Code:
/ FXUpdate3074 / FXUpdate3074 / 1.1 / untmp / whidbey / QFE / ndp / clr / src / BCL / System / Text / EncoderBestFitFallback.cs / 1 / EncoderBestFitFallback.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // EncoderBestFitFallback.cs // // This is used internally to create best fit behavior as per the original windows best fit behavior. // namespace System.Text { using System; using System.Globalization; using System.Text; using System.Threading; [Serializable()] internal class InternalEncoderBestFitFallback : EncoderFallback { // Our variables internal Encoding encoding = null; internal char[] arrayBestFit = null; internal InternalEncoderBestFitFallback(Encoding encoding) { // Need to load our replacement characters table. this.encoding = encoding; this.bIsMicrosoftBestFitFallback = true; } public override EncoderFallbackBuffer CreateFallbackBuffer() { return new InternalEncoderBestFitFallbackBuffer(this); } // Maximum number of characters that this instance of this fallback could return public override int MaxCharCount { get { return 1; } } public override bool Equals(Object value) { InternalEncoderBestFitFallback that = value as InternalEncoderBestFitFallback; if (that != null) { return (this.encoding.CodePage == that.encoding.CodePage); } return (false); } public override int GetHashCode() { return this.encoding.CodePage; } } internal sealed class InternalEncoderBestFitFallbackBuffer : EncoderFallbackBuffer { // Our variables private char cBestFit = '\0'; private InternalEncoderBestFitFallback oFallback; private int iCount = -1; private int iSize; // Private object for locking instead of locking on a public type for SQL reliability work. private static Object s_InternalSyncObject; private static Object InternalSyncObject { get { if (s_InternalSyncObject == null) { Object o = new Object(); Interlocked.CompareExchange(ref s_InternalSyncObject, o, null); } return s_InternalSyncObject; } } // Constructor public InternalEncoderBestFitFallbackBuffer(InternalEncoderBestFitFallback fallback) { this.oFallback = fallback; if (oFallback.arrayBestFit == null) { // Lock so we don't confuse ourselves. lock(InternalSyncObject) { // Double if (oFallback.arrayBestFit == null) oFallback.arrayBestFit = fallback.encoding.GetBestFitUnicodeToBytesData(); } } } // Fallback methods public override bool Fallback(char charUnknown, int index) { // If we had a buffer already we're being recursive, throw, it's probably at the suspect // character in our array. // Shouldn't be able to get here for all of our code pages, table would have to be messed up. BCLDebug.Assert(iCount < 1, "[InternalEncoderBestFitFallbackBuffer.Fallback(non surrogate)] Fallback char " + ((int)cBestFit).ToString("X4", CultureInfo.InvariantCulture) + " caused recursive fallback"); iCount = iSize = 1; cBestFit = TryBestFit(charUnknown); if (cBestFit == '\0') cBestFit = '?'; return true; } public override bool Fallback(char charUnknownHigh, char charUnknownLow, int index) { // Double if (!Char.IsHighSurrogate(charUnknownHigh)) throw new ArgumentOutOfRangeException("charUnknownHigh", Environment.GetResourceString("ArgumentOutOfRange_Range", 0xD800, 0xDBFF)); if (!Char.IsLowSurrogate(charUnknownLow)) throw new ArgumentOutOfRangeException("CharUnknownLow", Environment.GetResourceString("ArgumentOutOfRange_Range", 0xDC00, 0xDFFF)); // If we had a buffer already we're being recursive, throw, it's probably at the suspect // character in our array. 0 is processing last character, < 0 is not falling back // Shouldn't be able to get here, table would have to be messed up. BCLDebug.Assert(iCount < 1, "[InternalEncoderBestFitFallbackBuffer.Fallback(surrogate)] Fallback char " + ((int)cBestFit).ToString("X4", CultureInfo.InvariantCulture) + " caused recursive fallback"); // Go ahead and get our fallback, surrogates don't have best fit cBestFit = '?'; iCount = iSize = 2; return true; } // Default version is overridden in EncoderReplacementFallback.cs public override char GetNextChar() { // Just return cReturn, which is 0 if there's no best fit for it. return (iCount-- > 0) ? cBestFit : '\0'; } public override bool MovePrevious() { // Exception fallback doesn't have