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126 lines
2.1 KiB
JavaScript
126 lines
2.1 KiB
JavaScript
"use strict";
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const Node = require( "./Node" );
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const visitor = require( "./visitor" );
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const util = require( "../util" );
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class Grammar extends Node {
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// Creates a new AST
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constructor( initializer, rules, comments, location ) {
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super( "grammar", location );
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this.initializer = initializer;
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this.comments = comments;
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this.rules = rules;
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this._alwaysConsumesOnSuccess = new AlwaysConsumesOnSuccess( this );
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}
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alwaysConsumesOnSuccess( node ) {
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return this._alwaysConsumesOnSuccess.visit( node );
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}
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findRule( name ) {
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return this.rules.find( rule => rule.name === name );
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}
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indexOfRule( name ) {
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const rules = this.rules;
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for ( let i = 0; i < rules.length; ++i ) {
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if ( rules[ i ].name === name ) return i;
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}
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return -1;
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}
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}
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module.exports = Grammar;
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/* ***************************** @private ***************************** */
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class AlwaysConsumesOnSuccess extends visitor.ASTVisitor {
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constructor( ast ) {
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super();
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this.ast = ast;
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}
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choice( node ) {
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return node.alternatives.every( this.visit, this );
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}
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sequence( node ) {
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return node.elements.some( this.visit, this );
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}
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rule_ref( node ) {
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return this.visit( this.ast.findRule( node.name ) );
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}
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literal( node ) {
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return node.value !== "";
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}
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}
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function consumesTrue() {
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return true;
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}
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function consumesFalse() {
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return false;
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}
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function consumesExpression( node ) {
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return this.visit( node.expression );
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}
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util.extend( AlwaysConsumesOnSuccess.prototype, {
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rule: consumesExpression,
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named: consumesExpression,
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action: consumesExpression,
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labeled: consumesExpression,
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text: consumesExpression,
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simple_and: consumesFalse,
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simple_not: consumesFalse,
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optional: consumesFalse,
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zero_or_more: consumesFalse,
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one_or_more: consumesExpression,
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group: consumesExpression,
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semantic_and: consumesFalse,
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semantic_not: consumesFalse,
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class: consumesTrue,
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any: consumesTrue,
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} );
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