author Guptha Rajagopal <gupta.rajagopal@gmail.com>
Fri, 08 Aug 2014 09:15:00 -0400
changeset 198757 7079b7552946f5e7d274060206a785c340abbf1d
parent 197510 3d3945a8af7d18ca632d67a26df697ed0f259885
child 199988 1369bf46b89f115eaee703973018fdfe46c1c50b
permissions -rw-r--r--
Bug 924688 - Implement ES6 computed property names. r=jorendorff

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef frontend_SyntaxParseHandler_h
#define frontend_SyntaxParseHandler_h

#include "frontend/ParseNode.h"
#include "frontend/TokenStream.h"

namespace js {
namespace frontend {

template <typename ParseHandler>
class Parser;

// Parse handler used when processing the syntax in a block of code, to generate
// the minimal information which is required to detect syntax errors and allow
// bytecode to be emitted for outer functions.
// When parsing, we start at the top level with a full parse, and when possible
// only check the syntax for inner functions, so that they can be lazily parsed
// into bytecode when/if they first run. Checking the syntax of a function is
// several times faster than doing a full parse/emit, and lazy parsing improves
// both performance and memory usage significantly when pages contain large
// amounts of code that never executes (which happens often).
class SyntaxParseHandler
    // Remember the last encountered name or string literal during syntax parses.
    JSAtom *lastAtom;
    TokenPos lastStringPos;
    TokenStream &tokenStream;

    enum Node {
        NodeFailure = 0,
    typedef Definition::Kind DefinitionNode;

    SyntaxParseHandler(ExclusiveContext *cx, LifoAlloc &alloc,
                       TokenStream &tokenStream, bool foldConstants,
                       Parser<SyntaxParseHandler> *syntaxParser, LazyScript *lazyOuterFunction)
      : lastAtom(nullptr),

    static Node null() { return NodeFailure; }

    void trace(JSTracer *trc) {}

    Node newName(PropertyName *name, uint32_t blockid, const TokenPos &pos) {
        lastAtom = name;
        return NodeName;

    Node newComputedName(Node expr, uint32_t start, uint32_t end) {
        return NodeName;

    DefinitionNode newPlaceholder(JSAtom *atom, uint32_t blockid, const TokenPos &pos) {
        return Definition::PLACEHOLDER;

    Node newIdentifier(JSAtom *atom, const TokenPos &pos) { return NodeString; }
    Node newNumber(double value, DecimalPoint decimalPoint, const TokenPos &pos) { return NodeGeneric; }
    Node newBooleanLiteral(bool cond, const TokenPos &pos) { return NodeGeneric; }

    Node newStringLiteral(JSAtom *atom, const TokenPos &pos) {
        lastAtom = atom;
        lastStringPos = pos;
        return NodeString;

    Node newTemplateStringLiteral(JSAtom *atom, const TokenPos &pos) {
        return NodeGeneric;

    Node newCallSiteObject(uint32_t begin, unsigned blockidGen) {
        return NodeGeneric;

    bool addToCallSiteObject(Node callSiteObj, Node rawNode, Node cookedNode) {
        return true;

    Node newThisLiteral(const TokenPos &pos) { return NodeGeneric; }
    Node newNullLiteral(const TokenPos &pos) { return NodeGeneric; }

    template <class Boxer>
    Node newRegExp(JSObject *reobj, const TokenPos &pos, Boxer &boxer) { return NodeGeneric; }

    Node newConditional(Node cond, Node thenExpr, Node elseExpr) { return NodeGeneric; }

    Node newElision() { return NodeGeneric; }

    Node newDelete(uint32_t begin, Node expr) { return NodeGeneric; }

    Node newUnary(ParseNodeKind kind, JSOp op, uint32_t begin, Node kid) {
        return NodeGeneric;

    Node newBinary(ParseNodeKind kind, JSOp op = JSOP_NOP) { return NodeGeneric; }
    Node newBinary(ParseNodeKind kind, Node left, JSOp op = JSOP_NOP) { return NodeGeneric; }
    Node newBinary(ParseNodeKind kind, Node left, Node right, JSOp op = JSOP_NOP) {
        return NodeGeneric;
    Node newBinaryOrAppend(ParseNodeKind kind, Node left, Node right,
                           ParseContext<SyntaxParseHandler> *pc, JSOp op = JSOP_NOP) {
        return NodeGeneric;

    Node newTernary(ParseNodeKind kind, Node first, Node second, Node third, JSOp op = JSOP_NOP) {
        return NodeGeneric;

    // Expressions

    Node newArrayComprehension(Node body, unsigned blockid, const TokenPos &pos) {
        return NodeGeneric;
    Node newArrayLiteral(uint32_t begin, unsigned blockid) { return NodeGeneric; }
    bool addElision(Node literal, const TokenPos &pos) { return true; }
    bool addSpreadElement(Node literal, uint32_t begin, Node inner) { return true; }
    bool addArrayElement(Node literal, Node element) { return true; }

    Node newObjectLiteral(uint32_t begin) { return NodeGeneric; }
    bool addPrototypeMutation(Node literal, uint32_t begin, Node expr) { return true; }
    bool addPropertyDefinition(Node literal, Node name, Node expr, bool isShorthand = false) { return true; }
    bool addAccessorPropertyDefinition(Node literal, Node name, Node fn, JSOp op) { return true; }

    // Statements

    Node newStatementList(unsigned blockid, const TokenPos &pos) { return NodeGeneric; }
    void addStatementToList(Node list, Node stmt, ParseContext<SyntaxParseHandler> *pc) {}
    Node newEmptyStatement(const TokenPos &pos) { return NodeGeneric; }

