babel/src/parser/statement.js

1105 lines
34 KiB
JavaScript

/* eslint max-len: 0 */
import { types as tt } from "../tokenizer/types";
import Parser from "./index";
import { lineBreak } from "../util/whitespace";
const pp = Parser.prototype;
// ### Statement parsing
// Parse a program. Initializes the parser, reads any number of
// statements, and wraps them in a Program node. Optionally takes a
// `program` argument. If present, the statements will be appended
// to its body instead of creating a new node.
pp.parseTopLevel = function (file, program) {
program.sourceType = this.options.sourceType;
this.parseBlockBody(program, true, true, tt.eof);
file.program = this.finishNode(program, "Program");
file.comments = this.state.comments;
file.tokens = this.state.tokens;
return this.finishNode(file, "File");
};
const loopLabel = { kind: "loop" }, switchLabel = { kind: "switch" };
// TODO
pp.stmtToDirective = function (stmt) {
const expr = stmt.expression;
const directiveLiteral = this.startNodeAt(expr.start, expr.loc.start);
const directive = this.startNodeAt(stmt.start, stmt.loc.start);
const raw = this.input.slice(expr.start, expr.end);
const val = directiveLiteral.value = raw.slice(1, -1); // remove quotes
this.addExtra(directiveLiteral, "raw", raw);
this.addExtra(directiveLiteral, "rawValue", val);
directive.value = this.finishNodeAt(directiveLiteral, "DirectiveLiteral", expr.end, expr.loc.end);
return this.finishNodeAt(directive, "Directive", stmt.end, stmt.loc.end);
};
// Parse a single statement.
//
// If expecting a statement and finding a slash operator, parse a
// regular expression literal. This is to handle cases like
// `if (foo) /blah/.exec(foo)`, where looking at the previous token
// does not help.
pp.parseStatement = function (declaration, topLevel) {
if (this.match(tt.at)) {
this.parseDecorators(true);
}
const starttype = this.state.type;
const node = this.startNode();
// Most types of statements are recognized by the keyword they
// start with. Many are trivial to parse, some require a bit of
// complexity.
switch (starttype) {
case tt._break: case tt._continue: return this.parseBreakContinueStatement(node, starttype.keyword);
case tt._debugger: return this.parseDebuggerStatement(node);
case tt._do: return this.parseDoStatement(node);
case tt._for: return this.parseForStatement(node);
case tt._function:
if (!declaration) this.unexpected();
return this.parseFunctionStatement(node);
case tt._class:
if (!declaration) this.unexpected();
return this.parseClass(node, true);
case tt._if: return this.parseIfStatement(node);
case tt._return: return this.parseReturnStatement(node);
case tt._switch: return this.parseSwitchStatement(node);
case tt._throw: return this.parseThrowStatement(node);
case tt._try: return this.parseTryStatement(node);
case tt._let:
case tt._const:
if (!declaration) this.unexpected(); // NOTE: falls through to _var
case tt._var:
return this.parseVarStatement(node, starttype);
case tt._while: return this.parseWhileStatement(node);
case tt._with: return this.parseWithStatement(node);
case tt.braceL: return this.parseBlock();
case tt.semi: return this.parseEmptyStatement(node);
case tt._export:
case tt._import:
if (this.hasPlugin("dynamicImport") && this.lookahead().type === tt.parenL) break;
if (!this.options.allowImportExportEverywhere) {
if (!topLevel) {
this.raise(this.state.start, "'import' and 'export' may only appear at the top level");
}
if (!this.inModule) {
this.raise(this.state.start, "'import' and 'export' may appear only with 'sourceType: module'");
}
}
return starttype === tt._import ? this.parseImport(node) : this.parseExport(node);
case tt.name:
if (this.state.value === "async") {
// peek ahead and see if next token is a function
const state = this.state.clone();
this.next();
if (this.match(tt._function) && !this.canInsertSemicolon()) {
this.expect(tt._function);
return this.parseFunction(node, true, false, true);
} else {
this.state = state;
}
}
}
// If the statement does not start with a statement keyword or a
// brace, it's an ExpressionStatement or LabeledStatement. We
// simply start parsing an expression, and afterwards, if the
// next token is a colon and the expression was a simple
// Identifier node, we switch to interpreting it as a label.
const maybeName = this.state.value;
const expr = this.parseExpression();
if (starttype === tt.name && expr.type === "Identifier" && this.eat(tt.colon)) {
return this.parseLabeledStatement(node, maybeName, expr);
} else {
return this.parseExpressionStatement(node, expr);
}
};
pp.takeDecorators = function (node) {
if (this.state.decorators.length) {
node.decorators = this.state.decorators;
this.state.decorators = [];
}
};
pp.parseDecorators = function (allowExport) {
while (this.match(tt.at)) {
const decorator = this.parseDecorator();
this.state.decorators.push(decorator);
}
if (allowExport && this.match(tt._export)) {
return;
}
if (!this.match(tt._class)) {
this.raise(this.state.start, "Leading decorators must be attached to a class declaration");
}
};
pp.parseDecorator = function () {
if (!this.hasPlugin("decorators")) {
this.unexpected();
}
const node = this.startNode();
this.next();
node.expression = this.parseMaybeAssign();
return this.finishNode(node, "Decorator");
};
pp.parseBreakContinueStatement = function (node, keyword) {
const isBreak = keyword === "break";
this.next();
if (this.isLineTerminator()) {
node.label = null;
} else if (!this.match(tt.name)) {
this.unexpected();
} else {
node.label = this.parseIdentifier();
this.semicolon();
}
// Verify that there is an actual destination to break or
// continue to.
let i;
for (i = 0; i < this.state.labels.length; ++i) {
const lab = this.state.labels[i];
if (node.label == null || lab.name === node.label.name) {
if (lab.kind != null && (isBreak || lab.kind === "loop")) break;
if (node.label && isBreak) break;
}
}
if (i === this.state.labels.length) this.raise(node.start, "Unsyntactic " + keyword);
return this.finishNode(node, isBreak ? "BreakStatement" : "ContinueStatement");
};
pp.parseDebuggerStatement = function (node) {
this.next();
this.semicolon();
return this.finishNode(node, "DebuggerStatement");
};
pp.parseDoStatement = function (node) {
this.next();
this.state.labels.push(loopLabel);
node.body = this.parseStatement(false);
this.state.labels.pop();
this.expect(tt._while);
node.test = this.parseParenExpression();
this.eat(tt.semi);
return this.finishNode(node, "DoWhileStatement");
};
// Disambiguating between a `for` and a `for`/`in` or `for`/`of`
// loop is non-trivial. Basically, we have to parse the init `var`
// statement or expression, disallowing the `in` operator (see
// the second parameter to `parseExpression`), and then check
// whether the next token is `in` or `of`. When there is no init
// part (semicolon immediately after the opening parenthesis), it
// is a regular `for` loop.
pp.parseForStatement = function (node) {
this.next();
this.state.labels.push(loopLabel);
let forAwait = false;
if (this.hasPlugin("asyncGenerators") && this.state.inAsync && this.isContextual("await")) {
forAwait = true;
this.next();
}
this.expect(tt.parenL);
if (this.match(tt.semi)) {
if (forAwait) {
this.unexpected();
}
return this.parseFor(node, null);
}
if (this.match(tt._var) || this.match(tt._let) || this.match(tt._const)) {
const init = this.startNode();
const varKind = this.state.type;
this.next();
this.parseVar(init, true, varKind);
this.finishNode(init, "VariableDeclaration");
if (this.match(tt._in) || this.isContextual("of")) {
if (init.declarations.length === 1 && !init.declarations[0].init) {
return this.parseForIn(node, init, forAwait);
}
}
if (forAwait) {
this.unexpected();
}
return this.parseFor(node, init);
}
const refShorthandDefaultPos = { start: 0 };
const init = this.parseExpression(true, refShorthandDefaultPos);
if (this.match(tt._in) || this.isContextual("of")) {
const description = this.isContextual("of") ? "for-of statement" : "for-in statement";
this.toAssignable(init, undefined, description);
this.checkLVal(init, undefined, undefined, description);
return this.parseForIn(node, init, forAwait);
} else if (refShorthandDefaultPos.start) {
this.unexpected(refShorthandDefaultPos.start);
}
if (forAwait) {
this.unexpected();
}
return this.parseFor(node, init);
};
pp.parseFunctionStatement = function (node) {
this.next();
return this.parseFunction(node, true);
};
pp.parseIfStatement = function (node) {
this.next();
node.test = this.parseParenExpression();
node.consequent = this.parseStatement(false);
node.alternate = this.eat(tt._else) ? this.parseStatement(false) : null;
return this.finishNode(node, "IfStatement");
};
pp.parseReturnStatement = function (node) {
if (!this.state.inFunction && !this.options.allowReturnOutsideFunction) {
this.raise(this.state.start, "'return' outside of function");
}
this.next();
// In `return` (and `break`/`continue`), the keywords with
// optional arguments, we eagerly look for a semicolon or the
// possibility to insert one.
