Update src/parser.pegjs
- use value plucking - remove helpers not needed now - types in OPS_* are now returned by *Operator - RESERVED_WORDS is now a `Object<Identifier,true>` - use ES2015+ JavaScript - cleanup source code
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Futago-za Ryuu
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356
src/parser.pegjs
356
src/parser.pegjs
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@ -22,184 +22,175 @@
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// [1] http://www.ecma-international.org/publications/standards/Ecma-262.htm
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{
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const OPS_TO_PREFIXED_TYPES = {
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"$": "text",
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"&": "simple_and",
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"!": "simple_not"
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};
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const OPS_TO_SUFFIXED_TYPES = {
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"?": "optional",
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"*": "zero_or_more",
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"+": "one_or_more"
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};
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// Used as a shorthand property name for `LabeledExpression`
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const pick = true;
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const OPS_TO_SEMANTIC_PREDICATE_TYPES = {
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"&": "semantic_and",
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"!": "semantic_not"
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};
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// Used by `LabelIdentifier` to disallow the use of certain words as labels
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const RESERVED_WORDS = {};
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let RESERVED_WORDS = options.reservedWords || util.reservedWords;
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if ( !Array.isArray(RESERVED_WORDS) ) RESERVED_WORDS = [];
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// Populate `RESERVED_WORDS` using the optional option `reservedWords`
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const reservedWords = options.reservedWords || util.reservedWords;
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if ( Array.isArray( reservedWords ) ) {
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function extractOptional(optional, index) {
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return optional ? optional[index] : null;
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}
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for ( const word of reservedWords ) RESERVED_WORDS[ word ] = true;
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function extractList(list, index) {
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return list.map(element => element[index]);
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}
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function buildList(head, tail, index) {
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return [head].concat(extractList(tail, index));
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}
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function createNode( type, details ) {
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const node = new ast.Node( type, location() );
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util.extend( node, details );
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return util.enforceFastProperties( node );
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}
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let comments = options.extractComments ? {} : null;
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function addComment(comment, multiline) {
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if (options.extractComments) {
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let loc = location();
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comment = {
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text: comment,
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multiline: multiline,
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location: loc
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};
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comments[loc.start.offset] = comment;
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return comment;
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}
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}
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// Helper to construct a new AST Node
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function createNode( type, details ) {
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const node = new ast.Node( type, location() );
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if ( details === null ) return node;
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util.extend( node, details );
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return util.enforceFastProperties( node );
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}
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// Used by `addComment` to store comments for the Grammar AST
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const comments = options.extractComments ? {} : null;
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// Helper that collects all the comments to pass to the Grammar AST
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function addComment( text, multiline ) {
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if ( options.extractComments ) {
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const loc = location();
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comments[ loc.start.offset ] = {
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text: text,
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multiline: multiline,
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location: loc,
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};
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}
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return text;
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}
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}
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// ---- Syntactic Grammar -----
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Grammar
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= __ initializer:(Initializer __)? rules:(Rule __)+ {
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return new ast.Grammar(
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extractOptional(initializer, 0),
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extractList(rules, 0),
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comments,
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location()
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);
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= __ initializer:(@Initializer __)? rules:(@Rule __)+ {
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return new ast.Grammar( initializer, rules, comments, location() );
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}
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Initializer
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= code:CodeBlock EOS {
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return createNode( "initializer", { code: code } );
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return createNode( "initializer", { code } );
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}
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Rule
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= name:Identifier __
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displayName:(StringLiteral __)?
