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Support 'asserts this' and 'asserts this is T' type predicates

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This commit is contained in:
Anders Hejlsberg 2019-08-17 06:23:07 -07:00
parent 9791f1d28f
commit 0599f84857
3 changed files with 31 additions and 21 deletions
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34
src/compiler/checker.ts
View File

@ -4228,8 +4228,10 @@ namespace ts {
let returnTypeNode: TypeNode | undefined;
const typePredicate = getTypePredicateOfSignature(signature);
if (typePredicate) {
const assertsModifier = typePredicate.kind === TypePredicateKind.Assertion ? createToken(SyntaxKind.AssertsKeyword) : undefined;
const parameterName = typePredicate.kind !== TypePredicateKind.This ?
const assertsModifier = typePredicate.kind === TypePredicateKind.AssertsThis || typePredicate.kind === TypePredicateKind.AssertsIdentifier ?
createToken(SyntaxKind.AssertsKeyword) :
undefined;
const parameterName = typePredicate.kind === TypePredicateKind.Identifier || typePredicate.kind === TypePredicateKind.AssertsIdentifier ?
setEmitFlags(createIdentifier(typePredicate.parameterName), EmitFlags.NoAsciiEscaping) :
createThisTypeNode();
const typeNode = typePredicate.type && typeToTypeNodeHelper(typePredicate.type, context);
@ -4702,8 +4704,8 @@ namespace ts {
function typePredicateToStringWorker(writer: EmitTextWriter) {
const predicate = createTypePredicateNode(
typePredicate.kind === TypePredicateKind.Assertion ? createToken(SyntaxKind.AssertsKeyword) : undefined,
typePredicate.kind !== TypePredicateKind.This ? createIdentifier(typePredicate.parameterName) : createThisTypeNode(),
typePredicate.kind === TypePredicateKind.AssertsThis || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? createToken(SyntaxKind.AssertsKeyword) : undefined,
typePredicate.kind === TypePredicateKind.Identifier || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? createIdentifier(typePredicate.parameterName) : createThisTypeNode(),
typePredicate.type && nodeBuilder.typeToTypeNode(typePredicate.type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName)! // TODO: GH#18217
);
const printer = createPrinter({ removeComments: true });
@ -8721,8 +8723,8 @@ namespace ts {
const parameterName = node.parameterName;
const type = node.type && getTypeFromTypeNode(node.type);
return parameterName.kind === SyntaxKind.ThisType ?
createTypePredicate(TypePredicateKind.This, /*parameterName*/ undefined, /*parameterIndex*/ undefined, type) :
createTypePredicate(node.assertsModifier ? TypePredicateKind.Assertion : TypePredicateKind.Identifier, parameterName.escapedText as string,
createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsThis : TypePredicateKind.This, /*parameterName*/ undefined, /*parameterIndex*/ undefined, type) :
createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsIdentifier : TypePredicateKind.Identifier, parameterName.escapedText as string,
findIndex(signature.parameters, p => p.escapedName === parameterName.escapedText), type);
}
@ -9829,7 +9831,7 @@ namespace ts {
const types: Type[] = [];
for (const sig of signatures) {
const pred = getTypePredicateOfSignature(sig);
if (!pred || pred.kind === TypePredicateKind.Assertion) {
if (!pred || pred.kind === TypePredicateKind.AssertsThis || pred.kind === TypePredicateKind.AssertsIdentifier) {
continue;
}
@ -12400,7 +12402,7 @@ namespace ts {
return Ternary.False;
}
if (source.kind !== TypePredicateKind.This) {
if (source.kind === TypePredicateKind.Identifier || source.kind === TypePredicateKind.AssertsIdentifier) {
if (source.parameterIndex !== (target as IdentifierTypePredicate).parameterIndex) {
if (reportErrors) {
errorReporter!(Diagnostics.Parameter_0_is_not_in_the_same_position_as_parameter_1, source.parameterName, (target as IdentifierTypePredicate).parameterName);
@ -17119,12 +17121,12 @@ namespace ts {
const signature = getEffectsSignature(flow.node);
if (signature) {
const predicate = getTypePredicateOfSignature(signature);
if (predicate && predicate.kind === TypePredicateKind.Assertion) {
if (predicate && (predicate.kind === TypePredicateKind.AssertsThis || predicate.kind === TypePredicateKind.AssertsIdentifier)) {
const flowType = getTypeAtFlowNode(flow.antecedent);
const type = getTypeFromFlowType(flowType);
const narrowedType = predicate.type ?
narrowTypeByTypePredicate(type, predicate, flow.node, /*assumeTrue*/ true) :
narrowTypeByAssertion(type, flow.node.arguments[predicate.parameterIndex]);
const narrowedType = predicate.type ? narrowTypeByTypePredicate(type, predicate, flow.node, /*assumeTrue*/ true) :
predicate.kind === TypePredicateKind.AssertsIdentifier ? narrowTypeByAssertion(type, flow.node.arguments[predicate.parameterIndex]) :
type;
return narrowedType === type ? flowType : createFlowType(narrowedType, isIncomplete(flowType));
}
if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) {
@ -17721,7 +17723,7 @@ namespace ts {
if (hasMatchingArgument(callExpression, reference)) {
const signature = getEffectsSignature(callExpression);
const predicate = signature && getTypePredicateOfSignature(signature);
if (predicate && predicate.kind !== TypePredicateKind.Assertion) {
if (predicate && (predicate.kind === TypePredicateKind.This || predicate.kind === TypePredicateKind.Identifier)) {
return narrowTypeByTypePredicate(type, predicate, callExpression, assumeTrue);
}
}
@ -17733,7 +17735,7 @@ namespace ts {
if (isTypeAny(type) && (predicate.type === globalObjectType || predicate.type === globalFunctionType)) {
return type;
}
if (predicate.kind !== TypePredicateKind.This) {
if (predicate.kind === TypePredicateKind.Identifier || predicate.kind === TypePredicateKind.AssertsIdentifier) {
const predicateArgument = callExpression.arguments[predicate.parameterIndex];
if (predicateArgument && predicate.type) {
if (isMatchingReference(reference, predicateArgument)) {
@ -17746,7 +17748,7 @@ namespace ts {
}
else {
const invokedExpression = skipParentheses(callExpression.expression);
if (isAccessExpression(invokedExpression)) {
if (isAccessExpression(invokedExpression) && predicate.type) {
const possibleReference = skipParentheses(invokedExpression.expression);
if (isMatchingReference(reference, possibleReference)) {
return getNarrowedType(type, predicate.type, assumeTrue, isTypeSubtypeOf);
@ -25501,7 +25503,7 @@ namespace ts {
checkSourceElement(node.type);
const { parameterName } = node;
if (isThisTypePredicate(typePredicate)) {
if (typePredicate.kind === TypePredicateKind.This || typePredicate.kind === TypePredicateKind.AssertsThis) {
getTypeFromThisTypeNode(parameterName as ThisTypeNode);
}
else {