if (this.isLineTerminator()) {
node.argument = null;
} else {
node.argument = this.parseExpression();
this.semicolon();
}
return this.finishNode(node, "ReturnStatement");
};
pp.parseSwitchStatement = function (node) {
this.next();
node.discriminant = this.parseParenExpression();
node.cases = [];
this.expect(tt.braceL);
this.state.labels.push(switchLabel);
// Statements under must be grouped (by label) in SwitchCase
// nodes. `cur` is used to keep the node that we are currently
// adding statements to.
let cur;
for (let sawDefault; !this.match(tt.braceR); ) {
if (this.match(tt._case) || this.match(tt._default)) {
const isCase = this.match(tt._case);
if (cur) this.finishNode(cur, "SwitchCase");
node.cases.push(cur = this.startNode());
cur.consequent = [];
this.next();
if (isCase) {
cur.test = this.parseExpression();
} else {
if (sawDefault) this.raise(this.state.lastTokStart, "Multiple default clauses");
sawDefault = true;
cur.test = null;
}
this.expect(tt.colon);
} else {
if (cur) {
cur.consequent.push(this.parseStatement(true));
} else {
this.unexpected();
}
}
}
if (cur) this.finishNode(cur, "SwitchCase");
this.next(); // Closing brace
this.state.labels.pop();
return this.finishNode(node, "SwitchStatement");
};
pp.parseThrowStatement = function (node) {
this.next();
if (lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.start)))
this.raise(this.state.lastTokEnd, "Illegal newline after throw");
node.argument = this.parseExpression();
this.semicolon();
return this.finishNode(node, "ThrowStatement");
};
// Reused empty array added for node fields that are always empty.
const empty = [];
pp.parseTryStatement = function (node) {
this.next();
node.block = this.parseBlock();
node.handler = null;
if (this.match(tt._catch)) {
const clause = this.startNode();
this.next();
this.expect(tt.parenL);
clause.param = this.parseBindingAtom();
this.checkLVal(clause.param, true, Object.create(null), "catch clause");
this.expect(tt.parenR);
clause.body = this.parseBlock();
node.handler = this.finishNode(clause, "CatchClause");
}
node.guardedHandlers = empty;
node.finalizer = this.eat(tt._finally) ? this.parseBlock() : null;
if (!node.handler && !node.finalizer) {
this.raise(node.start, "Missing catch or finally clause");
}
return this.finishNode(node, "TryStatement");
};
pp.parseVarStatement = function (node, kind) {
this.next();
this.parseVar(node, false, kind);
this.semicolon();
return this.finishNode(node, "VariableDeclaration");
};
pp.parseWhileStatement = function (node) {
this.next();
node.test = this.parseParenExpression();
this.state.labels.push(loopLabel);
node.body = this.parseStatement(false);
this.state.labels.pop();
return this.finishNode(node, "WhileStatement");
};
pp.parseWithStatement = function (node) {
if (this.state.strict) this.raise(this.state.start, "'with' in strict mode");
this.next();
node.object = this.parseParenExpression();
node.body = this.parseStatement(false);
return this.finishNode(node, "WithStatement");
};
pp.parseEmptyStatement = function (node) {
this.next();
return this.finishNode(node, "EmptyStatement");
};
pp.parseLabeledStatement = function (node, maybeName, expr) {
for (const label of (this.state.labels: Array<Object>)) {
if (label.name === maybeName) {
this.raise(expr.start, `Label '${maybeName}' is already declared`);
}
}
const kind = this.state.type.isLoop ? "loop" : this.match(tt._switch) ? "switch" : null;
for (let i = this.state.labels.length - 1; i >= 0; i--) {
const label = this.state.labels[i];
if (label.statementStart === node.start) {
label.statementStart = this.state.start;
label.kind = kind;
} else {
break;
}
}
this.state.labels.push({ name: maybeName, kind: kind, statementStart: this.state.start });
node.body = this.parseStatement(true);
this.state.labels.pop();
node.label = expr;
return this.finishNode(node, "LabeledStatement");
};
pp.parseExpressionStatement = function (node, expr) {
node.expression = expr;
this.semicolon();
return this.finishNode(node, "ExpressionStatement");
};
// Parse a semicolon-enclosed block of statements, handling `"use
// strict"` declarations when `allowStrict` is true (used for
// function bodies).
