/*
 * Copyright 2002-2006 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/* Generated By:JJTree: Do not edit this line. JJTParserState.java */

package org.apache.commons.jexl.parser;

import java.util.Stack;

class JJTParserState {
    private final Stack nodes;

    private final Stack marks;

    private int sp; // number of nodes on stack

    private int mk; // current mark

    private boolean node_created;

    JJTParserState() {
        nodes = new Stack();
        marks = new Stack();
        sp = 0;
        mk = 0;
    }

    /*
     * Determines whether the current node was actually closed and pushed. This
     * should only be called in the final user action of a node scope.
     */
    boolean nodeCreated() {
        return node_created;
    }

    /*
     * Call this to reinitialize the node stack. It is called automatically by
     * the parser's ReInit() method.
     */
    void reset() {
        nodes.removeAllElements();
        marks.removeAllElements();
        sp = 0;
        mk = 0;
    }

    /*
     * Returns the root node of the AST. It only makes sense to call this after
     * a successful parse.
     */
    Node rootNode() {
        return (Node) nodes.elementAt(0);
    }

    /* Pushes a node on to the stack. */
    void pushNode(Node n) {
        nodes.push(n);
        ++sp;
    }

    /*
     * Returns the node on the top of the stack, and remove it from the stack.
     */
    Node popNode() {
        if (--sp < mk) {
            mk = ((Integer) marks.pop()).intValue();
        }
        return (Node) nodes.pop();
    }

    /* Returns the node currently on the top of the stack. */
    Node peekNode() {
        return (Node) nodes.peek();
    }

    /*
     * Returns the number of children on the stack in the current node scope.
     */
    int nodeArity() {
        return sp - mk;
    }

    void clearNodeScope(Node n) {
        while (sp > mk) {
            popNode();
        }
        mk = ((Integer) marks.pop()).intValue();
    }

    void openNodeScope(Node n) {
        marks.push(new Integer(mk));
        mk = sp;
        n.jjtOpen();
    }

    /*
     * A definite node is constructed from a specified number of children. That
     * number of nodes are popped from the stack and made the children of the
     * definite node. Then the definite node is pushed on to the stack.
     */
    void closeNodeScope(Node n, int num) {
        mk = ((Integer) marks.pop()).intValue();
        while (num-- > 0) {
            Node c = popNode();
            c.jjtSetParent(n);
            n.jjtAddChild(c, num);
        }
        n.jjtClose();
        pushNode(n);
        node_created = true;
    }

    /*
     * A conditional node is constructed if its condition is true. All the nodes
     * that have been pushed since the node was opened are made children of the
     * the conditional node, which is then pushed on to the stack. If the
     * condition is false the node is not constructed and they are left on the
     * stack.
     */
    void closeNodeScope(Node n, boolean condition) {
        if (condition) {
            int a = nodeArity();
            mk = ((Integer) marks.pop()).intValue();
            while (a-- > 0) {
                Node c = popNode();
                c.jjtSetParent(n);
                n.jjtAddChild(c, a);
            }
            n.jjtClose();
            pushNode(n);
            node_created = true;
        } else {
            mk = ((Integer) marks.pop()).intValue();
            node_created = false;
        }
    }
}
