AST refactoring 3/6: Rewrite checks to not extend the AST nodes
This commit is contained in:
David Majda
parent
c59516541f
commit
5885a34dde
241
lib/compiler.js
241
lib/compiler.js
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@ -2,8 +2,6 @@
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(function() {
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function nop() {}
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/* ===== PEG ===== */
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/* no var */ PEG = {};
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@ -142,31 +140,7 @@ PEG.RegExpUtils = {
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/* Namespace with grammar AST nodes. */
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PEG.Grammar = {
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/*
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* Extends specified AST node classes with a function named |name|. The
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* definition of the function is different for each node class and it is
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* specified in the |functions| object, which contains the functions keyed by
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* unqualified AST node names.
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*
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* Example:
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*
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* PEG.Grammar.extendNodes("foo", {
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* Literal: function() { return 1; },
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* Class: function() { return 2; }
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* });
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*
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* This is is equivalent to:
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*
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* PEG.Grammar.Literal.prototype.foo = function() { return 1; };
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* PEG.Grammar.Class.prototype.foo = function() { return 2; };
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*/
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extendNodes: function(name, functions) {
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for (var nodeName in functions) {
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PEG.Grammar[nodeName].prototype[name] = functions[nodeName];
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}
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}
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};
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PEG.Grammar = {};
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/* ===== PEG.Grammar.GrammarError ===== */
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@ -248,126 +222,6 @@ PEG.Grammar.Class = function(characters) {
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this.characters = characters;
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};
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/* ===== Referenced Rule Existence Checks ===== */
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PEG.Grammar.extendNodes("checkReferencedRulesExist", {
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Rule:
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function(grammar) {
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this.expression.checkReferencedRulesExist(grammar);
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},
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Choice:
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function(grammar) {
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PEG.ArrayUtils.each(this.alternatives, function(alternative) {
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alternative.checkReferencedRulesExist(grammar);
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});
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},
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Sequence:
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function(grammar) {
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PEG.ArrayUtils.each(this.elements, function(element) {
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element.checkReferencedRulesExist(grammar);
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});
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},
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AndPredicate:
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function(grammar) { this.expression.checkReferencedRulesExist(grammar); },
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NotPredicate:
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function(grammar) { this.expression.checkReferencedRulesExist(grammar); },
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Optional:
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function(grammar) { this.expression.checkReferencedRulesExist(grammar); },
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ZeroOrMore:
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function(grammar) { this.expression.checkReferencedRulesExist(grammar); },
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OneOrMore:
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function(grammar) { this.expression.checkReferencedRulesExist(grammar); },
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Action:
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function(grammar) { this.expression.checkReferencedRulesExist(grammar); },
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RuleRef:
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function(grammar) {
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if (grammar[this.name] === undefined) {
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throw new PEG.Grammar.GrammarError(
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"Referenced rule \"" + this.name + "\" does not exist."
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);
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}
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},
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Literal: nop,
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Any: nop,
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Class: nop
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});
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/* ===== Left Recursion Checks ===== */
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PEG.Grammar.extendNodes("checkNoLeftRecursion", {
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Rule:
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function(grammar, appliedRules) {
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this.expression.checkNoLeftRecursion(grammar, appliedRules.concat(this.name));
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},
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Choice:
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function(grammar, appliedRules) {
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PEG.ArrayUtils.each(this.alternatives, function(alternative) {
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alternative.checkNoLeftRecursion(grammar, appliedRules);
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});
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},
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Sequence:
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function(grammar, appliedRules) {
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if (this.elements.length > 0) {
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this.elements[0].checkNoLeftRecursion(grammar, appliedRules);
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}
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},
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AndPredicate:
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function(grammar, appliedRules) {
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this.expression.checkNoLeftRecursion(grammar, appliedRules);
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},
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NotPredicate:
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function(grammar, appliedRules) {
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this.expression.checkNoLeftRecursion(grammar, appliedRules);
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},
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Optional:
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function(grammar, appliedRules) {
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this.expression.checkNoLeftRecursion(grammar, appliedRules);
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},
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ZeroOrMore:
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function(grammar, appliedRules) {
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this.expression.checkNoLeftRecursion(grammar, appliedRules);
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},
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OneOrMore:
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function(grammar, appliedRules) {
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this.expression.checkNoLeftRecursion(grammar, appliedRules);
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},
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Action:
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function(grammar, appliedRules) {
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this.expression.checkNoLeftRecursion(grammar, appliedRules);
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},
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RuleRef:
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function(grammar, appliedRules) {
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if (PEG.ArrayUtils.contains(appliedRules, this.name)) {
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throw new PEG.Grammar.GrammarError("Left recursion detected for rule \"" + this.name + "\".");
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}
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grammar[this.name].checkNoLeftRecursion(grammar, appliedRules);
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},
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Literal: nop,
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Any: nop,
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Class: nop
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});
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/* ===== PEG.Compiler ===== */
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PEG.Compiler = {
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@ -482,8 +336,45 @@ PEG.Compiler = {
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_checks: [
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/* Checks that all referenced rules exist. */
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function(ast, startRule) {
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function nop() {}
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function checkExpression(node) { check(node.expression); }
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function checkSubnodes(propertyName) {
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return function(node) {
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PEG.ArrayUtils.each(node[propertyName], check);
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};
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}
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var checkFunctions = {
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rule: checkExpression,
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choice: checkSubnodes("alternatives"),
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sequence: checkSubnodes("elements"),
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and_predicate: checkExpression,
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not_predicate: checkExpression,
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optional: checkExpression,
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zero_or_more: checkExpression,
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one_or_more: checkExpression,
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action: checkExpression,
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rule_ref:
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function(node) {
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if (ast[node.name] === undefined) {
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throw new PEG.Grammar.GrammarError(
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"Referenced rule \"" + node.name + "\" does not exist."
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);
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}
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},
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literal: nop,
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any: nop,
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"class": nop
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};
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function check(node) { checkFunctions[node.type](node); }
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for (var rule in ast) {
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ast[rule].checkReferencedRulesExist(ast);
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check(ast[rule]);
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}
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},
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@ -498,8 +389,60 @@ PEG.Compiler = {
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/* Checks that no left recursion is present. */
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function(ast, startRule) {
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function nop() {}
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function checkExpression(node, appliedRules) {
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check(node.expression, appliedRules);
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}
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var checkFunctions = {
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rule:
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function(node, appliedRules) {
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check(node.expression, appliedRules.concat(node.name));
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},
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choice:
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function(node, appliedRules) {
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PEG.ArrayUtils.each(node.alternatives, function(alternative) {
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check(alternative, appliedRules);
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});
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},
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sequence:
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function(node, appliedRules) {
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if (node.elements.length > 0) {
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check(node.elements[0], appliedRules);
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}
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},
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and_predicate: checkExpression,
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not_predicate: checkExpression,
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optional: checkExpression,
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zero_or_more: checkExpression,
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one_or_more: checkExpression,
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action: checkExpression,
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rule_ref:
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function(node, appliedRules) {
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if (PEG.ArrayUtils.contains(appliedRules, node.name)) {
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throw new PEG.Grammar.GrammarError(
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"Left recursion detected for rule \"" + node.name + "\"."
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);
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}
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check(ast[node.name], appliedRules);
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},
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literal: nop,
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any: nop,
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"class": nop
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};
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function check(node, appliedRules) {
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checkFunctions[node.type](node, appliedRules);
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}
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for (var rule in ast) {
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ast[rule].checkNoLeftRecursion(ast, []);
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check(ast[rule], []);
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}
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}
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],
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