Fediversity/website/node_modules/sucrase/dist/esm/parser/plugins/flow.js

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2024-03-26 16:28:28 +01:00
/* eslint max-len: 0 */
import {
eat,
lookaheadType,
lookaheadTypeAndKeyword,
match,
next,
popTypeContext,
pushTypeContext,
} from "../tokenizer/index";
import {ContextualKeyword} from "../tokenizer/keywords";
import {TokenType, TokenType as tt} from "../tokenizer/types";
import {input, state} from "../traverser/base";
import {
baseParseMaybeAssign,
baseParseSubscript,
baseParseSubscripts,
parseArrow,
parseArrowExpression,
parseCallExpressionArguments,
parseExprAtom,
parseExpression,
parseFunctionBody,
parseIdentifier,
parseLiteral,
} from "../traverser/expression";
import {
baseParseExportStar,
parseExport,
parseExportFrom,
parseExportSpecifiers,
parseFunctionParams,
parseImport,
parseStatement,
} from "../traverser/statement";
import {
canInsertSemicolon,
eatContextual,
expect,
expectContextual,
isContextual,
isLookaheadContextual,
semicolon,
unexpected,
} from "../traverser/util";
function isMaybeDefaultImport(lookahead) {
return (
(lookahead.type === tt.name || !!(lookahead.type & TokenType.IS_KEYWORD)) &&
lookahead.contextualKeyword !== ContextualKeyword._from
);
}
function flowParseTypeInitialiser(tok) {
const oldIsType = pushTypeContext(0);
expect(tok || tt.colon);
flowParseType();
popTypeContext(oldIsType);
}
function flowParsePredicate() {
expect(tt.modulo);
expectContextual(ContextualKeyword._checks);
if (eat(tt.parenL)) {
parseExpression();
expect(tt.parenR);
}
}
function flowParseTypeAndPredicateInitialiser() {
const oldIsType = pushTypeContext(0);
expect(tt.colon);
if (match(tt.modulo)) {
flowParsePredicate();
} else {
flowParseType();
if (match(tt.modulo)) {
flowParsePredicate();
}
}
popTypeContext(oldIsType);
}
function flowParseDeclareClass() {
next();
flowParseInterfaceish(/* isClass */ true);
}
function flowParseDeclareFunction() {
next();
parseIdentifier();
if (match(tt.lessThan)) {
flowParseTypeParameterDeclaration();
}
expect(tt.parenL);
flowParseFunctionTypeParams();
expect(tt.parenR);
flowParseTypeAndPredicateInitialiser();
semicolon();
}
function flowParseDeclare() {
if (match(tt._class)) {
flowParseDeclareClass();
} else if (match(tt._function)) {
flowParseDeclareFunction();
} else if (match(tt._var)) {
flowParseDeclareVariable();
} else if (eatContextual(ContextualKeyword._module)) {
if (eat(tt.dot)) {
flowParseDeclareModuleExports();
} else {
flowParseDeclareModule();
}
} else if (isContextual(ContextualKeyword._type)) {
flowParseDeclareTypeAlias();
} else if (isContextual(ContextualKeyword._opaque)) {
flowParseDeclareOpaqueType();
} else if (isContextual(ContextualKeyword._interface)) {
flowParseDeclareInterface();
} else if (match(tt._export)) {
flowParseDeclareExportDeclaration();
} else {
unexpected();
}
}
function flowParseDeclareVariable() {
next();
flowParseTypeAnnotatableIdentifier();
semicolon();
}
function flowParseDeclareModule() {
if (match(tt.string)) {
parseExprAtom();
} else {
parseIdentifier();
}
expect(tt.braceL);
while (!match(tt.braceR) && !state.error) {
if (match(tt._import)) {
next();
parseImport();
} else {
unexpected();
}
}
expect(tt.braceR);
}
function flowParseDeclareExportDeclaration() {
expect(tt._export);
if (eat(tt._default)) {
if (match(tt._function) || match(tt._class)) {
// declare export default class ...
