From af8aefd4679c035e6bd195c2b458739c125f6733 Mon Sep 17 00:00:00 2001 From: Anders Hejlsberg Date: Sat, 23 May 2015 11:41:31 -0700 Subject: [PATCH] Single function to parse statements and module elements --- src/compiler/parser.ts | 439 +++++++++++++++++------------------------ src/compiler/types.ts | 6 + 2 files changed, 185 insertions(+), 260 deletions(-) diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts index af9b486a1da..783c1594297 100644 --- a/src/compiler/parser.ts +++ b/src/compiler/parser.ts @@ -1001,10 +1001,10 @@ module ts { switch (parsingContext) { case ParsingContext.SourceElements: case ParsingContext.ModuleElements: - return isSourceElement(inErrorRecovery); + return !(token === SyntaxKind.SemicolonToken && inErrorRecovery) && isModuleElement(); case ParsingContext.BlockStatements: case ParsingContext.SwitchClauseStatements: - return isStartOfStatement(inErrorRecovery); + return !(token === SyntaxKind.SemicolonToken && inErrorRecovery) && isStatement(); case ParsingContext.SwitchClauses: return token === SyntaxKind.CaseKeyword || token === SyntaxKind.DefaultKeyword; case ParsingContext.TypeMembers: @@ -2086,7 +2086,7 @@ module ts { case SyntaxKind.OpenBracketToken: // Indexer or computed property return isIndexSignature() - ? parseIndexSignatureDeclaration(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers:*/ undefined) + ? parseIndexSignatureDeclaration(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers*/ undefined) : parsePropertyOrMethodSignature(); case SyntaxKind.NewKeyword: if (lookAhead(isStartOfConstructSignature)) { @@ -2539,12 +2539,6 @@ module ts { return !scanner.hasPrecedingLineBreak() && isIdentifier() } - function nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine() { - nextToken(); - return !scanner.hasPrecedingLineBreak() && - (isIdentifier() || token === SyntaxKind.OpenBraceToken || token === SyntaxKind.OpenBracketToken); - } - function parseYieldExpression(): YieldExpression { let node = createNode(SyntaxKind.YieldExpression); @@ -2745,14 +2739,14 @@ module ts { function parseArrowFunctionExpressionBody(): Block | Expression { if (token === SyntaxKind.OpenBraceToken) { - return parseFunctionBlock(/*allowYield:*/ false, /* ignoreMissingOpenBrace */ false); + return parseFunctionBlock(/*allowYield*/ false, /*ignoreMissingOpenBrace*/ false); } - if (isStartOfStatement(/*inErrorRecovery:*/ true) && - !isStartOfExpressionStatement() && + if (token !== SyntaxKind.SemicolonToken && token !== SyntaxKind.FunctionKeyword && - token !== SyntaxKind.ClassKeyword) { - + token !== SyntaxKind.ClassKeyword && + isStatement() && + !isStartOfExpressionStatement()) { // Check if we got a plain statement (i.e. no expression-statements, no function/class expressions/declarations) // // Here we try to recover from a potential error situation in the case where the @@ -2767,7 +2761,7 @@ module ts { // up preemptively closing the containing construct. // // Note: even when 'ignoreMissingOpenBrace' is passed as true, parseBody will still error. - return parseFunctionBlock(/*allowYield:*/ false, /* ignoreMissingOpenBrace */ true); + return parseFunctionBlock(/*allowYield*/ false, /*ignoreMissingOpenBrace*/ true); } return parseAssignmentExpressionOrHigher(); @@ -3380,7 +3374,7 @@ module ts { function parseBlock(ignoreMissingOpenBrace: boolean, checkForStrictMode: boolean, diagnosticMessage?: DiagnosticMessage): Block { let node = createNode(SyntaxKind.Block); if (parseExpected(SyntaxKind.OpenBraceToken, diagnosticMessage) || ignoreMissingOpenBrace) { - node.statements = parseList(ParsingContext.BlockStatements, checkForStrictMode, parseStatement); + node.statements = >parseList(ParsingContext.BlockStatements, checkForStrictMode, parseStatement); parseExpected(SyntaxKind.CloseBraceToken); } else { @@ -3646,29 +3640,69 @@ module ts { } } - function isStartOfStatement(inErrorRecovery: