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Edit File: typescript.js

"use strict";Object.defineProperty(exports, "__esModule", {value: true});

var _index = require('../tokenizer/index');
var _keywords = require('../tokenizer/keywords');
var _types = require('../tokenizer/types');
var _base = require('../traverser/base');

var _expression = require('../traverser/expression');
var _lval = require('../traverser/lval');

var _statement = require('../traverser/statement');

var _util = require('../traverser/util');
var _jsx = require('./jsx');

function tsIsIdentifier() {
  // TODO: actually a bit more complex in TypeScript, but shouldn't matter.
  // See https://github.com/Microsoft/TypeScript/issues/15008
  return _index.match.call(void 0, _types.TokenType.name);
}

function isLiteralPropertyName() {
  return (
    _index.match.call(void 0, _types.TokenType.name) ||
    Boolean(_base.state.type & _types.TokenType.IS_KEYWORD) ||
    _index.match.call(void 0, _types.TokenType.string) ||
    _index.match.call(void 0, _types.TokenType.num) ||
    _index.match.call(void 0, _types.TokenType.bigint) ||
    _index.match.call(void 0, _types.TokenType.decimal)
  );
}

function tsNextTokenCanFollowModifier() {
  // Note: TypeScript's implementation is much more complicated because
  // more things are considered modifiers there.
  // This implementation only handles modifiers not handled by babylon itself. And "static".
  // TODO: Would be nice to avoid lookahead. Want a hasLineBreakUpNext() method...
  const snapshot = _base.state.snapshot();

_index.next.call(void 0, );
  const canFollowModifier =
    (_index.match.call(void 0, _types.TokenType.bracketL) ||
      _index.match.call(void 0, _types.TokenType.braceL) ||
      _index.match.call(void 0, _types.TokenType.star) ||
      _index.match.call(void 0, _types.TokenType.ellipsis) ||
      _index.match.call(void 0, _types.TokenType.hash) ||
      isLiteralPropertyName()) &&
    !_util.hasPrecedingLineBreak.call(void 0, );

if (canFollowModifier) {
    return true;
  } else {
    _base.state.restoreFromSnapshot(snapshot);
    return false;
  }
}

/** Parses a modifier matching one the given modifier names. */
 function tsParseModifier(
  allowedModifiers,
) {
  if (!_index.match.call(void 0, _types.TokenType.name)) {
    return null;
  }

const modifier = _base.state.contextualKeyword;
  if (allowedModifiers.indexOf(modifier) !== -1 && tsNextTokenCanFollowModifier()) {
    switch (modifier) {
      case _keywords.ContextualKeyword._readonly:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._readonly;
        break;
      case _keywords.ContextualKeyword._abstract:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._abstract;
        break;
      case _keywords.ContextualKeyword._static:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._static;
        break;
      case _keywords.ContextualKeyword._public:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._public;
        break;
      case _keywords.ContextualKeyword._private:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._private;
        break;
      case _keywords.ContextualKeyword._protected:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._protected;
        break;
      case _keywords.ContextualKeyword._override:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._override;
        break;
      case _keywords.ContextualKeyword._declare:
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._declare;
        break;
      default:
        break;
    }
    return modifier;
  }
  return null;
} exports.tsParseModifier = tsParseModifier;

function tsParseEntityName() {
  _expression.parseIdentifier.call(void 0, );
  while (_index.eat.call(void 0, _types.TokenType.dot)) {
    _expression.parseIdentifier.call(void 0, );
  }
}

function tsParseTypeReference() {
  tsParseEntityName();
  if (!_util.hasPrecedingLineBreak.call(void 0, ) && _index.match.call(void 0, _types.TokenType.lessThan)) {
    tsParseTypeArguments();
  }
}

function tsParseThisTypePredicate() {
  _index.next.call(void 0, );
  tsParseTypeAnnotation();
}

function tsParseThisTypeNode() {
  _index.next.call(void 0, );
}

function tsParseTypeParameter() {
  _index.eat.call(void 0, _types.TokenType._const);
  const hadIn = _index.eat.call(void 0, _types.TokenType._in);
  const hadOut = _util.eatContextual.call(void 0, _keywords.ContextualKeyword._out);
  _index.eat.call(void 0, _types.TokenType._const);
  if ((hadIn || hadOut) && !_index.match.call(void 0, _types.TokenType.name)) {
    // The "in" or "out" keyword must have actually been the type parameter
    // name, so set it as the name.
    _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType.name;
  } else {
    _expression.parseIdentifier.call(void 0, );
  }

if (_index.eat.call(void 0, _types.TokenType._extends)) {
    tsParseType();
  }
  if (_index.eat.call(void 0, _types.TokenType.eq)) {
    tsParseType();
  }
}

function tsTryParseTypeParameters() {
  if (_index.match.call(void 0, _types.TokenType.lessThan)) {
    tsParseTypeParameters();
  }
} exports.tsTryParseTypeParameters = tsTryParseTypeParameters;

function tsParseTypeParameters() {
  const oldIsType = _index.pushTypeContext.call(void 0, 0);
  if (_index.match.call(void 0, _types.TokenType.lessThan) || _index.match.call(void 0, _types.TokenType.typeParameterStart)) {
    _index.next.call(void 0, );
  } else {
    _util.unexpected.call(void 0, );
  }

while (!_index.eat.call(void 0, _types.TokenType.greaterThan) && !_base.state.error) {
    tsParseTypeParameter();
    _index.eat.call(void 0, _types.TokenType.comma);
  }
  _index.popTypeContext.call(void 0, oldIsType);
}

