73 lines
2.0 KiB
JavaScript
73 lines
2.0 KiB
JavaScript
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"use strict";
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var objects = require("../utils/objects"),
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arrays = require("../utils/arrays");
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/* Simple AST node visitor builder. */
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var visitor = {
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build: function(functions) {
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function visit(node) {
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return functions[node.type].apply(null, arguments);
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}
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function visitNop() { }
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function visitExpression(node) {
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var extraArgs = Array.prototype.slice.call(arguments, 1);
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visit.apply(null, [node.expression].concat(extraArgs));
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}
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function visitChildren(property) {
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return function(node) {
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var extraArgs = Array.prototype.slice.call(arguments, 1);
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arrays.each(node[property], function(child) {
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visit.apply(null, [child].concat(extraArgs));
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});
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};
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}
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var DEFAULT_FUNCTIONS = {
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grammar: function(node) {
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var extraArgs = Array.prototype.slice.call(arguments, 1);
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if (node.initializer) {
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visit.apply(null, [node.initializer].concat(extraArgs));
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}
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arrays.each(node.rules, function(rule) {
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visit.apply(null, [rule].concat(extraArgs));
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});
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},
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initializer: visitNop,
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rule: visitExpression,
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named: visitExpression,
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choice: visitChildren("alternatives"),
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action: visitExpression,
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sequence: visitChildren("elements"),
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labeled: visitExpression,
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text: visitExpression,
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simple_and: visitExpression,
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simple_not: visitExpression,
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optional: visitExpression,
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zero_or_more: visitExpression,
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one_or_more: visitExpression,
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group: visitExpression,
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semantic_and: visitNop,
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semantic_not: visitNop,
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rule_ref: visitNop,
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literal: visitNop,
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"class": visitNop,
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any: visitNop
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};
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objects.defaults(functions, DEFAULT_FUNCTIONS);
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return visit;
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}
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};
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module.exports = visitor;
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