boolean): boolean { - // Functions, variable statements and classes are allowed as a statement. But as per - // the grammar, they also allow modifiers. So we have to check for those statements - // that might be following modifiers.This ensures that things work properly when - // incrementally parsing as the parser will produce the same FunctionDeclaraiton, - // VariableStatement or ClassDeclaration, if it has the same text regardless of whether - // it is inside a block or not. - if (isModifier(token)) { - let result = lookAhead(parseVariableStatementOrFunctionDeclarationOrClassDeclarationWithDecoratorsOrModifiers); - if (result) { - return true; + function isIdentifierOrKeyword() { + return token >= SyntaxKind.Identifier; + } + + function nextTokenIsIdentifierOrKeywordOnSameLine() { + nextToken(); + return isIdentifierOrKeyword() && !scanner.hasPrecedingLineBreak(); + } + + function parseDeclarationFlags(): StatementFlags { + while (true) { + switch (token) { + case SyntaxKind.VarKeyword: + case SyntaxKind.LetKeyword: + case SyntaxKind.FunctionKeyword: + case SyntaxKind.ClassKeyword: + return StatementFlags.Statement; + case SyntaxKind.EnumKeyword: + return StatementFlags.ModuleElement; + case SyntaxKind.ConstKeyword: + nextToken(); + return token === SyntaxKind.EnumKeyword ? StatementFlags.ModuleElement : StatementFlags.Statement; + case SyntaxKind.InterfaceKeyword: + case SyntaxKind.TypeKeyword: + nextToken(); + return isIdentifierOrKeyword() ? StatementFlags.ModuleElement : 0; + case SyntaxKind.ModuleKeyword: + case SyntaxKind.NamespaceKeyword: + nextToken(); + return isIdentifierOrKeyword() || token === SyntaxKind.StringLiteral ? StatementFlags.ModuleElement : 0; + case SyntaxKind.ImportKeyword: + nextToken(); + return token === SyntaxKind.StringLiteral || token === SyntaxKind.AsteriskToken || + token === SyntaxKind.OpenBraceToken || isIdentifierOrKeyword() ? + StatementFlags.ModuleElement : 0; + case SyntaxKind.ExportKeyword: + nextToken(); + if (token === SyntaxKind.EqualsToken || token === SyntaxKind.AsteriskToken || + token === SyntaxKind.OpenBraceToken || token === SyntaxKind.DefaultKeyword) { + return StatementFlags.ModuleElement; + } + continue; + case SyntaxKind.DeclareKeyword: + case SyntaxKind.PublicKeyword: + case SyntaxKind.PrivateKeyword: + case SyntaxKind.ProtectedKeyword: + case SyntaxKind.StaticKeyword: + nextToken(); + continue; + default: + return 0; } } + } + function getDeclarationFlags(): StatementFlags { + return lookAhead(parseDeclarationFlags); + } + + function getStatementFlags(): StatementFlags { switch (token) { + case SyntaxKind.AtToken: case SyntaxKind.SemicolonToken: - // If we're in error recovery, then we don't want to treat ';' as an empty statement. - // The problem is that ';' can show up in far too many contexts, and if we see one - // and assume it's a statement, then we may bail out inappropriately from whatever - // we're parsing. For example, if we have a semicolon in the middle of a class, then - // we really don't want to assume the class is over and we're on a statement in the - // outer module. We just want to consume and move on. - return !inErrorRecovery; case SyntaxKind.OpenBraceToken: case SyntaxKind.VarKeyword: case SyntaxKind.LetKeyword: @@ -3690,62 +3724,84 @@ module ts { // however, we say they are here so that we may gracefully parse them and error later. case SyntaxKind.CatchKeyword: case SyntaxKind.FinallyKeyword: - return true; + return StatementFlags.Statement; + + case SyntaxKind.EnumKeyword: + return StatementFlags.ModuleElement; + case SyntaxKind.ConstKeyword: - // const keyword can precede enum keyword when defining constant enums - // 'const enum' do not start statement. - // In ES 6 'enum' is a future reserved keyword, so it should not be used as identifier - let isConstEnum = lookAhead(nextTokenIsEnumKeyword); - return !isConstEnum; + case SyntaxKind.ExportKeyword: + case SyntaxKind.ImportKeyword: + return getDeclarationFlags(); + + case SyntaxKind.DeclareKeyword: case SyntaxKind.InterfaceKeyword: case SyntaxKind.ModuleKeyword: case SyntaxKind.NamespaceKeyword: - case SyntaxKind.EnumKeyword: case SyntaxKind.TypeKeyword: - // When followed by an identifier, these do not start a statement but might - // instead be following declarations - if (isDeclarationStart()) { - return false; - } + return getDeclarationFlags() || StatementFlags.Statement; case SyntaxKind.PublicKeyword: case SyntaxKind.PrivateKeyword: case SyntaxKind.ProtectedKeyword: case SyntaxKind.StaticKeyword: - // When followed by an identifier or keyword, these do not start a statement but - // might instead be following type members - if (lookAhead(nextTokenIsIdentifierOrKeywordOnSameLine)) { - return false; - } + return getDeclarationFlags() || + (!lookAhead(nextTokenIsIdentifierOrKeywordOnSameLine) ? StatementFlags.Statement : 0); + default: - return isStartOfExpression(); + return isStartOfExpression() ? StatementFlags.Statement : 0; } } - function nextTokenIsEnumKeyword() { - nextToken(); - return token === SyntaxKind.EnumKeyword + function isStatement(): boolean { + return (getStatementFlags() & StatementFlags.Statement) !== 0; } - function nextTokenIsIdentifierOrKeywordOnSameLine() { + function isModuleElement(): boolean { + return (getStatementFlags() & StatementFlags.StatementOrModuleElement) !== 0; + } + + function nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine() { nextToken(); - return isIdentifierOrKeyword() && !scanner.hasPrecedingLineBreak(); + return !scanner.hasPrecedingLineBreak() && + (isIdentifier() || token === SyntaxKind.OpenBraceToken || token === SyntaxKind.OpenBracketToken); + } + + function isLetDeclaration() { + // It is let declaration if in strict mode or next token is identifier\open bracket\open curly on same line. + // otherwise it needs to be treated like identifier + return inStrictModeContext() || lookAhead(nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine); } function parseStatement(): Statement { + return parseModuleElementOfKind(StatementFlags.Statement); + } + + function parseModuleElement(): ModuleElement { + return parseModuleElementOfKind(StatementFlags.StatementOrModuleElement); + } + + function parseSourceElement(): ModuleElement { + return parseModuleElementOfKind(StatementFlags.StatementOrModuleElement); + } + + function parseModuleElementOfKind(flags: StatementFlags): ModuleElement { switch (token) { - case SyntaxKind.OpenBraceToken: - return parseBlock(/*ignoreMissingOpenBrace:*/ false, /*checkForStrictMode:*/ false); - case SyntaxKind.VarKeyword: - case SyntaxKind.ConstKeyword: - // const here should always be parsed as const declaration because of check in 'isStatement' - return parseVariableStatement(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers:*/ undefined); - case SyntaxKind.FunctionKeyword: - return parseFunctionDeclaration(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers:*/ undefined); - case SyntaxKind.ClassKeyword: - return parseClassDeclaration(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers:*/ undefined); case SyntaxKind.SemicolonToken: return parseEmptyStatement(); + case SyntaxKind.OpenBraceToken: + return parseBlock(/*ignoreMissingOpenBrace*/ false, /*checkForStrictMode*/ false); + case SyntaxKind.VarKeyword: + return parseVariableStatement(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers*/ undefined); + case SyntaxKind.LetKeyword: + if (isLetDeclaration()) { + return parseVariableStatement(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers*/ undefined); + } + break; + case SyntaxKind.FunctionKeyword: + return parseFunctionDeclaration(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers*/ undefined); + case SyntaxKind.ClassKeyword: + return