parser.java

java中比较著名的js引擎当属mozilla开源的rhino

                break;
        }
        return pn;
    }

    private Node expr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = assignExpr(inForInit);
        while (matchToken(Token.COMMA)) {
            decompiler.addToken(Token.COMMA);
            pn = nf.createBinary(Token.COMMA, pn, assignExpr(inForInit));
        }
        return pn;
    }

    private Node assignExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = condExpr(inForInit);

        int tt = peekToken();
        if (Token.FIRST_ASSIGN <= tt && tt <= Token.LAST_ASSIGN) {
            consumeToken();
            decompiler.addToken(tt);
            pn = nf.createAssignment(tt, pn, assignExpr(inForInit));
        }

        return pn;
    }

    private Node condExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node ifTrue;
        Node ifFalse;

        Node pn = orExpr(inForInit);

        if (matchToken(Token.HOOK)) {
            decompiler.addToken(Token.HOOK);
            ifTrue = assignExpr(false);
            mustMatchToken(Token.COLON, "msg.no.colon.cond");
            decompiler.addToken(Token.COLON);
            ifFalse = assignExpr(inForInit);
            return nf.createCondExpr(pn, ifTrue, ifFalse);
        }

        return pn;
    }

    private Node orExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = andExpr(inForInit);
        if (matchToken(Token.OR)) {
            decompiler.addToken(Token.OR);
            pn = nf.createBinary(Token.OR, pn, orExpr(inForInit));
        }

        return pn;
    }

    private Node andExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = bitOrExpr(inForInit);
        if (matchToken(Token.AND)) {
            decompiler.addToken(Token.AND);
            pn = nf.createBinary(Token.AND, pn, andExpr(inForInit));
        }

        return pn;
    }

    private Node bitOrExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = bitXorExpr(inForInit);
        while (matchToken(Token.BITOR)) {
            decompiler.addToken(Token.BITOR);
            pn = nf.createBinary(Token.BITOR, pn, bitXorExpr(inForInit));
        }
        return pn;
    }

    private Node bitXorExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = bitAndExpr(inForInit);
        while (matchToken(Token.BITXOR)) {
            decompiler.addToken(Token.BITXOR);
            pn = nf.createBinary(Token.BITXOR, pn, bitAndExpr(inForInit));
        }
        return pn;
    }

    private Node bitAndExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = eqExpr(inForInit);
        while (matchToken(Token.BITAND)) {
            decompiler.addToken(Token.BITAND);
            pn = nf.createBinary(Token.BITAND, pn, eqExpr(inForInit));
        }
        return pn;
    }

    private Node eqExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = relExpr(inForInit);
        for (;;) {
            int tt = peekToken();
            switch (tt) {
              case Token.EQ:
              case Token.NE:
              case Token.SHEQ:
              case Token.SHNE:
                consumeToken();
                int decompilerToken = tt;
                int parseToken = tt;
                if (compilerEnv.getLanguageVersion() == Context.VERSION_1_2) {
                    // JavaScript 1.2 uses shallow equality for == and != .
                    // In addition, convert === and !== for decompiler into
                    // == and != since the decompiler is supposed to show
                    // canonical source and in 1.2 ===, !== are allowed
                    // only as an alias to ==, !=.
                    switch (tt) {
                      case Token.EQ:
                        parseToken = Token.SHEQ;
                        break;
                      case Token.NE:
                        parseToken = Token.SHNE;
                        break;
                      case Token.SHEQ:
                        decompilerToken = Token.EQ;
                        break;
                      case Token.SHNE:
                        decompilerToken = Token.NE;
                        break;
                    }
                }
                decompiler.addToken(decompilerToken);
                pn = nf.createBinary(parseToken, pn, relExpr(inForInit));
                continue;
            }
            break;
        }
        return pn;
    }

    private Node relExpr(boolean inForInit)
        throws IOException, ParserException
    {
        Node pn = shiftExpr();
        for (;;) {
            int tt = peekToken();
            switch (tt) {
              case Token.IN:
                if (inForInit)
                    break;
                // fall through
              case Token.INSTANCEOF:
              case Token.LE:
              case Token.LT:
              case Token.GE:
              case Token.GT:
                consumeToken();
                decompiler.addToken(tt);
                pn = nf.createBinary(tt, pn, shiftExpr());
                continue;
            }
            break;
        }
        return pn;
    }

    private Node shiftExpr()
        throws IOException, ParserException
    {
        Node pn = addExpr();
        for (;;) {
            int tt = peekToken();
            switch (tt) {
              case Token.LSH:
              case Token.URSH:
              case Token.RSH:
                consumeToken();
                decompiler.addToken(tt);
                pn = nf.createBinary(tt, pn, addExpr());
                continue;
            }
            break;
        }
        return pn;
    }

    private Node addExpr()
        throws IOException, ParserException
    {
        Node pn = mulExpr();
        for (;;) {
            int tt = peekToken();
            if (tt == Token.ADD || tt == Token.SUB) {
                consumeToken();
                decompiler.addToken(tt);
                // flushNewLines
                pn = nf.createBinary(tt, pn, mulExpr());
                continue;
            }
            break;
        }

