5e146fce38
Implement a new syntax to extract matched strings from expressions. For
example, instead of:
identifier = first:[a-zA-Z_] rest:[a-zA-Z0-9_]* { return first + rest.join(""); }
you can now just write:
identifier = $([a-zA-Z_] [a-zA-Z0-9_]*)
This is useful mostly for "lexical" rules at the bottom of many
grammars.
Note that structured match results are still built for the expressions
prefixed by "$", they are just ignored. I plan to optimize this later
(sometime after the code generator rewrite).
97 lines
3 KiB
JavaScript
97 lines
3 KiB
JavaScript
describe("compiler pass |reportLeftRecursion|", function() {
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var pass = PEG.compiler.passes.reportLeftRecursion;
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beforeEach(function() {
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this.addMatchers({
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toReportLeftRecursionIn: function(grammar) {
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var ast = PEG.parser.parse(grammar);
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try {
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this.actual(ast);
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this.message = function() {
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return "Expected the pass to report left recursion for grammar "
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+ jasmine.pp(grammar) + ", "
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+ "but it didn't.";
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};
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return false;
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} catch (e) {
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if (this.isNot) {
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this.message = function() {
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return "Expected the pass not to report left recursion for grammar "
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+ jasmine.pp(grammar) + ", "
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+ "but it did.";
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};
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} else {
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this.message = function() {
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return "Expected the pass to report left recursion for grammar "
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+ jasmine.pp(grammar) + ", "
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+ "but it reported an error with message "
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+ jasmine.pp(e.message) + ".";
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};
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}
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return e.message === 'Left recursion detected for rule \"start\".';
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}
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}
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});
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});
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it("reports left recursion inside a rule", function() {
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expect(pass).toReportLeftRecursionIn('start = start');
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});
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it("reports left recursion inside a named", function() {
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expect(pass).toReportLeftRecursionIn('start "start" = start');
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});
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it("reports left recursion inside a choice", function() {
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expect(pass).toReportLeftRecursionIn('start = start / "a" / "b"');
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expect(pass).toReportLeftRecursionIn('start = "a" / "b" / start');
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});
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it("reports left recursion inside an action", function() {
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expect(pass).toReportLeftRecursionIn('start = start { }');
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});
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it("reports left recursion inside a sequence", function() {
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expect(pass).toReportLeftRecursionIn('start = start "a" "b"');
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});
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it("reports left recursion inside a labeled", function() {
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expect(pass).toReportLeftRecursionIn('start = label:start');
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});
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it("reports left recursion inside a text", function() {
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expect(pass).toReportLeftRecursionIn('start = $start');
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});
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it("reports left recursion inside a simple and", function() {
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expect(pass).toReportLeftRecursionIn('start = &start');
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});
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it("reports left recursion inside a simple not", function() {
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expect(pass).toReportLeftRecursionIn('start = &start');
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});
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it("reports left recursion inside an optional", function() {
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expect(pass).toReportLeftRecursionIn('start = start?');
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});
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it("reports left recursion inside a zero or more", function() {
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expect(pass).toReportLeftRecursionIn('start = start*');
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});
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it("reports left recursion inside a one or more", function() {
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expect(pass).toReportLeftRecursionIn('start = start+');
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});
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it("reports indirect left recursion", function() {
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expect(pass).toReportLeftRecursionIn([
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'start = stop',
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'stop = start'
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].join("\n"));
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});
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});
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