// Note: In TypeScript implementation we must provide `yieldContext` and `awaitContext`,
// but here it's always false, because this is only used for types.
function tsFillSignature(returnToken) {
  // Arrow fns *must* have return token (`=>`). Normal functions can omit it.
  const returnTokenRequired = returnToken === _types.TokenType.arrow;
  tsTryParseTypeParameters();
  _util.expect.call(void 0, _types.TokenType.parenL);
  // Create a scope even though we're doing type parsing so we don't accidentally
  // treat params as top-level bindings.
  _base.state.scopeDepth++;
  tsParseBindingListForSignature(false /* isBlockScope */);
  _base.state.scopeDepth--;
  if (returnTokenRequired) {
    tsParseTypeOrTypePredicateAnnotation(returnToken);
  } else if (_index.match.call(void 0, returnToken)) {
    tsParseTypeOrTypePredicateAnnotation(returnToken);
  }
}

function tsParseBindingListForSignature(isBlockScope) {
  _lval.parseBindingList.call(void 0, _types.TokenType.parenR, isBlockScope);
}

function tsParseTypeMemberSemicolon() {
  if (!_index.eat.call(void 0, _types.TokenType.comma)) {
    _util.semicolon.call(void 0, );
  }
}

function tsParseSignatureMember() {
  tsFillSignature(_types.TokenType.colon);
  tsParseTypeMemberSemicolon();
}

function tsIsUnambiguouslyIndexSignature() {
  const snapshot = _base.state.snapshot();
  _index.next.call(void 0, ); // Skip '{'
  const isIndexSignature = _index.eat.call(void 0, _types.TokenType.name) && _index.match.call(void 0, _types.TokenType.colon);
  _base.state.restoreFromSnapshot(snapshot);
  return isIndexSignature;
}

function tsTryParseIndexSignature() {
  if (!(_index.match.call(void 0, _types.TokenType.bracketL) && tsIsUnambiguouslyIndexSignature())) {
    return false;
  }

const oldIsType = _index.pushTypeContext.call(void 0, 0);

_util.expect.call(void 0, _types.TokenType.bracketL);
  _expression.parseIdentifier.call(void 0, );
  tsParseTypeAnnotation();
  _util.expect.call(void 0, _types.TokenType.bracketR);

tsTryParseTypeAnnotation();
  tsParseTypeMemberSemicolon();

_index.popTypeContext.call(void 0, oldIsType);
  return true;
}

function tsParsePropertyOrMethodSignature(isReadonly) {
  _index.eat.call(void 0, _types.TokenType.question);

if (!isReadonly && (_index.match.call(void 0, _types.TokenType.parenL) || _index.match.call(void 0, _types.TokenType.lessThan))) {
    tsFillSignature(_types.TokenType.colon);
    tsParseTypeMemberSemicolon();
  } else {
    tsTryParseTypeAnnotation();
    tsParseTypeMemberSemicolon();
  }
}

const found = tsTryParseIndexSignature();
  if (found) {
    return;
  }
  if (
    (_util.isContextual.call(void 0, _keywords.ContextualKeyword._get) || _util.isContextual.call(void 0, _keywords.ContextualKeyword._set)) &&
    tsNextTokenCanFollowModifier()
  ) {
    // This is a getter/setter on a type. The tsNextTokenCanFollowModifier
    // function already called next() for us, so continue parsing the name.
  }
  _expression.parsePropertyName.call(void 0, -1 /* Types don't need context IDs. */);
  tsParsePropertyOrMethodSignature(readonly);
}

function tsParseTypeLiteral() {
  tsParseObjectTypeMembers();
}

function tsParseObjectTypeMembers() {
  _util.expect.call(void 0, _types.TokenType.braceL);
  while (!_index.eat.call(void 0, _types.TokenType.braceR) && !_base.state.error) {
    tsParseTypeMember();
  }
}

function tsLookaheadIsStartOfMappedType() {
  const snapshot = _base.state.snapshot();
  const isStartOfMappedType = tsIsStartOfMappedType();
  _base.state.restoreFromSnapshot(snapshot);
  return isStartOfMappedType;
}

function tsParseMappedTypeParameter() {
  _expression.parseIdentifier.call(void 0, );
  _util.expect.call(void 0, _types.TokenType._in);
  tsParseType();
}

function tsParseTupleType() {
  _util.expect.call(void 0, _types.TokenType.bracketL);
  while (!_index.eat.call(void 0, _types.TokenType.bracketR) && !_base.state.error) {
    // Do not validate presence of either none or only labeled elements
    tsParseTupleElementType();
    _index.eat.call(void 0, _types.TokenType.comma);
  }
}

function tsParseTupleElementType() {
  // parses `...TsType[]`
  if (_index.eat.call(void 0, _types.TokenType.ellipsis)) {
    tsParseType();
  } else {
    // parses `TsType?`
    tsParseType();
    _index.eat.call(void 0, _types.TokenType.question);
  }

// The type we parsed above was actually a label
  if (_index.eat.call(void 0, _types.TokenType.colon)) {
    // Labeled tuple types must affix the label with `...` or `?`, so no need to handle those here
    tsParseType();
  }
}

function tsParseParenthesizedType() {
  _util.expect.call(void 0, _types.TokenType.parenL);
  tsParseType();
  _util.expect.call(void 0, _types.TokenType.parenR);
}

var FunctionType; (function (FunctionType) {
  const TSFunctionType = 0; FunctionType[FunctionType["TSFunctionType"] = TSFunctionType] = "TSFunctionType";
  const TSConstructorType = TSFunctionType + 1; FunctionType[FunctionType["TSConstructorType"] = TSConstructorType] = "TSConstructorType";
  const TSAbstractConstructorType = TSConstructorType + 1; FunctionType[FunctionType["TSAbstractConstructorType"] = TSAbstractConstructorType] = "TSAbstractConstructorType";
})(FunctionType || (FunctionType = {}));