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"=" __
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expression:Expression EOS
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{
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return createNode( "rule", {
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name: name,
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expression: displayName !== null
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? createNode( "named", {
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name: displayName[0],
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expression: expression,
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} )
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: expression,
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} );
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= name:Identifier __ displayName:(@StringLiteral __)? "=" __ expression:Expression EOS {
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if ( displayName )
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expression = createNode( "named", {
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name: displayName,
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expression: expression,
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} );
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return createNode( "rule", { name, expression } );
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}
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Expression
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= ChoiceExpression
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ChoiceExpression
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= head:ActionExpression tail:(__ "/" __ ActionExpression)* {
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return tail.length > 0
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? createNode( "choice", {
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alternatives: buildList(head, tail, 3),
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} )
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: head;
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= head:ActionExpression tail:(__ "/" __ @ActionExpression)* {
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if ( tail.length === 0 ) return head;
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return createNode( "choice", {
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alternatives: [ head ].concat( tail ),
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} );
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}
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ActionExpression
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= expression:SequenceExpression code:(__ CodeBlock)? {
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return code !== null
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? createNode( "action", {
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expression: expression,
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code: code[1],
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} )
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: expression;
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= expression:SequenceExpression code:(__ @CodeBlock)? {
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if ( code === null ) return expression;
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return createNode( "action", { expression, code } );
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}
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SequenceExpression
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= head:LabeledExpression tail:(__ LabeledExpression)* {
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if ( tail.length < 1 )
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= head:LabeledExpression tail:(__ @LabeledExpression)* {
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return head.type === "labeled" && head.pick
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? createNode( "sequence", { elements: [ head ] } )
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: head;
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let elements = [ head ];
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return createNode( "sequence", {
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if ( tail.length === 0 ) {
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elements: buildList( head, tail, 1 ),
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if ( head.type !== "labeled" || ! head.pick ) return head;
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} else {
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elements = elements.concat( tail );
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}
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return createNode( "sequence", { elements } );
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} );
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}
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LabeledExpression
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= "@" label:(IdentifierName __ ":")? __ expression:PrefixedExpression {
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const [ name, location ] = extractOptional(label, 0) || [];
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= "@" label:LabelIdentifier? __ expression:PrefixedExpression {
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if (name && RESERVED_WORDS.indexOf(name) >= 0) {
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error(`Label can't be a reserved word "${name}".`, location);
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}
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return createNode( "labeled", { pick, label, expression } );
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return createNode( "labeled", {
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pick: true,
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label: name,
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expression: expression,
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} );
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}
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/ label:IdentifierName __ ":" __ expression:PrefixedExpression {
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if (RESERVED_WORDS.indexOf(label[0]) >= 0) {
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error(`Label can't be a reserved word "${label[0]}".`, label[1]);
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}
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/ label:LabelIdentifier __ expression:PrefixedExpression {
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return createNode( "labeled", { label, expression } );
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return createNode( "labeled", {
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label: label[0],
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expression: expression,
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} );
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}
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/ PrefixedExpression
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IdentifierName
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= name:Identifier { return [name, location()]; }
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LabelIdentifier
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= name:Identifier __ ":" {
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if ( RESERVED_WORDS[ name ] !== true ) return name;
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error( `Label can't be a reserved word "${ name }".`, location() );
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}
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PrefixedExpression
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= operator:PrefixedOperator __ expression:SuffixedExpression {
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return createNode( OPS_TO_PREFIXED_TYPES[operator], {
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expression: expression,
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} );
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return createNode( operator, { expression } );
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}
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/ SuffixedExpression
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PrefixedOperator
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= "$"
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/ "&"
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/ "!"
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= "$" { return "text"; }
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/ "&" { return "simple_and"; }
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/ "!" { return "simple_not"; }
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SuffixedExpression
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= expression:PrimaryExpression __ operator:SuffixedOperator {
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return createNode( OPS_TO_SUFFIXED_TYPES[operator], {
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expression: expression,
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} );
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return createNode( operator, { expression } );
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}
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/ PrimaryExpression
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SuffixedOperator
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= "?"
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/ "*"
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/ "+"
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= "?" { return "optional"; }
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/ "*" { return "zero_or_more"; }
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/ "+" { return "one_or_more"; }
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PrimaryExpression
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= LiteralMatcher
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@ -207,29 +198,35 @@ PrimaryExpression
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/ AnyMatcher
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/ RuleReferenceExpression
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/ SemanticPredicateExpression
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/ "(" __ expression:Expression __ ")" {
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// The purpose of the "group" AST node is just to isolate label scope. We
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// don't need to put it around nodes that can't contain any labels or
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// nodes that already isolate label scope themselves. This leaves us with
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// "labeled" and "sequence".
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return expression.type === "labeled" || expression.type === "sequence"
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? createNode( "group", { expression: expression } )
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: expression;
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/ "(" __ e:Expression __ ")" {
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// The purpose of the "group" AST node is just to isolate label scope. We
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// don't need to put it around nodes that can't contain any labels or
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// nodes that already isolate label scope themselves.
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if ( e.type !== "labeled" && e.type !== "sequence" ) return e;
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// This leaves us with "labeled" and "sequence".
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return createNode( "group", { expression: e } );
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}
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RuleReferenceExpression
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= name:Identifier !(__ (StringLiteral __)? "=") {
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return createNode( "rule_ref", { name: name } );
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return createNode( "rule_ref", { name } );
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}
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SemanticPredicateExpression
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= operator:SemanticPredicateOperator __ code:CodeBlock {
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return createNode( OPS_TO_SEMANTIC_PREDICATE_TYPES[operator], { code: code } );
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return createNode( operator, { code } );
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}
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SemanticPredicateOperator
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= "&"
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/ "!"
