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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
// Description: The CultureMapper class implements static methods for mapping
// CultureInfo objects from WPF clients to CultureInfo objects
// that can be used internally by text formatting code.
//
//
using System;
using System.Globalization;
using System.Diagnostics;
using MS.Internal.PresentationCore;
using System.Windows.Markup;
namespace MS.Internal.TextFormatting
{
/// <summary>
/// Implements static methods for mapping CultureInfo objects.
/// </summary>
internal static class CultureMapper
{
/// <summary>
/// Returns a specific culture given an arbitrary CultureInfo, which may be null, the invariant
/// culture, or a neutral culture.
/// </summary>
public static CultureInfo GetSpecificCulture(CultureInfo runCulture)
{
// Assume default culture unless we can do better.
CultureInfo specificCulture = TypeConverterHelper.InvariantEnglishUS;
if (runCulture != null)
{
// Assign _cachedCultureMap to a local variable for thread safety. The reference assignment
// is atomic and the CachedCultureMap class is immutable.
CachedCultureMap cachedCultureMap = _cachedCultureMap;
if (cachedCultureMap != null && object.ReferenceEquals(cachedCultureMap.OriginalCulture, runCulture))
return cachedCultureMap.SpecificCulture;
// Unfortunately we cannot use reference comparison here because, for example, new CultureInfo("")
// creates an invariant culture which (being a new object) is obviously not the same instance as
// CultureInfo.InvariantCulture.
if (runCulture != CultureInfo.InvariantCulture)
{
if (!runCulture.IsNeutralCulture)
{
// It's already a specific culture (neither neutral nor InvariantCulture)
specificCulture = runCulture;
}
else
{
// Get the culture name. Note that the string expected by CreateSpecificCulture corresponds
// to the Name property, not IetfLanguageTag, so that's what we use.
string cultureName = runCulture.Name;
if (!string.IsNullOrEmpty(cultureName))
{
try
{
CultureInfo culture = CultureInfo.CreateSpecificCulture(cultureName);
specificCulture = SafeSecurityHelper.GetCultureInfoByIetfLanguageTag(culture.IetfLanguageTag);
}
catch (ArgumentException)
{
// This exception occurs if the culture name is invalid or has no corresponding specific
// culture. we can safely ignore the exception and fall back to TypeConverterHelper.InvariantEnglishUS.
specificCulture = TypeConverterHelper.InvariantEnglishUS;
}
}
}
}
// Save the mapping so the next call will be fast if we're given the same runCulture.
// Again, the reference assignment is atomic so this is thread safe.
_cachedCultureMap = new CachedCultureMap(runCulture, specificCulture);
}
return specificCulture;
}
private class CachedCultureMap
{
public CachedCultureMap(CultureInfo originalCulture, CultureInfo specificCulture)
{
_originalCulture = originalCulture;
_specificCulture = specificCulture;
}
/// <summary>
/// Original CultureInfo object from text formatting client; could be the invariant culture,
/// a neutral culture, or a specific culture.
/// </summary>
public CultureInfo OriginalCulture
{
get { return _originalCulture; }
}
/// <summary>
/// CultureInfo object to use for text formatting. This is guaranteed to be a specific (i.e.,
/// neither neutral nor invariant) culture. It may be the same object as OriginalCulture if
/// the latter is already a specific culture.
/// </summary>
public CultureInfo SpecificCulture
{
get { return _specificCulture; }
}
private CultureInfo _originalCulture;
private CultureInfo _specificCulture;
}
private static CachedCultureMap _cachedCultureMap = null;
}
}
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