Duration.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Duration.cs / 1305600 / Duration.cs
                        
                        
                            //------------------------------------------------------------------------------ 
//  Microsoft Windows Client Platform
//  Copyright (c) Microsoft Corporation, 2004
//
//  File: Duration.cs 
//-----------------------------------------------------------------------------
 
// Allow suppression of certain presharp messages 
#pragma warning disable 1634, 1691
 
using System.ComponentModel;

using SR=MS.Internal.PresentationCore.SR;
using SRID=MS.Internal.PresentationCore.SRID; 

namespace System.Windows 
{ 
    /// 
    /// Duration struct provides sentinel values that are not included in TimeSpan. 
    /// This structure may represent a TimeSpan, Automatic, or Forever value.
    /// 
    [TypeConverter(typeof(DurationConverter))]
    public struct Duration 
    {
        private TimeSpan _timeSpan; 
        private DurationType _durationType; 

        ///  
        /// Creates a Duration from a TimeSpan.
        /// 
        /// 
        public Duration(TimeSpan timeSpan) 
        {
            if (timeSpan < TimeSpan.Zero) 
            { 
                throw new ArgumentException(SR.Get(SRID.Timing_InvalidArgNonNegative), "timeSpan");
            } 
            _durationType = DurationType.TimeSpan;
            _timeSpan = timeSpan;
        }
 
        #region Operators
 
        // 
        // Since Duration has two special values, for comparison purposes
        // Duration.Forever behaves like Double.PositiveInfinity and 
        // Duration.Automatic behaves almost entirely like Double.NaN
        // Any comparision with Automatic returns false, except for ==.
        // Unlike NaN, Automatic == Automatic is true.
        // 

 
        ///  
        /// Implicitly creates a Duration from a TimeSpan.
        ///  
        /// 
        /// 
        public static implicit operator Duration(TimeSpan timeSpan)
        { 
            if (timeSpan < TimeSpan.Zero)
            { 
                throw new ArgumentException(SR.Get(SRID.Timing_InvalidArgNonNegative), "timeSpan"); 
            }
            return new Duration(timeSpan); 
        }

        /// 
        /// Adds two Durations together. 
        /// 
        ///  
        ///  
        /// If both Durations have values then this returns a Duration
        /// representing the sum of those two values; otherwise a Duration representing null. 
        public static Duration operator +(Duration t1, Duration t2)
        {
            if (t1.HasTimeSpan && t2.HasTimeSpan)
            { 
                return new Duration(t1._timeSpan + t2._timeSpan);
            } 
            else if (t1._durationType != DurationType.Automatic 
                     && t2._durationType != DurationType.Automatic)
            { 
                // Neither t1 nor t2 are Automatic, so one is Forever
                // while the other is Forever or a TimeSpan.  Either way
                // the sum is Forever.
                return Duration.Forever; 
            }
            else 
            { 
                // Automatic + anything is Automatic
                return Duration.Automatic; 
            }
        }

        ///  
        /// Subracts one Duration from another.
        ///  
        ///  
        /// 
        /// If both Durations have values then this returns a Duration 
        /// representing the value of the second subtracted from the first; otherwise a Duration representing null.
        public static Duration operator -(Duration t1, Duration t2)
        {
            if (t1.HasTimeSpan && t2.HasTimeSpan) 
            {
                return new Duration(t1._timeSpan - t2._timeSpan); 
            } 
            else if (t1._durationType == DurationType.Forever
                     && t2.HasTimeSpan) 
            {
                // The only way for the result to be Forever is
                // if t1 is Forever and t2 is a TimeSpan
                return Duration.Forever; 
            }
            else 
            { 
                // This covers the following conditions:
                // Forever - Forever 
                // TimeSpan - Forever
                // TimeSpan - Automatic
                // Forever - Automatic
                // Automatic - Automatic 
                // Automatic - Forever
                // Automatic - TimeSpan 
                return Duration.Automatic; 
            }
        } 

        /// 
        /// Indicates whether two Durations are equal.
        ///  
        /// 
        ///  
        /// true if both of the Durations have values and those values are equal or if both 
        /// Durations represent null; otherwise false.
        public static bool operator ==(Duration t1, Duration t2) 
        {
            return t1.Equals(t2);
        }
 
        /// 
        /// Indicates whether two Durations are not equal. 
        ///  
        /// 
        ///  
        /// true if exactly one of t1 and t2 represents a value or if they both represent
        /// values and those values are not equal; otherwise false.
        public static bool operator !=(Duration t1, Duration t2)
        { 
            return !(t1.Equals(t2));
        } 
 