pp.parseBlock = function (allowDirectives?) {
const node = this.startNode();
this.expect(tt.braceL);
this.parseBlockBody(node, allowDirectives, false, tt.braceR);
return this.finishNode(node, "BlockStatement");
};
pp.isValidDirective = function (stmt) {
return stmt.type === "ExpressionStatement" &&
stmt.expression.type === "StringLiteral" &&
!stmt.expression.extra.parenthesized;
};
pp.parseBlockBody = function (node, allowDirectives, topLevel, end) {
node.body = [];
node.directives = [];
let parsedNonDirective = false;
let oldStrict;
let octalPosition;
while (!this.eat(end)) {
if (!parsedNonDirective && this.state.containsOctal && !octalPosition) {
octalPosition = this.state.octalPosition;
}
const stmt = this.parseStatement(true, topLevel);
if (allowDirectives && !parsedNonDirective && this.isValidDirective(stmt)) {
const directive = this.stmtToDirective(stmt);
node.directives.push(directive);
if (oldStrict === undefined && directive.value.value === "use strict") {
oldStrict = this.state.strict;
this.setStrict(true);
if (octalPosition) {
this.raise(octalPosition, "Octal literal in strict mode");
}
}
continue;
}
parsedNonDirective = true;
node.body.push(stmt);
}
if (oldStrict === false) {
this.setStrict(false);
}
};
// Parse a regular `for` loop. The disambiguation code in
// `parseStatement` will already have parsed the init statement or
// expression.
pp.parseFor = function (node, init) {
node.init = init;
this.expect(tt.semi);
node.test = this.match(tt.semi) ? null : this.parseExpression();
this.expect(tt.semi);
node.update = this.match(tt.parenR) ? null : this.parseExpression();
this.expect(tt.parenR);
node.body = this.parseStatement(false);
this.state.labels.pop();
return this.finishNode(node, "ForStatement");
};
// Parse a `for`/`in` and `for`/`of` loop, which are almost
// same from parser's perspective.
pp.parseForIn = function (node, init, forAwait) {
const type = this.match(tt._in) ? "ForInStatement" : "ForOfStatement";
if (forAwait) {
this.eatContextual("of");
} else {
this.next();
}
node.await = !!forAwait;
node.left = init;
node.right = this.parseExpression();
this.expect(tt.parenR);
node.body = this.parseStatement(false);
this.state.labels.pop();
return this.finishNode(node, type);
};
// Parse a list of variable declarations.
pp.parseVar = function (node, isFor, kind) {
node.declarations = [];
node.kind = kind.keyword;
for (;;) {
const decl = this.startNode();
this.parseVarHead(decl);
if (this.eat(tt.eq)) {
decl.init = this.parseMaybeAssign(isFor);
} else if (kind === tt._const && !(this.match(tt._in) || this.isContextual("of"))) {
this.unexpected();
} else if (decl.id.type !== "Identifier" && !(isFor && (this.match(tt._in) || this.isContextual("of")))) {
this.raise(this.state.lastTokEnd, "Complex binding patterns require an initialization value");
} else {
decl.init = null;
}
node.declarations.push(this.finishNode(decl, "VariableDeclarator"));
if (!this.eat(tt.comma)) break;
}
return node;
};
pp.parseVarHead = function (decl) {
decl.id = this.parseBindingAtom();
this.checkLVal(decl.id, true, undefined, "variable declaration");
};
// Parse a function declaration or literal (depending on the
// `isStatement` parameter).
