//------------------------------------------------------------------------------
// <copyright file="Operator.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
 
namespace MS.Internal.Xml.XPath {
    using System;
    using System.Xml;
    using System.Xml.XPath;
    using System.Diagnostics;
    using System.Globalization;
    internal class Operator : AstNode {
        public enum Op { // order is alligned with XPathOperator
            INVALID,
            /*Logical   */
            OR,
            AND,
            /*Equality  */
            EQ,
            NE,
            /*Relational*/
            LT,
            LE,
            GT,
            GE,
            /*Arithmetic*/
            PLUS,
            MINUS,
            MUL,
            DIV,
            MOD,
            /*Union     */
            UNION,
        };
 
        static Op[] invertOp = {
            /*INVALID*/ Op.INVALID,
            /*OR     */ Op.INVALID,
            /*END    */ Op.INVALID,
            /*EQ     */ Op.EQ,
            /*NE     */ Op.NE,
            /*LT     */ Op.GT,
            /*LE     */ Op.GE,
            /*GT     */ Op.LT,
            /*GE     */ Op.LE,
        };
 
        static public Operator.Op InvertOperator(Operator.Op op) {
            Debug.Assert(Op.EQ <= op && op <= Op.GE);
            return invertOp[(int)op];
        }
        
        private Op opType;
        private AstNode opnd1;
        private AstNode opnd2;
 
        public Operator(Op op, AstNode opnd1, AstNode opnd2) {
            this.opType = op;
            this.opnd1 = opnd1;
            this.opnd2 = opnd2;
        }
 
        public override AstType Type { get {return  AstType.Operator;} }
        public override XPathResultType ReturnType {
            get {
                if (opType <= Op.GE) {
                    return XPathResultType.Boolean;
                }
                if (opType <= Op.MOD) {
                    return XPathResultType.Number;
                }
                return XPathResultType.NodeSet;
            }
        }
 
        public Op      OperatorType { get { return opType; } }
        public AstNode Operand1     { get { return opnd1;  } }
        public AstNode Operand2     { get { return opnd2;  } }
    }
}