//------------------------------------------------------------------------------
// <copyright file="TriState.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
//------------------------------------------------------------------------------
 
namespace System.Drawing.Printing {
 
    using System.ComponentModel;
    using System.Diagnostics;
    using System;
 
    [Serializable]
    internal struct TriState {
        private byte value; // 0 is "default", not false
 
        public static readonly TriState Default = new TriState(0);
        public static readonly TriState False = new TriState(1);
        public static readonly TriState True = new TriState(2);
 
        private TriState(byte value) {
            this.value = value;
        }
 
        public bool IsDefault {
            get { return this == Default;}
        }
 
        public bool IsFalse {
            get { return this == False;}
        }
 
        public bool IsNotDefault {
            get { return this != Default;}
        }
 
        public bool IsTrue {
            get { return this == True;}
        }
 
        public static bool operator ==(TriState left, TriState right) {
            return left.value == right.value;
        }
        
        public static bool operator !=(TriState left, TriState right) {
            return !(left == right);
        }
 
        public override bool Equals( object o ) {
            TriState state = (TriState)o;
            return this.value == state.value;
        }
        
        public override int GetHashCode() {
            return value;
        }
 
        public static implicit operator TriState(bool value) {
            return(value) ? True : False;
        }
 
        public static explicit operator bool(TriState value) {
            if (value.IsDefault)
                throw new InvalidCastException(SR.GetString(SR.TriStateCompareError));
            else
                return(value == TriState.True);
        }
 
        /// <include file='doc\TriState.uex' path='docs/doc[@for="TriState.ToString"]/*' />
        /// <internalonly/>
        /// <devdoc>
        ///    <para>
        ///       Provides some interesting information about the TriState in
        ///       String form.
        ///    </para>
        /// </devdoc>
        public override string ToString() {
            if (this == Default) return "Default";
            else if (this == False) return "False";
            else return "True";
        }
    }
}