using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Windows;
using System.Windows.Markup;namespace SwitchConverterDemo
{/// <summary>/// An individual case in the switch statement./// </summary>[ContentProperty( "Then" )]public sealed class SwitchCase : DependencyObject{#region Constructors/// <summary>/// Initializes a new instance of the <see cref="T:SwitchCase"/> class./// </summary>public SwitchCase( ){}#endregion#region Properties/// <summary>/// Dependency property for the <see cref="P:When"/> property./// </summary>public static readonly DependencyProperty WhenProperty = DependencyProperty.Register( "When", typeof( object ), typeof( SwitchCase ), new PropertyMetadata( default( object ) ) );/// <summary>/// The value to match against the input value./// </summary>public object When{get{return (object)GetValue( WhenProperty );}set{SetValue( WhenProperty, value );}}/// <summary>/// Dependency property for the <see cref="P:Then"/> property./// </summary>public static readonly DependencyProperty ThenProperty = DependencyProperty.Register( "Then", typeof( object ), typeof( SwitchCase ), new PropertyMetadata( default( object ) ) );/// <summary>/// The output value to use if the current case matches./// </summary>public object Then{get{return (object)GetValue( ThenProperty );}set{SetValue( ThenProperty, value );}}#endregion}   // class

}   // namespace

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics.Contracts;
using System.Linq;namespace SwitchConverterDemo
{/// <summary>/// A collection of switch cases./// </summary>public sealed class SwitchCaseCollection : Collection<SwitchCase>{#region Constructors/// <summary>/// Initializes a new instance of the <see cref="T:SwitchCaseCollection"/> class./// </summary>internal SwitchCaseCollection( ){}#endregion#region Methods/// <summary>/// Adds a new case to the collection./// </summary>/// <param name="when">The value to compare against the input.</param>/// <param name="then">The output value to use if the case matches.</param>public void Add( object when, object then ){Add(new SwitchCase {When = when,Then = then});}#endregion}   // class

}   // namespace

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics.Contracts;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Data;
using System.Windows.Markup;namespace SwitchConverterDemo
{/// <summary>/// Produces an output value based upon a collection of case statements./// </summary>[ContentProperty( "Cases" )]public class SwitchConverter : IValueConverter{#region Constructors/// <summary>/// Initializes a new instance of the <see cref="T:SwitchConverter"/> class./// </summary>public SwitchConverter( ): this( new SwitchCaseCollection( ) ){}/// <summary>/// Initializes a new instance of the <see cref="T:SwitchConverter"/> class./// </summary>/// <param name="cases">The case collection.</param>internal SwitchConverter( SwitchCaseCollection cases ){Contract.Requires( cases != null );Cases = cases;StringComparison = StringComparison.OrdinalIgnoreCase;}#endregion#region Properties/// <summary>/// Holds a collection of switch cases that determine which output/// value will be produced for a given input value./// </summary>public SwitchCaseCollection Cases{get;private set;}/// <summary>/// Specifies the type of comparison performed when comparing the input/// value against a case./// </summary>public StringComparison StringComparison{get;set;}/// <summary>/// An optional value that will be output if none of the cases match./// </summary>public object Else{get;set;}#endregion#region Methods/// <summary>/// Converts a value./// </summary>/// <param name="value">The value produced by the binding source.</param>/// <param name="targetType">The type of the binding target property.</param>/// <param name="parameter">The converter parameter to use.</param>/// <param name="culture">The culture to use in the converter.</param>/// <returns>A converted value. If the method returns null, the valid null value is used.</returns>public object Convert( object value, Type targetType, object parameter, CultureInfo culture ){if ( value == null ) {// Special case for null// Null input can only equal null, no convert necessaryreturn Cases.FirstOrDefault( x => x.When == null ) ?? Else;}foreach ( var c in Cases.Where( x => x.When != null ) ) {// Special case for string to string comparisonif ( value is string && c.When is string ) {if ( String.Equals( (string)value, (string)c.When, StringComparison ) ) {return c.Then;}}object when = c.When;// Normalize the types using IConvertible if possibleif ( TryConvert( culture, value, ref when ) ) {if ( value.Equals( when ) ) {return c.Then;}}}return Else;}/// <summary>/// Converts a value./// </summary>/// <param name="value">The value that is produced by the binding target.</param>/// <param name="targetType">The type to convert to.</param>/// <param name="parameter">The converter parameter to use.</param>/// <param name="culture">The culture to use in the converter.</param>/// <returns>A converted value. If the method returns null, the valid null value is used.</returns>public object ConvertBack( object value, Type targetType, object parameter, CultureInfo culture ){throw new NotSupportedException( );}/// <summary>/// Attempts to use the IConvertible interface to convert <paramref name="value2"/> into a type/// compatible with <paramref name="value1"/>./// </summary>/// <param name="culture">The culture.</param>/// <param name="value1">The input value.</param>/// <param name="value2">The case value.</param>/// <returns>True if conversion was performed, otherwise false.</returns>private static bool TryConvert( CultureInfo culture, object value1, ref object value2 ){Type type1 = value1.GetType( );Type type2 = value2.GetType( );if ( type1 == type2 ) {return true;}if ( type1.IsEnum ) {value2 = Enum.Parse( type1, value2.ToString( ), true );return true;}var convertible1 = value1 as IConvertible;var convertible2 = value2 as IConvertible;if ( convertible1 != null && convertible2 != null ) {value2 = System.Convert.ChangeType( value2, type1, culture );return true;}return false;}#endregion}   // class

}   // namespace