TypeScript/src/services/signatureHelp.ts
Eli Barzilay 5ca7983ebe Fix the code that checks for variadic signatures
This code looks strange, like there's a typo in it (eg, using `lists` in
the `parameterList` loop, etc) -- so I also refactored it a bit to look
more intentional.  The new format makes it clearer that `lists` is
checked once *outside* the loop, as well as the role of
`hasEffectiveRestParameter`.

The actual bug fix is checking `pList.length` in the new `isVariadic()`.

Fixes 41059.
2021-05-20 09:27:57 -04:00

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/* @internal */
namespace ts.SignatureHelp {
const enum InvocationKind { Call, TypeArgs, Contextual }
interface CallInvocation { readonly kind: InvocationKind.Call; readonly node: CallLikeExpression; }
interface TypeArgsInvocation { readonly kind: InvocationKind.TypeArgs; readonly called: Identifier; }
interface ContextualInvocation {
readonly kind: InvocationKind.Contextual;
readonly signature: Signature;
readonly node: Node; // Just for enclosingDeclaration for printing types
readonly symbol: Symbol;
}
type Invocation = CallInvocation | TypeArgsInvocation | ContextualInvocation;
interface ArgumentListInfo {
readonly isTypeParameterList: boolean;
readonly invocation: Invocation;
readonly argumentsSpan: TextSpan;
readonly argumentIndex: number;
/** argumentCount is the *apparent* number of arguments. */
readonly argumentCount: number;
}
export function getSignatureHelpItems(program: Program, sourceFile: SourceFile, position: number, triggerReason: SignatureHelpTriggerReason | undefined, cancellationToken: CancellationToken): SignatureHelpItems | undefined {
const typeChecker = program.getTypeChecker();
// Decide whether to show signature help
const startingToken = findTokenOnLeftOfPosition(sourceFile, position);
if (!startingToken) {
// We are at the beginning of the file
return undefined;
}
// Only need to be careful if the user typed a character and signature help wasn't showing.
const onlyUseSyntacticOwners = !!triggerReason && triggerReason.kind === "characterTyped";
// Bail out quickly in the middle of a string or comment, don't provide signature help unless the user explicitly requested it.
if (onlyUseSyntacticOwners && (isInString(sourceFile, position, startingToken) || isInComment(sourceFile, position))) {
return undefined;
}
const isManuallyInvoked = !!triggerReason && triggerReason.kind === "invoked";
const argumentInfo = getContainingArgumentInfo(startingToken, position, sourceFile, typeChecker, isManuallyInvoked);
if (!argumentInfo) return undefined;
cancellationToken.throwIfCancellationRequested();
// Extra syntactic and semantic filtering of signature help
const candidateInfo = getCandidateOrTypeInfo(argumentInfo, typeChecker, sourceFile, startingToken, onlyUseSyntacticOwners);
cancellationToken.throwIfCancellationRequested();
if (!candidateInfo) {
// We didn't have any sig help items produced by the TS compiler. If this is a JS
// file, then see if we can figure out anything better.
return isSourceFileJS(sourceFile) ? createJSSignatureHelpItems(argumentInfo, program, cancellationToken) : undefined;
}
return typeChecker.runWithCancellationToken(cancellationToken, typeChecker =>
candidateInfo.kind === CandidateOrTypeKind.Candidate
? createSignatureHelpItems(candidateInfo.candidates, candidateInfo.resolvedSignature, argumentInfo, sourceFile, typeChecker)
: createTypeHelpItems(candidateInfo.symbol, argumentInfo, sourceFile, typeChecker));
}
const enum CandidateOrTypeKind { Candidate, Type }
interface CandidateInfo {
readonly kind: CandidateOrTypeKind.Candidate;
readonly candidates: readonly Signature[];
readonly resolvedSignature: Signature;
}
interface TypeInfo {
readonly kind: CandidateOrTypeKind.Type;
readonly symbol: Symbol;
}
function getCandidateOrTypeInfo({ invocation, argumentCount }: ArgumentListInfo, checker: TypeChecker, sourceFile: SourceFile, startingToken: Node, onlyUseSyntacticOwners: boolean): CandidateInfo | TypeInfo | undefined {
switch (invocation.kind) {
case InvocationKind.Call: {
if (onlyUseSyntacticOwners && !isSyntacticOwner(startingToken, invocation.node, sourceFile)) {
return undefined;
}
const candidates: Signature[] = [];
const resolvedSignature = checker.getResolvedSignatureForSignatureHelp(invocation.node, candidates, argumentCount)!; // TODO: GH#18217
return candidates.length === 0 ? undefined : { kind: CandidateOrTypeKind.Candidate, candidates, resolvedSignature };
}
case InvocationKind.TypeArgs: {
const { called } = invocation;
if (onlyUseSyntacticOwners && !containsPrecedingToken(startingToken, sourceFile, isIdentifier(called) ? called.parent : called)) {
return undefined;