pp.parseFunction = function (node, isStatement, allowExpressionBody, isAsync, optionalId) {
const oldInMethod = this.state.inMethod;
this.state.inMethod = false;
this.initFunction(node, isAsync);
if (this.match(tt.star)) {
if (node.async && !this.hasPlugin("asyncGenerators")) {
this.unexpected();
} else {
node.generator = true;
this.next();
}
}
if (isStatement && !optionalId && !this.match(tt.name) && !this.match(tt._yield)) {
this.unexpected();
}
if (this.match(tt.name) || this.match(tt._yield)) {
node.id = this.parseBindingIdentifier();
}
this.parseFunctionParams(node);
this.parseFunctionBody(node, allowExpressionBody);
this.state.inMethod = oldInMethod;
return this.finishNode(node, isStatement ? "FunctionDeclaration" : "FunctionExpression");
};
pp.parseFunctionParams = function (node) {
this.expect(tt.parenL);
node.params = this.parseBindingList(tt.parenR);
};
// Parse a class declaration or literal (depending on the
// `isStatement` parameter).
pp.parseClass = function (node, isStatement, optionalId) {
this.next();
this.takeDecorators(node);
this.parseClassId(node, isStatement, optionalId);
this.parseClassSuper(node);
this.parseClassBody(node);
return this.finishNode(node, isStatement ? "ClassDeclaration" : "ClassExpression");
};
pp.isClassProperty = function () {
return this.match(tt.eq) || this.match(tt.semi) || this.match(tt.braceR);
};
pp.isClassMethod = function () {
return this.match(tt.parenL);
};
pp.isNonstaticConstructor = function (method) {
return !method.computed && !method.static && (
(method.key.name === "constructor") || // Identifier
(method.key.value === "constructor") // Literal
);
};
pp.parseClassBody = function (node) {
// class bodies are implicitly strict
const oldStrict = this.state.strict;
this.state.strict = true;
let hadConstructor = false;
let decorators = [];
const classBody = this.startNode();
classBody.body = [];
this.expect(tt.braceL);
while (!this.eat(tt.braceR)) {
if (this.eat(tt.semi)) {
if (decorators.length > 0) {
this.raise(this.state.lastTokEnd, "Decorators must not be followed by a semicolon");
}
continue;
}
if (this.match(tt.at)) {
decorators.push(this.parseDecorator());
continue;
}
const method = this.startNode();
// steal the decorators if there are any
if (decorators.length) {
method.decorators = decorators;
decorators = [];
}
method.static = false;
if (this.match(tt.name) && this.state.value === "static") {
const key = this.parseIdentifier(true); // eats 'static'
if (this.isClassMethod()) {
// a method named 'static'
method.kind = "method";
method.computed = false;
method.key = key;
this.parseClassMethod(classBody, method, false, false);
continue;
} else if (this.isClassProperty()) {
// a property named 'static'
method.computed = false;
method.key = key;
classBody.body.push(this.parseClassProperty(method));
continue;
}
// otherwise something static
method.static = true;
}
if (this.eat(tt.star)) {
// a generator
method.kind = "method";
this.parsePropertyName(method);
if (this.isNonstaticConstructor(method)) {
this.raise(method.key.start, "Constructor can't be a generator");
}
if (!method.computed && method.static && (method.key.name === "prototype" || method.key.value === "prototype")) {
this.raise(method.key.start, "Classes may not have static property named prototype");
}
this.parseClassMethod(classBody, method, true, false);
} else {
const isSimple = this.match(tt.name);
const key = this.parsePropertyName(method);
if (!method.computed && method.static && (method.key.name === "prototype" || method.key.value === "prototype")) {
this.raise(method.key.start, "Classes may not have static property named prototype");
}
if (this.isClassMethod()) {
// a normal method
if (this.isNonstaticConstructor(method)) {
if (hadConstructor) {
this.raise(key.start, "Duplicate constructor in the same class");
} else if (method.decorators) {
this.raise(method.start, "You can't attach decorators to a class constructor");
}
hadConstructor = true;
method.kind = "constructor";
} else {
method.kind = "method";
}