        /// 
        /// Indicates whether one Duration is greater than another. 
        /// 
        /// 
        /// 
        /// true if both t1 and t2 have values and the value of t1 
        /// is greater than the value of t2; otherwise false.  Forever is
        /// considered greater than all finite values and any comparison 
        /// with Automatic returns false. 
        public static bool operator >(Duration t1, Duration t2)
        { 
            if (t1.HasTimeSpan && t2.HasTimeSpan)
            {
                return t1._timeSpan > t2._timeSpan;
            } 
            else if (t1.HasTimeSpan && t2._durationType == DurationType.Forever)
            { 
                // TimeSpan > Forever is false; 
                return false;
            } 
            else if (t1._durationType == DurationType.Forever && t2.HasTimeSpan)
            {
                // Forever > TimeSpan is true;
                return true; 
            }
            else 
            { 
                // Cases covered:
                // Either t1 or t2 are Automatic, 
                // or t1 and t2 are both Forever
                return false;
            }
        } 

        ///  
        /// Indicates whether one Duration is greater than or equal to another. 
        /// 
        ///  
        /// 
        /// true if both t1 and t2 have values and the value of t1
        /// is greater than or equal to the value of t2; otherwise false.
        /// Forever is considered greater than all finite values and any 
        /// comparison with Automatic returns false.
        public static bool operator >=(Duration t1, Duration t2) 
        { 
            if (t1._durationType == DurationType.Automatic && t2._durationType == DurationType.Automatic)
            { 
                // Automatic == Automatic
                return true;
            }
            else if (t1._durationType == DurationType.Automatic || t2._durationType == DurationType.Automatic) 
            {
                // Automatic compared to anything else is false 
                return false; 
            }
            else 
            {
                return !(t1 < t2);
            }
        } 

        ///  
        /// Indicates whether one Duration is less than another. 
        /// 
        ///  
        /// 
        /// true if both t1 and t2 have values and the value of t1
        /// is less than the value of t2; otherwise false.  Forever is
        /// considered greater than all finite values and any comparison 
        /// with Automatic returns false
        public static bool operator <(Duration t1, Duration t2) 
        { 
            if (t1.HasTimeSpan && t2.HasTimeSpan)
            { 
                return t1._timeSpan < t2._timeSpan;
            }
            else if (t1.HasTimeSpan && t2._durationType == DurationType.Forever)
            { 
                // TimeSpan < Forever is true;
                return true; 
            } 
            else if (t1._durationType == DurationType.Forever && t2.HasTimeSpan)
            { 
                // Forever < TimeSpan is true;
                return false;
            }
            else 
            {
                // Cases covered: 
                // Either t1 or t2 are Automatic, 
                // or t1 and t2 are both Forever
                return false; 
            }
        }

        ///  
        /// Indicates whether one Duration is less than or equal to another.
        ///  
        ///  
        /// 
        /// true if both t1 and t2 have values and the value of t1 
        /// is less than or equal to the value of t2; otherwise false.
        /// Forever is considered greater than all finite values and any
        /// comparison with Automatic returns false.
        public static bool operator <=(Duration t1, Duration t2) 
        {
            if (t1._durationType == DurationType.Automatic && t2._durationType == DurationType.Automatic) 
            { 
                // Automatic == Automatic
                return true; 
            }
            else if (t1._durationType == DurationType.Automatic || t2._durationType == DurationType.Automatic)
            {
                // Automatic compared to anything else is false 
                return false;
            } 
            else 
            {
                return !(t1 > t2); 
            }
        }

        ///  
        /// Compares one Duration value to another.
        ///  
        ///  
        /// 
        ///  
        /// A negative value, zero or a positive value, respectively, if t1 is
        /// less than, equal or greater than t2.
        ///
        /// Duration.Automatic is a special case and has the following return values: 
        ///
        ///  -1 if t1 is Automatic and t2 is not Automatic 
        ///   0 if t1 and t2 are Automatic 
        ///   1 if t1 is not Automatic and t2 is Automatic
        /// 
        /// This mirrors Double.CompareTo()'s treatment of Double.NaN
        /// 
        public static int Compare(Duration t1, Duration t2)
        { 

            if (t1._durationType == DurationType.Automatic) 
            { 
                if (t2._durationType == DurationType.Automatic)
                { 
                    return 0;
                }
                else
                { 
                    return -1;
                } 
            } 
            else if (t2._durationType == DurationType.Automatic)
            { 
                return 1;
            }
            else // Neither are Automatic, do a standard comparison
            { 
                if (t1 < t2)
                { 
                    return -1; 
                }
                else if (t1 > t2) 
                {
                    return 1;
                }
                else  // Neither is greater than the other 
                {
                    return 0; 
                } 
            }
        } 