// declare export default function ...
flowParseDeclare();
} else {
// declare export default [type];
flowParseType();
semicolon();
}
} else if (
match(tt._var) || // declare export var ...
match(tt._function) || // declare export function ...
match(tt._class) || // declare export class ...
isContextual(ContextualKeyword._opaque) // declare export opaque ..
) {
flowParseDeclare();
} else if (
match(tt.star) || // declare export * from ''
match(tt.braceL) || // declare export {} ...
isContextual(ContextualKeyword._interface) || // declare export interface ...
isContextual(ContextualKeyword._type) || // declare export type ...
isContextual(ContextualKeyword._opaque) // declare export opaque type ...
) {
parseExport();
} else {
unexpected();
}
}
function flowParseDeclareModuleExports() {
expectContextual(ContextualKeyword._exports);
flowParseTypeAnnotation();
semicolon();
}
function flowParseDeclareTypeAlias() {
next();
flowParseTypeAlias();
}
function flowParseDeclareOpaqueType() {
next();
flowParseOpaqueType(true);
}
function flowParseDeclareInterface() {
next();
flowParseInterfaceish();
}
// Interfaces
function flowParseInterfaceish(isClass = false) {
flowParseRestrictedIdentifier();
if (match(tt.lessThan)) {
flowParseTypeParameterDeclaration();
}
if (eat(tt._extends)) {
do {
flowParseInterfaceExtends();
} while (!isClass && eat(tt.comma));
}
if (isContextual(ContextualKeyword._mixins)) {
next();
do {
flowParseInterfaceExtends();
} while (eat(tt.comma));
}
if (isContextual(ContextualKeyword._implements)) {
next();
do {
flowParseInterfaceExtends();
} while (eat(tt.comma));
}
flowParseObjectType(isClass, false, isClass);
}
function flowParseInterfaceExtends() {
flowParseQualifiedTypeIdentifier(false);
if (match(tt.lessThan)) {
flowParseTypeParameterInstantiation();
}
}
function flowParseInterface() {
flowParseInterfaceish();
}
function flowParseRestrictedIdentifier() {
parseIdentifier();
}
function flowParseTypeAlias() {
flowParseRestrictedIdentifier();
if (match(tt.lessThan)) {
flowParseTypeParameterDeclaration();
}
flowParseTypeInitialiser(tt.eq);
semicolon();
}
function flowParseOpaqueType(declare) {
expectContextual(ContextualKeyword._type);
flowParseRestrictedIdentifier();
if (match(tt.lessThan)) {
flowParseTypeParameterDeclaration();
}
// Parse the supertype
if (match(tt.colon)) {
flowParseTypeInitialiser(tt.colon);
}
if (!declare) {
flowParseTypeInitialiser(tt.eq);
}
semicolon();
}
function flowParseTypeParameter() {
flowParseVariance();
flowParseTypeAnnotatableIdentifier();
if (eat(tt.eq)) {
flowParseType();
}
}
export function flowParseTypeParameterDeclaration() {
const oldIsType = pushTypeContext(0);
// istanbul ignore else: this condition is already checked at all call sites
if (match(tt.lessThan) || match(tt.typeParameterStart)) {
next();
} else {
unexpected();
}
do {
flowParseTypeParameter();
if (!match(tt.greaterThan)) {
expect(tt.comma);
}
} while (!match(tt.greaterThan) && !state.error);
expect(tt.greaterThan);