this.parseClassMethod(classBody, method, false, false);
} else if (this.isClassProperty()) {
// a normal property
if (this.isNonstaticConstructor(method)) {
this.raise(method.key.start, "Classes may not have a non-static field named 'constructor'");
}
classBody.body.push(this.parseClassProperty(method));
} else if (isSimple && key.name === "async" && !this.isLineTerminator()) {
// an async method
const isGenerator = this.hasPlugin("asyncGenerators") && this.eat(tt.star);
method.kind = "method";
this.parsePropertyName(method);
if (this.isNonstaticConstructor(method)) {
this.raise(method.key.start, "Constructor can't be an async function");
}
this.parseClassMethod(classBody, method, isGenerator, true);
} else if (isSimple && (key.name === "get" || key.name === "set") && !(this.isLineTerminator() && this.match(tt.star))) { // `get\n*` is an uninitialized property named 'get' followed by a generator.
// a getter or setter
method.kind = key.name;
this.parsePropertyName(method);
if (this.isNonstaticConstructor(method)) {
this.raise(method.key.start, "Constructor can't have get/set modifier");
}
this.parseClassMethod(classBody, method, false, false);
this.checkGetterSetterParamCount(method);
} else if (this.isLineTerminator()) {
// an uninitialized class property (due to ASI, since we don't otherwise recognize the next token)
if (this.isNonstaticConstructor(method)) {
this.raise(method.key.start, "Classes may not have a non-static field named 'constructor'");
}
classBody.body.push(this.parseClassProperty(method));
} else {
this.unexpected();
}
}
}
if (decorators.length) {
this.raise(this.state.start, "You have trailing decorators with no method");
}
node.body = this.finishNode(classBody, "ClassBody");
this.state.strict = oldStrict;
};
pp.parseClassProperty = function (node) {
const noPluginMsg = "You can only use Class Properties when the 'classProperties' plugin is enabled.";
if (!node.typeAnnotation && !this.hasPlugin("classProperties")) {
this.raise(node.start, noPluginMsg);
}
if (this.match(tt.eq)) {
if (!this.hasPlugin("classProperties")) this.raise(this.state.start, noPluginMsg);
this.next();
node.value = this.parseMaybeAssign();
} else {
node.value = null;
}
this.semicolon();
return this.finishNode(node, "ClassProperty");
};
pp.parseClassMethod = function (classBody, method, isGenerator, isAsync) {
this.parseMethod(method, isGenerator, isAsync);
classBody.body.push(this.finishNode(method, "ClassMethod"));
};
pp.parseClassId = function (node, isStatement, optionalId) {
if (this.match(tt.name)) {
node.id = this.parseIdentifier();
} else {
if (optionalId || !isStatement) {
node.id = null;
} else {
this.unexpected();
}
}
};
pp.parseClassSuper = function (node) {
node.superClass = this.eat(tt._extends) ? this.parseExprSubscripts() : null;
};
// Parses module export declaration.
pp.parseExport = function (node) {
this.next();
// export * from '...'
if (this.match(tt.star)) {
const specifier = this.startNode();
this.next();
if (this.hasPlugin("exportExtensions") && this.eatContextual("as")) {
specifier.exported = this.parseIdentifier(true);
node.specifiers = [this.finishNode(specifier, "ExportNamespaceSpecifier")];
this.parseExportSpecifiersMaybe(node);
this.parseExportFrom(node, true);
} else {
this.parseExportFrom(node, true);
return this.finishNode(node, "ExportAllDeclaration");
}
} else if (this.hasPlugin("exportExtensions") && this.isExportDefaultSpecifier()) {
const specifier = this.startNode();
specifier.exported = this.parseIdentifier(true);
node.specifiers = [this.finishNode(specifier, "ExportDefaultSpecifier")];
if (this.match(tt.comma) && this.lookahead().type === tt.star) {
this.expect(tt.comma);
const specifier = this.startNode();
this.expect(tt.star);
this.expectContextual("as");
specifier.exported = this.parseIdentifier();
node.specifiers.push(this.finishNode(specifier, "ExportNamespaceSpecifier"));
} else {
this.parseExportSpecifiersMaybe(node);
}
this.parseExportFrom(node, true);
} else if (this.eat(tt._default)) { // export default ...