}
const candidates = getPossibleGenericSignatures(called, argumentCount, checker);
if (candidates.length !== 0) return { kind: CandidateOrTypeKind.Candidate, candidates, resolvedSignature: first(candidates) };
const symbol = checker.getSymbolAtLocation(called);
return symbol && { kind: CandidateOrTypeKind.Type, symbol };
}
case InvocationKind.Contextual:
return { kind: CandidateOrTypeKind.Candidate, candidates: [invocation.signature], resolvedSignature: invocation.signature };
default:
return Debug.assertNever(invocation);
}
}
function isSyntacticOwner(startingToken: Node, node: CallLikeExpression, sourceFile: SourceFile): boolean {
if (!isCallOrNewExpression(node)) return false;
const invocationChildren = node.getChildren(sourceFile);
switch (startingToken.kind) {
case SyntaxKind.OpenParenToken:
return contains(invocationChildren, startingToken);
case SyntaxKind.CommaToken: {
const containingList = findContainingList(startingToken);
return !!containingList && contains(invocationChildren, containingList);
}
case SyntaxKind.LessThanToken:
return containsPrecedingToken(startingToken, sourceFile, node.expression);
default:
return false;
}
}
function createJSSignatureHelpItems(argumentInfo: ArgumentListInfo, program: Program, cancellationToken: CancellationToken): SignatureHelpItems | undefined {
if (argumentInfo.invocation.kind === InvocationKind.Contextual) return undefined;
// See if we can find some symbol with the call expression name that has call signatures.
const expression = getExpressionFromInvocation(argumentInfo.invocation);
const name = isPropertyAccessExpression(expression) ? expression.name.text : undefined;
const typeChecker = program.getTypeChecker();
return name === undefined ? undefined : firstDefined(program.getSourceFiles(), sourceFile =>
firstDefined(sourceFile.getNamedDeclarations().get(name), declaration => {
const type = declaration.symbol && typeChecker.getTypeOfSymbolAtLocation(declaration.symbol, declaration);
const callSignatures = type && type.getCallSignatures();
if (callSignatures && callSignatures.length) {
return typeChecker.runWithCancellationToken(
cancellationToken,
typeChecker => createSignatureHelpItems(
callSignatures,
callSignatures[0],
argumentInfo,
sourceFile,
typeChecker,
/*useFullPrefix*/ true));
}
}));
}
function containsPrecedingToken(startingToken: Node, sourceFile: SourceFile, container: Node) {
const pos = startingToken.getFullStart();
// Theres a possibility that `startingToken.parent` contains only `startingToken` and
// missing nodes, none of which are valid to be returned by `findPrecedingToken`. In that
// case, the preceding token we want is actually higher up the tree—almost definitely the
// next parent, but theoretically the situation with missing nodes might be happening on
// multiple nested levels.
let currentParent: Node | undefined = startingToken.parent;
while (currentParent) {
const precedingToken = findPrecedingToken(pos, sourceFile, currentParent, /*excludeJsdoc*/ true);
if (precedingToken) {
return rangeContainsRange(container, precedingToken);
}
currentParent = currentParent.parent;
}
return Debug.fail("Could not find preceding token");
}
export interface ArgumentInfoForCompletions {
readonly invocation: CallLikeExpression;
readonly argumentIndex: number;
readonly argumentCount: number;
}
export function getArgumentInfoForCompletions(node: Node, position: number, sourceFile: SourceFile): ArgumentInfoForCompletions | undefined {
const info = getImmediatelyContainingArgumentInfo(node, position, sourceFile);
return !info || info.isTypeParameterList || info.invocation.kind !== InvocationKind.Call ? undefined
: { invocation: info.invocation.node, argumentCount: info.argumentCount, argumentIndex: info.argumentIndex };
}
function getArgumentOrParameterListInfo(node: Node, sourceFile: SourceFile): { readonly list: Node, readonly argumentIndex: number, readonly argumentCount: number, readonly argumentsSpan: TextSpan } | undefined {
const info = getArgumentOrParameterListAndIndex(node, sourceFile);
if (!info) return undefined;
const { list, argumentIndex } = info;
const argumentCount = getArgumentCount(list);
if (argumentIndex !== 0) {
Debug.assertLessThan(argumentIndex, argumentCount);
}
const argumentsSpan = getApplicableSpanForArguments(list, sourceFile);
return { list, argumentIndex, argumentCount, argumentsSpan };
}
function getArgumentOrParameterListAndIndex(node: Node, sourceFile: SourceFile): { readonly list: Node, readonly argumentIndex: number } | undefined {
if (node.kind === SyntaxKind.LessThanToken || node.kind === SyntaxKind.OpenParenToken) {
// Find the list that starts right *after* the < or ( token.