popTypeContext(oldIsType);
}
function flowParseTypeParameterInstantiation() {
const oldIsType = pushTypeContext(0);
expect(tt.lessThan);
while (!match(tt.greaterThan) && !state.error) {
flowParseType();
if (!match(tt.greaterThan)) {
expect(tt.comma);
}
}
expect(tt.greaterThan);
popTypeContext(oldIsType);
}
function flowParseInterfaceType() {
expectContextual(ContextualKeyword._interface);
if (eat(tt._extends)) {
do {
flowParseInterfaceExtends();
} while (eat(tt.comma));
}
flowParseObjectType(false, false, false);
}
function flowParseObjectPropertyKey() {
if (match(tt.num) || match(tt.string)) {
parseExprAtom();
} else {
parseIdentifier();
}
}
function flowParseObjectTypeIndexer() {
// Note: bracketL has already been consumed
if (lookaheadType() === tt.colon) {
flowParseObjectPropertyKey();
flowParseTypeInitialiser();
} else {
flowParseType();
}
expect(tt.bracketR);
flowParseTypeInitialiser();
}
function flowParseObjectTypeInternalSlot() {
// Note: both bracketL have already been consumed
flowParseObjectPropertyKey();
expect(tt.bracketR);
expect(tt.bracketR);
if (match(tt.lessThan) || match(tt.parenL)) {
flowParseObjectTypeMethodish();
} else {
eat(tt.question);
flowParseTypeInitialiser();
}
}
function flowParseObjectTypeMethodish() {
if (match(tt.lessThan)) {
flowParseTypeParameterDeclaration();
}
expect(tt.parenL);
while (!match(tt.parenR) && !match(tt.ellipsis) && !state.error) {
flowParseFunctionTypeParam();
if (!match(tt.parenR)) {
expect(tt.comma);
}
}
if (eat(tt.ellipsis)) {
flowParseFunctionTypeParam();
}
expect(tt.parenR);
flowParseTypeInitialiser();
}
function flowParseObjectTypeCallProperty() {
flowParseObjectTypeMethodish();
}
function flowParseObjectType(allowStatic, allowExact, allowProto) {
let endDelim;
if (allowExact && match(tt.braceBarL)) {
expect(tt.braceBarL);
endDelim = tt.braceBarR;
} else {
expect(tt.braceL);
endDelim = tt.braceR;
}
while (!match(endDelim) && !state.error) {
if (allowProto && isContextual(ContextualKeyword._proto)) {
const lookahead = lookaheadType();
if (lookahead !== tt.colon && lookahead !== tt.question) {
next();
allowStatic = false;
}
}
if (allowStatic && isContextual(ContextualKeyword._static)) {
const lookahead = lookaheadType();
if (lookahead !== tt.colon && lookahead !== tt.question) {
next();
}
}
flowParseVariance();
if (eat(tt.bracketL)) {
if (eat(tt.bracketL)) {
flowParseObjectTypeInternalSlot();
} else {
flowParseObjectTypeIndexer();
}
} else if (match(tt.parenL) || match(tt.lessThan)) {
flowParseObjectTypeCallProperty();
} else {
if (isContextual(ContextualKeyword._get) || isContextual(ContextualKeyword._set)) {
const lookahead = lookaheadType();
if (lookahead === tt.name || lookahead === tt.string || lookahead === tt.num) {
next();
}
}
flowParseObjectTypeProperty();
}
flowObjectTypeSemicolon();
}
expect(endDelim);
}
function flowParseObjectTypeProperty() {
if (match(tt.ellipsis)) {
expect(tt.ellipsis);
if (!eat(tt.comma)) {
eat(tt.semi);
}
// Explicit inexact object syntax.