parseClassDeclaration(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers*/ undefined); case SyntaxKind.IfKeyword: return parseIfStatement(); case SyntaxKind.DoKeyword: @@ -3773,61 +3829,69 @@ module ts { return parseTryStatement(); case SyntaxKind.DebuggerKeyword: return parseDebuggerStatement(); - case SyntaxKind.LetKeyword: - // If let follows identifier on the same line, it is declaration parse it as variable statement - if (isLetDeclaration()) { - return parseVariableStatement(scanner.getStartPos(), /*decorators*/ undefined, /*modifiers:*/ undefined); + case SyntaxKind.AtToken: + return parseDeclaration(); + case SyntaxKind.ConstKeyword: + case SyntaxKind.DeclareKeyword: + case SyntaxKind.EnumKeyword: + case SyntaxKind.ExportKeyword: + case SyntaxKind.ImportKeyword: + case SyntaxKind.InterfaceKeyword: + case SyntaxKind.ModuleKeyword: + case SyntaxKind.NamespaceKeyword: + case SyntaxKind.PrivateKeyword: + case SyntaxKind.ProtectedKeyword: + case SyntaxKind.PublicKeyword: + case SyntaxKind.StaticKeyword: + case SyntaxKind.TypeKeyword: + if (getDeclarationFlags() & flags) { + return parseDeclaration(); } - // Else parse it like identifier - fall through - default: - // Functions and variable statements are allowed as a statement. But as per - // the grammar, they also allow modifiers. So we have to check for those - // statements that might be following modifiers. This ensures that things - // work properly when incrementally parsing as the parser will produce the - // same FunctionDeclaraiton or VariableStatement if it has the same text - // regardless of whether it is inside a block or not. - // Even though variable statements and function declarations cannot have decorators, - // we parse them here to provide better error recovery. - if (isModifier(token) || token === SyntaxKind.AtToken) { - let result = tryParse(parseVariableStatementOrFunctionDeclarationOrClassDeclarationWithDecoratorsOrModifiers); - if (result) { - return result; - } - } - - return parseExpressionOrLabeledStatement(); + break; } + return parseExpressionOrLabeledStatement(); } - function parseVariableStatementOrFunctionDeclarationOrClassDeclarationWithDecoratorsOrModifiers(): FunctionDeclaration | VariableStatement | ClassDeclaration { - let start = scanner.getStartPos(); + function parseDeclaration(): ModuleElement { + let fullStart = getNodePos(); let decorators = parseDecorators(); let modifiers = parseModifiers(); switch (token) { - case SyntaxKind.ConstKeyword: - let nextTokenIsEnum = lookAhead(nextTokenIsEnumKeyword) - if (nextTokenIsEnum) { - return undefined; - } - return parseVariableStatement(start, decorators, modifiers); - - case SyntaxKind.LetKeyword: - if (!isLetDeclaration()) { - return undefined; - } - return parseVariableStatement(start, decorators, modifiers); - case SyntaxKind.VarKeyword: - return parseVariableStatement(start, decorators, modifiers); - + case SyntaxKind.LetKeyword: + case SyntaxKind.ConstKeyword: + return parseVariableStatement(fullStart, decorators, modifiers); case SyntaxKind.FunctionKeyword: - return parseFunctionDeclaration(start, decorators, modifiers); - + return parseFunctionDeclaration(fullStart, decorators, modifiers); case SyntaxKind.ClassKeyword: - return parseClassDeclaration(start, decorators, modifiers); + return parseClassDeclaration(fullStart, decorators, modifiers); + case SyntaxKind.InterfaceKeyword: + return parseInterfaceDeclaration(fullStart, decorators, modifiers); + case SyntaxKind.TypeKeyword: + return parseTypeAliasDeclaration(fullStart, decorators, modifiers); + case SyntaxKind.EnumKeyword: + return parseEnumDeclaration(fullStart, decorators, modifiers); + case SyntaxKind.ModuleKeyword: + case SyntaxKind.NamespaceKeyword: + return parseModuleDeclaration(fullStart, decorators, modifiers); + case SyntaxKind.ImportKeyword: + return