// If the user has just opened a list, consider this item 0.
return { list: getChildListThatStartsWithOpenerToken(node.parent, node, sourceFile), argumentIndex: 0 };
}
else {
// findListItemInfo can return undefined if we are not in parent's argument list
// or type argument list. This includes cases where the cursor is:
// - To the right of the closing parenthesis, non-substitution template, or template tail.
// - Between the type arguments and the arguments (greater than token)
// - On the target of the call (parent.func)
// - On the 'new' keyword in a 'new' expression
const list = findContainingList(node);
return list && { list, argumentIndex: getArgumentIndex(list, node) };
}
}
/**
* Returns relevant information for the argument list and the current argument if we are
* in the argument of an invocation; returns undefined otherwise.
*/
function getImmediatelyContainingArgumentInfo(node: Node, position: number, sourceFile: SourceFile): ArgumentListInfo | undefined {
const { parent } = node;
if (isCallOrNewExpression(parent)) {
const invocation = parent;
// There are 3 cases to handle:
// 1. The token introduces a list, and should begin a signature help session
// 2. The token is either not associated with a list, or ends a list, so the session should end
// 3. The token is buried inside a list, and should give signature help
//
// The following are examples of each:
//
// Case 1:
// foo<#T, U>(#a, b) -> The token introduces a list, and should begin a signature help session
// Case 2:
// fo#o<T, U>#(a, b)# -> The token is either not associated with a list, or ends a list, so the session should end
// Case 3:
// foo<T#, U#>(a#, #b#) -> The token is buried inside a list, and should give signature help
// Find out if 'node' is an argument, a type argument, or neither
const info = getArgumentOrParameterListInfo(node, sourceFile);
if (!info) return undefined;
const { list, argumentIndex, argumentCount, argumentsSpan } = info;
const isTypeParameterList = !!parent.typeArguments && parent.typeArguments.pos === list.pos;
return { isTypeParameterList, invocation: { kind: InvocationKind.Call, node: invocation }, argumentsSpan, argumentIndex, argumentCount };
}
else if (isNoSubstitutionTemplateLiteral(node) && isTaggedTemplateExpression(parent)) {
// Check if we're actually inside the template;
// otherwise we'll fall out and return undefined.
if (isInsideTemplateLiteral(node, position, sourceFile)) {
return getArgumentListInfoForTemplate(parent, /*argumentIndex*/ 0, sourceFile);
}
return undefined;
}
else if (isTemplateHead(node) && parent.parent.kind === SyntaxKind.TaggedTemplateExpression) {
const templateExpression = parent as TemplateExpression;
const tagExpression = templateExpression.parent as TaggedTemplateExpression;
Debug.assert(templateExpression.kind === SyntaxKind.TemplateExpression);
const argumentIndex = isInsideTemplateLiteral(node, position, sourceFile) ? 0 : 1;
return getArgumentListInfoForTemplate(tagExpression, argumentIndex, sourceFile);
}
else if (isTemplateSpan(parent) && isTaggedTemplateExpression(parent.parent.parent)) {
const templateSpan = parent;
const tagExpression = parent.parent.parent;
// If we're just after a template tail, don't show signature help.
if (isTemplateTail(node) && !isInsideTemplateLiteral(node, position, sourceFile)) {
return undefined;
}
const spanIndex = templateSpan.parent.templateSpans.indexOf(templateSpan);
const argumentIndex = getArgumentIndexForTemplatePiece(spanIndex, node, position, sourceFile);
return getArgumentListInfoForTemplate(tagExpression, argumentIndex, sourceFile);
}
else if (isJsxOpeningLikeElement(parent)) {
// Provide a signature help for JSX opening element or JSX self-closing element.