if (match(tt.braceR)) {
return;
}
flowParseType();
} else {
flowParseObjectPropertyKey();
if (match(tt.lessThan) || match(tt.parenL)) {
// This is a method property
flowParseObjectTypeMethodish();
} else {
eat(tt.question);
flowParseTypeInitialiser();
}
}
}
function flowObjectTypeSemicolon() {
if (!eat(tt.semi) && !eat(tt.comma) && !match(tt.braceR) && !match(tt.braceBarR)) {
unexpected();
}
}
function flowParseQualifiedTypeIdentifier(initialIdAlreadyParsed) {
if (!initialIdAlreadyParsed) {
parseIdentifier();
}
while (eat(tt.dot)) {
parseIdentifier();
}
}
function flowParseGenericType() {
flowParseQualifiedTypeIdentifier(true);
if (match(tt.lessThan)) {
flowParseTypeParameterInstantiation();
}
}
function flowParseTypeofType() {
expect(tt._typeof);
flowParsePrimaryType();
}
function flowParseTupleType() {
expect(tt.bracketL);
// We allow trailing commas
while (state.pos < input.length && !match(tt.bracketR)) {
flowParseType();
if (match(tt.bracketR)) {
break;
}
expect(tt.comma);
}
expect(tt.bracketR);
}
function flowParseFunctionTypeParam() {
const lookahead = lookaheadType();
if (lookahead === tt.colon || lookahead === tt.question) {
parseIdentifier();
eat(tt.question);
flowParseTypeInitialiser();
} else {
flowParseType();
}
}
function flowParseFunctionTypeParams() {
while (!match(tt.parenR) && !match(tt.ellipsis) && !state.error) {
flowParseFunctionTypeParam();
if (!match(tt.parenR)) {
expect(tt.comma);
}
}
if (eat(tt.ellipsis)) {
flowParseFunctionTypeParam();
}
}
// The parsing of types roughly parallels the parsing of expressions, and
// primary types are kind of like primary expressions...they're the
// primitives with which other types are constructed.
function flowParsePrimaryType() {
let isGroupedType = false;
const oldNoAnonFunctionType = state.noAnonFunctionType;
switch (state.type) {
case tt.name: {
if (isContextual(ContextualKeyword._interface)) {
flowParseInterfaceType();
return;
}
parseIdentifier();
flowParseGenericType();
return;
}
case tt.braceL:
flowParseObjectType(false, false, false);
return;
case tt.braceBarL:
flowParseObjectType(false, true, false);
return;
case tt.bracketL:
flowParseTupleType();
return;
case tt.lessThan:
flowParseTypeParameterDeclaration();
expect(tt.parenL);
flowParseFunctionTypeParams();
expect(tt.parenR);
expect(tt.arrow);
flowParseType();
return;
case tt.parenL:
next();
// Check to see if this is actually a grouped type
if (!match(tt.parenR) && !match(tt.ellipsis)) {
if (match(tt.name)) {
const token = lookaheadType();
isGroupedType = token !== tt.question && token !== tt.colon;
} else {
isGroupedType = true;
}
}
if (isGroupedType) {
state.noAnonFunctionType = false;
flowParseType();
state.noAnonFunctionType = oldNoAnonFunctionType;
// A `,` or a `) =>` means this is an anonymous function type
if (
state.noAnonFunctionType ||
!(match(tt.comma) || (match(tt.parenR) && lookaheadType() === tt.arrow))
) {
expect(tt.parenR);
return;
} else {
// Eat a comma if there is one
eat(tt.comma);
}
}
flowParseFunctionTypeParams();
expect(tt.parenR);
expect(tt.arrow);
flowParseType();
return;
case tt.minus:
next();
parseLiteral();
return;
case tt.string:
case tt.num:
case tt._true:
case tt._false:
case tt._null:
case tt._this:
case tt._void:
case tt.star:
next();
return;
default:
if (state.type === tt._typeof) {
flowParseTypeofType();
return;
} else if (state.type & TokenType.IS_KEYWORD) {
next();
state.tokens[state.tokens.length - 1].type = tt.name;
return;
}
}
unexpected();
}
function flowParsePostfixType() {
flowParsePrimaryType();
while (!canInsertSemicolon() && (match(tt.bracketL) || match(tt.questionDot))) {
eat(tt.questionDot);
expect(tt.bracketL);
if (eat(tt.bracketR)) {
// Array type
} else {
// Indexed access type
flowParseType();
expect(tt.bracketR);
}
}
}
function flowParsePrefixType() {
if (eat(tt.question)) {
flowParsePrefixType();
} else {
flowParsePostfixType();
}
}
function flowParseAnonFunctionWithoutParens() {
flowParsePrefixType();
if (!state.noAnonFunctionType && eat(tt.arrow)) {
flowParseType();
}
}
function flowParseIntersectionType() {
eat(tt.bitwiseAND);
flowParseAnonFunctionWithoutParens();
while (eat(tt.bitwiseAND)) {
flowParseAnonFunctionWithoutParens();
}
}
function flowParseUnionType() {
eat(tt.bitwiseOR);
flowParseIntersectionType();
while (eat(tt.bitwiseOR)) {
flowParseIntersectionType();
}
}
function flowParseType() {
flowParseUnionType();
}
export function flowParseTypeAnnotation() {
flowParseTypeInitialiser();
}
function flowParseTypeAnnotatableIdentifier() {
parseIdentifier();
if (match(tt.colon)) {
flowParseTypeAnnotation();
}
}
export function flowParseVariance() {
if (match(tt.plus) || match(tt.minus)) {
next();
state.tokens[state.tokens.length - 1].isType = true;
}
}
// ==================================
// Overrides
// ==================================
export function flowParseFunctionBodyAndFinish(funcContextId) {
// For arrow functions, `parseArrow` handles the return type itself.
