquals:
>+        name = String("operator&", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::OrEquals:
>+        name = String("operator|", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::RightShiftEquals:
>+        name = String("operator>>", String::ConstructFromLiteral);
>+        break;
>+    case Lexer::Token::Type::LeftShiftEquals:
>+        name = String("operator<<", String::ConstructFromLiteral);
>+        break;
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+    }
>+
>+    auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*origin), WTFMove(*left));
>+    Vector<std::unique_ptr<AST::Expression>> callArguments;
>+    callArguments.append(result->oldVariableReference());
>+    callArguments.append(WTFMove(*right));
>+    result->setNewValueExpression(std::make_unique<AST::CallExpression>(WTFMove(*origin), WTFMove(name), WTFMove(callArguments)));
>+    result->setResultExpression(result->newVariableReference());
>+    return std::unique_ptr<AST::Expression>(WTFMove(result));
>+}
>+
>+auto Parser::parsePossibleTernaryConditional() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto ternaryExpression = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() {
>+        return parseTernaryConditional();
>+    });
>+    if (ternaryExpression)
>+        return ternaryExpression;
>+
>+    auto assignmentExpression = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() {
>+        return parseAssignment();
>+    });
>+    if (assignmentExpression)
>+        return assignmentExpression;
>+
>+    auto binaryOperation = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() {
>+        return parsePossibleLogicalBinaryOperation();
>+    });
>+    if (binaryOperation)
>+        return binaryOperation;
>+
>+    return Unexpected<Error>(binaryOperation.error());
>+}
>+
>+auto Parser::parsePossibleLogicalBinaryOperation() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    std::unique_ptr<AST::Expression> previous;
>+    auto parsedPrevious = parsePossibleRelationalBinaryOperation();
>+    if (!parsedPrevious)
>+        return Unexpected<Error>(parsedPrevious.error());
>+    previous = WTFMove(*parsedPrevious);
>+
>+    while (auto logicalBinaryOperation = tryTypes({
>+        Lexer::Token::Type::OrOr,
>+        Lexer::Token::Type::AndAnd,
>+        Lexer::Token::Type::Or,
>+        Lexer::Token::Type::Xor,
>+        Lexer::Token::Type::And
>+        })) {
>+        auto next = parsePossibleRelationalBinaryOperation();
>+        if (!next)
>+            return Unexpected<Error>(next.error());
>+
>+        switch (logicalBinaryOperation->type) {
>+        case Lexer::Token::Type::OrOr:
>+            previous = std::make_unique<AST::LogicalExpression>(WTFMove(*logicalBinaryOperation), AST::LogicalExpression::Type::Or, WTFMove(previous), WTFMove(*next));
>+            break;
>+        case Lexer::Token::Type::AndAnd:
>+            previous = std::make_unique<AST::LogicalExpression>(WTFMove(*logicalBinaryOperation), AST::LogicalExpression::Type::And, WTFMove(previous), WTFMove(*next));
>+            break;
>+        case Lexer::Token::Type::Or: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*logicalBinaryOperation), String("operator|", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::Xor: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*logicalBinaryOperation), String("operator^", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::And: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*logicalBinaryOperation), String("operator&", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+        }
>+    }
>+
>+    return WTFMove(previous);
>+}
>+
>+auto Parser::parsePossibleRelationalBinaryOperation() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    std::unique_ptr<AST::Expression> previous;
>+    auto parsedPrevious = parsePossibleShift();
>+    if (!parsedPrevious)
>+        return Unexpected<Error>(parsedPrevious.error());
>+    previous = WTFMove(*parsedPrevious);
>+
>+    while (auto relationalBinaryOperation = tryTypes({
>+        Lexer::Token::Type::LessThanSign,
>+        Lexer::Token::Type::GreaterThanSign,
>+        Lexer::Token::Type::LessThanOrEqualTo,
>+        Lexer::Token::Type::GreaterThanOrEqualTo,
>+        Lexer::Token::Type::EqualComparison,
