parser.java

這是一個javascript 的 interpreter是了解 web browser的好材料

                        break;
                    }
                } else {
                    n = statement();
                }
                nf.addChildToBack(pn, n);
            }
        } catch (StackOverflowError ex) {
            String msg = ScriptRuntime.getMessage0(
                "msg.too.deep.parser.recursion");
            throw Context.reportRuntimeError(msg, sourceURI,
                                             ts.getLineno(), null, 0);
        }

        if (this.syntaxErrorCount != 0) {
            String msg = String.valueOf(this.syntaxErrorCount);
            msg = ScriptRuntime.getMessage1("msg.got.syntax.errors", msg);
            throw errorReporter.runtimeError(msg, sourceURI, baseLineno,
                                             null, 0);
        }

        currentScriptOrFn.setSourceName(sourceURI);
        currentScriptOrFn.setBaseLineno(baseLineno);
        currentScriptOrFn.setEndLineno(ts.getLineno());

        int sourceEndOffset = decompiler.getCurrentOffset();
        currentScriptOrFn.setEncodedSourceBounds(sourceStartOffset,
                                                 sourceEndOffset);

        nf.initScript(currentScriptOrFn, pn);

        if (compilerEnv.isGeneratingSource()) {
            encodedSource = decompiler.getEncodedSource();
        }
        this.decompiler = null; // It helps GC

        return currentScriptOrFn;
    }

    /*
     * The C version of this function takes an argument list,
     * which doesn't seem to be needed for tree generation...
     * it'd only be useful for checking argument hiding, which
     * I'm not doing anyway...
     */
    private Node parseFunctionBody()
        throws IOException
    {
        ++nestingOfFunction;
        Node pn = nf.createBlock(ts.getLineno());
        try {
            bodyLoop: for (;;) {
                Node n;
                int tt = peekToken();
                switch (tt) {
                  case Token.ERROR:
                  case Token.EOF:
                  case Token.RC:
                    break bodyLoop;

                  case Token.FUNCTION:
                    consumeToken();
                    n = function(FunctionNode.FUNCTION_STATEMENT);
                    break;
                  default:
                    n = statement();
                    break;
                }
                nf.addChildToBack(pn, n);
            }
        } catch (ParserException e) {
            // Ignore it
        } finally {
            --nestingOfFunction;
        }

        return pn;
    }

    private Node function(int functionType)
        throws IOException, ParserException
    {
        int syntheticType = functionType;
        int baseLineno = ts.getLineno();  // line number where source starts

        int functionSourceStart = decompiler.markFunctionStart(functionType);
        String name;
        Node memberExprNode = null;
        if (matchToken(Token.NAME)) {
            name = ts.getString();
            decompiler.addName(name);
            if (!matchToken(Token.LP)) {
                if (compilerEnv.isAllowMemberExprAsFunctionName()) {
                    // Extension to ECMA: if 'function <name>' does not follow
                    // by '(', assume <name> starts memberExpr
                    Node memberExprHead = nf.createName(name);
                    name = "";
                    memberExprNode = memberExprTail(false, memberExprHead);
                }
                mustMatchToken(Token.LP, "msg.no.paren.parms");
            }
        } else if (matchToken(Token.LP)) {
            // Anonymous function
            name = "";
        } else {
            name = "";
            if (compilerEnv.isAllowMemberExprAsFunctionName()) {
                // Note that memberExpr can not start with '(' like
                // in function (1+2).toString(), because 'function (' already
                // processed as anonymous function
                memberExprNode = memberExpr(false);
            }
            mustMatchToken(Token.LP, "msg.no.paren.parms");
        }

        if (memberExprNode != null) {
            syntheticType = FunctionNode.FUNCTION_EXPRESSION;
        } 
        
        if (syntheticType != FunctionNode.FUNCTION_EXPRESSION && 
            name.length() > 0)
        {
            // Function statements define a symbol in the enclosing scope
            defineSymbol(Token.FUNCTION, name);
        }

        boolean nested = insideFunction();

        FunctionNode fnNode = nf.createFunction(name);
        if (nested || nestingOfWith > 0) {
            // 1. Nested functions are not affected by the dynamic scope flag
            // as dynamic scope is already a parent of their scope.
            // 2. Functions defined under the with statement also immune to
            // this setup, in which case dynamic scope is ignored in favor
            // of with object.
            fnNode.itsIgnoreDynamicScope = true;
        }
        int functionIndex = currentScriptOrFn.addFunction(fnNode);

        int functionSourceEnd;

