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Report left recursion and infinite loops only as "possible"

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A semantic predicate can prevent the parser to actually enter infinite
recursion or loop. This is undetectable at compile-time.
This commit is contained in:
David Majda 2015-09-11 14:58:53 +02:00
parent ebf5d969b2
commit 491106c347
4 changed files with 7 additions and 7 deletions
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4
lib/compiler/passes/report-infinite-loops.js
View file

@ -12,13 +12,13 @@ function reportInfiniteLoops(ast) {
var check = visitor.build({ var check = visitor.build({
zero_or_more: function(node) { zero_or_more: function(node) {
if (!asts.alwaysConsumesOnSuccess(ast, node.expression)) { if (!asts.alwaysConsumesOnSuccess(ast, node.expression)) {
throw new GrammarError("Infinite loop detected.", node.location); throw new GrammarError("Possible infinite loop detected.", node.location);
} }
}, },
one_or_more: function(node) { one_or_more: function(node) {
if (!asts.alwaysConsumesOnSuccess(ast, node.expression)) { if (!asts.alwaysConsumesOnSuccess(ast, node.expression)) {
throw new GrammarError("Infinite loop detected.", node.location); throw new GrammarError("Possible infinite loop detected.", node.location);
} }
} }
}); });

2
lib/compiler/passes/report-left-recursion.js
View file

@ -38,7 +38,7 @@ function reportLeftRecursion(ast) {
rule_ref: function(node) { rule_ref: function(node) {
if (arrays.contains(visitedRules, node.name)) { if (arrays.contains(visitedRules, node.name)) {
throw new GrammarError( throw new GrammarError(
"Left recursion detected for rule \"" + node.name + "\".", "Possible left recursion detected for rule \"" + node.name + "\".",
node.location node.location
); );
} }

4
spec/unit/compiler/passes/report-infinite-loops.spec.js
View file

@ -8,7 +8,7 @@ describe("compiler pass |reportInfiniteLoops|", function() {
it("reports infinite loops for zero_or_more", function() { it("reports infinite loops for zero_or_more", function() {
expect(pass).toReportError('start = ("")*', { expect(pass).toReportError('start = ("")*', {
message: "Infinite loop detected.", message: "Possible infinite loop detected.",
location: { location: {
start: { offset: 8, line: 1, column: 9 }, start: { offset: 8, line: 1, column: 9 },
end: { offset: 13, line: 1, column: 14 } end: { offset: 13, line: 1, column: 14 }
@ -18,7 +18,7 @@ describe("compiler pass |reportInfiniteLoops|", function() {
it("reports infinite loops for one_or_more", function() { it("reports infinite loops for one_or_more", function() {
expect(pass).toReportError('start = ("")+', { expect(pass).toReportError('start = ("")+', {
message: "Infinite loop detected.", message: "Possible infinite loop detected.",
location: { location: {
start: { offset: 8, line: 1, column: 9 }, start: { offset: 8, line: 1, column: 9 },
end: { offset: 13, line: 1, column: 14 } end: { offset: 13, line: 1, column: 14 }

4
spec/unit/compiler/passes/report-left-recursion.spec.js
View file

@ -8,7 +8,7 @@ describe("compiler pass |reportLeftRecursion|", function() {
it("reports direct left recursion", function() { it("reports direct left recursion", function() {
expect(pass).toReportError('start = start', { expect(pass).toReportError('start = start', {
message: 'Left recursion detected for rule \"start\".', message: 'Possible left recursion detected for rule \"start\".',
location: { location: {
start: { offset: 8, line: 1, column: 9 }, start: { offset: 8, line: 1, column: 9 },
end: { offset: 13, line: 1, column: 14 } end: { offset: 13, line: 1, column: 14 }
@ -21,7 +21,7 @@ describe("compiler pass |reportLeftRecursion|", function() {
'start = stop', 'start = stop',
'stop = start' 'stop = start'
].join("\n"), { ].join("\n"), {
message: 'Left recursion detected for rule \"start\".', message: 'Possible left recursion detected for rule \"start\".',
location: { location: {
start: { offset: 21, line: 2, column: 9 }, start: { offset: 21, line: 2, column: 9 },
end: { offset: 26, line: 2, column: 14 } end: { offset: 26, line: 2, column: 14 }