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66 lines
1.5 KiB
JavaScript
66 lines
1.5 KiB
JavaScript
"use strict";
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let arrays = require("../utils/arrays"),
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visitor = require("./visitor");
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/* AST utilities. */
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let asts = {
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findRule: function(ast, name) {
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return arrays.find(ast.rules, r => r.name === name);
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},
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indexOfRule: function(ast, name) {
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return arrays.indexOf(ast.rules, r => r.name === name);
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},
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alwaysConsumesOnSuccess: function(ast, node) {
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function consumesTrue() { return true; }
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function consumesFalse() { return false; }
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function consumesExpression(node) {
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return consumes(node.expression);
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}
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let consumes = visitor.build({
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rule: consumesExpression,
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named: consumesExpression,
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choice: function(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: function(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: function(node) {
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return consumes(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": 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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