_util.unexpected.call(void 0, );
}

function tsIsStartOfFunctionType() {
  if (_index.match.call(void 0, _types.TokenType.lessThan)) {
    return true;
  }
  return _index.match.call(void 0, _types.TokenType.parenL) && tsLookaheadIsUnambiguouslyStartOfFunctionType();
}

function tsLookaheadIsUnambiguouslyStartOfFunctionType() {
  const snapshot = _base.state.snapshot();
  const isUnambiguouslyStartOfFunctionType = tsIsUnambiguouslyStartOfFunctionType();
  _base.state.restoreFromSnapshot(snapshot);
  return isUnambiguouslyStartOfFunctionType;
}

function tsParseTypeOrTypePredicateAnnotation(returnToken) {
  const oldIsType = _index.pushTypeContext.call(void 0, 0);
  _util.expect.call(void 0, returnToken);
  const finishedReturn = tsParseTypePredicateOrAssertsPrefix();
  if (!finishedReturn) {
    tsParseType();
  }
  _index.popTypeContext.call(void 0, oldIsType);
}

function tsTryParseTypeOrTypePredicateAnnotation() {
  if (_index.match.call(void 0, _types.TokenType.colon)) {
    tsParseTypeOrTypePredicateAnnotation(_types.TokenType.colon);
  }
}

function tsTryParseTypeAnnotation() {
  if (_index.match.call(void 0, _types.TokenType.colon)) {
    tsParseTypeAnnotation();
  }
} exports.tsTryParseTypeAnnotation = tsTryParseTypeAnnotation;

function tsTryParseType() {
  if (_index.eat.call(void 0, _types.TokenType.colon)) {
    tsParseType();
  }
}

/**
 * Detect a few special return syntax cases: `x is T`, `asserts x`, `asserts x is T`,
 * `asserts this is T`.
 *
 * Returns true if we parsed the return type, false if there's still a type to be parsed.
 */
function tsParseTypePredicateOrAssertsPrefix() {
  const snapshot = _base.state.snapshot();
  if (_util.isContextual.call(void 0, _keywords.ContextualKeyword._asserts)) {
    // Normally this is `asserts x is T`, but at this point, it might be `asserts is T` (a user-
    // defined type guard on the `asserts` variable) or just a type called `asserts`.
    _index.next.call(void 0, );
    if (_util.eatContextual.call(void 0, _keywords.ContextualKeyword._is)) {
      // If we see `asserts is`, then this must be of the form `asserts is T`, since
      // `asserts is is T` isn't valid.
      tsParseType();
      return true;
    } else if (tsIsIdentifier() || _index.match.call(void 0, _types.TokenType._this)) {
      _index.next.call(void 0, );
      if (_util.eatContextual.call(void 0, _keywords.ContextualKeyword._is)) {
        // If we see `is`, then this is `asserts x is T`. Otherwise, it's `asserts x`.
        tsParseType();
      }
      return true;
    } else {
      // Regular type, so bail out and start type parsing from scratch.
      _base.state.restoreFromSnapshot(snapshot);
      return false;
    }
  } else if (tsIsIdentifier() || _index.match.call(void 0, _types.TokenType._this)) {
    // This is a regular identifier, which may or may not have "is" after it.
    _index.next.call(void 0, );
    if (_util.isContextual.call(void 0, _keywords.ContextualKeyword._is) && !_util.hasPrecedingLineBreak.call(void 0, )) {
      _index.next.call(void 0, );
      tsParseType();
      return true;
    } else {
      // Regular type, so bail out and start type parsing from scratch.
      _base.state.restoreFromSnapshot(snapshot);
      return false;
    }
  }
  return false;
}

function tsParseTypeAnnotation() {
  const oldIsType = _index.pushTypeContext.call(void 0, 0);
  _util.expect.call(void 0, _types.TokenType.colon);
  tsParseType();
  _index.popTypeContext.call(void 0, oldIsType);
} exports.tsParseTypeAnnotation = tsParseTypeAnnotation;

function tsParseType() {
  tsParseNonConditionalType();
  if (_base.state.inDisallowConditionalTypesContext || _util.hasPrecedingLineBreak.call(void 0, ) || !_index.eat.call(void 0, _types.TokenType._extends)) {
    return;
  }
  // extends type
  const oldInDisallowConditionalTypesContext = _base.state.inDisallowConditionalTypesContext;
  _base.state.inDisallowConditionalTypesContext = true;
  tsParseNonConditionalType();
  _base.state.inDisallowConditionalTypesContext = oldInDisallowConditionalTypesContext;