>+        Lexer::Token::Type::NotEqual
>+        })) {
>+        auto next = parsePossibleShift();
>+        if (!next)
>+            return Unexpected<Error>(next.error());
>+
>+        switch (relationalBinaryOperation->type) {
>+        case Lexer::Token::Type::LessThanSign: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*relationalBinaryOperation), String("operator<", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::GreaterThanSign: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*relationalBinaryOperation), String("operator>", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::LessThanOrEqualTo: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*relationalBinaryOperation), String("operator<=", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::GreaterThanOrEqualTo: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*relationalBinaryOperation), String("operator>=", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::EqualComparison: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*relationalBinaryOperation), String("operator==", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::NotEqual: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(Lexer::Token(*relationalBinaryOperation), String("operator==", String::ConstructFromLiteral), WTFMove(callArguments));
>+            // FIXME: Cast the argument to a bool
>+            previous = std::make_unique<AST::LogicalNotExpression>(WTFMove(*relationalBinaryOperation), WTFMove(previous));
>+            break;
>+        }
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+        }
>+    }
>+
>+    return WTFMove(previous);
>+}
>+
>+auto Parser::parsePossibleShift() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    std::unique_ptr<AST::Expression> previous;
>+    auto parsedPrevious = parsePossibleAdd();
>+    if (!parsedPrevious)
>+        return Unexpected<Error>(parsedPrevious.error());
>+    previous = WTFMove(*parsedPrevious);
>+
>+    while (auto shift = tryTypes({
>+        Lexer::Token::Type::LeftShift,
>+        Lexer::Token::Type::RightShift
>+        })) {
>+        auto next = parsePossibleAdd();
>+        if (!next)
>+            return Unexpected<Error>(next.error());
>+
>+        switch (shift->type) {
>+        case Lexer::Token::Type::LeftShift: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*shift), String("operator<<", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::RightShift: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*shift), String("operator>>", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+        }
>+    }
>+
>+    return WTFMove(previous);
>+}
>+
>+auto Parser::parsePossibleAdd() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    std::unique_ptr<AST::Expression> previous;
>+    auto parsedPrevious = parsePossibleMultiply();
>+    if (!parsedPrevious)
>+        return Unexpected<Error>(parsedPrevious.error());
>+    previous = WTFMove(*parsedPrevious);
>+
>+    while (auto add = tryTypes({
>+        Lexer::Token::Type::Plus,
>+        Lexer::Token::Type::Minus
>+        })) {
>+        auto next = parsePossibleMultiply();
>+        if (!next)
>+            return Unexpected<Error>(next.error());
>+
>+        switch (add->type) {
>+        case Lexer::Token::Type::Plus: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*add), String("operator+", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::Minus: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*add), String("operator-", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+        }
>+    }
>+
>+    return WTFMove(previous);
>+}
>+
>+auto Parser::parsePossibleMultiply() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    std::unique_ptr<AST::Expression> previous;
>+    auto parsedPrevious = parsePossiblePrefix();
>+    if (!parsedPrevious)
>+        return Unexpected<Error>(parsedPrevious.error());
>+    previous = WTFMove(*parsedPrevious);
>+
>+    while (auto multiply = tryTypes({
>+        Lexer::Token::Type::Star,
>+        Lexer::Token::Type::Divide,
>+        Lexer::Token::Type::Mod
>+        })) {
>+        auto next = parsePossiblePrefix();
>+        if (!next)
>+            return Unexpected<Error>(next.error());
>+
>+        switch (multiply->type) {