2
src/compiler/parser.ts
View File

@ -3258,7 +3258,7 @@ namespace ts {
function parseAssertsTypePredicate(): TypeNode {
const node = <TypePredicateNode>createNode(SyntaxKind.TypePredicate);
node.assertsModifier = parseExpectedToken(SyntaxKind.AssertsKeyword);
node.parameterName = parseIdentifier();
node.parameterName = token() === SyntaxKind.ThisKeyword ? parseThisTypeNode() : parseIdentifier();
node.type = parseOptional(SyntaxKind.IsKeyword) ? parseType() : undefined;
return finishNode(node);
}

16
src/compiler/types.ts
View File

@ -3514,7 +3514,8 @@ namespace ts {
export const enum TypePredicateKind {
This,
Identifier,
Assertion
AssertsThis,
AssertsIdentifier
}
export interface ThisTypePredicate {
@ -3531,14 +3532,21 @@ namespace ts {
type: Type;
}
export interface AssertionTypePredicate {
kind: TypePredicateKind.Assertion;
export interface AssertsThisTypePredicate {
kind: TypePredicateKind.AssertsThis;
parameterName: undefined;
parameterIndex: undefined;
type: Type | undefined;
}
export interface AssertsIdentifierTypePredicate {
kind: TypePredicateKind.AssertsIdentifier;
parameterName: string;
parameterIndex: number;
type: Type | undefined;
}
export type TypePredicate = ThisTypePredicate | IdentifierTypePredicate | AssertionTypePredicate;
export type TypePredicate = ThisTypePredicate | IdentifierTypePredicate | AssertsThisTypePredicate | AssertsIdentifierTypePredicate;
/* @internal */
export type AnyImportSyntax = ImportDeclaration | ImportEqualsDeclaration;