kpdecker
120 lines
2.8 KiB
JavaScript
120 lines
2.8 KiB
JavaScript
import Exception from "../exception";
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import AST from "./ast";
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function Visitor() {
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this.parents = [];
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}
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Visitor.prototype = {
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constructor: Visitor,
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mutating: false,
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// Visits a given value. If mutating, will replace the value if necessary.
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acceptKey: function(node, name) {
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var value = this.accept(node[name]);
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if (this.mutating) {
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// Hacky sanity check:
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if (value && (!value.type || !AST[value.type])) {
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throw new Exception('Unexpected node type "' + value.type + '" found when accepting ' + name + ' on ' + node.type);
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}
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node[name] = value;
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}
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},
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// Performs an accept operation with added sanity check to ensure
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// required keys are not removed.
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acceptRequired: function(node, name) {
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this.acceptKey(node, name);
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if (!node[name]) {
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throw new Exception(node.type + ' requires ' + name);
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}
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},
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// Traverses a given array. If mutating, empty respnses will be removed
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// for child elements.
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acceptArray: function(array) {
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for (var i = 0, l = array.length; i < l; i++) {
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this.acceptKey(array, i);
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if (!array[i]) {
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array.splice(i, 1);
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i--;
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l--;
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}
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}
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},
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accept: function(object) {
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if (!object) {
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return;
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}
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if (this.current) {
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this.parents.unshift(this.current);
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}
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this.current = object;
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var ret = this[object.type](object);
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this.current = this.parents.shift();
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if (!this.mutating || ret) {
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return ret;
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} else if (ret !== false) {
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return object;
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}
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},
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Program: function(program) {
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this.acceptArray(program.body);
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},
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MustacheStatement: function(mustache) {
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this.acceptRequired(mustache, 'path');
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this.acceptArray(mustache.params);
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this.acceptKey(mustache, 'hash');
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},
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BlockStatement: function(block) {
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this.acceptRequired(block, 'path');
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this.acceptArray(block.params);
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this.acceptKey(block, 'hash');
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this.acceptKey(block, 'program');
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this.acceptKey(block, 'inverse');
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},
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PartialStatement: function(partial) {
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this.acceptRequired(partial, 'name');
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this.acceptArray(partial.params);
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this.acceptKey(partial, 'hash');
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},
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ContentStatement: function(/* content */) {},
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CommentStatement: function(/* comment */) {},
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SubExpression: function(sexpr) {
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this.acceptRequired(sexpr, 'path');
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this.acceptArray(sexpr.params);
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this.acceptKey(sexpr, 'hash');
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},
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PathExpression: function(/* path */) {},
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StringLiteral: function(/* string */) {},
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NumberLiteral: function(/* number */) {},
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BooleanLiteral: function(/* bool */) {},
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UndefinedLiteral: function(/* literal */) {},
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NullLiteral: function(/* literal */) {},
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Hash: function(hash) {
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this.acceptArray(hash.pairs);
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},
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HashPair: function(pair) {
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this.acceptRequired(pair, 'value');
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}
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};
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export default Visitor;
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