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Simplify return type parsing #18206

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Merged
2 commits merged into from
Sep 1, 2017
Merged

Simplify return type parsing #18206

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1622b7f
Simplify return type parsing
Sep 1, 2017
f426374
Make control flow clearer
Sep 1, 2017
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4 changes: 1 addition & 3 deletions src/compiler/core.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1316,14 +1316,12 @@ namespace ts {

export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage, ...args: (string | number)[]): Diagnostic;
export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage): Diagnostic {
const end = start + length;

Debug.assertGreaterThanOrEqual(start, 0);
Debug.assertGreaterThanOrEqual(length, 0);

if (file) {
Debug.assertLessThanOrEqual(start, file.text.length);
Debug.assertLessThanOrEqual(end, file.text.length);
Debug.assertLessThanOrEqual(start + length, file.text.length);
}

let text = getLocaleSpecificMessage(message);
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30 changes: 16 additions & 14 deletions src/compiler/parser.ts
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Expand Up @@ -2290,25 +2290,27 @@ namespace ts {
signature.typeParameters = parseTypeParameters();
}
signature.parameters = parseParameterList(flags);
signature.type = parseReturnType(returnToken, !!(flags & SignatureFlags.Type));
}

const returnTokenRequired = returnToken === SyntaxKind.EqualsGreaterThanToken;
if (returnTokenRequired) {
function parseReturnType(returnToken: SyntaxKind.ColonToken | SyntaxKind.EqualsGreaterThanToken, isType: boolean): TypeNode | undefined {
return shouldParseReturnType(returnToken, isType) ? parseTypeOrTypePredicate() : undefined;
}
function shouldParseReturnType(returnToken: SyntaxKind.ColonToken | SyntaxKind.EqualsGreaterThanToken, isType: boolean): boolean {
if (returnToken === SyntaxKind.EqualsGreaterThanToken) {
parseExpected(returnToken);
signature.type = parseTypeOrTypePredicate();
return true;
}
else if (parseOptional(returnToken)) {
signature.type = parseTypeOrTypePredicate();
else if (parseOptional(SyntaxKind.ColonToken)) {
return true;
}
else if (flags & SignatureFlags.Type) {
const start = scanner.getTokenPos();
const length = scanner.getTextPos() - start;
const backwardToken = parseOptional(returnToken === SyntaxKind.ColonToken ? SyntaxKind.EqualsGreaterThanToken : SyntaxKind.ColonToken);
if (backwardToken) {
// This is easy to get backward, especially in type contexts, so parse the type anyway
signature.type = parseTypeOrTypePredicate();
parseErrorAtPosition(start, length, Diagnostics._0_expected, tokenToString(returnToken));
}
else if (isType && token() === SyntaxKind.EqualsGreaterThanToken) {
// This is easy to get backward, especially in type contexts, so parse the type anyway
parseErrorAtCurrentToken(Diagnostics._0_expected, tokenToString(SyntaxKind.ColonToken));
nextToken();
return true;
}
return false;
}

function parseParameterList(flags: SignatureFlags) {
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2 changes: 1 addition & 1 deletion src/compiler/types.ts
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Expand Up @@ -668,7 +668,7 @@ namespace ts {
name?: PropertyName;
typeParameters?: NodeArray<TypeParameterDeclaration>;
parameters: NodeArray<ParameterDeclaration>;
type?: TypeNode;
type: TypeNode | undefined;
}

export interface CallSignatureDeclaration extends SignatureDeclaration, TypeElement {
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