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= "&" { return "semantic_and"; }
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/ "!" { return "semantic_not"; }
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// ---- Lexical Grammar -----
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@ -261,27 +258,37 @@ Comment "comment"
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MultiLineComment
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= "/*" comment:$(!"*/" SourceCharacter)* "*/" {
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return addComment(comment, true);
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return addComment( comment, true );
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}
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MultiLineCommentNoLineTerminator
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= "/*" comment:$(!("*/" / LineTerminator) SourceCharacter)* "*/" {
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return addComment(comment, true);
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return addComment( comment, true );
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}
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SingleLineComment
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= "//" comment:$(!LineTerminator SourceCharacter)* {
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return addComment(comment, false);
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return addComment( comment, false );
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}
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Identifier "identifier"
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= head:IdentifierStart tail:IdentifierPart* { return head + tail.join(""); }
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= head:IdentifierStart tail:IdentifierPart* {
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return head + tail.join("");
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}
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IdentifierStart
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= UnicodeLetter
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/ "$"
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/ "_"
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/ "\\" sequence:UnicodeEscapeSequence { return sequence; }
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/ "\\" @UnicodeEscapeSequence
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IdentifierPart
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= IdentifierStart
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@ -311,10 +318,12 @@ UnicodeConnectorPunctuation
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LiteralMatcher "literal"
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= value:StringLiteral ignoreCase:"i"? {
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return createNode( "literal", {
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value: value,
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ignoreCase: ignoreCase !== null,
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} );
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return createNode( "literal", {
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value: value,
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ignoreCase: ignoreCase !== null,
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} );
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}
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StringLiteral "string"
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@ -322,43 +331,44 @@ StringLiteral "string"
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/ "'" chars:SingleStringCharacter* "'" { return chars.join(""); }
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DoubleStringCharacter
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= !('"' / "\\" / LineTerminator) SourceCharacter { return text(); }
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/ "\\" sequence:EscapeSequence { return sequence; }
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= !('"' / "\\" / LineTerminator) @SourceCharacter
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/ "\\" @EscapeSequence
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/ LineContinuation
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SingleStringCharacter
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= !("'" / "\\" / LineTerminator) SourceCharacter { return text(); }
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/ "\\" sequence:EscapeSequence { return sequence; }
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= !("'" / "\\" / LineTerminator) @SourceCharacter
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/ "\\" @EscapeSequence
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/ LineContinuation
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CharacterClassMatcher "character class"
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= "["
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inverted:"^"?
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parts:(ClassCharacterRange / ClassCharacter)*
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"]"
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ignoreCase:"i"?
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{
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return createNode( "class", {
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parts: parts.filter(part => part !== ""),
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inverted: inverted !== null,
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ignoreCase: ignoreCase !== null,
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} );
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= "[" inverted:"^"? parts:CharacterPart* "]" ignoreCase:"i"? {
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return createNode( "class", {
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parts: parts.filter( part => part !== "" ),
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inverted: inverted !== null,
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ignoreCase: ignoreCase !== null,
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} );
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}
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CharacterPart
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= ClassCharacterRange
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/ ClassCharacter
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ClassCharacterRange
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= begin:ClassCharacter "-" end:ClassCharacter {
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if (begin.charCodeAt(0) > end.charCodeAt(0)) {
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error(
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"Invalid character range: " + text() + "."
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);
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}
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return [begin, end];
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if ( begin.charCodeAt( 0 ) > end.charCodeAt( 0 ) )
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error( "Invalid character range: " + text() + "." );
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return [ begin, end ];
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}
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ClassCharacter
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= !("]" / "\\" / LineTerminator) SourceCharacter { return text(); }
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/ "\\" sequence:EscapeSequence { return sequence; }
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= !("]" / "\\" / LineTerminator) @SourceCharacter
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/ "\\" @EscapeSequence
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/ LineContinuation
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LineContinuation
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@ -386,7 +396,7 @@ SingleEscapeCharacter
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/ "v" { return "\v"; }
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NonEscapeCharacter
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= !(EscapeCharacter / LineTerminator) SourceCharacter { return text(); }
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= !(EscapeCharacter / LineTerminator) @SourceCharacter
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EscapeCharacter
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= SingleEscapeCharacter
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@ -396,12 +406,16 @@ EscapeCharacter
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HexEscapeSequence
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= "x" digits:$(HexDigit HexDigit) {
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return String.fromCharCode(parseInt(digits, 16));
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return String.fromCharCode( parseInt( digits, 16 ) );
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}
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UnicodeEscapeSequence
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= "u" digits:$(HexDigit HexDigit HexDigit HexDigit) {
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return String.fromCharCode(parseInt(digits, 16));
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return String.fromCharCode( parseInt( digits, 16 ) );
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}
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DecimalDigit
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@ -411,10 +425,14 @@ HexDigit
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= [0-9a-f]i
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AnyMatcher
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= "." { return createNode( "any", {} ); }
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= "." {
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return createNode( "any" );
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}
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CodeBlock "code block"
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= "{" code:Code "}" { return code; }
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= "{" @Code "}"
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/ "{" { error("Unbalanced brace."); }
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Code
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@ -441,7 +441,7 @@ describe( "PEG.js grammar parser", function () {
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return {
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type: "labeled",
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pick: true,
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label: label || void 0,
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label: label,
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expression: expression
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};
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