anywhere to back up to. if (iCount >= 0) iCount++; // Return true if we could do it. return (iCount >= 0 && iCount <= iSize); } // How many characters left to output? public override int Remaining { get { return (iCount > 0) ? iCount : 0; } } // Clear the buffer public override unsafe void Reset() { iCount = -1; charStart = null; bFallingBack = false; } // private helper methods private char TryBestFit(char cUnknown) { // Need to figure out our best fit character, low is beginning of array, high is 1 AFTER end of array int lowBound = 0; int highBound = oFallback.arrayBestFit.Length; int index; // Binary search the array int iDiff; while ((iDiff = (highBound - lowBound)) > 6) { // Look in the middle, which is complicated by the fact that we have 2 #s for each pair, // so we don't want index to be odd because we want to be on word boundaries. // Also index = ((iDiff / 2) + lowBound) & 0xFFFE; char cTest = oFallback.arrayBestFit[index]; if (cTest == cUnknown) { // We found it BCLDebug.Assert(index + 1 < oFallback.arrayBestFit.Length, "[InternalEncoderBestFitFallbackBuffer.TryBestFit]Expected replacement character at end of array"); return oFallback.arrayBestFit[index + 1]; } else if (cTest < cUnknown) { // We weren't high enough lowBound = index; } else { // We weren't low enough highBound = index; } } for (index = lowBound; index < highBound; index += 2) { if (oFallback.arrayBestFit[index] == cUnknown) { // We found it BCLDebug.Assert(index + 1 < oFallback.arrayBestFit.Length, "[InternalEncoderBestFitFallbackBuffer.TryBestFit]Expected replacement character at end of array"); return oFallback.arrayBestFit[index + 1]; } } // Char wasn't in our table return '\0'; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
Link Menu

This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- BitmapFrameEncode.cs
- DynamicRouteExpression.cs
- HintTextConverter.cs
- EdmToObjectNamespaceMap.cs
- DTCTransactionManager.cs
- InvalidPropValue.cs
- LinqDataSource.cs
- BezierSegment.cs
- GridViewHeaderRowPresenterAutomationPeer.cs
- EventLogPermissionAttribute.cs
- DesignUtil.cs
- HttpServerUtilityBase.cs
- WindowsToolbarAsMenu.cs
- LayoutDump.cs
- AttachedPropertyBrowsableWhenAttributePresentAttribute.cs
- BypassElementCollection.cs
- Binding.cs
- FilterQuery.cs
- PocoPropertyAccessorStrategy.cs
- ButtonRenderer.cs
- DataGridPagerStyle.cs
- PassportAuthenticationEventArgs.cs
- OracleEncoding.cs
- SiteMapNode.cs
- DependencyPropertyHelper.cs
- Preprocessor.cs
- WorkflowQueue.cs
- CodeTypeOfExpression.cs
- ProfileSection.cs
- SmiEventSink.cs
- Color.cs
- Behavior.cs
- ExpressionLexer.cs
- PropertyGeneratedEventArgs.cs
- RemotingConfigParser.cs
- Selector.cs
- DoubleUtil.cs
- EnumBuilder.cs
- ComboBoxItem.cs
- SqlCacheDependencyDatabase.cs
- GridViewPageEventArgs.cs
- IndexedString.cs
- RelationshipWrapper.cs
- SessionParameter.cs
- SharedPerformanceCounter.cs
- Substitution.cs
- RC2.cs
- XsdBuildProvider.cs
- VisualStyleRenderer.cs
- BaseCodeDomTreeGenerator.cs
- VectorAnimation.cs
- DefaultHttpHandler.cs
- streamingZipPartStream.cs
- ScriptResourceAttribute.cs
- DrawListViewColumnHeaderEventArgs.cs
- XmlObjectSerializerWriteContext.cs
- XPathArrayIterator.cs
- XPathQueryGenerator.cs
- VisualBrush.cs
- RawStylusInput.cs
- TextRunCacheImp.cs
- CatalogZoneBase.cs
- XPathDocumentIterator.cs
- NullableDoubleSumAggregationOperator.cs
- DataGridViewIntLinkedList.cs
- IconHelper.cs
- Solver.cs
- PointLight.cs
- Logging.cs
- RepeatButtonAutomationPeer.cs
- RSAPKCS1SignatureFormatter.cs
- TypeConverterHelper.cs
- AttributeTableBuilder.cs
- DefaultSerializationProviderAttribute.cs
- PropertyManager.cs
- DependencyPropertyDescriptor.cs
- PowerEase.cs
- SqlDataSourceCommandEventArgs.cs
- QuerySetOp.cs
- DivideByZeroException.cs
- DataGridComboBoxColumn.cs
- precedingquery.cs
- _SafeNetHandles.cs
- DefaultAuthorizationContext.cs
- WebPartMinimizeVerb.cs
- SafeFileMappingHandle.cs
- NestedContainer.cs
- DataObjectAttribute.cs
- ACL.cs
- FontStretches.cs
- Win32.cs
- MultiSelectRootGridEntry.cs
- UnknownWrapper.cs
- TableCell.cs
- FontUnit.cs
- TokenBasedSetEnumerator.cs
- ResourceReferenceExpression.cs
- CheckBox.cs
- NetSectionGroup.cs
- NameTable.cs