        ScriptOrFnNode savedScriptOrFn = currentScriptOrFn;
        currentScriptOrFn = fnNode;
        Node.Scope savedCurrentScope = currentScope;
        currentScope = fnNode;
        int savedNestingOfWith = nestingOfWith;
        nestingOfWith = 0;
        Hashtable savedLabelSet = labelSet;
        labelSet = null;
        ObjArray savedLoopSet = loopSet;
        loopSet = null;
        ObjArray savedLoopAndSwitchSet = loopAndSwitchSet;
        loopAndSwitchSet = null;
        boolean savedHasReturnValue = hasReturnValue;
        int savedFunctionEndFlags = endFlags;

        Node destructuring = null;
        Node body;
        try {
            decompiler.addToken(Token.LP);
            if (!matchToken(Token.RP)) {
                boolean first = true;
                do {
                    if (!first)
                        decompiler.addToken(Token.COMMA);
                    first = false;
                    int tt = peekToken();
                    if (tt == Token.LB || tt == Token.LC) {
                        // Destructuring assignment for parameters: add a 
                        // dummy parameter name, and add a statement to the
                        // body to initialize variables from the destructuring
                        // assignment
                        if (destructuring == null) {
                            destructuring = new Node(Token.COMMA);
                        }
                        String parmName = currentScriptOrFn.getNextTempName();
                        defineSymbol(Token.LP, parmName);
                        destructuring.addChildToBack(
                            nf.createDestructuringAssignment(Token.VAR,
                                primaryExpr(), nf.createName(parmName)));
                    } else {
                        mustMatchToken(Token.NAME, "msg.no.parm");
                        String s = ts.getString();
                        defineSymbol(Token.LP, s);
                        decompiler.addName(s);
                    }
                } while (matchToken(Token.COMMA));

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

            mustMatchToken(Token.LC, "msg.no.brace.body");
            decompiler.addEOL(Token.LC);
            body = parseFunctionBody();
            if (destructuring != null) {
                body.addChildToFront(
                    new Node(Token.EXPR_VOID, destructuring, ts.getLineno()));
            }
            mustMatchToken(Token.RC, "msg.no.brace.after.body");

            if (compilerEnv.isStrictMode() && !body.hasConsistentReturnUsage())
            {
              String msg = name.length() > 0 ? "msg.no.return.value"
                                             : "msg.anon.no.return.value";
              addStrictWarning(msg, name);
            }
            
            if (syntheticType == FunctionNode.FUNCTION_EXPRESSION &&
                name.length() > 0 && currentScope.getSymbol(name) == null) 
            {
                // Function expressions define a name only in the body of the 
                // function, and only if not hidden by a parameter name
                defineSymbol(Token.FUNCTION, name);
            }
            
            decompiler.addToken(Token.RC);
            functionSourceEnd = decompiler.markFunctionEnd(functionSourceStart);
            if (functionType != FunctionNode.FUNCTION_EXPRESSION) {
                // Add EOL only if function is not part of expression
                // since it gets SEMI + EOL from Statement in that case
                decompiler.addToken(Token.EOL);
            }
        }
        finally {
            hasReturnValue = savedHasReturnValue;
            endFlags = savedFunctionEndFlags;
            loopAndSwitchSet = savedLoopAndSwitchSet;
            loopSet = savedLoopSet;
            labelSet = savedLabelSet;
            nestingOfWith = savedNestingOfWith;
            currentScriptOrFn = savedScriptOrFn;
            currentScope = savedCurrentScope;
        }

        fnNode.setEncodedSourceBounds(functionSourceStart, functionSourceEnd);
        fnNode.setSourceName(sourceURI);
        fnNode.setBaseLineno(baseLineno);
        fnNode.setEndLineno(ts.getLineno());