_util.expect.call(void 0, _types.TokenType.question);
  // true type
  tsParseType();
  _util.expect.call(void 0, _types.TokenType.colon);
  // false type
  tsParseType();
} exports.tsParseType = tsParseType;

function isAbstractConstructorSignature() {
  return _util.isContextual.call(void 0, _keywords.ContextualKeyword._abstract) && _index.lookaheadType.call(void 0, ) === _types.TokenType._new;
}

function tsParseTypeAssertion() {
  const oldIsType = _index.pushTypeContext.call(void 0, 1);
  tsParseType();
  _util.expect.call(void 0, _types.TokenType.greaterThan);
  _index.popTypeContext.call(void 0, oldIsType);
  _expression.parseMaybeUnary.call(void 0, );
} exports.tsParseTypeAssertion = tsParseTypeAssertion;

function tsParseHeritageClause() {
  while (!_index.match.call(void 0, _types.TokenType.braceL) && !_base.state.error) {
    tsParseExpressionWithTypeArguments();
    _index.eat.call(void 0, _types.TokenType.comma);
  }
}

function tsParseExpressionWithTypeArguments() {
  // Note: TS uses parseLeftHandSideExpressionOrHigher,
  // then has grammar errors later if it's not an EntityName.
  tsParseEntityName();
  if (_index.match.call(void 0, _types.TokenType.lessThan)) {
    tsParseTypeArguments();
  }
}

function tsParseInterfaceDeclaration() {
  _lval.parseBindingIdentifier.call(void 0, false);
  tsTryParseTypeParameters();
  if (_index.eat.call(void 0, _types.TokenType._extends)) {
    tsParseHeritageClause();
  }
  tsParseObjectTypeMembers();
}

function tsParseTypeAliasDeclaration() {
  _lval.parseBindingIdentifier.call(void 0, false);
  tsTryParseTypeParameters();
  _util.expect.call(void 0, _types.TokenType.eq);
  tsParseType();
  _util.semicolon.call(void 0, );
}

function tsParseEnumDeclaration() {
  _lval.parseBindingIdentifier.call(void 0, false);
  _util.expect.call(void 0, _types.TokenType.braceL);
  while (!_index.eat.call(void 0, _types.TokenType.braceR) && !_base.state.error) {
    tsParseEnumMember();
    _index.eat.call(void 0, _types.TokenType.comma);
  }
}

function tsParseModuleBlock() {
  _util.expect.call(void 0, _types.TokenType.braceL);
  _statement.parseBlockBody.call(void 0, /* end */ _types.TokenType.braceR);
}

if (_index.match.call(void 0, _types.TokenType.braceL)) {
    tsParseModuleBlock();
  } else {
    _util.semicolon.call(void 0, );
  }
}

function tsParseImportEqualsDeclaration() {
  _lval.parseImportedIdentifier.call(void 0, );
  _util.expect.call(void 0, _types.TokenType.eq);
  tsParseModuleReference();
  _util.semicolon.call(void 0, );
} exports.tsParseImportEqualsDeclaration = tsParseImportEqualsDeclaration;

function tsIsExternalModuleReference() {
  return _util.isContextual.call(void 0, _keywords.ContextualKeyword._require) && _index.lookaheadType.call(void 0, ) === _types.TokenType.parenL;
}

function tsParseModuleReference() {
  if (tsIsExternalModuleReference()) {
    tsParseExternalModuleReference();
  } else {
    tsParseEntityName();
  }
}

function tsParseExternalModuleReference() {
  _util.expectContextual.call(void 0, _keywords.ContextualKeyword._require);
  _util.expect.call(void 0, _types.TokenType.parenL);
  if (!_index.match.call(void 0, _types.TokenType.string)) {
    _util.unexpected.call(void 0, );
  }
  _expression.parseLiteral.call(void 0, );
  _util.expect.call(void 0, _types.TokenType.parenR);
}

// Utilities

// Returns true if a statement matched.
function tsTryParseDeclare() {
  if (_util.isLineTerminator.call(void 0, )) {
    return false;
  }
  switch (_base.state.type) {
    case _types.TokenType._function: {
      const oldIsType = _index.pushTypeContext.call(void 0, 1);
      _index.next.call(void 0, );
      // We don't need to precisely get the function start here, since it's only used to mark
      // the function as a type if it's bodiless, and it's already a type here.
      const functionStart = _base.state.start;
      _statement.parseFunction.call(void 0, functionStart, /* isStatement */ true);
      _index.popTypeContext.call(void 0, oldIsType);
      return true;
    }
    case _types.TokenType._class: {
      const oldIsType = _index.pushTypeContext.call(void 0, 1);
      _statement.parseClass.call(void 0, /* isStatement */ true, /* optionalId */ false);
      _index.popTypeContext.call(void 0, oldIsType);
      return true;
    }
    case _types.TokenType._const: {
      if (_index.match.call(void 0, _types.TokenType._const) && _util.isLookaheadContextual.call(void 0, _keywords.ContextualKeyword._enum)) {
        const oldIsType = _index.pushTypeContext.call(void 0, 1);
        // `const enum = 0;` not allowed because "enum" is a strict mode reserved word.
        _util.expect.call(void 0, _types.TokenType._const);
        _util.expectContextual.call(void 0, _keywords.ContextualKeyword._enum);
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._enum;
        tsParseEnumDeclaration();
        _index.popTypeContext.call(void 0, oldIsType);
        return true;
      }
    }
    // falls through
    case _types.TokenType._var:
    case _types.TokenType._let: {
      const oldIsType = _index.pushTypeContext.call(void 0, 1);
      _statement.parseVarStatement.call(void 0, _base.state.type !== _types.TokenType._var);
      _index.popTypeContext.call(void 0, oldIsType);
      return true;
    }
    case _types.TokenType.name: {
      const oldIsType = _index.pushTypeContext.call(void 0, 1);
      const contextualKeyword = _base.state.contextualKeyword;
      let matched = false;
      if (contextualKeyword === _keywords.ContextualKeyword._global) {
        tsParseAmbientExternalModuleDeclaration();
        matched = true;
      } else {
        matched = tsParseDeclaration(contextualKeyword, /* isBeforeToken */ true);
      }
      _index.popTypeContext.call(void 0, oldIsType);
      return matched;
    }
    default:
      return false;
  }
}