if (match(tt.colon)) {
flowParseTypeAndPredicateInitialiser();
}
parseFunctionBody(false, funcContextId);
}
export function flowParseSubscript(
startTokenIndex,
noCalls,
stopState,
) {
if (match(tt.questionDot) && lookaheadType() === tt.lessThan) {
if (noCalls) {
stopState.stop = true;
return;
}
next();
flowParseTypeParameterInstantiation();
expect(tt.parenL);
parseCallExpressionArguments();
return;
} else if (!noCalls && match(tt.lessThan)) {
const snapshot = state.snapshot();
flowParseTypeParameterInstantiation();
expect(tt.parenL);
parseCallExpressionArguments();
if (state.error) {
state.restoreFromSnapshot(snapshot);
} else {
return;
}
}
baseParseSubscript(startTokenIndex, noCalls, stopState);
}
export function flowStartParseNewArguments() {
if (match(tt.lessThan)) {
const snapshot = state.snapshot();
flowParseTypeParameterInstantiation();
if (state.error) {
state.restoreFromSnapshot(snapshot);
}
}
}
// interfaces
export function flowTryParseStatement() {
if (match(tt.name) && state.contextualKeyword === ContextualKeyword._interface) {
const oldIsType = pushTypeContext(0);
next();
flowParseInterface();
popTypeContext(oldIsType);
return true;
} else if (isContextual(ContextualKeyword._enum)) {
flowParseEnumDeclaration();
return true;
}
return false;
}
export function flowTryParseExportDefaultExpression() {
if (isContextual(ContextualKeyword._enum)) {
flowParseEnumDeclaration();
return true;
}
return false;
}
// declares, interfaces and type aliases
export function flowParseIdentifierStatement(contextualKeyword) {
if (contextualKeyword === ContextualKeyword._declare) {
if (
match(tt._class) ||
match(tt.name) ||
match(tt._function) ||
match(tt._var) ||
match(tt._export)
) {
const oldIsType = pushTypeContext(1);
flowParseDeclare();
popTypeContext(oldIsType);
}
} else if (match(tt.name)) {
if (contextualKeyword === ContextualKeyword._interface) {
const oldIsType = pushTypeContext(1);
flowParseInterface();
popTypeContext(oldIsType);
} else if (contextualKeyword === ContextualKeyword._type) {
const oldIsType = pushTypeContext(1);
flowParseTypeAlias();
popTypeContext(oldIsType);
} else if (contextualKeyword === ContextualKeyword._opaque) {
const oldIsType = pushTypeContext(1);
flowParseOpaqueType(false);
popTypeContext(oldIsType);
}
}
semicolon();
}
// export type
export function flowShouldParseExportDeclaration() {
return (
isContextual(ContextualKeyword._type) ||
isContextual(ContextualKeyword._interface) ||
isContextual(ContextualKeyword._opaque) ||
isContextual(ContextualKeyword._enum)
);
}
export function flowShouldDisallowExportDefaultSpecifier() {
return (
match(tt.name) &&
(state.contextualKeyword === ContextualKeyword._type ||
state.contextualKeyword === ContextualKeyword._interface ||
state.contextualKeyword === ContextualKeyword._opaque ||
state.contextualKeyword === ContextualKeyword._enum)
);
}
export function flowParseExportDeclaration() {
if (isContextual(ContextualKeyword._type)) {
const oldIsType = pushTypeContext(1);
next();
if (match(tt.braceL)) {
// export type { foo, bar };
