Code:
/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Shared / MS / Internal / CharacterBuffer.cs / 1 / CharacterBuffer.cs
//---------------------------------------------------------------------------- // // Copyright (c) Microsoft Corporation. All rights reserved. // // // Description: Definition of readonly character memory buffer // // // History: // 03/31/2003 : [....] - Created // 12/01/2004 : [....] - Moved to wcp\shared and made CharacterBuffer implement IList// //--------------------------------------------------------------------------- using System; using System.Windows; using System.Collections; using System.Collections.Generic; using System.Diagnostics; using System.Text; using System.Runtime.InteropServices; using System.Security; using System.Security.Permissions; using SR=MS.Internal.PresentationCore.SR; using SRID=MS.Internal.PresentationCore.SRID; namespace MS.Internal { /// /// Abstraction of a readonly character buffer /// internal abstract class CharacterBuffer : IList{ /// /// Get fixed address of the character buffer /// public abstract unsafe char* GetCharacterPointer(); ////// Add character buffer's content to a StringBuilder /// /// string builder to add content to /// character offset to first character to append /// number of character appending ///string builder public abstract void AppendToStringBuilder( StringBuilder stringBuilder, int characterOffset, int length ); #region IListMembers public int IndexOf(char item) { for (int i = 0; i < Count; ++i) { if (item == this[i]) return i; } return -1; } public void Insert(int index, char item) { // CharacterBuffer is read only. throw new NotSupportedException(); } public abstract char this[int index] { get; set; } public void RemoveAt(int index) { // CharacterBuffer is read only. throw new NotSupportedException(); } #endregion #region ICollection Members public void Add(char item) { // CharacterBuffer is read only. throw new NotSupportedException(); } public void Clear() { // CharacterBuffer is read only. throw new NotSupportedException(); } public bool Contains(char item) { return IndexOf(item) != -1; } public void CopyTo(char[] array, int arrayIndex) { for (int i = 0; i < Count; ++i) { array[arrayIndex + i] = this[i]; } } public abstract int Count { get; } public bool IsReadOnly { get { return true; } } public bool Remove(char item) { // CharacterBuffer is read only. throw new NotSupportedException(); } #endregion #region IEnumerable Members IEnumerator IEnumerable .GetEnumerator() { for (int i = 0; i < Count; ++i) yield return this[i]; } #endregion #region IEnumerable Members IEnumerator IEnumerable.GetEnumerator() { return ((IEnumerable )this).GetEnumerator(); } #endregion } /// /// Character memory buffer implemented by managed character array /// internal sealed class CharArrayCharacterBuffer : CharacterBuffer { private char[] _characterArray; ////// Creating a character memory buffer from character array /// /// character array public CharArrayCharacterBuffer( char[] characterArray ) { if (characterArray == null) { throw new ArgumentNullException("characterArray"); } _characterArray = characterArray; } ////// Read a character from buffer at the specified character index /// public override char this[int characterOffset] { get { return _characterArray[characterOffset]; } set { throw new NotSupportedException(); } } ////// Buffer character length /// public override int Count { get { return _characterArray.Length; } } ////// Get fixed address of the character buffer /// ////// Critical:This code manipulates a pointer and returns it /// [SecurityCritical] public override unsafe char* GetCharacterPointer() { // Even though we could allocate GCHandle for this purpose, we would need // to manage how to release them appropriately. It is even worse if we // consider performance implication of doing so. In typical UI scenario, // there are so many string objects running around in GC heap. Getting // GCHandle for every one of them is very expensive and demote GC's ability // to compact its heap. return null; } ////// Add character buffer's content to a StringBuilder /// /// string builder to add content to /// index to first character in the buffer to append /// number of character appending public override void AppendToStringBuilder( StringBuilder stringBuilder, int characterOffset, int characterLength ) { Debug.Assert(characterOffset >= 0 && characterOffset < _characterArray.Length, "Invalid character index"); if ( characterLength < 0 || characterOffset + characterLength > _characterArray.Length) { characterLength = _characterArray.Length - characterOffset; } stringBuilder.Append(_characterArray, characterOffset, characterLength); } } ////// Character buffer implemented by string /// internal sealed class StringCharacterBuffer : CharacterBuffer { private string _string; ////// Creating a character buffer from string /// /// character