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65 lines
1.5 KiB
JavaScript
65 lines
1.5 KiB
JavaScript
"use strict";
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var arrays = require("../utils/arrays"),
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visitor = require("./visitor");
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/* AST utilities. */
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var asts = {
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findRule: function(ast, name) {
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return arrays.find(ast.rules, function(r) { return r.name === name; });
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},
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indexOfRule: function(ast, name) {
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return arrays.indexOf(ast.rules, function(r) { return r.name === name; });
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},
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alwaysAdvancesOnSuccess: function(ast, node) {
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function advancesTrue() { return true; }
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function advancesFalse() { return false; }
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function advancesExpression(node) {
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return advances(node.expression);
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}
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var advances = visitor.build({
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rule: advancesExpression,
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named: advancesExpression,
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choice: function(node) {
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return arrays.every(node.alternatives, advances);
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},
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action: advancesExpression,
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sequence: function(node) {
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return arrays.some(node.elements, advances);
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},
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labeled: advancesExpression,
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text: advancesExpression,
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simple_and: advancesFalse,
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simple_not: advancesFalse,
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optional: advancesFalse,
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zero_or_more: advancesFalse,
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one_or_more: advancesExpression,
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semantic_and: advancesFalse,
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semantic_not: advancesFalse,
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rule_ref: function(node) {
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return advances(asts.findRule(ast, node.name));
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},
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literal: function(node) {
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return node.value !== "";
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},
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"class": advancesTrue,
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any: advancesTrue
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});
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return advances(node);
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}
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};
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module.exports = asts;
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