        Node pn = nf.initFunction(fnNode, functionIndex, body, syntheticType);
        if (memberExprNode != null) {
            pn = nf.createAssignment(Token.ASSIGN, memberExprNode, pn);
            if (functionType != FunctionNode.FUNCTION_EXPRESSION) {
                // XXX check JScript behavior: should it be createExprStatement?
                pn = nf.createExprStatementNoReturn(pn, baseLineno);
            }
        }
        return pn;
    }

    private Node statements(Node scope)
        throws IOException
    {
        Node pn = scope != null ? scope : nf.createBlock(ts.getLineno());

        int tt;
        while ((tt = peekToken()) > Token.EOF && tt != Token.RC) {
            nf.addChildToBack(pn, statement());
        }

        return pn;
    }

    private Node condition()
        throws IOException, ParserException
    {
        mustMatchToken(Token.LP, "msg.no.paren.cond");
        decompiler.addToken(Token.LP);
        Node pn = expr(false);
        mustMatchToken(Token.RP, "msg.no.paren.after.cond");
        decompiler.addToken(Token.RP);

        // Report strict warning on code like "if (a = 7) ...". Suppress the
        // warning if the condition is parenthesized, like "if ((a = 7)) ...".
        if (pn.getProp(Node.PARENTHESIZED_PROP) == null &&
            (pn.getType() == Token.SETNAME || pn.getType() == Token.SETPROP ||
             pn.getType() == Token.SETELEM))
        {
            addStrictWarning("msg.equal.as.assign", "");
        }
        return pn;
    }

    // match a NAME; return null if no match.
    private Node matchJumpLabelName()
        throws IOException, ParserException
    {
        Node label = null;

        int tt = peekTokenOrEOL();
        if (tt == Token.NAME) {
            consumeToken();
            String name = ts.getString();
            decompiler.addName(name);
            if (labelSet != null) {
                label = (Node)labelSet.get(name);
            }
            if (label == null) {
                reportError("msg.undef.label");
            }
        }

        return label;
    }

    private Node statement()
        throws IOException
    {
        try {
            Node pn = statementHelper(null);
            if (pn != null) {
                if (compilerEnv.isStrictMode() && !pn.hasSideEffects())
                    addStrictWarning("msg.no.side.effects", "");
                return pn;
            }
        } catch (ParserException e) { }

        // skip to end of statement
        int lineno = ts.getLineno();
        guessingStatementEnd: for (;;) {
            int tt = peekTokenOrEOL();
            consumeToken();
            switch (tt) {
              case Token.ERROR:
              case Token.EOF:
              case Token.EOL:
              case Token.SEMI:
                break guessingStatementEnd;
            }
        }
        return nf.createExprStatement(nf.createName("error"), lineno);
    }

    private Node statementHelper(Node statementLabel)
        throws IOException, ParserException
    {
        Node pn = null;
        int tt = peekToken();

        switch (tt) {
          case Token.IF: {
            consumeToken();

            decompiler.addToken(Token.IF);
            int lineno = ts.getLineno();
            Node cond = condition();
            decompiler.addEOL(Token.LC);
            Node ifTrue = statement();
            Node ifFalse = null;
            if (matchToken(Token.ELSE)) {
                decompiler.addToken(Token.RC);
                decompiler.addToken(Token.ELSE);
                decompiler.addEOL(Token.LC);
                ifFalse = statement();
            }
            decompiler.addEOL(Token.RC);
            pn = nf.createIf(cond, ifTrue, ifFalse, lineno);
            return pn;
          }

          case Token.SWITCH: {
            consumeToken();

            decompiler.addToken(Token.SWITCH);
            int lineno = ts.getLineno();
            mustMatchToken(Token.LP, "msg.no.paren.switch");
            decompiler.addToken(Token.LP);
            pn = enterSwitch(expr(false), lineno);
            try {
                mustMatchToken(Token.RP, "msg.no.paren.after.switch");
                decompiler.addToken(Token.RP);
                mustMatchToken(Token.LC, "msg.no.brace.switch");
                decompiler.addEOL(Token.LC);

                boolean hasDefault = false;
                switchLoop: for (;;) {
                    tt = nextToken();
                    Node caseExpression;
                    switch (tt) {
                      case Token.RC:
                        break switchLoop;

                      case Token.CASE:
                        decompiler.addToken(Token.CASE);
                        caseExpression = expr(false);
                        mustMatchToken(Token.COLON, "msg.no.colon.case");
                        decompiler.addEOL(Token.COLON);
                        break;

                      case Token.DEFAULT:
                        if (hasDefault) {
                            reportError("msg.double.switch.default");
                        }
                        decompiler.addToken(Token.DEFAULT);
                        hasDefault = true;
                        caseExpression = null;