let expr = this.startNode();
let needsSemi = false;
if (this.eat(tt._function)) {
expr = this.parseFunction(expr, true, false, false, true);
} else if (
this.isContextual("async") &&
this.lookahead().type === tt._function
) { // async function declaration
this.eatContextual("async");
this.eat(tt._function);
expr = this.parseFunction(expr, true, false, true, true);
} else if (this.match(tt._class)) {
expr = this.parseClass(expr, true, true);
} else {
needsSemi = true;
expr = this.parseMaybeAssign();
}
node.declaration = expr;
if (needsSemi) this.semicolon();
this.checkExport(node, true, true);
return this.finishNode(node, "ExportDefaultDeclaration");
} else if (this.shouldParseExportDeclaration()) {
node.specifiers = [];
node.source = null;
node.declaration = this.parseExportDeclaration(node);
} else { // export { x, y as z } [from '...']
node.declaration = null;
node.specifiers = this.parseExportSpecifiers();
this.parseExportFrom(node);
}
this.checkExport(node, true);
return this.finishNode(node, "ExportNamedDeclaration");
};
pp.parseExportDeclaration = function () {
return this.parseStatement(true);
};
pp.isExportDefaultSpecifier = function () {
if (this.match(tt.name)) {
return this.state.value !== "type"
&& this.state.value !== "async"
&& this.state.value !== "interface";
}
if (!this.match(tt._default)) {
return false;
}
const lookahead = this.lookahead();
return lookahead.type === tt.comma || (lookahead.type === tt.name && lookahead.value === "from");
};
pp.parseExportSpecifiersMaybe = function (node) {
if (this.eat(tt.comma)) {
node.specifiers = node.specifiers.concat(this.parseExportSpecifiers());
}
};
pp.parseExportFrom = function (node, expect?) {
if (this.eatContextual("from")) {
node.source = this.match(tt.string) ? this.parseExprAtom() : this.unexpected();
this.checkExport(node);
} else {
if (expect) {
this.unexpected();
} else {
node.source = null;
}
}
this.semicolon();
};
pp.shouldParseExportDeclaration = function (): boolean {
return this.state.type.keyword === "var"
|| this.state.type.keyword === "const"
|| this.state.type.keyword === "let"
|| this.state.type.keyword === "function"
|| this.state.type.keyword === "class"
|| this.isContextual("async");
};
pp.checkExport = function (node, checkNames, isDefault) {
if (checkNames) {
// Check for duplicate exports
if (isDefault) {
// Default exports
this.checkDuplicateExports(node, "default");
} else if (node.specifiers && node.specifiers.length) {
// Named exports
for (const specifier of node.specifiers) {
this.checkDuplicateExports(specifier, specifier.exported.name);
}
} else if (node.declaration) {
// Exported declarations
if (node.declaration.type === "FunctionDeclaration" || node.declaration.type === "ClassDeclaration") {
this.checkDuplicateExports(node, node.declaration.id.name);
} else if (node.declaration.type === "VariableDeclaration") {
for (const declaration of node.declaration.declarations) {
this.checkDeclaration(declaration.id);
}
}
}
}
if (this.state.decorators.length) {
const isClass = node.declaration && (node.declaration.type === "ClassDeclaration" || node.declaration.type === "ClassExpression");
if (!node.declaration || !isClass) {
this.raise(node.start, "You can only use decorators on an export when exporting a class");
}
this.takeDecorators(node.declaration);
}
};
pp.checkDeclaration = function(node) {
if (node.type === "ObjectPattern") {
for (const prop of node.properties) {
this.checkDeclaration(prop);
}
} else if (node.type === "ArrayPattern") {
for (const elem of node.elements) {
if (elem) {
this.checkDeclaration(elem);
}
}
} else if (node.type === "ObjectProperty") {
this.checkDeclaration(node.value);
} else if (node.type === "RestElement") {
this.checkDeclaration(node.argument);
} else if (node.type === "Identifier") {
this.checkDuplicateExports(node, node.name);
}
};
pp.checkDuplicateExports = function(node, name) {
if (this.state.exportedIdentifiers.indexOf(name) > -1) {
this.raiseDuplicateExportError(node, name);
}
this.state.exportedIdentifiers.push(name);
};
pp.raiseDuplicateExportError = function(node, name) {
this.raise(node.start, name === "default" ?
