IListConverters.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / MS / Internal / IListConverters.cs / 1305600 / IListConverters.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
// Description: Converters for IList, IList, IList 
//              IList and IList.
// 
// History: 
//    7/20/2005 garyyang - created
// 
//---------------------------------------------------------------------------

using System;
using System.Collections.Generic; 
using System.ComponentModel;
using System.Globalization; 
using System.Text; 
using System.Windows;
using MS.Internal; 
using SR=MS.Internal.PresentationCore.SR;
using SRID=MS.Internal.PresentationCore.SRID;
using MS.Internal.PresentationCore;
 
namespace System.Windows.Media.Converters
{ 
    // 
    // The following are IList converters for IList, IList, IList, IList, IList.
    // More code sharing might be achieved by creating a generic TypeConverter. But XAML parser doesn't 
    // support generic TypeConverter now.
    //

    ///  
    /// The base converter for IList of T to string conversion in XAML serialization
    ///  
    [FriendAccessAllowed]   // all implementations are used by Framework at serialization 
    public abstract class BaseIListConverter : TypeConverter
    { 
        /// 
        /// Indicates if a type can be converted from (returns true for string).
        /// 
        public override bool CanConvertFrom(ITypeDescriptorContext td, Type t) 
        {
            return t == typeof(string); // can only convert from string 
        } 

        ///  
        /// Indicates if a type can be converted to (returns true for string).
        /// 
        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
        { 
            return destinationType == typeof(string); // can only convert to string
        } 
 
        /// 
        /// Converts from a string. 
        /// 
        public override object ConvertFrom(ITypeDescriptorContext td, CultureInfo ci, object value)
        {
            if (null == value) 
            {
                throw GetConvertFromException(value); 
            } 

            string s = value as string; 

            if (null == s)
            {
                throw new ArgumentException(SR.Get(SRID.General_BadType, "ConvertFrom"), "value"); 
            }
 
            return ConvertFromCore(td, ci, s); 
        }
 
        /// 
        /// Converts to a string
        /// 
        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType) 
        {
            if (destinationType != null) 
                return ConvertToCore(context, culture, value, destinationType); 

            // Pass unhandled cases to base class (which will throw exceptions for null value or destinationType.) 
            return base.ConvertTo(context, culture, value, destinationType);
        }

        ///  
        /// To be implemented by subclasses to convert to various types from string.
        ///  
        internal abstract object ConvertFromCore(ITypeDescriptorContext td, CultureInfo ci, string value); 

        ///  
        /// To be implemented by subclasses to convert string to various types.
        /// 
        internal abstract object ConvertToCore(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType);
 
        internal TokenizerHelper _tokenizer;
        internal  const char DelimiterChar = ' '; 
    } 

    ///  
    /// TypeConverter to convert IList of double to and from string.
    /// The converted string is a sequence of delimited double number.
    /// 
    public sealed class DoubleIListConverter : BaseIListConverter 
    {
        internal sealed override object ConvertFromCore(ITypeDescriptorContext td, CultureInfo ci, string value) 
        { 
            _tokenizer = new TokenizerHelper(value, '\0' /* quote char */, DelimiterChar);
 
            // Estimate the output list's capacity from length of the input string.
            List list = new List(Math.Min(256, value.Length / EstimatedCharCountPerItem + 1));

            while (_tokenizer.NextToken()) 
            {
                list.Add(Convert.ToDouble(_tokenizer.GetCurrentToken(), ci)); 
            } 
            return list;
        } 

        internal override object ConvertToCore(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
        {
            IList list = value as IList; 
            if (list == null)
            { 
               throw GetConvertToException(value, destinationType); 
            }
 
            // Estimate the output string's length from the element count of the List.
            StringBuilder builder = new StringBuilder(EstimatedCharCountPerItem * list.Count);
            for (int i = 0; i < list.Count; i++)
            { 
                if (i > 0)
                    builder.Append(DelimiterChar); 
 
                builder.Append(list[i].ToString(culture));
            } 

            return builder.ToString();
        }
 
        // A double is estimated to take 5 characters on average, plus 1 delimiter, e.g. "5.328 ".
        private const int EstimatedCharCountPerItem = 6; 
    } 

