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isAritySmaller runs later: getNonGenericSignature

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Nathan Shively-Sanders 2016-10-28 08:57:19 -07:00
parent 2c09574f18
commit a163641bd3
1 changed files with 20 additions and 28 deletions
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48
src/compiler/checker.ts
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@ -10299,16 +10299,32 @@ namespace ts {
// If the given type is an object or union type, if that type has a single signature, and if
// that signature is non-generic, return the signature. Otherwise return undefined.
function getNonGenericSignature(type: Type): Signature {
function getNonGenericSignature(type: Type, node: FunctionExpression | ArrowFunction | MethodDeclaration): Signature {
const signatures = getSignaturesOfStructuredType(type, SignatureKind.Call);
if (signatures.length === 1) {
const signature = signatures[0];
if (!signature.typeParameters) {
if (!signature.typeParameters && !isAritySmaller(signature, node)) {
return signature;
}
}
}
/** If the contextual signature has fewer parameters than the function expression, do not use it */
function isAritySmaller(signature: Signature, target: FunctionExpression | ArrowFunction | MethodDeclaration) {
let targetParameterCount = 0;
for (; targetParameterCount < target.parameters.length; targetParameterCount++) {
const param = target.parameters[targetParameterCount];
if (param.initializer || param.questionToken || param.dotDotDotToken || isJSDocOptionalParameter(param)) {
break;
}
}
if (target.parameters.length && parameterIsThisKeyword(target.parameters[0])) {
targetParameterCount--;
}
const sourceLength = signature.hasRestParameter ? Number.MAX_VALUE : signature.parameters.length;
return sourceLength < targetParameterCount;
}
function isFunctionExpressionOrArrowFunction(node: Node): node is FunctionExpression | ArrowFunction {
return node.kind === SyntaxKind.FunctionExpression || node.kind === SyntaxKind.ArrowFunction;
}
@ -10337,17 +10353,13 @@ namespace ts {
if (!type) {
return undefined;
}
// If the contextual signature has fewer parameters than the function expression, do not use it
if (isFunctionExpressionOrArrowFunction(node) && isAritySmaller(type, node)) {
return undefined;
}
if (!(type.flags & TypeFlags.Union)) {
return getNonGenericSignature(type);
return getNonGenericSignature(type, node);
}
let signatureList: Signature[];
const types = (<UnionType>type).types;
for (const current of types) {
const signature = getNonGenericSignature(current);
const signature = getNonGenericSignature(current, node);
if (signature) {
if (!signatureList) {
// This signature will contribute to contextual union signature
@ -10375,26 +10387,6 @@ namespace ts {
return result;
}
function isAritySmaller(sourceType: Type, target: FunctionExpression | ArrowFunction) {
if (isFunctionType(sourceType)) {
let targetParameterCount = 0;
for (; targetParameterCount < target.parameters.length; targetParameterCount++) {
const param = target.parameters[targetParameterCount];
if (param.initializer || param.questionToken || param.dotDotDotToken || isJSDocOptionalParameter(param)) {
break;
}
}
if (target.parameters.length && parameterIsThisKeyword(target.parameters[0])) {
targetParameterCount--;
}
const sourceSignatures = getSignaturesOfType(sourceType, SignatureKind.Call);
const sourceLengths = sourceSignatures.map(sig => !sig.hasRestParameter ? sig.parameters.length : Number.MAX_VALUE);
return forEach(sourceLengths, len => len < targetParameterCount);
}
return false;
}
/**
* Detect if the mapper implies an inference context. Specifically, there are 4 possible values
* for a mapper. Let's go through each one of them: