irfactory.java

java中比较著名的js引擎当属mozilla开源的rhino

        }
        return new Node(Token.GET_REF, ref);
    }

    /**
     * Binary
     */
    Node createBinary(int nodeType, Node left, Node right)
    {
        switch (nodeType) {

          case Token.ADD:
            // numerical addition and string concatenation
            if (left.type == Token.STRING) {
                String s2;
                if (right.type == Token.STRING) {
                    s2 = right.getString();
                } else if (right.type == Token.NUMBER) {
                    s2 = ScriptRuntime.numberToString(right.getDouble(), 10);
                } else {
                    break;
                }
                String s1 = left.getString();
                left.setString(s1.concat(s2));
                return left;
            } else if (left.type == Token.NUMBER) {
                if (right.type == Token.NUMBER) {
                    left.setDouble(left.getDouble() + right.getDouble());
                    return left;
                } else if (right.type == Token.STRING) {
                    String s1, s2;
                    s1 = ScriptRuntime.numberToString(left.getDouble(), 10);
                    s2 = right.getString();
                    right.setString(s1.concat(s2));
                    return right;
                }
            }
            // can't do anything if we don't know  both types - since
            // 0 + object is supposed to call toString on the object and do
            // string concantenation rather than addition
            break;

          case Token.SUB:
            // numerical subtraction
            if (left.type == Token.NUMBER) {
                double ld = left.getDouble();
                if (right.type == Token.NUMBER) {
                    //both numbers
                    left.setDouble(ld - right.getDouble());
                    return left;
                } else if (ld == 0.0) {
                    // first 0: 0-x -> -x
                    return new Node(Token.NEG, right);
                }
            } else if (right.type == Token.NUMBER) {
                if (right.getDouble() == 0.0) {
                    //second 0: x - 0 -> +x
                    // can not make simply x because x - 0 must be number
                    return new Node(Token.POS, left);
                }
            }
            break;

          case Token.MUL:
            // numerical multiplication
            if (left.type == Token.NUMBER) {
                double ld = left.getDouble();
                if (right.type == Token.NUMBER) {
                    //both numbers
                    left.setDouble(ld * right.getDouble());
                    return left;
                } else if (ld == 1.0) {
                    // first 1: 1 *  x -> +x
                    return new Node(Token.POS, right);
                }
            } else if (right.type == Token.NUMBER) {
                if (right.getDouble() == 1.0) {
                    //second 1: x * 1 -> +x
                    // can not make simply x because x - 0 must be number
                    return new Node(Token.POS, left);
                }
            }
            // can't do x*0: Infinity * 0 gives NaN, not 0
            break;

          case Token.DIV:
            // number division
            if (right.type == Token.NUMBER) {
                double rd = right.getDouble();
                if (left.type == Token.NUMBER) {
                    // both constants -- just divide, trust Java to handle x/0
                    left.setDouble(left.getDouble() / rd);
                    return left;
               } else if (rd == 1.0) {
                    // second 1: x/1 -> +x
                    // not simply x to force number convertion
                    return new Node(Token.POS, left);
                }
            }
            break;

          case Token.AND: {
            // Since x && y gives x, not false, when Boolean(x) is false,
            // and y, not Boolean(y), when Boolean(x) is true, x && y
            // can only be simplified if x is defined. See bug 309957.

            int leftStatus = isAlwaysDefinedBoolean(left);
            if (leftStatus == ALWAYS_FALSE_BOOLEAN) {
                // if the first one is false, just return it
                return left;
            } else if (leftStatus == ALWAYS_TRUE_BOOLEAN) {
                // if first is true, set to second
                return right;
            }
            break;
          }

          case Token.OR: {
            // Since x || y gives x, not true, when Boolean(x) is true,
            // and y, not Boolean(y), when Boolean(x) is false, x || y
            // can only be simplified if x is defined. See bug 309957.

            int leftStatus = isAlwaysDefinedBoolean(left);
            if (leftStatus == ALWAYS_TRUE_BOOLEAN) {
                // if the first one is true, just return it
                return left;
            } else if (leftStatus == ALWAYS_FALSE_BOOLEAN) {
                // if first is false, set to second
                return right;
            }
            break;
          }
        }

        return new Node(nodeType, left, right);
    }

    private Node simpleAssignment(Node left, Node right)
    {
        int nodeType = left.getType();
        switch (nodeType) {
          case Token.NAME:
            left.setType(Token.BINDNAME);
            return new Node(Token.SETNAME, left, right);

          case Token.GETPROP:
          case Token.GETELEM: {
            Node obj = left.getFirstChild();
            Node id = left.getLastChild();
            int type;
            if (nodeType == Token.GETPROP) {
                type = Token.SETPROP;
            } else {
                type = Token.SETELEM;
            }
            return new Node(type, obj, id, right);
          }
          case Token.GET_REF: {
            Node ref = left.getFirstChild();
            checkMutableReference(ref);
            return new Node(Token.SET_REF, ref, right);
          }
        }

        throw Kit.codeBug();
    }

    private void checkMutableReference(Node n)
    {
        int memberTypeFlags = n.getIntProp(Node.MEMBER_TYPE_PROP, 0);
        if ((memberTypeFlags & Node.DESCENDANTS_FLAG) != 0) {
            parser.reportError("msg.bad.assign.left");
        }
    }

    Node createAssignment(int assignType, Node left, Node right)
    {
        left = makeReference(left);
        if (left == null) {
            parser.reportError("msg.bad.assign.left");
            return right;
        }

        int assignOp;
        switch (assignType) {
          case Token.ASSIGN:
            return simpleAssignment(left, right);
          case Token.ASSIGN_BITOR:  assignOp = Token.BITOR;  break;
          case Token.ASSIGN_BITXOR: assignOp = Token.BITXOR; break;
          case Token.ASSIGN_BITAND: assignOp = Token.BITAND; break;
          case Token.ASSIGN_LSH:    assignOp = Token.LSH;    break;
          case Token.ASSIGN_RSH:    assignOp = Token.RSH;    break;
          case Token.ASSIGN_URSH:   assignOp = Token.URSH;   break;
          case Token.ASSIGN_ADD:    assignOp = Token.ADD;    break;
          case Token.ASSIGN_SUB:    assignOp = Token.SUB;    break;
          case Token.ASSIGN_MUL:    assignOp = Token.MUL;    break;
          case Token.ASSIGN_DIV:    assignOp = Token.DIV;    break;
          case Token.ASSIGN_MOD:    assignOp = Token.MOD;    break;
          default: throw Kit.codeBug();
        }

        int nodeType = left.getType();
        switch (nodeType) {
          case Token.NAME: {
            String s = left.getString();

            Node opLeft = Node.newString(Token.NAME, s);
            Node op = new Node(assignOp, opLeft, right);
            Node lvalueLeft = Node.newString(Token.BINDNAME, s);
            return new Node(Token.SETNAME, lvalueLeft, op);
          }
          case Token.GETPROP:
          case Token.GETELEM: {
            Node obj = left.getFirstChild();
            Node id = left.getLastChild();

            int type = nodeType == Token.GETPROP
                       ? Token.SETPROP_OP
                       : Token.SETELEM_OP;

            Node opLeft = new Node(Token.USE_STACK);
            Node op = new Node(assignOp, opLeft, right);
            return new Node(type, obj, id, op);
          }
          case Token.GET_REF: {
            Node ref = left.getFirstChild();
            checkMutableReference(ref);
            Node opLeft = new Node(Token.USE_STACK);
            Node op = new Node(assignOp, opLeft, right);
            return new Node(Token.SET_REF_OP, ref, op);
          }
        }

        throw Kit.codeBug();
    }

    Node createUseLocal(Node localBlock)
    {
        if (Token.LOCAL_BLOCK != localBlock.getType()) throw Kit.codeBug();
        Node result = new Node(Token.LOCAL_LOAD);
        result.putProp(Node.LOCAL_BLOCK_PROP, localBlock);
        return result;
    }

    private Node.Jump makeJump(int type, Node target)
    {
        Node.Jump n = new Node.Jump(type);
        n.target = target;
        return n;
    }

    private Node makeReference(Node node)
    {
        int type = node.getType();
        switch (type) {
          case Token.NAME:
          case Token.GETPROP:
          case Token.GETELEM:
          case Token.GET_REF:
            return node;
          case Token.CALL:
            node.setType(Token.REF_CALL);
            return new Node(Token.GET_REF, node);
        }
        // Signal caller to report error
        return null;
    }

    // Check if Node always mean true or false in boolean context
    private static int isAlwaysDefinedBoolean(Node node)
    {
        switch (node.getType()) {
          case Token.FALSE:
          case Token.NULL:
            return ALWAYS_FALSE_BOOLEAN;
          case Token.TRUE:
            return ALWAYS_TRUE_BOOLEAN;
          case Token.NUMBER: {
            double num = node.getDouble();
            if (num == num && num != 0.0) {
                return ALWAYS_TRUE_BOOLEAN;
            } else {
                return ALWAYS_FALSE_BOOLEAN;
            }
          }
        }
        return 0;
    }

// Commented-out: no longer used    
//     private static boolean hasSideEffects(Node exprTree)
//     {
//         switch (exprTree.getType()) {
//           case Token.INC:
//           case Token.DEC:
//           case Token.SETPROP:
//           case Token.SETELEM:
//           case Token.SETNAME:
//           case Token.CALL:
//           case Token.NEW:
//             return true;
//           default:
//             Node child = exprTree.getFirstChild();
//             while (child != null) {
//                 if (hasSideEffects(child))
//                     return true;
//                 child = child.getNext();
//             }
//             break;
//         }
//         return false;
//     }
    
    private void checkActivationName(String name, int token)
    {
        if (parser.insideFunction()) {
            boolean activation = false;
            if ("arguments".equals(name)
                || (parser.compilerEnv.activationNames != null
                    && parser.compilerEnv.activationNames.containsKey(name)))
            {
                activation = true;
            } else if ("length".equals(name)) {
                if (token == Token.GETPROP
                    && parser.compilerEnv.getLanguageVersion()
                       == Context.VERSION_1_2)
                {
                    // Use of "length" in 1.2 requires an activation object.
                    activation = true;
                }
            }
            if (activation) {
                setRequiresActivation();
            }
        }
    }

    private void setRequiresActivation()
    {
        if (parser.insideFunction()) {
            ((FunctionNode)parser.currentScriptOrFn).itsNeedsActivation = true;
        }
    }

    private Parser parser;

    private static final int LOOP_DO_WHILE = 0;
    private static final int LOOP_WHILE    = 1;
    private static final int LOOP_FOR      = 2;

    private static final int ALWAYS_TRUE_BOOLEAN = 1;
    private static final int ALWAYS_FALSE_BOOLEAN = -1;
}