    ///  
    /// TypeConverter to convert IList of ushort to and from string.
    /// The converted string is a sequence of delimited ushort number.
    /// 
    public sealed class UShortIListConverter : BaseIListConverter 
    {
        internal override object ConvertFromCore(ITypeDescriptorContext td, CultureInfo ci, string value) 
        { 
            _tokenizer = new TokenizerHelper(value, '\0' /* quote char */, DelimiterChar);
            List list = new List(Math.Min(256, value.Length / EstimatedCharCountPerItem + 1)); 
            while (_tokenizer.NextToken())
            {
                list.Add(Convert.ToUInt16(_tokenizer.GetCurrentToken(), ci));
            } 
            return list;
        } 
 
        internal override object ConvertToCore(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
        { 
            IList list = value as IList;
            if (list == null)
            {
                throw GetConvertToException(value, destinationType); 
            }
 
            StringBuilder builder = new StringBuilder(EstimatedCharCountPerItem * list.Count); 
            for (int i = 0; i < list.Count; i++)
            { 
                if (i > 0)
                    builder.Append(DelimiterChar);

                builder.Append(list[i].ToString(culture)); 
            }
 
            return builder.ToString(); 
        }
 
        // A ushort is estimated to take 2 characters on average, plus 1 delimiter.
        private const int EstimatedCharCountPerItem = 3;
    }
 
    /// 
    /// TypeConverter to convert IList of bool to and from string. 
    /// The converted string is a sequence of delimited 0s and 1s. "0" for false and "1" for true. 
    /// 
    public sealed class BoolIListConverter : BaseIListConverter 
    {
        internal override object ConvertFromCore(ITypeDescriptorContext td, CultureInfo ci, string value)
        {
             _tokenizer = new TokenizerHelper(value, '\0' /* quote char */, DelimiterChar); 
            List list = new List(Math.Min(256, value.Length / EstimatedCharCountPerItem + 1));
            while (_tokenizer.NextToken()) 
            { 
                list.Add(Convert.ToInt32(_tokenizer.GetCurrentToken(), ci) != 0);
            } 
            return list;
        }

        internal override object ConvertToCore(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType) 
        {
            IList list = value as IList; 
            if (list == null) 
            {
                throw GetConvertToException(value, destinationType); 
            }

            StringBuilder builder = new StringBuilder(EstimatedCharCountPerItem * list.Count);
            for (int i = 0; i < list.Count; i++) 
            {
                if (i > 0) 
                    builder.Append(DelimiterChar); 

                builder.Append((list[i] ? 1 : 0)); 
            }

            return builder.ToString();
        } 

        // A bool takes 1 character plus 1 delimiter. 
        private const int EstimatedCharCountPerItem = 2; 
    }
 
    /// 
    /// TypeConverter to convert IList of Point to and from string.
    /// The converted string is a sequence of delimited Point values. Point values are converted by PointConverter.
    ///  
    public sealed class PointIListConverter : BaseIListConverter
    { 
        internal override object ConvertFromCore(ITypeDescriptorContext td, CultureInfo ci, string value) 
        {
            _tokenizer = new TokenizerHelper(value, '\0' /* quote char */, DelimiterChar); 

            List list = new List(Math.Min(256, value.Length / EstimatedCharCountPerItem + 1));
            while (_tokenizer.NextToken())
            { 
                list.Add((Point) converter.ConvertFrom(td, ci, _tokenizer.GetCurrentToken()));
            } 
            return list; 
        }
 
        internal override object ConvertToCore(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
        {
            IList list = value as IList;
            if (list == null) 
            {
                throw GetConvertToException(value, destinationType); 
            } 

            StringBuilder builder = new StringBuilder(EstimatedCharCountPerItem * list.Count); 
            for (int i = 0; i < list.Count; i++)
            {
                if (i > 0)
                    builder.Append(DelimiterChar); 

                builder.Append((string) converter.ConvertTo(context, culture, list[i], typeof(string))); 
            } 

            return builder.ToString(); 
        }

        private PointConverter converter = new PointConverter();
 
        // A point takes 2 double and 2 delimiters. Estimated to be 12 characters.
        private const int EstimatedCharCountPerItem = 12; 
    } 

 
    /// 
    /// TypeConverter to convert IList of Char to and from string.
    /// The converted string is a concatenation of all the chars in the IList. There is no delimiter.
    ///  
    public sealed class CharIListConverter : BaseIListConverter
    { 
        internal override object ConvertFromCore(ITypeDescriptorContext td, CultureInfo ci, string value) 
        {
            return value.ToCharArray(); 
        }

        internal override object ConvertToCore(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
        { 
            IList list = value as IList;
            if (list == null) 
            { 
                throw GetConvertToException(value, destinationType);
            } 

            // An intermediate allocation is needed to construct the string as string doesn't take IList
            // in its constructor.
            char[] chars = new char[list.Count]; 
            list.CopyTo(chars, 0);
            return new string(chars); 
        } 
    }
} 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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