parseImportDeclarationOrImportEqualsDeclaration(fullStart, decorators, modifiers); + case SyntaxKind.ExportKeyword: + nextToken(); + return token === SyntaxKind.DefaultKeyword || token === SyntaxKind.EqualsToken ? + parseExportAssignment(fullStart, decorators, modifiers) : + parseExportDeclaration(fullStart, decorators, modifiers); + default: + if (decorators) { + // We reached this point because we encountered decorators and/or modifiers and assumed a declaration + // would follow. For recovery and error reporting purposes, return an incomplete declaration. + let node = createMissingNode(SyntaxKind.MissingDeclaration, /*reportAtCurrentPosition*/ true, Diagnostics.Declaration_expected); + node.pos = fullStart; + node.decorators = decorators; + setModifiers(node, modifiers); + return finishNode(node); + } } - - return undefined; } function parseFunctionBlockOrSemicolon(isGenerator: boolean, diagnosticMessage?: DiagnosticMessage): Block { @@ -4214,9 +4278,9 @@ module ts { function parseClassExpression(): ClassExpression { return parseClassDeclarationOrExpression( - /*fullStart:*/ scanner.getStartPos(), - /*decorators:*/ undefined, - /*modifiers:*/ undefined, + /*fullStart*/ scanner.getStartPos(), + /*decorators*/ undefined, + /*modifiers*/ undefined, SyntaxKind.ClassExpression); } @@ -4374,7 +4438,7 @@ module ts { node.flags |= flags; node.name = parseIdentifier(); node.body = parseOptional(SyntaxKind.DotToken) - ? parseModuleOrNamespaceDeclaration(getNodePos(), /*decorators*/ undefined, /*modifiers:*/undefined, NodeFlags.Export) + ? parseModuleOrNamespaceDeclaration(getNodePos(), /*decorators*/ undefined, /*modifiers*/ undefined, NodeFlags.Export) : parseModuleBlock(); return finishNode(node); } @@ -4610,151 +4674,6 @@ module ts { return finishNode(node); } - function isLetDeclaration() { - // It is let declaration if in strict mode or next token is identifier\open bracket\open curly on same line. - // otherwise it needs to be treated like identifier - return inStrictModeContext() || lookAhead(nextTokenIsIdentifierOrStartOfDestructuringOnTheSameLine); - } - - function isDeclarationStart(followsModifier?: boolean): boolean { - switch (token) { - case SyntaxKind.VarKeyword: - case SyntaxKind.ConstKeyword: - case SyntaxKind.FunctionKeyword: - return true; - case SyntaxKind.LetKeyword: - return isLetDeclaration(); - case SyntaxKind.ClassKeyword: - case SyntaxKind.InterfaceKeyword: - case SyntaxKind.EnumKeyword: - case SyntaxKind.TypeKeyword: - // Not true keywords so ensure an identifier follows - return lookAhead(nextTokenIsIdentifierOrKeyword); - case SyntaxKind.ImportKeyword: - // Not true keywords so ensure an identifier follows or is string literal or asterisk or open brace - return lookAhead(nextTokenCanFollowImportKeyword); - case SyntaxKind.ModuleKeyword: - case SyntaxKind.NamespaceKeyword: - // Not a true keyword so ensure an identifier or string literal follows - return lookAhead(nextTokenIsIdentifierOrKeywordOrStringLiteral); - case SyntaxKind.ExportKeyword: - // Check for export assignment or modifier on source element - return lookAhead(nextTokenCanFollowExportKeyword); - case SyntaxKind.DeclareKeyword: - case SyntaxKind.PublicKeyword: - case SyntaxKind.PrivateKeyword: - case SyntaxKind.ProtectedKeyword: - case SyntaxKind.StaticKeyword: - // Check for modifier on source element - return lookAhead(nextTokenIsDeclarationStart); - case SyntaxKind.AtToken: - // a lookahead here is too costly, and decorators are only valid on a declaration. - // We will assume we are parsing a declaration here and report an error later - return !followsModifier; - } - } - - function isIdentifierOrKeyword() { - return token >= SyntaxKind.Identifier; - } - - function nextTokenIsIdentifierOrKeyword() { - nextToken(); - return isIdentifierOrKeyword(); - } - - function nextTokenIsIdentifierOrKeywordOrStringLiteral() { - nextToken(); - return isIdentifierOrKeyword() || token === SyntaxKind.StringLiteral; - } - - function nextTokenCanFollowImportKeyword() { - nextToken(); - return isIdentifierOrKeyword() || token === SyntaxKind.StringLiteral || - token === SyntaxKind.AsteriskToken || token === SyntaxKind.OpenBraceToken; - } - - function nextTokenCanFollowExportKeyword() { - nextToken(); - return token === SyntaxKind.EqualsToken || token === SyntaxKind.AsteriskToken || - token === SyntaxKind.OpenBraceToken || token === SyntaxKind.DefaultKeyword || isDeclarationStart(/*followsModifier*/ true); - } - - function nextTokenIsDeclarationStart() { - nextToken(); - return isDeclarationStart(/*followsModifier*/ true); - } - - function nextTokenIsAsKeyword() { - return nextToken() === SyntaxKind.AsKeyword; - } - - function parseDeclaration(): ModuleElement { - let fullStart = getNodePos(); - let decorators = parseDecorators(); - let modifiers = parseModifiers(); - if (token === SyntaxKind.ExportKeyword) { - nextToken(); - if (token === SyntaxKind.DefaultKeyword || token === SyntaxKind.EqualsToken) { - return parseExportAssignment(fullStart, decorators, modifiers); - } - if (token === SyntaxKind.AsteriskToken || token === SyntaxKind.OpenBraceToken) { - return parseExportDeclaration(fullStart, decorators, modifiers); - } - } - - switch (token) { - case SyntaxKind.VarKeyword: - case SyntaxKind.LetKeyword: - case SyntaxKind.ConstKeyword: - return parseVariableStatement(fullStart, decorators, modifiers); - case SyntaxKind.FunctionKeyword: - return parseFunctionDeclaration(fullStart, decorators, modifiers); - case SyntaxKind.ClassKeyword: - return parseClassDeclaration(fullStart, decorators, modifiers); - case SyntaxKind.InterfaceKeyword: - return parseInterfaceDeclaration(fullStart, decorators, modifiers); - case SyntaxKind.TypeKeyword: - return parseTypeAliasDeclaration(fullStart, decorators, modifiers); - case SyntaxKind.EnumKeyword: - return parseEnumDeclaration(fullStart, decorators, modifiers); - case SyntaxKind.ModuleKeyword: - case SyntaxKind.NamespaceKeyword: - return parseModuleDeclaration(fullStart, decorators, modifiers); - case SyntaxKind.ImportKeyword: - return parseImportDeclarationOrImportEqualsDeclaration(fullStart, decorators, modifiers); - default: - if (decorators) { - // We reached this point because we encountered an AtToken and assumed a declaration would - // follow. For recovery and error reporting purposes, return an incomplete declaration. - let node = createMissingNode(SyntaxKind.MissingDeclaration, /*reportAtCurrentPosition*/ true, Diagnostics.Declaration_expected); - node.pos = fullStart; - node.decorators = decorators; - setModifiers(node, modifiers); - return finishNode(node); - } - Debug.fail("Mismatch between isDeclarationStart and parseDeclaration"); - } - } - - function isSourceElement(inErrorRecovery: boolean): boolean { - return isDeclarationStart() || isStartOfStatement(inErrorRecovery); - } - - function parseSourceElement() { - return parseSourceElementOrModuleElement(); - } - - function parseModuleElement() { - return parseSourceElementOrModuleElement(); - } - - function parseSourceElementOrModuleElement(): ModuleElement { - return isDeclarationStart() - ? parseDeclaration() - : parseStatement(); - } - function processReferenceComments(sourceFile: SourceFile): void { let triviaScanner = createScanner(sourceFile.languageVersion, /*skipTrivia*/false, sourceText); let referencedFiles: FileReference[] = []; diff --git a/src/compiler/types.ts b/src/compiler/types.ts index 86e680ca8b0..622083a8046 100644 --- a/src/compiler/types.ts +++ b/src/compiler/types.ts @@ -300,6 +300,12 @@ module ts { FirstNode = QualifiedName, } + export const enum StatementFlags { + Statement = 1, + ModuleElement = 2, + StatementOrModuleElement = Statement | ModuleElement + } + export const enum NodeFlags { Export = 0x00000001, // Declarations Ambient = 0x00000002, // Declarations