        return pn;
    }

    private Node mulExpr()
        throws IOException, ParserException
    {
        Node pn = unaryExpr();
        for (;;) {
            int tt = peekToken();
            switch (tt) {
              case Token.MUL:
              case Token.DIV:
              case Token.MOD:
                consumeToken();
                decompiler.addToken(tt);
                pn = nf.createBinary(tt, pn, unaryExpr());
                continue;
            }
            break;
        }

        return pn;
    }

    private Node unaryExpr()
        throws IOException, ParserException
    {
        int tt;

        tt = peekToken();

        switch(tt) {
        case Token.VOID:
        case Token.NOT:
        case Token.BITNOT:
        case Token.TYPEOF:
            consumeToken();
            decompiler.addToken(tt);
            return nf.createUnary(tt, unaryExpr());

        case Token.ADD:
            consumeToken();
            // Convert to special POS token in decompiler and parse tree
            decompiler.addToken(Token.POS);
            return nf.createUnary(Token.POS, unaryExpr());

        case Token.SUB:
            consumeToken();
            // Convert to special NEG token in decompiler and parse tree
            decompiler.addToken(Token.NEG);
            return nf.createUnary(Token.NEG, unaryExpr());

        case Token.INC:
        case Token.DEC:
            consumeToken();
            decompiler.addToken(tt);
            return nf.createIncDec(tt, false, memberExpr(true));

        case Token.DELPROP:
            consumeToken();
            decompiler.addToken(Token.DELPROP);
            return nf.createUnary(Token.DELPROP, unaryExpr());

        case Token.ERROR:
            consumeToken();
            break;

        // XML stream encountered in expression.
        case Token.LT:
            if (compilerEnv.isXmlAvailable()) {
                consumeToken();
                Node pn = xmlInitializer();
                return memberExprTail(true, pn);
            }
            // Fall thru to the default handling of RELOP

        default:
            Node pn = memberExpr(true);

            // Don't look across a newline boundary for a postfix incop.
            tt = peekTokenOrEOL();
            if (tt == Token.INC || tt == Token.DEC) {
                consumeToken();
                decompiler.addToken(tt);
                return nf.createIncDec(tt, true, pn);
            }
            return pn;
        }
        return nf.createName("err"); // Only reached on error.  Try to continue.

    }

    private Node xmlInitializer() throws IOException
    {
        int tt = ts.getFirstXMLToken();
        if (tt != Token.XML && tt != Token.XMLEND) {
            reportError("msg.syntax");
            return null;
        }

        /* Make a NEW node to append to. */
        Node pnXML = nf.createLeaf(Token.NEW);

        String xml = ts.getString();
        boolean fAnonymous = xml.trim().startsWith("<>");

        Node pn = nf.createName(fAnonymous ? "XMLList" : "XML");
        nf.addChildToBack(pnXML, pn);

        pn = null;
        Node expr;
        for (;;tt = ts.getNextXMLToken()) {
            switch (tt) {
            case Token.XML:
                xml = ts.getString();
                decompiler.addName(xml);
                mustMatchToken(Token.LC, "msg.syntax");
                decompiler.addToken(Token.LC);
                expr = (peekToken() == Token.RC)
                    ? nf.createString("")
                    : expr(false);
                mustMatchToken(Token.RC, "msg.syntax");
                decompiler.addToken(Token.RC);
                if (pn == null) {
                    pn = nf.createString(xml);
                } else {
                    pn = nf.createBinary(Token.ADD, pn, nf.createString(xml));
                }
                int nodeType;
                if (ts.isXMLAttribute()) {
                    nodeType = Token.ESCXMLATTR;
                } else {
                    nodeType = Token.ESCXMLTEXT;
                }
                expr = nf.createUnary(nodeType, expr);
                pn = nf.createBinary(Token.ADD, pn, expr);
                break;
            case Token.XMLEND:
                xml = ts.getString();
                decompiler.addName(xml);
                if (pn == null) {
                    pn = nf.createString(xml);
                } else {
                    pn = nf.createBinary(Token.ADD, pn, nf.createString(xml));
                }

                nf.addChildToBack(pnXML, pn);
                return pnXML;
            default:
                reportError("msg.syntax");
                return null;
            }
        }
    }

    private void argumentList(Node listNode)
        throws IOException, ParserException
    {
        boolean matched;
        matched = matchToken(Token.RP);
        if (!matched) {
            boolean first = true;
            do {
                if (!first)
                    decompiler.addToken(Token.COMMA);
                first = false;
                nf.addChildToBack(listNode, assignExpr(false));
            } while (matchToken(Token.COMMA));

            mustMatchToken(Token.RP, "msg.no.paren.arg");
        }
        decompiler.addToken(Token.RP);
    }

    private Node memberExpr(boolean allowCallSyntax)
        throws IOException, ParserException
    {
        int tt;

        Node pn;

        /* Check for new expressions. */
        tt = peekToken();
        if (tt == Token.NEW) {
            /* Eat the NEW token. */
            consumeToken();
            decompiler.addToken(Token.NEW);

            /* Make a NEW node to append to. */
            pn = nf.createCallOrNew(Token.NEW, memberExpr(false));