// Note: this won't be called unless the keyword is allowed in `shouldParseExportDeclaration`.
// Returns true if it matched a declaration.
function tsTryParseExportDeclaration() {
  return tsParseDeclaration(_base.state.contextualKeyword, /* isBeforeToken */ true);
}

// Returns true if it matched a statement.
function tsParseExpressionStatement(contextualKeyword) {
  switch (contextualKeyword) {
    case _keywords.ContextualKeyword._declare: {
      const declareTokenIndex = _base.state.tokens.length - 1;
      const matched = tsTryParseDeclare();
      if (matched) {
        _base.state.tokens[declareTokenIndex].type = _types.TokenType._declare;
        return true;
      }
      break;
    }
    case _keywords.ContextualKeyword._global:
      // `global { }` (with no `declare`) may appear inside an ambient module declaration.
      // Would like to use tsParseAmbientExternalModuleDeclaration here, but already ran past "global".
      if (_index.match.call(void 0, _types.TokenType.braceL)) {
        tsParseModuleBlock();
        return true;
      }
      break;

default:
      return tsParseDeclaration(contextualKeyword, /* isBeforeToken */ false);
  }
  return false;
}

/**
 * Common code for parsing a declaration.
 *
 * isBeforeToken indicates that the current parser state is at the contextual
 * keyword (and that it is not yet emitted) rather than reading the token after
 * it. When isBeforeToken is true, we may be preceded by an `export` token and
 * should include that token in a type context we create, e.g. to handle
 * `export interface` or `export type`. (This is a bit of a hack and should be
 * cleaned up at some point.)
 *
 * Returns true if it matched a declaration.
 */
function tsParseDeclaration(contextualKeyword, isBeforeToken) {
  switch (contextualKeyword) {
    case _keywords.ContextualKeyword._abstract:
      if (tsCheckLineTerminator(isBeforeToken) && _index.match.call(void 0, _types.TokenType._class)) {
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._abstract;
        _statement.parseClass.call(void 0, /* isStatement */ true, /* optionalId */ false);
        return true;
      }
      break;

case _keywords.ContextualKeyword._enum:
      if (tsCheckLineTerminator(isBeforeToken) && _index.match.call(void 0, _types.TokenType.name)) {
        _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._enum;
        tsParseEnumDeclaration();
        return true;
      }
      break;

case _keywords.ContextualKeyword._interface:
      if (tsCheckLineTerminator(isBeforeToken) && _index.match.call(void 0, _types.TokenType.name)) {
        // `next` is true in "export" and "declare" contexts, so we want to remove that token
        // as well.
        const oldIsType = _index.pushTypeContext.call(void 0, isBeforeToken ? 2 : 1);
        tsParseInterfaceDeclaration();
        _index.popTypeContext.call(void 0, oldIsType);
        return true;
      }
      break;

case _keywords.ContextualKeyword._module:
      if (tsCheckLineTerminator(isBeforeToken)) {
        if (_index.match.call(void 0, _types.TokenType.string)) {
          const oldIsType = _index.pushTypeContext.call(void 0, isBeforeToken ? 2 : 1);
          tsParseAmbientExternalModuleDeclaration();
          _index.popTypeContext.call(void 0, oldIsType);
          return true;
        } else if (_index.match.call(void 0, _types.TokenType.name)) {
          const oldIsType = _index.pushTypeContext.call(void 0, isBeforeToken ? 2 : 1);
          tsParseModuleOrNamespaceDeclaration();
          _index.popTypeContext.call(void 0, oldIsType);
          return true;
        }
      }
      break;

case _keywords.ContextualKeyword._namespace:
      if (tsCheckLineTerminator(isBeforeToken) && _index.match.call(void 0, _types.TokenType.name)) {
        const oldIsType = _index.pushTypeContext.call(void 0, isBeforeToken ? 2 : 1);
        tsParseModuleOrNamespaceDeclaration();
        _index.popTypeContext.call(void 0, oldIsType);
        return true;
      }
      break;

case _keywords.ContextualKeyword._type:
      if (tsCheckLineTerminator(isBeforeToken) && _index.match.call(void 0, _types.TokenType.name)) {
        const oldIsType = _index.pushTypeContext.call(void 0, isBeforeToken ? 2 : 1);
        tsParseTypeAliasDeclaration();
        _index.popTypeContext.call(void 0, oldIsType);
        return true;
      }
      break;

default:
      break;
  }
  return false;
}

// Returns true if there was a generic async arrow function.
function tsTryParseGenericAsyncArrowFunction() {
  const snapshot = _base.state.snapshot();

tsParseTypeParameters();
  _statement.parseFunctionParams.call(void 0, );
  tsTryParseTypeOrTypePredicateAnnotation();
  _util.expect.call(void 0, _types.TokenType.arrow);

if (_base.state.error) {
    _base.state.restoreFromSnapshot(snapshot);
    return false;
  }