    Node newExprStatement(Node expr, uint32_t end) {
        return expr == NodeString ? NodeStringExprStatement : NodeGeneric;

    Node newIfStatement(uint32_t begin, Node cond, Node then, Node else_) { return NodeGeneric; }
    Node newDoWhileStatement(Node body, Node cond, const TokenPos &pos) { return NodeGeneric; }
    Node newWhileStatement(uint32_t begin, Node cond, Node body) { return NodeGeneric; }
    Node newSwitchStatement(uint32_t begin, Node discriminant, Node caseList) { return NodeGeneric; }
    Node newCaseOrDefault(uint32_t begin, Node expr, Node body) { return NodeGeneric; }
    Node newContinueStatement(PropertyName *label, const TokenPos &pos) { return NodeGeneric; }
    Node newBreakStatement(PropertyName *label, const TokenPos &pos) { return NodeGeneric; }
    Node newReturnStatement(Node expr, const TokenPos &pos) { return NodeGeneric; }

    Node newLabeledStatement(PropertyName *label, Node stmt, uint32_t begin) {
        return NodeGeneric;

    Node newThrowStatement(Node expr, const TokenPos &pos) { return NodeGeneric; }
    Node newTryStatement(uint32_t begin, Node body, Node catchList, Node finallyBlock) {
        return NodeGeneric;
    Node newDebuggerStatement(const TokenPos &pos) { return NodeGeneric; }

    Node newPropertyAccess(Node pn, PropertyName *name, uint32_t end) {
        lastAtom = name;
        return NodeGetProp;

    Node newPropertyByValue(Node pn, Node kid, uint32_t end) { return NodeLValue; }

    bool addCatchBlock(Node catchList, Node letBlock,
                       Node catchName, Node catchGuard, Node catchBody) { return true; }

    void setLastFunctionArgumentDefault(Node funcpn, Node pn) {}
    Node newFunctionDefinition() { return NodeGeneric; }
    void setFunctionBody(Node pn, Node kid) {}
    void setFunctionBox(Node pn, FunctionBox *funbox) {}
    void addFunctionArgument(Node pn, Node argpn) {}

    Node newForStatement(uint32_t begin, Node forHead, Node body, unsigned iflags) {
        return NodeGeneric;

    Node newForHead(ParseNodeKind kind, Node decls, Node lhs, Node rhs, const TokenPos &pos) {
        return NodeGeneric;

    Node newLexicalScope(ObjectBox *blockbox) { return NodeGeneric; }
    void setLexicalScopeBody(Node block, Node body) {}

    bool isOperationWithoutParens(Node pn, ParseNodeKind kind) {
        // It is OK to return false here, callers should only use this method
        // for reporting strict option warnings and parsing code which the
        // syntax parser does not handle.
        return false;

    bool finishInitializerAssignment(Node pn, Node init, JSOp op) { return true; }

    void setBeginPosition(Node pn, Node oth) {}
    void setBeginPosition(Node pn, uint32_t begin) {}

    void setEndPosition(Node pn, Node oth) {}
    void setEndPosition(Node pn, uint32_t end) {}

    void setPosition(Node pn, const TokenPos &pos) {}
    TokenPos getPosition(Node pn) {
        return tokenStream.currentToken().pos;

    Node newList(ParseNodeKind kind, Node kid = NodeGeneric, JSOp op = JSOP_NOP) {
        return NodeGeneric;
    void addList(Node pn, Node kid) {}
    bool isUnparenthesizedYield(Node pn) { return false; }

    void setOp(Node pn, JSOp op) {}
    void setBlockId(Node pn, unsigned blockid) {}
    void setFlag(Node pn, unsigned flag) {}
    void setListFlag(Node pn, unsigned flag) {}
    Node setInParens(Node pn) {
        // String literals enclosed by parentheses are ignored during
        // strict mode parsing.
        return NodeGeneric;
    void setPrologue(Node pn) {}

    bool isConstant(Node pn) { return false; }
    PropertyName *isName(Node pn) {
        return (pn == NodeName) ? lastAtom->asPropertyName() : nullptr;
    PropertyName *isGetProp(Node pn) {
        return (pn == NodeGetProp) ? lastAtom->asPropertyName() : nullptr;
    JSAtom *isStringExprStatement(Node pn, TokenPos *pos) {
        if (pn == NodeStringExprStatement) {
            *pos = lastStringPos;
            return lastAtom;
        return nullptr;

    Node makeAssignment(Node pn, Node rhs) { return NodeGeneric; }

    static Node getDefinitionNode(DefinitionNode dn) { return NodeGeneric; }
    static Definition::Kind getDefinitionKind(DefinitionNode dn) { return dn; }
    void linkUseToDef(Node pn, DefinitionNode dn) {}
    DefinitionNode resolve(DefinitionNode dn) { return dn; }
    void deoptimizeUsesWithin(DefinitionNode dn, const TokenPos &pos) {}
    bool dependencyCovered(Node pn, unsigned blockid, bool functionScope) {
        // Only resolve lexical dependencies in cases where a definition covers
        // the entire function. Not enough information is kept to compare the
        // dependency location with blockid.
        return functionScope;

    static uintptr_t definitionToBits(DefinitionNode dn) {
        // Use a shift, as DefinitionList tags the lower bit of its associated union.
        return uintptr_t(dn << 1);
    static DefinitionNode definitionFromBits(uintptr_t bits) {
        return (DefinitionNode) (bits >> 1);
    static DefinitionNode nullDefinition() {
        return Definition::MISSING;
    void disableSyntaxParser() {

} // namespace frontend
} // namespace js

#endif /* frontend_SyntaxParseHandler_h */