>+        case Lexer::Token::Type::Star: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*multiply), String("operator*", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::Divide: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*multiply), String("operator/", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        case Lexer::Token::Type::Mod: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(previous));
>+            callArguments.append(WTFMove(*next));
>+            previous = std::make_unique<AST::CallExpression>(WTFMove(*multiply), String("operator%", String::ConstructFromLiteral), WTFMove(callArguments));
>+            break;
>+        }
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+        }
>+    }
>+
>+    return WTFMove(previous);
>+}
>+
>+auto Parser::parsePossiblePrefix() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    if (auto prefix = tryTypes({
>+        Lexer::Token::Type::PlusPlus,
>+        Lexer::Token::Type::MinusMinus,
>+        Lexer::Token::Type::Plus,
>+        Lexer::Token::Type::Minus,
>+        Lexer::Token::Type::Tilde,
>+        Lexer::Token::Type::ExclamationPoint,
>+        Lexer::Token::Type::And,
>+        Lexer::Token::Type::At,
>+        Lexer::Token::Type::Star
>+    })) {
>+        auto next = parsePossiblePrefix();
>+        if (!next)
>+            return Unexpected<Error>(next.error());
>+
>+        switch (prefix->type) {
>+        case Lexer::Token::Type::PlusPlus: {
>+            auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*prefix), WTFMove(*next));
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(result->oldVariableReference());
>+            result->setNewValueExpression(std::make_unique<AST::CallExpression>(Lexer::Token(*prefix), String("operator++", String::ConstructFromLiteral), WTFMove(callArguments)));
>+            result->setResultExpression(result->newVariableReference());
>+            return std::unique_ptr<AST::Expression>(WTFMove(result));
>+        }
>+        case Lexer::Token::Type::MinusMinus: {
>+            auto result = std::make_unique<AST::ReadModifyWriteExpression>(Lexer::Token(*prefix), WTFMove(*next));
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(result->oldVariableReference());
>+            result->setNewValueExpression(std::make_unique<AST::CallExpression>(Lexer::Token(*prefix), String("operator--", String::ConstructFromLiteral), WTFMove(callArguments)));
>+            result->setResultExpression(result->newVariableReference());
>+            return std::unique_ptr<AST::Expression>(WTFMove(result));
>+        }
>+        case Lexer::Token::Type::Plus: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(*next));
>+            return std::unique_ptr<AST::Expression>(std::make_unique<AST::CallExpression>(Lexer::Token(*prefix), String("operator+", String::ConstructFromLiteral), WTFMove(callArguments)));
>+        }
>+        case Lexer::Token::Type::Minus: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(*next));
>+            return std::unique_ptr<AST::Expression>(std::make_unique<AST::CallExpression>(Lexer::Token(*prefix), String("operator-", String::ConstructFromLiteral), WTFMove(callArguments)));
>+        }
>+        case Lexer::Token::Type::Tilde: {
>+            Vector<std::unique_ptr<AST::Expression>> callArguments;
>+            callArguments.append(WTFMove(*next));
>+            return std::unique_ptr<AST::Expression>(std::make_unique<AST::CallExpression>(Lexer::Token(*prefix), String("operator~", String::ConstructFromLiteral), WTFMove(callArguments)));
>+        }
>+        case Lexer::Token::Type::ExclamationPoint:
>+            return std::unique_ptr<AST::Expression>(std::make_unique<AST::LogicalNotExpression>(Lexer::Token(*prefix), WTFMove(*next)));
>+        case Lexer::Token::Type::And:
>+            return std::unique_ptr<AST::Expression>(std::make_unique<AST::MakePointerExpression>(Lexer::Token(*prefix), WTFMove(*next)));
>+        case Lexer::Token::Type::At:
>+            return std::unique_ptr<AST::Expression>(std::make_unique<AST::MakeArrayReferenceExpression>(Lexer::Token(*prefix), WTFMove(*next)));
>+        case Lexer::Token::Type::Star:
>+            return std::unique_ptr<AST::Expression>(std::make_unique<AST::DereferenceExpression>(Lexer::Token(*prefix), WTFMove(*next)));