_expression.parseFunctionBody.call(void 0, true);
  return true;
}

/**
 * If necessary, hack the tokenizer state so that this bitshift was actually a
 * less-than token, then keep parsing. This should only be used in situations
 * where we restore from snapshot on error (which reverts this change) or
 * where bitshift would be illegal anyway (e.g. in a class "extends" clause).
 *
 * This hack is useful to handle situations like foo<<T>() => void>() where
 * there can legitimately be two open-angle-brackets in a row in TS.
 */
function tsParseTypeArgumentsWithPossibleBitshift() {
  if (_base.state.type === _types.TokenType.bitShiftL) {
    _base.state.pos -= 1;
    _index.finishToken.call(void 0, _types.TokenType.lessThan);
  }
  tsParseTypeArguments();
}

function tsIsDeclarationStart() {
  if (_index.match.call(void 0, _types.TokenType.name)) {
    switch (_base.state.contextualKeyword) {
      case _keywords.ContextualKeyword._abstract:
      case _keywords.ContextualKeyword._declare:
      case _keywords.ContextualKeyword._enum:
      case _keywords.ContextualKeyword._interface:
      case _keywords.ContextualKeyword._module:
      case _keywords.ContextualKeyword._namespace:
      case _keywords.ContextualKeyword._type:
        return true;
      default:
        break;
    }
  }

return false;
} exports.tsIsDeclarationStart = tsIsDeclarationStart;

// ======================================================
// OVERRIDES
// ======================================================

function tsParseFunctionBodyAndFinish(functionStart, funcContextId) {
  // For arrow functions, `parseArrow` handles the return type itself.
  if (_index.match.call(void 0, _types.TokenType.colon)) {
    tsParseTypeOrTypePredicateAnnotation(_types.TokenType.colon);
  }

// The original code checked the node type to make sure this function type allows a missing
  // body, but we skip that to avoid sending around the node type. We instead just use the
  // allowExpressionBody boolean to make sure it's not an arrow function.
  if (!_index.match.call(void 0, _types.TokenType.braceL) && _util.isLineTerminator.call(void 0, )) {
    // Retroactively mark the function declaration as a type.
    let i = _base.state.tokens.length - 1;
    while (
      i >= 0 &&
      (_base.state.tokens[i].start >= functionStart ||
        _base.state.tokens[i].type === _types.TokenType._default ||
        _base.state.tokens[i].type === _types.TokenType._export)
    ) {
      _base.state.tokens[i].isType = true;
      i--;
    }
    return;
  }

_expression.parseFunctionBody.call(void 0, false, funcContextId);
} exports.tsParseFunctionBodyAndFinish = tsParseFunctionBodyAndFinish;

function tsParseSubscript(
  startTokenIndex,
  noCalls,
  stopState,
) {
  if (!_util.hasPrecedingLineBreak.call(void 0, ) && _index.eat.call(void 0, _types.TokenType.bang)) {
    _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType.nonNullAssertion;
    return;
  }

if (_index.match.call(void 0, _types.TokenType.lessThan) || _index.match.call(void 0, _types.TokenType.bitShiftL)) {
    // There are number of things we are going to "maybe" parse, like type arguments on
    // tagged template expressions. If any of them fail, walk it back and continue.
    const snapshot = _base.state.snapshot();

if (!noCalls && _expression.atPossibleAsync.call(void 0, )) {
      // Almost certainly this is a generic async function `async <T>() => ...
      // But it might be a call with a type argument `async<T>();`
      const asyncArrowFn = tsTryParseGenericAsyncArrowFunction();
      if (asyncArrowFn) {
        return;
      }
    }
    tsParseTypeArgumentsWithPossibleBitshift();
    if (!noCalls && _index.eat.call(void 0, _types.TokenType.parenL)) {
      // With f<T>(), the subscriptStartIndex marker is on the ( token.
      _base.state.tokens[_base.state.tokens.length - 1].subscriptStartIndex = startTokenIndex;
      _expression.parseCallExpressionArguments.call(void 0, );
    } else if (_index.match.call(void 0, _types.TokenType.backQuote)) {
      // Tagged template with a type argument.
      _expression.parseTemplate.call(void 0, );
    } else if (
      // The remaining possible case is an instantiation expression, e.g.
      // Array<number> . Check for a few cases that would disqualify it and
      // cause us to bail out.
      // a<b>>c is not (a<b>)>c, but a<(b>>c)
      _base.state.type === _types.TokenType.greaterThan ||
      // a<b>c is (a<b)>c
      (_base.state.type !== _types.TokenType.parenL &&
        Boolean(_base.state.type & _types.TokenType.IS_EXPRESSION_START) &&
        !_util.hasPrecedingLineBreak.call(void 0, ))
    ) {
      // Bail out. We have something like a<b>c, which is not an expression with
      // type arguments but an (a < b) > c comparison.
      _util.unexpected.call(void 0, );
    }

if (_base.state.error) {
      _base.state.restoreFromSnapshot(snapshot);
    } else {
      return;
    }
  } else if (!noCalls && _index.match.call(void 0, _types.TokenType.questionDot) && _index.lookaheadType.call(void 0, ) === _types.TokenType.lessThan) {
    // If we see f?.<, then this must be an optional call with a type argument.
    _index.next.call(void 0, );
    _base.state.tokens[startTokenIndex].isOptionalChainStart = true;
    // With f?.<T>(), the subscriptStartIndex marker is on the ?. token.
    _base.state.tokens[_base.state.tokens.length - 1].subscriptStartIndex = startTokenIndex;

tsParseTypeArguments();
    _util.expect.call(void 0, _types.TokenType.parenL);
    _expression.parseCallExpressionArguments.call(void 0, );
  }
  _expression.baseParseSubscript.call(void 0, startTokenIndex, noCalls, stopState);
} exports.tsParseSubscript = tsParseSubscript;

