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103 lines
1.9 KiB
JavaScript
103 lines
1.9 KiB
JavaScript
"use strict";
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const visitor = require( "./visitor" );
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// AST utilities.
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const asts = {
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findRule( ast, name ) {
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for ( let i = 0; i < ast.rules.length; i++ ) {
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if ( ast.rules[ i ].name === name ) return ast.rules[ i ];
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}
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return void 0;
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},
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indexOfRule( ast, name ) {
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for ( let i = 0; i < ast.rules.length; i++ ) {
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if ( ast.rules[ i ].name === name ) return i;
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}
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return -1;
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},
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alwaysConsumesOnSuccess( ast, node ) {
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let consumes;
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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 consumes( node.expression );
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}
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consumes = visitor.build( {
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rule: consumesExpression,
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named: consumesExpression,
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choice( node ) {
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return node.alternatives.every( consumes );
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},
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action: consumesExpression,
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sequence( node ) {
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return node.elements.some( consumes );
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},
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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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rule_ref( node ) {
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return consumes( asts.findRule( ast, 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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class: consumesTrue,
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any: consumesTrue
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} );
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return consumes( node );
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}
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};
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module.exports = asts;
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