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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.
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Runtime;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Text;
using Internal.Runtime.CompilerServices;
namespace System
{
[StructLayout(LayoutKind.Sequential)]
[System.Runtime.CompilerServices.EagerStaticClassConstructionAttribute]
[System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
public partial class String
{
#if BIT64
private const int POINTER_SIZE = 8;
#else
private const int POINTER_SIZE = 4;
#endif
// m_pEEType + _stringLength
internal const int FIRST_CHAR_OFFSET = POINTER_SIZE + sizeof(int);
// CS0169: The private field '{blah}' is never used
// CS0649: Field '{blah}' is never assigned to, and will always have its default value
#pragma warning disable 169, 649
#if PROJECTN
[Bound]
#endif
// WARNING: We allow diagnostic tools to directly inspect these two members (_stringLength, _firstChar)
// See https://github.com/dotnet/corert/blob/master/Documentation/design-docs/diagnostics/diagnostics-tools-contract.md for more details.
// Please do not change the type, the name, or the semantic usage of this member without understanding the implication for tools.
// Get in touch with the diagnostics team if you have questions.
[NonSerialized]
private int _stringLength;
[NonSerialized]
private char _firstChar;
#pragma warning restore
public static readonly String Empty = "";
// Gets the character at a specified position.
//
// Spec#: Apply the precondition here using a contract assembly. Potential perf issue.
[System.Runtime.CompilerServices.IndexerName("Chars")]
public unsafe char this[int index]
{
#if PROJECTN
[BoundsChecking]
get
{
return Unsafe.Add(ref _firstChar, index);
}
#else
[Intrinsic]
get
{
if ((uint)index >= _stringLength)
ThrowHelper.ThrowIndexOutOfRangeException();
return Unsafe.Add(ref _firstChar, index);
}
#endif
}
internal static String FastAllocateString(int length)
{
// We allocate one extra char as an interop convenience so that our strings are null-
// terminated, however, we don't pass the extra +1 to the string allocation because the base
// size of this object includes the _firstChar field.
string newStr = RuntimeImports.RhNewString(EETypePtr.EETypePtrOf<string>(), length);
Debug.Assert(newStr._stringLength == length);
return newStr;
}
}
}
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