string public StringCharacterBuffer( string characterString ) { if (characterString == null) { throw new ArgumentNullException("characterString"); } _string = characterString; } ////// Read a character from buffer at the specified character index /// public override char this[int characterOffset] { get { return _string[characterOffset]; } set { throw new NotSupportedException(); } } ////// Buffer character length /// public override int Count { get { return _string.Length; } } ////// Get fixed address of the character buffer /// ////// Critical:This code manipulates a pointer and returns it /// [SecurityCritical] public override unsafe char* GetCharacterPointer() { // Even though we could allocate GCHandle for this purpose, we would need // to manage how to release them appropriately. It is even worse if we // consider performance implication of doing so. In typical UI scenario, // there are so many string objects running around in GC heap. Getting // GCHandle for every one of them is very expensive and demote GC's ability // to compact its heap. return null; } ////// Add character buffer's content to a StringBuilder /// /// string builder to add content to /// index to first character in the buffer to append /// number of character appending public override void AppendToStringBuilder( StringBuilder stringBuilder, int characterOffset, int characterLength ) { Debug.Assert(characterOffset >= 0 && characterOffset < _string.Length, "Invalid character index"); if ( characterLength < 0 || characterOffset + characterLength > _string.Length) { characterLength = _string.Length - characterOffset; } stringBuilder.Append(_string, characterOffset, characterLength); } } ////// Character buffer implemented as unsafe pointer to character string /// internal sealed unsafe class UnsafeStringCharacterBuffer : CharacterBuffer { ////// Critical: This code is unsafe since it holds a pointer /// EnforcementCritical /// [SecurityCritical] private char* _unsafeString; ////// Critical: Length is critical to avoid buffer overrun. /// [SecurityCritical] private int _length; ////// Creating a character buffer from an unsafe pointer to character string /// /// unsafe pointer to character string /// number of valid characters referenced by the unsafe pointer ////// Critical: This code is unsafe since it manipulates a pointer, it constructs an object with /// length data from user /// [SecurityCritical] public UnsafeStringCharacterBuffer( char* characterString, int length ) { if (characterString == null) { throw new ArgumentNullException("characterString"); } if (length <= 0) { throw new ArgumentOutOfRangeException("length", SR.Get(SRID.ParameterValueMustBeGreaterThanZero)); } _unsafeString = characterString; _length = length; } ////// Read a character from buffer at the specified character index /// ////// Critical: This code is unsafe since it manipulates a pointer /// Safe: Info is safe to expose and method does bound check /// public override char this[int characterOffset] { [SecurityCritical, SecurityTreatAsSafe] get { if (characterOffset >= _length || characterOffset < 0) throw new ArgumentOutOfRangeException("characterOffset", SR.Get(SRID.ParameterMustBeBetween,0,_length)); return _unsafeString[characterOffset]; } [SecurityCritical, SecurityTreatAsSafe] set { throw new NotSupportedException(); } } ////// Buffer character length /// ////// Critical: Lenght is critical data when dealing with unsafe pointer. /// Safe: This value is safe to give out. /// public override int Count { [SecurityCritical, SecurityTreatAsSafe] get { return _length; } } ////// Get fixed address of the character buffer /// ////// Critical:This returns the pointer /// [SecurityCritical] public override unsafe char* GetCharacterPointer() { return _unsafeString; } ////// Add character buffer's content to a StringBuilder /// /// string builder to add content to /// index to first character in the buffer to append /// number of character appending ////// Critical: This returns the string in a string builder object, critical because it accesses the pointer /// and returns its contents embedded in the stringbuilder passed in. /// Safe: This method does proper bound check. /// [SecurityCritical, SecurityTreatAsSafe] public override void AppendToStringBuilder( StringBuilder stringBuilder, int characterOffset, int characterLength ) { if (characterOffset >= _length || characterOffset < 0) { throw new ArgumentOutOfRangeException("characterOffset", SR.Get(SRID.ParameterMustBeBetween,0,_length)); } if (characterLength < 0 || characterOffset + characterLength > _length) { throw new ArgumentOutOfRangeException("characterLength", SR.Get(SRID.ParameterMustBeBetween,0, _length - characterOffset)); } stringBuilder.Append(new string(_unsafeString, characterOffset, characterLength)); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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