// This is not guarantee that JSX tag-name is resolved into stateless function component. (that is done in "getSignatureHelpItems")
// i.e
// export function MainButton(props: ButtonProps, context: any): JSX.Element { ... }
// <MainButton /*signatureHelp*/
const attributeSpanStart = parent.attributes.pos;
const attributeSpanEnd = skipTrivia(sourceFile.text, parent.attributes.end, /*stopAfterLineBreak*/ false);
return {
isTypeParameterList: false,
invocation: { kind: InvocationKind.Call, node: parent },
argumentsSpan: createTextSpan(attributeSpanStart, attributeSpanEnd - attributeSpanStart),
argumentIndex: 0,
argumentCount: 1
};
}
else {
const typeArgInfo = getPossibleTypeArgumentsInfo(node, sourceFile);
if (typeArgInfo) {
const { called, nTypeArguments } = typeArgInfo;
const invocation: Invocation = { kind: InvocationKind.TypeArgs, called };
const argumentsSpan = createTextSpanFromBounds(called.getStart(sourceFile), node.end);
return { isTypeParameterList: true, invocation, argumentsSpan, argumentIndex: nTypeArguments, argumentCount: nTypeArguments + 1 };
}
return undefined;
}
}
function getImmediatelyContainingArgumentOrContextualParameterInfo(node: Node, position: number, sourceFile: SourceFile, checker: TypeChecker): ArgumentListInfo | undefined {
return tryGetParameterInfo(node, position, sourceFile, checker) || getImmediatelyContainingArgumentInfo(node, position, sourceFile);
}
function getHighestBinary(b: BinaryExpression): BinaryExpression {
return isBinaryExpression(b.parent) ? getHighestBinary(b.parent) : b;
}
function countBinaryExpressionParameters(b: BinaryExpression): number {
return isBinaryExpression(b.left) ? countBinaryExpressionParameters(b.left) + 1 : 2;
}
function tryGetParameterInfo(startingToken: Node, _position: number, sourceFile: SourceFile, checker: TypeChecker): ArgumentListInfo | undefined {
const info = getContextualSignatureLocationInfo(startingToken, sourceFile, checker);
if (!info) return undefined;
const { contextualType, argumentIndex, argumentCount, argumentsSpan } = info;
// for optional function condition.
const nonNullableContextualType = contextualType.getNonNullableType();
const signatures = nonNullableContextualType.getCallSignatures();
if (signatures.length !== 1) return undefined;
const invocation: ContextualInvocation = { kind: InvocationKind.Contextual, signature: first(signatures), node: startingToken, symbol: chooseBetterSymbol(nonNullableContextualType.symbol) };
return { isTypeParameterList: false, invocation, argumentsSpan, argumentIndex, argumentCount };
}
interface ContextualSignatureLocationInfo { readonly contextualType: Type; readonly argumentIndex: number; readonly argumentCount: number; readonly argumentsSpan: TextSpan; }
function getContextualSignatureLocationInfo(startingToken: Node, sourceFile: SourceFile, checker: TypeChecker): ContextualSignatureLocationInfo | undefined {
if (startingToken.kind !== SyntaxKind.OpenParenToken && startingToken.kind !== SyntaxKind.CommaToken) return undefined;
const { parent } = startingToken;
switch (parent.kind) {
case SyntaxKind.ParenthesizedExpression:
case SyntaxKind.MethodDeclaration:
case SyntaxKind.FunctionExpression:
case SyntaxKind.ArrowFunction:
const info = getArgumentOrParameterListInfo(startingToken, sourceFile);
if (!info) return undefined;
const { argumentIndex, argumentCount, argumentsSpan } = info;
const contextualType = isMethodDeclaration(parent) ? checker.getContextualTypeForObjectLiteralElement(parent) : checker.getContextualType(parent as ParenthesizedExpression | FunctionExpression | ArrowFunction);
return contextualType && { contextualType, argumentIndex, argumentCount, argumentsSpan };
case SyntaxKind.BinaryExpression: {
const highestBinary = getHighestBinary(parent as BinaryExpression);
const contextualType = checker.getContextualType(highestBinary);
const argumentIndex = startingToken.kind === SyntaxKind.OpenParenToken ? 0 : countBinaryExpressionParameters(parent as BinaryExpression) - 1;
const argumentCount = countBinaryExpressionParameters(highestBinary);
return contextualType && { contextualType, argumentIndex, argumentCount, argumentsSpan: createTextSpanFromNode(parent) };
}
default:
return undefined;
}
}
// The type of a function type node has a symbol at that node, but it's better to use the symbol for a parameter or type alias.
function chooseBetterSymbol(s: Symbol): Symbol {
return s.name === InternalSymbolName.Type
? firstDefined(s.declarations, d => isFunctionTypeNode(d) ? d.parent.symbol : undefined) || s
: s;
}
function getArgumentIndex(argumentsList: Node, node: Node) {
// The list we got back can include commas. In the presence of errors it may
// also just have nodes without commas. For example "Foo(a b c)" will have 3
// args without commas. We want to find what index we're at. So we count
// forward until we hit ourselves, only incrementing the index if it isn't a
// comma.
