Optimize redundant fail checks (#400)
eliminate unnecessary checks for the result of parse, when it can be statically determinedmaster
Mingun
7 years ago
committed by
Futago-za Ryuu
parent
f5699d63fb
commit
534dc53ac2
@ -0,0 +1,173 @@
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"use strict";
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const visitor = require( "../visitor" );
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const asts = require( "../asts" );
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const GrammarError = require( "../../grammar-error" );
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// Inference match result of the rule. Can be:
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// -1: negative result, always fails
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// 0: neutral result, may be fail, may be match
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// 1: positive result, always match
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function inferenceMatchResult( ast ) {
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let inference;
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function sometimesMatch( node ) {
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node.match = 0;
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return node.match;
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}
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function alwaysMatch( node ) {
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inference( node.expression );
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node.match = 1;
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return node.match;
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}
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function inferenceExpression( node ) {
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node.match = inference( node.expression );
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return node.match;
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}
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function inferenceElements( elements, forChoice ) {
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const length = elements.length;
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let always = 0;
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let never = 0;
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for ( let i = 0; i < length; ++i ) {
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const result = inference( elements[ i ] );
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if ( result > 0 ) {
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++always;
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}
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if ( result < 0 ) {
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++never;
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}
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}
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if ( always === length ) {
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return 1;
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}
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if ( forChoice ) {
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return never === length ? -1 : 0;
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}
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return never > 0 ? -1 : 0;
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}
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inference = visitor.build( {
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rule( node ) {
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let oldResult;
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let count = 0;
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if ( typeof node.match === "undefined" ) {
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node.match = 0;
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do {
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oldResult = node.match;
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node.match = inference( node.expression );
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// 6 == 3! -- permutations count for all transitions from one match
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// state to another.
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// After 6 iterations the cycle with guarantee begins
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// istanbul ignore next
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if ( ++count > 6 ) {
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throw new GrammarError(
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"Infinity cycle detected when trying evaluate node match result",
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node.location
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);
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}
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} while ( oldResult !== node.match );
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}
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return node.match;
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},
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named: inferenceExpression,
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choice( node ) {
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node.match = inferenceElements( node.alternatives, true );
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return node.match;
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},
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action: inferenceExpression,
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sequence( node ) {
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node.match = inferenceElements( node.elements, false );
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return node.match;
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},
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labeled: inferenceExpression,
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text: inferenceExpression,
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simple_and: inferenceExpression,
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simple_not( node ) {
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node.match = -inference( node.expression );
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return node.match;
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},
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optional: alwaysMatch,
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zero_or_more: alwaysMatch,
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one_or_more: inferenceExpression,
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group: inferenceExpression,
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semantic_and: sometimesMatch,
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semantic_not: sometimesMatch,
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rule_ref( node ) {
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const rule = asts.findRule( ast, node.name );
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node.match = inference( rule );
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return node.match;
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},
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literal( node ) {
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// Empty literal always match on any input
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node.match = node.value.length === 0 ? 1 : 0;
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return node.match;
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},
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class( node ) {
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// Empty character class never match on any input
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node.match = node.parts.length === 0 ? -1 : 0;
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return node.match;
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},
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// |any| not match on empty input
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any: sometimesMatch
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} );
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inference( ast );
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}
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module.exports = inferenceMatchResult;
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File diff suppressed because it is too large
Load Diff
@ -0,0 +1,164 @@
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"use strict";
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const chai = require( "chai" );
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const helpers = require( "./helpers" );
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const pass = require( "pegjs-dev" ).compiler.passes.generate.inferenceMatchResult;
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chai.use( helpers );
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const expect = chai.expect;
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describe( "compiler pass |inferenceMatchResult|", function () {
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it( "calculate |match| property for |any| correctly", function () {
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expect( pass ).to.changeAST( "start = . ", { rules: [ { match: 0 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |literal| correctly", function () {
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expect( pass ).to.changeAST( "start = '' ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = ''i ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = 'a' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = 'a'i ", { rules: [ { match: 0 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |class| correctly", function () {
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expect( pass ).to.changeAST( "start = [] ", { rules: [ { match: -1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = []i ", { rules: [ { match: -1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [a] ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [a]i ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [a-b] ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [a-b]i ", { rules: [ { match: 0 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |sequence| correctly", function () {
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expect( pass ).to.changeAST( "start = 'a' 'b' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = 'a' '' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = '' 'b' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = '' '' ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = 'a' [] ", { rules: [ { match: -1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [] 'b' ", { rules: [ { match: -1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [] [] ", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |choice| correctly", function () {
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expect( pass ).to.changeAST( "start = 'a' / 'b' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = 'a' / '' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = '' / 'b' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = '' / '' ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = 'a' / [] ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [] / 'b' ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [] / [] ", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for predicates correctly", function () {
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expect( pass ).to.changeAST( "start = &. ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = &'' ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = &[] ", { rules: [ { match: -1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = !. ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = !'' ", { rules: [ { match: -1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = ![] ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = &{ code } ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = !{ code } ", { rules: [ { match: 0 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |text| correctly", function () {
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expect( pass ).to.changeAST( "start = $. ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = $'' ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = $[] ", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |action| correctly", function () {
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expect( pass ).to.changeAST( "start = . { code }", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = '' { code }", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [] { code }", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |labeled| correctly", function () {
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expect( pass ).to.changeAST( "start = a:. ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = a:'' ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = a:[] ", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |named| correctly", function () {
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expect( pass ).to.changeAST( "start 'start' = . ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start 'start' = '' ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start 'start' = [] ", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |optional| correctly", function () {
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expect( pass ).to.changeAST( "start = .? ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = ''? ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = []? ", { rules: [ { match: 1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |zero_or_more| correctly", function () {
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expect( pass ).to.changeAST( "start = .* ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = ''* ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = []* ", { rules: [ { match: 1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |one_or_more| correctly", function () {
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expect( pass ).to.changeAST( "start = .+ ", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = ''+ ", { rules: [ { match: 1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = []+ ", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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it( "calculate |match| property for |rule_ref| correctly", function () {
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expect( pass ).to.changeAST(
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[ "start = end", "end = . " ].join( "\n" ),
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{ rules: [ { match: 0 }, { match: 0 } ] },
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{}, {}
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);
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expect( pass ).to.changeAST(
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[ "start = end", "end = ''" ].join( "\n" ),
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{ rules: [ { match: 1 }, { match: 1 } ] },
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{}, {}
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);
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expect( pass ).to.changeAST(
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[ "start = end", "end = []" ].join( "\n" ),
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{ rules: [ { match: -1 }, { match: -1 } ] },
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{}, {}
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);
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expect( pass ).to.changeAST( "start = . start", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = '' start", { rules: [ { match: 0 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = [] start", { rules: [ { match: -1 } ] }, {}, {} );
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expect( pass ).to.changeAST( "start = . start []", { rules: [ { match: -1 } ] }, {}, {} );
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} );
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} );
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