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Correct partial signature matching

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This commit is contained in:
Anders Hejlsberg
2015-10-29 14:53:14 -07:00
parent 067e1ccef2
commit c5b47fb5c8
1 changed files with 19 additions and 8 deletions
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27
src/compiler/checker.ts
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@@ -5603,18 +5603,29 @@ namespace ts {
return compareTypes(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp));
}
// A source signature matches a target signature if the two signatures have the same number of required,
// optional, and rest parameters.
function isMatchingSignature(source: Signature, target: Signature) {
return source.parameters.length === target.parameters.length &&
source.minArgumentCount === target.minArgumentCount &&
source.hasRestParameter === target.hasRestParameter;
}
// A source signature partially matches a target signature if the target signature has no fewer required
// parameters and no more overall parameters than the source signature (where a signature with a rest
// parameter is always considered to have more overall parameters than one without).
function isPartiallyMatchingSignature(source: Signature, target: Signature) {
return source.minArgumentCount <= target.minArgumentCount && (
source.hasRestParameter && !target.hasRestParameter ||
source.hasRestParameter === target.hasRestParameter && source.parameters.length >= target.parameters.length);
}
function compareSignatures(source: Signature, target: Signature, partialMatch: boolean, ignoreReturnTypes: boolean, compareTypes: (s: Type, t: Type) => Ternary): Ternary {
if (source === target) {
return Ternary.True;
}
if (source.parameters.length !== target.parameters.length ||
source.minArgumentCount !== target.minArgumentCount ||
source.hasRestParameter !== target.hasRestParameter) {
if (!partialMatch ||
source.parameters.length < target.parameters.length && !source.hasRestParameter ||
source.minArgumentCount > target.minArgumentCount) {
return Ternary.False;
}
if (!(isMatchingSignature(source, target) || partialMatch && isPartiallyMatchingSignature(source, target))) {
return Ternary.False;
}
let result = Ternary.True;
if (source.typeParameters && target.typeParameters) {