>+        default:
>+            ASSERT_NOT_REACHED();
>+            return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+        }
>+    }
>+
>+    return parsePossibleSuffix();
>+}
>+
>+auto Parser::parsePossibleSuffix() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto suffix = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+        auto expression = parseCallExpression();
>+        if (!expression)
>+            return Unexpected<Error>(expression.error());
>+
>+        while (true) {
>+            auto result = backtrackingScope<SuffixExpression>([&]() -> SuffixExpression {
>+                return parseLimitedSuffixOperator(WTFMove(*expression));
>+            });
>+            expression = WTFMove(result.result);
>+            if (!result)
>+                break;
>+        }
>+        return expression;
>+    });
>+    if (suffix)
>+        return suffix;
>+
>+    suffix = backtrackingScope<Expected<std::unique_ptr<AST::Expression>, Error>>([&]() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+        auto expression = parseTerm();
>+        if (!expression)
>+            return Unexpected<Error>(expression.error());
>+
>+        while (true) {
>+            auto result = backtrackingScope<SuffixExpression>([&]() -> SuffixExpression {
>+                return parseSuffixOperator(WTFMove(*expression));
>+            });
>+            expression = WTFMove(result.result);
>+            if (!result)
>+                break;
>+        }
>+        return expression;
>+    });
>+    if (suffix)
>+        return suffix;
>+
>+    return Unexpected<Error>(suffix.error());
>+}
>+
>+auto Parser::parseCallExpression() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto name = consumeType(Lexer::Token::Type::Identifier);
>+    if (!name)
>+        return Unexpected<Error>(name.error());
>+    auto callName = name->stringView.toString();
>+
>+    auto leftParenthesis = consumeType(Lexer::Token::Type::LeftParenthesis);
>+    if (!leftParenthesis)
>+        return Unexpected<Error>(leftParenthesis.error());
>+
>+    Vector<std::unique_ptr<AST::Expression>> arguments;
>+    if (tryType(Lexer::Token::Type::RightParenthesis))
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::CallExpression>(WTFMove(*name), WTFMove(callName), WTFMove(arguments)));
>+
>+    auto firstArgument = parsePossibleTernaryConditional();
>+    if (!firstArgument)
>+        return Unexpected<Error>(firstArgument.error());
>+    arguments.append(WTFMove(*firstArgument));
>+    while (tryType(Lexer::Token::Type::Comma)) {
>+        auto argument = parsePossibleTernaryConditional();
>+        if (!argument)
>+            return Unexpected<Error>(argument.error());
>+        arguments.append(WTFMove(*argument));
>+    }
>+
>+    auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+    if (!rightParenthesis)
>+        return Unexpected<Error>(rightParenthesis.error());
>+
>+    return std::unique_ptr<AST::Expression>(std::make_unique<AST::CallExpression>(WTFMove(*name), WTFMove(callName), WTFMove(arguments)));
>+}
>+
>+auto Parser::parseTerm() -> Expected<std::unique_ptr<AST::Expression>, Error> {
>+    auto type = consumeTypes({
>+        Lexer::Token::Type::IntLiteral,
>+        Lexer::Token::Type::UintLiteral,
>+        Lexer::Token::Type::FloatLiteral,
>+        Lexer::Token::Type::Null,
>+        Lexer::Token::Type::True,
>+        Lexer::Token::Type::False,
>+        Lexer::Token::Type::Identifier,
>+        Lexer::Token::Type::LeftParenthesis
>+    });
>+    if (!type)
>+        return Unexpected<Error>(type.error());
>+
>+    switch (type->type) {
>+    case Lexer::Token::Type::IntLiteral: {
>+        auto value = intLiteralToInt(type->stringView);
>+        if (!value)
>+            return Unexpected<Error>(value.error());
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::IntegerLiteral>(WTFMove(*type), *value));
>+    }
>+    case Lexer::Token::Type::UintLiteral: {
>+        auto value = uintLiteralToUint(type->stringView);
>+        if (!value)
>+            return Unexpected<Error>(value.error());
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::UnsignedIntegerLiteral>(WTFMove(*type), *value));
>+    }