//
// Note: the subtlety around trailing commas (in getArgumentCount) does not apply
// here. That's because we're only walking forward until we hit the node we're
// on. In that case, even if we're after the trailing comma, we'll still see
// that trailing comma in the list, and we'll have generated the appropriate
// arg index.
let argumentIndex = 0;
for (const child of argumentsList.getChildren()) {
if (child === node) {
break;
}
if (child.kind !== SyntaxKind.CommaToken) {
argumentIndex++;
}
}
return argumentIndex;
}
function getArgumentCount(argumentsList: Node) {
// The argument count for a list is normally the number of non-comma children it has.
// For example, if you have "Foo(a,b)" then there will be three children of the arg
// list 'a' '<comma>' 'b'. So, in this case the arg count will be 2. However, there
// is a small subtlety. If you have "Foo(a,)", then the child list will just have
// 'a' '<comma>'. So, in the case where the last child is a comma, we increase the
// arg count by one to compensate.
//
// Note: this subtlety only applies to the last comma. If you had "Foo(a,," then
// we'll have: 'a' '<comma>' '<missing>'
// That will give us 2 non-commas. We then add one for the last comma, giving us an
// arg count of 3.
const listChildren = argumentsList.getChildren();
let argumentCount = countWhere(listChildren, arg => arg.kind !== SyntaxKind.CommaToken);
if (listChildren.length > 0 && last(listChildren).kind === SyntaxKind.CommaToken) {
argumentCount++;
}
return argumentCount;
}
// spanIndex is either the index for a given template span.
// This does not give appropriate results for a NoSubstitutionTemplateLiteral
function getArgumentIndexForTemplatePiece(spanIndex: number, node: Node, position: number, sourceFile: SourceFile): number {
// Because the TemplateStringsArray is the first argument, we have to offset each substitution expression by 1.
// There are three cases we can encounter:
// 1. We are precisely in the template literal (argIndex = 0).
// 2. We are in or to the right of the substitution expression (argIndex = spanIndex + 1).
// 3. We are directly to the right of the template literal, but because we look for the token on the left,
// not enough to put us in the substitution expression; we should consider ourselves part of
// the *next* span's expression by offsetting the index (argIndex = (spanIndex + 1) + 1).
//
/* eslint-disable no-double-space */
// Example: f `# abcd $#{# 1 + 1# }# efghi ${ #"#hello"# } # `
// ^ ^ ^ ^ ^ ^ ^ ^ ^
// Case: 1 1 3 2 1 3 2 2 1
/* eslint-enable no-double-space */
Debug.assert(position >= node.getStart(), "Assumed 'position' could not occur before node.");
if (isTemplateLiteralToken(node)) {
if (isInsideTemplateLiteral(node, position, sourceFile)) {
return 0;
}
return spanIndex + 2;
}
return spanIndex + 1;
}
function getArgumentListInfoForTemplate(tagExpression: TaggedTemplateExpression, argumentIndex: number, sourceFile: SourceFile): ArgumentListInfo {
// argumentCount is either 1 or (numSpans + 1) to account for the template strings array argument.
const argumentCount = isNoSubstitutionTemplateLiteral(tagExpression.template) ? 1 : tagExpression.template.templateSpans.length + 1;
if (argumentIndex !== 0) {
Debug.assertLessThan(argumentIndex, argumentCount);
}
return {
isTypeParameterList: false,
invocation: { kind: InvocationKind.Call, node: tagExpression },
argumentsSpan: getApplicableSpanForTaggedTemplate(tagExpression, sourceFile),
argumentIndex,
argumentCount
};
}
function getApplicableSpanForArguments(argumentsList: Node, sourceFile: SourceFile): TextSpan {
// We use full start and skip trivia on the end because we want to include trivia on
// both sides. For example,
//
// foo( /*comment */ a, b, c /*comment*/ )
// | |
//
// The applicable span is from the first bar to the second bar (inclusive,
// but not including parentheses)
const applicableSpanStart = argumentsList.getFullStart();
const applicableSpanEnd = skipTrivia(sourceFile.text, argumentsList.getEnd(), /*stopAfterLineBreak*/ false);
return createTextSpan(applicableSpanStart, applicableSpanEnd - applicableSpanStart);
}
function getApplicableSpanForTaggedTemplate(taggedTemplate: TaggedTemplateExpression, sourceFile: SourceFile): TextSpan {
const template = taggedTemplate.template;
const applicableSpanStart = template.getStart();
let applicableSpanEnd = template.getEnd();
// We need to adjust the end position for the case where the template does not have a tail.