/**
 * Parse a TS import specifier, which may be prefixed with "type" and may be of
 * the form `foo as bar`.
 *
 * The number of identifier-like tokens we see happens to be enough to uniquely
 * identify the form, so simply count the number of identifiers rather than
 * matching the words `type` or `as`. This is particularly important because
 * `type` and `as` could each actually be plain identifiers rather than
 * keywords.
 */
 function tsParseImportSpecifier() {
  _expression.parseIdentifier.call(void 0, );
  if (_index.match.call(void 0, _types.TokenType.comma) || _index.match.call(void 0, _types.TokenType.braceR)) {
    // import {foo}
    _base.state.tokens[_base.state.tokens.length - 1].identifierRole = _index.IdentifierRole.ImportDeclaration;
    return;
  }
  _expression.parseIdentifier.call(void 0, );
  if (_index.match.call(void 0, _types.TokenType.comma) || _index.match.call(void 0, _types.TokenType.braceR)) {
    // import {type foo}
    _base.state.tokens[_base.state.tokens.length - 1].identifierRole = _index.IdentifierRole.ImportDeclaration;
    _base.state.tokens[_base.state.tokens.length - 2].isType = true;
    _base.state.tokens[_base.state.tokens.length - 1].isType = true;
    return;
  }
  _expression.parseIdentifier.call(void 0, );
  if (_index.match.call(void 0, _types.TokenType.comma) || _index.match.call(void 0, _types.TokenType.braceR)) {
    // import {foo as bar}
    _base.state.tokens[_base.state.tokens.length - 3].identifierRole = _index.IdentifierRole.ImportAccess;
    _base.state.tokens[_base.state.tokens.length - 1].identifierRole = _index.IdentifierRole.ImportDeclaration;
    return;
  }
  _expression.parseIdentifier.call(void 0, );
  // import {type foo as bar}
  _base.state.tokens[_base.state.tokens.length - 3].identifierRole = _index.IdentifierRole.ImportAccess;
  _base.state.tokens[_base.state.tokens.length - 1].identifierRole = _index.IdentifierRole.ImportDeclaration;
  _base.state.tokens[_base.state.tokens.length - 4].isType = true;
  _base.state.tokens[_base.state.tokens.length - 3].isType = true;
  _base.state.tokens[_base.state.tokens.length - 2].isType = true;
  _base.state.tokens[_base.state.tokens.length - 1].isType = true;
} exports.tsParseImportSpecifier = tsParseImportSpecifier;

/**
 * Just like named import specifiers, export specifiers can have from 1 to 4
 * tokens, inclusive, and the number of tokens determines the role of each token.
 */
 function tsParseExportSpecifier() {
  _expression.parseIdentifier.call(void 0, );
  if (_index.match.call(void 0, _types.TokenType.comma) || _index.match.call(void 0, _types.TokenType.braceR)) {
    // export {foo}
    _base.state.tokens[_base.state.tokens.length - 1].identifierRole = _index.IdentifierRole.ExportAccess;
    return;
  }
  _expression.parseIdentifier.call(void 0, );
  if (_index.match.call(void 0, _types.TokenType.comma) || _index.match.call(void 0, _types.TokenType.braceR)) {
    // export {type foo}
    _base.state.tokens[_base.state.tokens.length - 1].identifierRole = _index.IdentifierRole.ExportAccess;
    _base.state.tokens[_base.state.tokens.length - 2].isType = true;
    _base.state.tokens[_base.state.tokens.length - 1].isType = true;
    return;
  }
  _expression.parseIdentifier.call(void 0, );
  if (_index.match.call(void 0, _types.TokenType.comma) || _index.match.call(void 0, _types.TokenType.braceR)) {
    // export {foo as bar}
    _base.state.tokens[_base.state.tokens.length - 3].identifierRole = _index.IdentifierRole.ExportAccess;
    return;
  }
  _expression.parseIdentifier.call(void 0, );
  // export {type foo as bar}
  _base.state.tokens[_base.state.tokens.length - 3].identifierRole = _index.IdentifierRole.ExportAccess;
  _base.state.tokens[_base.state.tokens.length - 4].isType = true;
  _base.state.tokens[_base.state.tokens.length - 3].isType = true;
  _base.state.tokens[_base.state.tokens.length - 2].isType = true;
  _base.state.tokens[_base.state.tokens.length - 1].isType = true;
} exports.tsParseExportSpecifier = tsParseExportSpecifier;

function tsTryParseClassMemberWithIsStatic(isStatic) {
  const memberStartIndexAfterStatic = _base.state.tokens.length;
  tsParseModifiers([
    _keywords.ContextualKeyword._abstract,
    _keywords.ContextualKeyword._readonly,
    _keywords.ContextualKeyword._declare,
    _keywords.ContextualKeyword._static,
    _keywords.ContextualKeyword._override,
  ]);

const modifiersEndIndex = _base.state.tokens.length;
  const found = tsTryParseIndexSignature();
  if (found) {
    // Index signatures are type declarations, so set the modifier tokens as
    // type tokens. Most tokens could be assumed to be type tokens, but `static`
    // is ambiguous unless we set it explicitly here.
    const memberStartIndex = isStatic
      ? memberStartIndexAfterStatic - 1
      : memberStartIndexAfterStatic;
    for (let i = memberStartIndex; i < modifiersEndIndex; i++) {
      _base.state.tokens[i].isType = true;
    }
    return true;
  }
  return false;
} exports.tsTryParseClassMemberWithIsStatic = tsTryParseClassMemberWithIsStatic;