>+    case Lexer::Token::Type::FloatLiteral: {
>+        auto value = floatLiteralToFloat(type->stringView);
>+        if (!value)
>+            return Unexpected<Error>(value.error());
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::FloatLiteral>(WTFMove(*type), *value));
>+    }
>+    case Lexer::Token::Type::Null:
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::NullLiteral>(WTFMove(*type)));
>+    case Lexer::Token::Type::True:
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::BooleanLiteral>(WTFMove(*type), true));
>+    case Lexer::Token::Type::False:
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::BooleanLiteral>(WTFMove(*type), false));
>+    case Lexer::Token::Type::Identifier: {
>+        auto name = type->stringView.toString();
>+        return std::unique_ptr<AST::Expression>(std::make_unique<AST::VariableReference>(WTFMove(*type), WTFMove(name)));
>+    }
>+    case Lexer::Token::Type::LeftParenthesis: {
>+        auto expression = parseExpression();
>+        if (!expression)
>+            return Unexpected<Error>(expression.error());
>+
>+        auto rightParenthesis = consumeType(Lexer::Token::Type::RightParenthesis);
>+        if (!rightParenthesis)
>+            return Unexpected<Error>(rightParenthesis.error());
>+
>+        return std::unique_ptr<AST::Expression>(WTFMove(*expression));
>+    }
>+    default:
>+        ASSERT_NOT_REACHED();
>+        return Unexpected<Error>(Error(String("Something really bad happened", String::ConstructFromLiteral)));
>+    }
>+}
>+
> }
> 
> }
>diff --git a/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.h b/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.h
>index 5c57a99a9f6..da3e06b01e4 100644
>--- a/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.h
>+++ b/Source/WebCore/Modules/webgpu/WHLSL/WHLSLParser.h
>@@ -105,7 +105,131 @@ namespace WebCore {
> namespace WHLSL {
> 
> class Parser {
>+public:
>+    enum class Mode {
>+        StandardLibrary,
>+        User
>+    };
> 
>+    struct Error {
>+        Error(String&& error)
>+            : error(WTFMove(error))
>+        {
>+        }
>+
>+        String error;
>+    };
>+
>+    Parser();
>+
>+    Optional<Error> parse(Program&, StringView, Mode);
>+
>+private:
>+    template<typename T> T backtrackingScope(std::function<T()> callback)
>+    {
>+        auto state = m_lexer.state();
>+        auto result = callback();
>+        if (result)
>+            return result;
>+        m_lexer.setState(WTFMove(state));
>+        return result;
>+    }
>+
>+    Unexpected<Error> fail(const String& message);
>+    Expected<Lexer::Token, Error> peek();
>+    Optional<Lexer::Token> tryType(Lexer::Token::Type);
>+    Optional<Lexer::Token> tryTypes(Vector<Lexer::Token::Type>);
>+    Expected<Lexer::Token, Error> consumeType(Lexer::Token::Type);
>+    Expected<Lexer::Token, Error> consumeTypes(Vector<Lexer::Token::Type>);
>+
>+    Expected<Variant<int, unsigned>, Error> consumeIntegralLiteral();
>+    Expected<unsigned, Error> consumeNonNegativeIntegralLiteral();
>+    Expected<AST::ConstantExpression, Error> parseConstantExpression();
>+    Expected<AST::TypeArgument, Error> parseTypeArgument();
>+    Expected<AST::TypeArguments, Error> parseTypeArguments();
>+    struct TypeSuffixAbbreviated {
>+        Lexer::Token token;
>+        Optional<unsigned> numElements;
>+    };
>+    Expected<TypeSuffixAbbreviated, Error> parseTypeSuffixAbbreviated();
>+    struct TypeSuffixNonAbbreviated {
>+        Lexer::Token token;
>+        Optional<Lexer::Token> addressSpace;
>+        Optional<unsigned> numElements;
>+    };
>+    Expected<TypeSuffixNonAbbreviated, Error> parseTypeSuffixNonAbbreviated();
>+    Expected<std::unique_ptr<AST::Type>, Error> parseAddressSpaceType();
>+    Expected<std::unique_ptr<AST::Type>, Error> parseNonAddressSpaceType();
>+    Expected<std::unique_ptr<AST::Type>, Error> parseType();
>+    Expected<AST::TypeDefinition, Error> parseTypeDefinition();
>+    Expected<AST::BuiltInSemantic, Error> parseBuiltInSemantic();
>+    Expected<AST::ResourceSemantic, Error> parseResourceSemantic();
>+    Expected<AST::SpecializationConstantSemantic, Error> parseSpecializationConstantSemantic();
>+    Expected<AST::StageInOutSemantic, Error> parseStageInOutSemantic();