"Only one default export allowed per module." :
`\`${name}\` has already been exported. Exported identifiers must be unique.`
);
};
// Parses a comma-separated list of module exports.
pp.parseExportSpecifiers = function () {
const nodes = [];
let first = true;
let needsFrom;
// export { x, y as z } [from '...']
this.expect(tt.braceL);
while (!this.eat(tt.braceR)) {
if (first) {
first = false;
} else {
this.expect(tt.comma);
if (this.eat(tt.braceR)) break;
}
const isDefault = this.match(tt._default);
if (isDefault && !needsFrom) needsFrom = true;
const node = this.startNode();
node.local = this.parseIdentifier(isDefault);
node.exported = this.eatContextual("as") ? this.parseIdentifier(true) : node.local.__clone();
nodes.push(this.finishNode(node, "ExportSpecifier"));
}
// https://github.com/ember-cli/ember-cli/pull/3739
if (needsFrom && !this.isContextual("from")) {
this.unexpected();
}
return nodes;
};
// Parses import declaration.
pp.parseImport = function (node) {
this.eat(tt._import);
// import '...'
if (this.match(tt.string)) {
node.specifiers = [];
node.source = this.parseExprAtom();
} else {
node.specifiers = [];
this.parseImportSpecifiers(node);
this.expectContextual("from");
node.source = this.match(tt.string) ? this.parseExprAtom() : this.unexpected();
}
this.semicolon();
return this.finishNode(node, "ImportDeclaration");
};
// Parses a comma-separated list of module imports.
pp.parseImportSpecifiers = function (node) {
let first = true;
if (this.match(tt.name)) {
// import defaultObj, { x, y as z } from '...'
const startPos = this.state.start;
const startLoc = this.state.startLoc;
node.specifiers.push(this.parseImportSpecifierDefault(this.parseIdentifier(), startPos, startLoc));
if (!this.eat(tt.comma)) return;
}
if (this.match(tt.star)) {
const specifier = this.startNode();
this.next();
this.expectContextual("as");
specifier.local = this.parseIdentifier();
this.checkLVal(specifier.local, true, undefined, "import namespace specifier");
node.specifiers.push(this.finishNode(specifier, "ImportNamespaceSpecifier"));
return;
}
this.expect(tt.braceL);
while (!this.eat(tt.braceR)) {
if (first) {
first = false;
} else {
// Detect an attempt to deep destructure
if (this.eat(tt.colon)) {
this.unexpected(null, "ES2015 named imports do not destructure. Use another statement for destructuring after the import.");
}
this.expect(tt.comma);
if (this.eat(tt.braceR)) break;
}
this.parseImportSpecifier(node);
}
};
pp.parseImportSpecifier = function (node) {
const specifier = this.startNode();
specifier.imported = this.parseIdentifier(true);
if (this.eatContextual("as")) {
specifier.local = this.parseIdentifier();
} else {
this.checkReservedWord(specifier.imported.name, specifier.start, true, true);
specifier.local = specifier.imported.__clone();
}
this.checkLVal(specifier.local, true, undefined, "import specifier");
node.specifiers.push(this.finishNode(specifier, "ImportSpecifier"));
};
pp.parseImportSpecifierDefault = function (id, startPos, startLoc) {
const node = this.startNodeAt(startPos, startLoc);
node.local = id;
this.checkLVal(node.local, true, undefined, "default import specifier");
return this.finishNode(node, "ImportDefaultSpecifier");
};