// Note: The reason we do this in `parseIdentifierStatement` and not `parseStatement`
// is that e.g. `type()` is valid JS, so we must try parsing that first.
// If it's really a type, we will parse `type` as the statement, and can correct it here
// by parsing the rest.
 function tsParseIdentifierStatement(contextualKeyword) {
  const matched = tsParseExpressionStatement(contextualKeyword);
  if (!matched) {
    _util.semicolon.call(void 0, );
  }
} exports.tsParseIdentifierStatement = tsParseIdentifierStatement;

function tsParseExportDeclaration() {
  // "export declare" is equivalent to just "export".
  const isDeclare = _util.eatContextual.call(void 0, _keywords.ContextualKeyword._declare);
  if (isDeclare) {
    _base.state.tokens[_base.state.tokens.length - 1].type = _types.TokenType._declare;
  }

function tsStartParseObjPropValue() {
  tsTryParseTypeParameters();
} exports.tsStartParseObjPropValue = tsStartParseObjPropValue;

function tsStartParseFunctionParams() {
  tsTryParseTypeParameters();
} exports.tsStartParseFunctionParams = tsStartParseFunctionParams;

// `let x: number;`
 function tsAfterParseVarHead() {
  const oldIsType = _index.pushTypeContext.call(void 0, 0);
  if (!_util.hasPrecedingLineBreak.call(void 0, )) {
    _index.eat.call(void 0, _types.TokenType.bang);
  }
  tsTryParseTypeAnnotation();
  _index.popTypeContext.call(void 0, oldIsType);
} exports.tsAfterParseVarHead = tsAfterParseVarHead;

// parse the return type of an async arrow function - let foo = (async (): number => {});
 function tsStartParseAsyncArrowFromCallExpression() {
  if (_index.match.call(void 0, _types.TokenType.colon)) {
    tsParseTypeAnnotation();
  }
} exports.tsStartParseAsyncArrowFromCallExpression = tsStartParseAsyncArrowFromCallExpression;

// Returns true if the expression was an arrow function.
 function tsParseMaybeAssign(noIn, isWithinParens) {
  // Note: When the JSX plugin is on, type assertions (`<T> x`) aren't valid syntax.
  if (_base.isJSXEnabled) {
    return tsParseMaybeAssignWithJSX(noIn, isWithinParens);
  } else {
    return tsParseMaybeAssignWithoutJSX(noIn, isWithinParens);
  }
} exports.tsParseMaybeAssign = tsParseMaybeAssign;

function tsParseMaybeAssignWithJSX(noIn, isWithinParens) {
  if (!_index.match.call(void 0, _types.TokenType.lessThan)) {
    return _expression.baseParseMaybeAssign.call(void 0, noIn, isWithinParens);
  }

// Prefer to parse JSX if possible. But may be an arrow fn.
  const snapshot = _base.state.snapshot();
  let wasArrow = _expression.baseParseMaybeAssign.call(void 0, noIn, isWithinParens);
  if (_base.state.error) {
    _base.state.restoreFromSnapshot(snapshot);
  } else {
    return wasArrow;
  }

// Otherwise, try as type-parameterized arrow function.
  _base.state.type = _types.TokenType.typeParameterStart;
  // This is similar to TypeScript's `tryParseParenthesizedArrowFunctionExpression`.
  tsParseTypeParameters();
  wasArrow = _expression.baseParseMaybeAssign.call(void 0, noIn, isWithinParens);
  if (!wasArrow) {
    _util.unexpected.call(void 0, );
  }

return wasArrow;
} exports.tsParseMaybeAssignWithJSX = tsParseMaybeAssignWithJSX;

function tsParseMaybeAssignWithoutJSX(noIn, isWithinParens) {
  if (!_index.match.call(void 0, _types.TokenType.lessThan)) {
    return _expression.baseParseMaybeAssign.call(void 0, noIn, isWithinParens);
  }

// Try parsing a type cast instead of an arrow function.
  // This will start with a type assertion (via parseMaybeUnary).
  // But don't directly call `tsParseTypeAssertion` because we want to handle any binary after it.
  return _expression.baseParseMaybeAssign.call(void 0, noIn, isWithinParens);
} exports.tsParseMaybeAssignWithoutJSX = tsParseMaybeAssignWithoutJSX;

function tsParseArrow() {
  if (_index.match.call(void 0, _types.TokenType.colon)) {
    // This is different from how the TS parser does it.
    // TS uses lookahead. Babylon parses it as a parenthesized expression and converts.
    const snapshot = _base.state.snapshot();

tsParseTypeOrTypePredicateAnnotation(_types.TokenType.colon);
    if (_util.canInsertSemicolon.call(void 0, )) _util.unexpected.call(void 0, );
    if (!_index.match.call(void 0, _types.TokenType.arrow)) _util.unexpected.call(void 0, );

if (_base.state.error) {
      _base.state.restoreFromSnapshot(snapshot);
    }
  }
  return _index.eat.call(void 0, _types.TokenType.arrow);
} exports.tsParseArrow = tsParseArrow;

// Allow type annotations inside of a parameter list.
 function tsParseAssignableListItemTypes() {
  const oldIsType = _index.pushTypeContext.call(void 0, 0);
  _index.eat.call(void 0, _types.TokenType.question);
  tsTryParseTypeAnnotation();
  _index.popTypeContext.call(void 0, oldIsType);
} exports.tsParseAssignableListItemTypes = tsParseAssignableListItemTypes;

function tsParseMaybeDecoratorArguments() {
  if (_index.match.call(void 0, _types.TokenType.lessThan) || _index.match.call(void 0, _types.TokenType.bitShiftL)) {
    tsParseTypeArgumentsWithPossibleBitshift();
  }
  _statement.baseParseMaybeDecoratorArguments.call(void 0, );
} exports.tsParseMaybeDecoratorArguments = tsParseMaybeDecoratorArguments;

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