// Otherwise, we will not show signature help past the expression.
// For example,
//
// ` ${ 1 + 1 foo(10)
// | |
// This is because a Missing node has no width. However, what we actually want is to include trivia
// leading up to the next token in case the user is about to type in a TemplateMiddle or TemplateTail.
if (template.kind === SyntaxKind.TemplateExpression) {
const lastSpan = last(template.templateSpans);
if (lastSpan.literal.getFullWidth() === 0) {
applicableSpanEnd = skipTrivia(sourceFile.text, applicableSpanEnd, /*stopAfterLineBreak*/ false);
}
}
return createTextSpan(applicableSpanStart, applicableSpanEnd - applicableSpanStart);
}
function getContainingArgumentInfo(node: Node, position: number, sourceFile: SourceFile, checker: TypeChecker, isManuallyInvoked: boolean): ArgumentListInfo | undefined {
for (let n = node; !isSourceFile(n) && (isManuallyInvoked || !isBlock(n)); n = n.parent) {
// If the node is not a subspan of its parent, this is a big problem.
// There have been crashes that might be caused by this violation.
Debug.assert(rangeContainsRange(n.parent, n), "Not a subspan", () => `Child: ${Debug.formatSyntaxKind(n.kind)}, parent: ${Debug.formatSyntaxKind(n.parent.kind)}`);
const argumentInfo = getImmediatelyContainingArgumentOrContextualParameterInfo(n, position, sourceFile, checker);
if (argumentInfo) {
return argumentInfo;
}
}
return undefined;
}
function getChildListThatStartsWithOpenerToken(parent: Node, openerToken: Node, sourceFile: SourceFile): Node {
const children = parent.getChildren(sourceFile);
const indexOfOpenerToken = children.indexOf(openerToken);
Debug.assert(indexOfOpenerToken >= 0 && children.length > indexOfOpenerToken + 1);
return children[indexOfOpenerToken + 1];
}
function getExpressionFromInvocation(invocation: CallInvocation | TypeArgsInvocation): Expression {
return invocation.kind === InvocationKind.Call ? getInvokedExpression(invocation.node) : invocation.called;
}
function getEnclosingDeclarationFromInvocation(invocation: Invocation): Node {
return invocation.kind === InvocationKind.Call ? invocation.node : invocation.kind === InvocationKind.TypeArgs ? invocation.called : invocation.node;
}
const signatureHelpNodeBuilderFlags = NodeBuilderFlags.OmitParameterModifiers | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope;
function createSignatureHelpItems(
candidates: readonly Signature[],
resolvedSignature: Signature,
{ isTypeParameterList, argumentCount, argumentsSpan: applicableSpan, invocation, argumentIndex }: ArgumentListInfo,
sourceFile: SourceFile,
typeChecker: TypeChecker,
useFullPrefix?: boolean,
): SignatureHelpItems {
const enclosingDeclaration = getEnclosingDeclarationFromInvocation(invocation);
const callTargetSymbol = invocation.kind === InvocationKind.Contextual ? invocation.symbol : (typeChecker.getSymbolAtLocation(getExpressionFromInvocation(invocation)) || useFullPrefix && resolvedSignature.declaration?.symbol);
const callTargetDisplayParts = callTargetSymbol ? symbolToDisplayParts(typeChecker, callTargetSymbol, useFullPrefix ? sourceFile : undefined, /*meaning*/ undefined) : emptyArray;
const items = map(candidates, candidateSignature => getSignatureHelpItem(candidateSignature, callTargetDisplayParts, isTypeParameterList, typeChecker, enclosingDeclaration, sourceFile));
if (argumentIndex !== 0) {
Debug.assertLessThan(argumentIndex, argumentCount);
}
let selectedItemIndex = 0;
let itemsSeen = 0;
for (let i = 0; i < items.length; i++) {
const item = items[i];
if (candidates[i] === resolvedSignature) {
selectedItemIndex = itemsSeen;
if (item.length > 1) {
// check to see if any items in the list better match than the first one, as the checker isn't filtering the nested lists
// (those come from tuple parameter expansion)
let count = 0;
for (const i of item) {
if (i.isVariadic || i.parameters.length >= argumentCount) {
selectedItemIndex = itemsSeen + count;
break;
}
count++;
}
}
}
itemsSeen += item.length;
}
Debug.assert(selectedItemIndex !== -1); // If candidates is non-empty it should always include bestSignature. We check for an empty candidates before calling this function.
