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Annotation of objc/NXUniquedString.m, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.0 (the 'License').  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License."
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: /*
        !            25:        NXUniquedString.m
        !            26:        Copyright 1991, NeXT, Inc.
        !            27:        Responsibility:
        !            28: */
        !            29: 
        !            30: #ifndef KERNEL
        !            31: #ifdef SHLIB
        !            32: #import "shlib.h"
        !            33: #endif SHLIB
        !            34: 
        !            35: #import <mach/cthreads.h>
        !            36: #import "NXStringPrivate.h"
        !            37: #import "HashTable.h"
        !            38: 
        !            39: /* Mutex for mucking around with global stuff */
        !            40: static struct mutex stringLock;
        !            41: 
        !            42: /* For storing unique strings... Maps objects to objects. */
        !            43: static HashTable *uniquedStringHashTable = nil;
        !            44: 
        !            45: #if SEPARATE_UNIQUED_ZONE
        !            46: static NXZone *uniquedStringZone = NULL;       /* Zone for uniqued strings */
        !            47: #else
        !            48: #define uniquedStringZone stringZone
        !            49: #endif
        !            50: 
        !            51: 
        !            52: @implementation NXUniquedString
        !            53: 
        !            54: + initialize
        !            55: {
        !            56:     if ([self class] == [NXUniquedString class]) {
        !            57:         mutex_init(&stringLock);
        !            58: #if SEPARATE_UNIQUED_ZONE
        !            59:        uniquedStringZone = NXCreateZone(vm_page_size, vm_page_size, YES);
        !            60: #endif
        !            61:         uniquedStringHashTable = [[HashTable allocFromZone:uniquedStringZone] init];
        !            62:     }
        !            63:     return self;
        !            64: }
        !            65: 
        !            66: + newFromString:(NXString *)string
        !            67: {
        !            68:     NXUniquedString *result;
        !            69:     if ([string isKindOf:self]) {
        !            70:        result = (NXUniquedString *)string;
        !            71:     } else {
        !            72:        mutex_lock(&stringLock);
        !            73:        if (!(result = [uniquedStringHashTable valueForKey:string])) {
        !            74:            unsigned newLength = [string length];
        !            75:            result = [self allocFromZone:uniquedStringZone];
        !            76:            result->characters = [result allocateCharacterBuffer:newLength];
        !            77:            result->_length = newLength;
        !            78:            [string getCharacters:result->characters];
        !            79:            [uniquedStringHashTable insertKey:result value:result];
        !            80:        }
        !            81:        mutex_unlock(&stringLock);
        !            82:     }
        !            83:     return result;
        !            84: }
        !            85: 
        !            86: + newFromCharacters:(const unichar *)chars length:(unsigned)length
        !            87: {
        !            88:     NXReadOnlyString *string = [[NXReadOnlyString alloc] initFromCharactersNoCopy:(unichar *)chars length:length freeWhenDone:NO];
        !            89:     NXUniquedString *result = [self newFromString:string];
        !            90:     [string free];
        !            91:     return result;
        !            92: }
        !            93: 
        !            94: - initFromCharactersNoCopy:(unichar *)chars length:(unsigned)len
        !            95: {
        !            96:     NXUniquedString *result;
        !            97:     NXReadOnlyString *string = [[NXReadOnlyString alloc] initFromCharactersNoCopy:chars length:len freeWhenDone:NO];
        !            98:     mutex_lock(&stringLock);
        !            99:     if ((result = [uniquedStringHashTable valueForKey:string])) {
        !           100:        // Already in the hash table
        !           101:        [self free];
        !           102:     } else {   
        !           103:        // Not in the table; create a new string
        !           104:        [super initFromCharactersNoCopy:chars length:len];
        !           105:         [uniquedStringHashTable insertKey:self value:self];
        !           106:        result = self;
        !           107:     }
        !           108:     mutex_unlock(&stringLock);
        !           109:     [string free];
        !           110:     return result;
        !           111: }
        !           112: 
        !           113: + allocFromZone:(NXZone *)zone
        !           114: {
        !           115:     return [super allocFromZone:uniquedStringZone];
        !           116: }
        !           117: 
        !           118: + alloc
        !           119: {
        !           120:     return [super allocFromZone:uniquedStringZone];
        !           121: }
        !           122: 
        !           123: - free
        !           124: {
        !           125:     return nil;
        !           126: }
        !           127: 
        !           128: - copyFromZone:(NXZone *)zone
        !           129: {
        !           130:     return self;
        !           131: }
        !           132: 
        !           133: - (BOOL)isEqual:string
        !           134: {
        !           135:     static id uniquedStringClass = nil;                // Cache to avoid hash lookup...
        !           136:     if (!uniquedStringClass) {                 // No mutex necessary
        !           137:        uniquedStringClass = [NXUniquedString class];
        !           138:     }
        !           139:     if ([string isKindOf:uniquedStringClass]) {
        !           140:        return (self == string) ? YES : NO;
        !           141:     } else {
        !           142:         return [super isEqual:string];
        !           143:     }
        !           144: }
        !           145: 
        !           146: /*
        !           147: finishUnarchiving not only has to look the string up in the hash table, it also has to make sure the object itself was allocated in the appropriate zone. 
        !           148: */
        !           149: 
        !           150: - finishUnarchiving
        !           151: {
        !           152:     id actual;
        !           153:     mutex_lock(&stringLock);
        !           154:     if (!(actual = [uniquedStringHashTable valueForKey:self])) {
        !           155:        // If not in this zone, reallocate...
        !           156:        actual = ([self zone] == uniquedStringZone) ? self : object_copyFromZone (self, 0, uniquedStringZone);
        !           157:        [uniquedStringHashTable insertKey:actual value:actual];
        !           158:     } else {
        !           159:        free (characters);      // Already in the hash table, so we free this guy       
        !           160:     }    
        !           161:     mutex_unlock(&stringLock);
        !           162:     if (actual != self) {
        !           163:         object_dispose(self);
        !           164:        return actual;
        !           165:     } else {
        !           166:        return nil;
        !           167:     }
        !           168: }
        !           169: 
        !           170: @end
        !           171: #endif /* KERNEL */

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