        /// 
        /// Returns the specified instance of Duration.
        ///  
        /// 
        /// Returns duration. 
        public static Duration Plus(Duration duration) 
        {
            return duration; 
        }

        /// 
        /// Returns the specified instance of Duration. 
        /// 
        ///  
        /// Returns duration. 
        public static Duration operator +(Duration duration)
        { 
            return duration;
        }

        #endregion 

        #region Properties 
 
        /// 
        /// Indicates whether this Duration is a TimeSpan value. 
        /// 
        /// true if this Duration is a TimeSpan value.
        public bool HasTimeSpan
        { 
            get
            { 
                return (_durationType == DurationType.TimeSpan); 
            }
        } 

        /// 
        /// Returns a Duration that represents an Automatic value.
        ///  
        /// A Duration that represents an Automatic value.
        public static Duration Automatic 
        { 
            get
            { 
                Duration duration = new Duration();
                duration._durationType = DurationType.Automatic;

                return duration; 
            }
        } 
 
        /// 
        /// Returns a Duration that represents a Forever value. 
        /// 
        /// A Duration that represents a Forever value.
        public static Duration Forever
        { 
            get
            { 
                Duration duration = new Duration(); 
                duration._durationType = DurationType.Forever;
 
                return duration;
            }
        }
 
        /// 
        /// Returns the TimeSpan value that this Duration represents. 
        ///  
        /// The TimeSpan value that this Duration represents.
        /// Thrown if this Duration represents null. 
        public TimeSpan TimeSpan
        {
            get
            { 
                if (HasTimeSpan)
                { 
                    return _timeSpan; 
                }
                else 
                {
#pragma warning suppress 56503 // Suppress presharp warning: Follows a pattern similar to Nullable.
                    throw new InvalidOperationException(SR.Get(SRID.Timing_NotTimeSpan, this));
                } 
            }
        } 
 
        #endregion
 
        #region Methods

        /// 
        /// Adds the specified Duration to this instance. 
        /// 
        ///  
        /// A Duration that represents the value of this instance plus the value of duration. 
        public Duration Add(Duration duration)
        { 
            return this + duration;
        }

        ///  
        /// Indicates whether the specified Object is equal to this Duration.
        ///  
        ///  
        /// true if value is a Duration and is equal to this instance; otherwise false.
        public override bool Equals(Object value) 
        {
            if (value == null)
            {
                return false; 
            }
            else if (value is Duration) 
            { 
                return Equals((Duration)value);
            } 
            else
            {
                return false;
            } 
        }
 
        ///  
        /// Indicates whether the specified Duration is equal to this Duration.
        ///  
        /// 
        /// true if duration is equal to this instance; otherwise false.
        public bool Equals(Duration duration)
        { 
            if (HasTimeSpan)
            { 
                if (duration.HasTimeSpan) 
                {
                    return _timeSpan == duration._timeSpan; 
                }
                else
                {
                    return false; 
                }
            } 
            else 
            {
                return _durationType == duration._durationType; 
            }
        }

        ///  
        /// Indicates whether the specified Durations are equal.
        ///  
        ///  
        /// 
        /// true if t1 equals t2; otherwise false. 
        public static bool Equals(Duration t1, Duration t2)
        {
            return t1.Equals(t2);
        } 

        ///  
        /// Returns a hash code for this instance. 
        /// 
        /// A 32-bit signed integer hash code. 
        public override int GetHashCode()
        {
            if (HasTimeSpan)
            { 
                return _timeSpan.GetHashCode();
            } 
            else 
            {
                return _durationType.GetHashCode() + 17; 
            }
        }

        ///  
        /// Subtracts the specified Duration from this instance.
        ///  
        ///  
        /// A Duration whose value is the result of the value of this instance minus the value of duration.
        public Duration Subtract(Duration duration) 
        {
            return this - duration;
        }
 
        /// 
        /// Creates a string representation of this Duration. 
        ///  
        /// A string representation of this Duration.
        public override string ToString() 
        {
            if (HasTimeSpan)
            {
                return TypeDescriptor.GetConverter(_timeSpan).ConvertToString(_timeSpan); 
            }
            else if (_durationType == DurationType.Forever) 
            { 
                return "Forever";
            } 
            else // IsAutomatic
            {
                return "Automatic";
            } 
        }
 
        #endregion 

        ///  
        /// An enumeration of the different types of Duration behaviors.
        /// 
        private enum DurationType
        { 
            Automatic,
            TimeSpan, 
            Forever 
        }
 
    }
}


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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