const help = { items: flatMapToMutable(items, identity), applicableSpan, selectedItemIndex, argumentIndex, argumentCount };
const selected = help.items[selectedItemIndex];
if (selected.isVariadic) {
const firstRest = findIndex(selected.parameters, p => !!p.isRest);
if (-1 < firstRest && firstRest < selected.parameters.length - 1) {
// We don't have any code to get this correct; instead, don't highlight a current parameter AT ALL
help.argumentIndex = selected.parameters.length;
}
else {
help.argumentIndex = Math.min(help.argumentIndex, selected.parameters.length - 1);
}
}
return help;
}
function createTypeHelpItems(
symbol: Symbol,
{ argumentCount, argumentsSpan: applicableSpan, invocation, argumentIndex }: ArgumentListInfo,
sourceFile: SourceFile,
checker: TypeChecker
): SignatureHelpItems | undefined {
const typeParameters = checker.getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol);
if (!typeParameters) return undefined;
const items = [getTypeHelpItem(symbol, typeParameters, checker, getEnclosingDeclarationFromInvocation(invocation), sourceFile)];
return { items, applicableSpan, selectedItemIndex: 0, argumentIndex, argumentCount };
}
function getTypeHelpItem(symbol: Symbol, typeParameters: readonly TypeParameter[], checker: TypeChecker, enclosingDeclaration: Node, sourceFile: SourceFile): SignatureHelpItem {
const typeSymbolDisplay = symbolToDisplayParts(checker, symbol);
const printer = createPrinter({ removeComments: true });
const parameters = typeParameters.map(t => createSignatureHelpParameterForTypeParameter(t, checker, enclosingDeclaration, sourceFile, printer));
const documentation = symbol.getDocumentationComment(checker);
const tags = symbol.getJsDocTags(checker);
const prefixDisplayParts = [...typeSymbolDisplay, punctuationPart(SyntaxKind.LessThanToken)];
return { isVariadic: false, prefixDisplayParts, suffixDisplayParts: [punctuationPart(SyntaxKind.GreaterThanToken)], separatorDisplayParts, parameters, documentation, tags };
}
const separatorDisplayParts: SymbolDisplayPart[] = [punctuationPart(SyntaxKind.CommaToken), spacePart()];
function getSignatureHelpItem(candidateSignature: Signature, callTargetDisplayParts: readonly SymbolDisplayPart[], isTypeParameterList: boolean, checker: TypeChecker, enclosingDeclaration: Node, sourceFile: SourceFile): SignatureHelpItem[] {
const infos = (isTypeParameterList ? itemInfoForTypeParameters : itemInfoForParameters)(candidateSignature, checker, enclosingDeclaration, sourceFile);
return map(infos, ({ isVariadic, parameters, prefix, suffix }) => {
const prefixDisplayParts = [...callTargetDisplayParts, ...prefix];
const suffixDisplayParts = [...suffix, ...returnTypeToDisplayParts(candidateSignature, enclosingDeclaration, checker)];
const documentation = candidateSignature.getDocumentationComment(checker);
const tags = candidateSignature.getJsDocTags();
return { isVariadic, prefixDisplayParts, suffixDisplayParts, separatorDisplayParts, parameters, documentation, tags };
});
}
function returnTypeToDisplayParts(candidateSignature: Signature, enclosingDeclaration: Node, checker: TypeChecker): readonly SymbolDisplayPart[] {
return mapToDisplayParts(writer => {
writer.writePunctuation(":");
writer.writeSpace(" ");
const predicate = checker.getTypePredicateOfSignature(candidateSignature);
if (predicate) {
checker.writeTypePredicate(predicate, enclosingDeclaration, /*flags*/ undefined, writer);
}
else {
checker.writeType(checker.getReturnTypeOfSignature(candidateSignature), enclosingDeclaration, /*flags*/ undefined, writer);
}
});
}
interface SignatureHelpItemInfo { readonly isVariadic: boolean; readonly parameters: SignatureHelpParameter[]; readonly prefix: readonly SymbolDisplayPart[]; readonly suffix: readonly SymbolDisplayPart[]; }
