__FastResourceComparer.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Resources / __FastResourceComparer.cs / 1305376 / __FastResourceComparer.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*============================================================
** 
** [....] 
**
** Class:  FastResourceComparer 
**
**
** Purpose: A collection of quick methods for comparing
**          resource keys (strings) 
**
** 
===========================================================*/ 
namespace System.Resources {
    using System; 
    using System.Collections;
    using System.Collections.Generic;
    using System.Diagnostics.Contracts;
 
    internal sealed class FastResourceComparer : IComparer, IEqualityComparer, IComparer, IEqualityComparer
    { 
        internal static readonly FastResourceComparer Default = new FastResourceComparer(); 

        // Implements IHashCodeProvider too, due to Hashtable requirements. 
        public int GetHashCode(Object key)
        {
            String s = (String) key;
            return FastResourceComparer.HashFunction(s); 
        }
 
        public int GetHashCode(String key) 
        {
            return FastResourceComparer.HashFunction(key); 
        }

        // This hash function MUST be publically documented with the resource
        // file format, AND we may NEVER change this hash function's return 
        // value (without changing the file format).
        internal static int HashFunction(String key) 
        { 
            // Never change this hash function.  We must standardize it so that
            // others can read & write our .resources files.  Additionally, we 
            // have a copy of it in InternalResGen as well.
            uint hash = 5381;
            for(int i=0; i bCharLength)
                numChars = bCharLength; 
            if (bCharLength == 0)   // Can't use fixed on a 0-element array.
                return (a.Length == 0) ? 0 : -1; 
            fixed(byte* pb = bytes) { 

                byte *pChar = pb; 
                while (i < numChars && r == 0) {
                    // little endian format
                    int b = pChar[0] | pChar[1] << 8;
                    r = a[i++] - b; 
                    pChar += sizeof(char);
                } 
            } 
            if (r != 0) return r;
            return a.Length - bCharLength; 
        }

        [System.Security.SecurityCritical]  // auto-generated
        public static int CompareOrdinal(byte[] bytes, int aCharLength, String b) 
        {
            return -CompareOrdinal(b, bytes, aCharLength); 
        } 

        // This method is to handle potentially misaligned data accesses. 
        // The byte* must point to little endian Unicode characters.
        [System.Security.SecurityCritical]  // auto-generated
        internal unsafe static int CompareOrdinal(byte* a, int byteLen, String b)
        { 
            Contract.Assert((byteLen & 1) == 0, "CompareOrdinal is expecting a UTF-16 string length, which must be even!");
            Contract.Assert(a != null && b != null, "Null args not allowed."); 
            Contract.Assert(byteLen >= 0, "byteLen must be non-negative."); 

            int r = 0; 
            int i = 0;
            // Compare the min length # of characters, then return length diffs.
            int numChars = byteLen >> 1;
            if (numChars > b.Length) 
                numChars = b.Length;
            while(i < numChars && r == 0) { 
                // Must compare character by character, not byte by byte. 
                char aCh = (char) (*a++ | (*a++ << 8));
                r = aCh - b[i++]; 
            }
            if (r != 0) return r;
            return byteLen - b.Length * 2;
        } 
    }
} 
 

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

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