>+    Expected<AST::Semantic, Error> parseSemantic();
>+    AST::Qualifiers parseQualifiers();
>+    Expected<AST::StructureElement, Error> parseStructureElement();
>+    Expected<AST::StructureDefinition, Error> parseStructureDefinition();
>+    Expected<AST::EnumerationDefinition, Error> parseEnumerationDefinition();
>+    Expected<AST::EnumerationMember, Error> parseEnumerationMember();
>+    Expected<AST::NativeTypeDeclaration, Error> parseNativeTypeDeclaration();
>+    Expected<AST::NumThreadsFunctionAttribute, Error> parseNumThreadsFunctionAttribute();
>+    Expected<AST::AttributeBlock, Error> parseAttributeBlock();
>+    Expected<AST::Parameter, Error> parseParameter();
>+    Expected<AST::Parameters, Error> parseParameters();
>+    Expected<AST::FunctionDeclaration, Error> parseEntryPointFunctionDeclaration();
>+    Expected<AST::FunctionDeclaration, Error> parseRegularFunctionDeclaration();
>+    Expected<AST::FunctionDeclaration, Error> parseOperatorFunctionDeclaration();
>+    Expected<AST::FunctionDeclaration, Error> parseFunctionDeclaration();
>+    Expected<AST::FunctionDefinition, Error> parseFunctionDefinition();
>+    Expected<AST::NativeFunctionDeclaration, Error> parseNativeFunctionDeclaration();
>+
>+    Expected<AST::Block, Error> parseBlock();
>+    AST::Block parseBlockBody(Lexer::Token&& origin);
>+    Expected<AST::IfStatement, Error> parseIfStatement();
>+    Expected<AST::SwitchStatement, Error> parseSwitchStatement();
>+    Expected<AST::SwitchCase, Error> parseSwitchCase();
>+    Expected<AST::ForLoop, Error> parseForLoop();
>+    Expected<AST::WhileLoop, Error> parseWhileLoop();
>+    Expected<AST::DoWhileLoop, Error> parseDoWhileLoop();
>+    Expected<AST::VariableDeclaration, Error> parseVariableDeclaration(std::unique_ptr<AST::Type>&&);
>+    Expected<AST::VariableDeclarationsStatement, Error> parseVariableDeclarations();
>+    Expected<std::unique_ptr<AST::Statement>, Error> parseStatement();
>+
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseEffectfulExpression();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseEffectfulAssignment();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseEffectfulPrefix();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseEffectfulSuffix();
>+    struct SuffixExpression {
>+        SuffixExpression(std::unique_ptr<AST::Expression>&& result, bool success)
>+            : result(WTFMove(result))
>+            , success(success)
>+        {
>+        }
>+
>+        std::unique_ptr<AST::Expression> result;
>+        bool success;
>+        operator bool() const { return success; }
>+    };
>+    SuffixExpression parseLimitedSuffixOperator(std::unique_ptr<AST::Expression>&&);
>+    SuffixExpression parseSuffixOperator(std::unique_ptr<AST::Expression>&&);
>+
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseExpression();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseTernaryConditional();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseAssignment();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossibleTernaryConditional();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossibleLogicalBinaryOperation();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossibleRelationalBinaryOperation();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossibleShift();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossibleAdd();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossibleMultiply();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossiblePrefix();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parsePossibleSuffix();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseCallExpression();
>+    Expected<std::unique_ptr<AST::Expression>, Error> parseTerm();
>+
>+    Lexer m_lexer;
>+    Mode m_mode;
> };
> 
> }

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Attachments on bug 192355: 356468 | 356569 | 356570 | 356585 | 356695 | 356778 | 356863 | 356947 | 357031 | 357035 | 357038 | 357081 | 357103 | 357199 | 357207 | 357225 | 357245 | 357268 | 357277 | 357303 | 357304 | 357361 | 357410 | 357430 | 357458 | 357520 | 357602 | 357749 | 357754 | 357765 | 357869 | 357889 | 357929 | 357932 | 357975 | 358866 | 358880 | 358902 | 359250