parseExportSpecifiers();
parseExportFrom();
} else {
// export type Foo = Bar;
flowParseTypeAlias();
}
popTypeContext(oldIsType);
} else if (isContextual(ContextualKeyword._opaque)) {
const oldIsType = pushTypeContext(1);
next();
// export opaque type Foo = Bar;
flowParseOpaqueType(false);
popTypeContext(oldIsType);
} else if (isContextual(ContextualKeyword._interface)) {
const oldIsType = pushTypeContext(1);
next();
flowParseInterface();
popTypeContext(oldIsType);
} else {
parseStatement(true);
}
}
export function flowShouldParseExportStar() {
return match(tt.star) || (isContextual(ContextualKeyword._type) && lookaheadType() === tt.star);
}
export function flowParseExportStar() {
if (eatContextual(ContextualKeyword._type)) {
const oldIsType = pushTypeContext(2);
baseParseExportStar();
popTypeContext(oldIsType);
} else {
baseParseExportStar();
}
}
// parse a the super class type parameters and implements
export function flowAfterParseClassSuper(hasSuper) {
if (hasSuper && match(tt.lessThan)) {
flowParseTypeParameterInstantiation();
}
if (isContextual(ContextualKeyword._implements)) {
const oldIsType = pushTypeContext(0);
next();
state.tokens[state.tokens.length - 1].type = tt._implements;
do {
flowParseRestrictedIdentifier();
if (match(tt.lessThan)) {
flowParseTypeParameterInstantiation();
}
} while (eat(tt.comma));
popTypeContext(oldIsType);
}
}
// parse type parameters for object method shorthand
export function flowStartParseObjPropValue() {
// method shorthand
if (match(tt.lessThan)) {
flowParseTypeParameterDeclaration();
if (!match(tt.parenL)) unexpected();
}
}
export function flowParseAssignableListItemTypes() {
const oldIsType = pushTypeContext(0);
eat(tt.question);
if (match(tt.colon)) {
flowParseTypeAnnotation();
}
popTypeContext(oldIsType);
}
// parse typeof and type imports
export function flowStartParseImportSpecifiers() {
if (match(tt._typeof) || isContextual(ContextualKeyword._type)) {
const lh = lookaheadTypeAndKeyword();
if (isMaybeDefaultImport(lh) || lh.type === tt.braceL || lh.type === tt.star) {
next();
}
}
}
// parse import-type/typeof shorthand
export function flowParseImportSpecifier() {
const isTypeKeyword =
state.contextualKeyword === ContextualKeyword._type || state.type === tt._typeof;
if (isTypeKeyword) {
next();
} else {
parseIdentifier();
}
if (isContextual(ContextualKeyword._as) && !isLookaheadContextual(ContextualKeyword._as)) {
parseIdentifier();
if (isTypeKeyword && !match(tt.name) && !(state.type & TokenType.IS_KEYWORD)) {
// `import {type as ,` or `import {type as }`
} else {
// `import {type as foo`
parseIdentifier();
}
} else {
if (isTypeKeyword && (match(tt.name) || !!(state.type & TokenType.IS_KEYWORD))) {
// `import {type foo`
parseIdentifier();
}
if (eatContextual(ContextualKeyword._as)) {
parseIdentifier();
}
}
}
// parse function type parameters - function foo<T>() {}
export function flowStartParseFunctionParams() {
// Originally this checked if the method is a getter/setter, but if it was, we'd crash soon
// anyway, so don't try to propagate that information.