function itemInfoForTypeParameters(candidateSignature: Signature, checker: TypeChecker, enclosingDeclaration: Node, sourceFile: SourceFile): SignatureHelpItemInfo[] {
const typeParameters = (candidateSignature.target || candidateSignature).typeParameters;
const printer = createPrinter({ removeComments: true });
const parameters = (typeParameters || emptyArray).map(t => createSignatureHelpParameterForTypeParameter(t, checker, enclosingDeclaration, sourceFile, printer));
const thisParameter = candidateSignature.thisParameter ? [checker.symbolToParameterDeclaration(candidateSignature.thisParameter, enclosingDeclaration, signatureHelpNodeBuilderFlags)!] : [];
return checker.getExpandedParameters(candidateSignature).map(paramList => {
const params = factory.createNodeArray([...thisParameter, ...map(paramList, param => checker.symbolToParameterDeclaration(param, enclosingDeclaration, signatureHelpNodeBuilderFlags)!)]);
const parameterParts = mapToDisplayParts(writer => {
printer.writeList(ListFormat.CallExpressionArguments, params, sourceFile, writer);
});
return { isVariadic: false, parameters, prefix: [punctuationPart(SyntaxKind.LessThanToken)], suffix: [punctuationPart(SyntaxKind.GreaterThanToken), ...parameterParts] };
});
}
function itemInfoForParameters(candidateSignature: Signature, checker: TypeChecker, enclosingDeclaration: Node, sourceFile: SourceFile): SignatureHelpItemInfo[] {
const printer = createPrinter({ removeComments: true });
const typeParameterParts = mapToDisplayParts(writer => {
if (candidateSignature.typeParameters && candidateSignature.typeParameters.length) {
const args = factory.createNodeArray(candidateSignature.typeParameters.map(p => checker.typeParameterToDeclaration(p, enclosingDeclaration, signatureHelpNodeBuilderFlags)!));
printer.writeList(ListFormat.TypeParameters, args, sourceFile, writer);
}
});
const lists = checker.getExpandedParameters(candidateSignature);
const isVariadic: (parameterList: readonly Symbol[]) => boolean =
!checker.hasEffectiveRestParameter(candidateSignature) ? _ => false
: lists.length === 1 ? _ => true
: pList => !!(pList.length && (pList[pList.length - 1] as TransientSymbol).checkFlags & CheckFlags.RestParameter);
return lists.map(parameterList => ({
isVariadic: isVariadic(parameterList),
parameters: parameterList.map(p => createSignatureHelpParameterForParameter(p, checker, enclosingDeclaration, sourceFile, printer)),
prefix: [...typeParameterParts, punctuationPart(SyntaxKind.OpenParenToken)],
suffix: [punctuationPart(SyntaxKind.CloseParenToken)]
}));
}
function createSignatureHelpParameterForParameter(parameter: Symbol, checker: TypeChecker, enclosingDeclaration: Node, sourceFile: SourceFile, printer: Printer): SignatureHelpParameter {
const displayParts = mapToDisplayParts(writer => {
const param = checker.symbolToParameterDeclaration(parameter, enclosingDeclaration, signatureHelpNodeBuilderFlags)!;
printer.writeNode(EmitHint.Unspecified, param, sourceFile, writer);
});
const isOptional = checker.isOptionalParameter(parameter.valueDeclaration as ParameterDeclaration);
const isRest = !!((parameter as TransientSymbol).checkFlags & CheckFlags.RestParameter);
return { name: parameter.name, documentation: parameter.getDocumentationComment(checker), displayParts, isOptional, isRest };
}
function createSignatureHelpParameterForTypeParameter(typeParameter: TypeParameter, checker: TypeChecker, enclosingDeclaration: Node, sourceFile: SourceFile, printer: Printer): SignatureHelpParameter {
const displayParts = mapToDisplayParts(writer => {
const param = checker.typeParameterToDeclaration(typeParameter, enclosingDeclaration, signatureHelpNodeBuilderFlags)!;
printer.writeNode(EmitHint.Unspecified, param, sourceFile, writer);
});
return { name: typeParameter.symbol.name, documentation: typeParameter.symbol.getDocumentationComment(checker), displayParts, isOptional: false, isRest: false };
}
}