if (match(tt.lessThan)) {
const oldIsType = pushTypeContext(0);
flowParseTypeParameterDeclaration();
popTypeContext(oldIsType);
}
}
// parse flow type annotations on variable declarator heads - let foo: string = bar
export function flowAfterParseVarHead() {
if (match(tt.colon)) {
flowParseTypeAnnotation();
}
}
// parse the return type of an async arrow function - let foo = (async (): number => {});
export function flowStartParseAsyncArrowFromCallExpression() {
if (match(tt.colon)) {
const oldNoAnonFunctionType = state.noAnonFunctionType;
state.noAnonFunctionType = true;
flowParseTypeAnnotation();
state.noAnonFunctionType = oldNoAnonFunctionType;
}
}
// We need to support type parameter declarations for arrow functions. This
// is tricky. There are three situations we need to handle
//
// 1. This is either JSX or an arrow function. We'll try JSX first. If that
// fails, we'll try an arrow function. If that fails, we'll throw the JSX
// error.
// 2. This is an arrow function. We'll parse the type parameter declaration,
// parse the rest, make sure the rest is an arrow function, and go from
// there
// 3. This is neither. Just call the super method
export function flowParseMaybeAssign(noIn, isWithinParens) {
if (match(tt.lessThan)) {
const snapshot = state.snapshot();
let wasArrow = baseParseMaybeAssign(noIn, isWithinParens);
if (state.error) {
state.restoreFromSnapshot(snapshot);
state.type = tt.typeParameterStart;
} else {
return wasArrow;
}
const oldIsType = pushTypeContext(0);
flowParseTypeParameterDeclaration();
popTypeContext(oldIsType);
wasArrow = baseParseMaybeAssign(noIn, isWithinParens);
if (wasArrow) {
return true;
}
unexpected();
}
return baseParseMaybeAssign(noIn, isWithinParens);
}
// handle return types for arrow functions
export function flowParseArrow() {
if (match(tt.colon)) {
const oldIsType = pushTypeContext(0);
const snapshot = state.snapshot();
const oldNoAnonFunctionType = state.noAnonFunctionType;
state.noAnonFunctionType = true;
flowParseTypeAndPredicateInitialiser();
state.noAnonFunctionType = oldNoAnonFunctionType;
if (canInsertSemicolon()) unexpected();
if (!match(tt.arrow)) unexpected();
if (state.error) {
state.restoreFromSnapshot(snapshot);
}
popTypeContext(oldIsType);
}
return eat(tt.arrow);
}
export function flowParseSubscripts(startTokenIndex, noCalls = false) {
if (
state.tokens[state.tokens.length - 1].contextualKeyword === ContextualKeyword._async &&
match(tt.lessThan)
) {
const snapshot = state.snapshot();
const wasArrow = parseAsyncArrowWithTypeParameters();
if (wasArrow && !state.error) {
return;
}
state.restoreFromSnapshot(snapshot);
}
baseParseSubscripts(startTokenIndex, noCalls);
}
// Returns true if there was an arrow function here.
function parseAsyncArrowWithTypeParameters() {
state.scopeDepth++;
const startTokenIndex = state.tokens.length;
parseFunctionParams();
if (!parseArrow()) {
return false;
}
parseArrowExpression(startTokenIndex);
return true;
}
function flowParseEnumDeclaration() {
expectContextual(ContextualKeyword._enum);
state.tokens[state.tokens.length - 1].type = tt._enum;
parseIdentifier();
flowParseEnumBody();
}
function flowParseEnumBody() {
if (eatContextual(ContextualKeyword._of)) {
next();
}
expect(tt.braceL);
flowParseEnumMembers();
expect(tt.braceR);
}
function flowParseEnumMembers() {
while (!match(tt.braceR) && !state.error) {
if (eat(tt.ellipsis)) {
break;
}
flowParseEnumMember();
if (!match(tt.braceR)) {
expect(tt.comma);
}
}
}
function flowParseEnumMember() {
parseIdentifier();
if (eat(tt.eq)) {
// Flow enum values are always just one token (a string, number, or boolean literal).
next();
}
}