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373 lines
8.2 KiB
C
373 lines
8.2 KiB
C
/*
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* Copyright 1993, 1995 Christopher Seiwald.
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* Copyright 2011 Steven Watanabe
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*
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* This file is part of Jam - see jam.c for Copyright information.
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*/
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# include "jam.h"
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# include "object.h"
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# include <stddef.h>
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# include <stdlib.h>
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# include <assert.h>
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/*
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* object.c - object manipulation routines
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*
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* External functions:
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*
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* object_new() - create an object from a string
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* object_copy() - return a copy of an object
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* object_free() - free an object
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* object_str() - get the string value of an object
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* object_done() - free string tables
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*
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* This implementation builds a hash table of all strings, so that multiple
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* calls of object_new() on the same string allocate memory for the string once.
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* Strings are never actually freed.
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*/
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#define OBJECT_MAGIC 0xa762e0e3u
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struct hash_header
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{
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#ifndef NDEBUG
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unsigned int magic;
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#endif
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unsigned int hash;
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struct hash_item * next;
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};
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struct hash_item
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{
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struct hash_header header;
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char data[1];
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};
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#define ALLOC_ALIGNMENT ( sizeof( struct hash_item ) - sizeof( struct hash_header ) )
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typedef struct string_set
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{
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unsigned int num;
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unsigned int size;
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struct hash_item * * data;
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} string_set;
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static string_set strhash;
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static int strtotal = 0;
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static int strcount_in = 0;
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static int strcount_out = 0;
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/*
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* Immortal string allocator implementation speeds string allocation and cuts
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* down on internal fragmentation.
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*/
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# define STRING_BLOCK 4096
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typedef struct strblock
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{
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struct strblock * next;
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char data[STRING_BLOCK];
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} strblock;
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static strblock * strblock_chain = 0;
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/* Storage remaining in the current strblock */
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static char * storage_start = 0;
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static char * storage_finish = 0;
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/*
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* allocate() - Allocate n bytes of immortal string storage.
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*/
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static char * allocate( size_t n )
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{
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#ifdef BJAM_NEWSTR_NO_ALLOCATE
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return (char*)BJAM_MALLOC(n);
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#else
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/* See if we can grab storage from an existing block. */
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size_t remaining = storage_finish - storage_start;
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n = ((n + ALLOC_ALIGNMENT - 1) / ALLOC_ALIGNMENT) * ALLOC_ALIGNMENT;
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if ( remaining >= n )
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{
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char * result = storage_start;
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storage_start += n;
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return result;
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}
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else /* Must allocate a new block. */
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{
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strblock * new_block;
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size_t nalloc = n;
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if ( nalloc < STRING_BLOCK )
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nalloc = STRING_BLOCK;
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/* Allocate a new block and link into the chain. */
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new_block = (strblock *)BJAM_MALLOC( offsetof( strblock, data[0] ) + nalloc * sizeof( new_block->data[0] ) );
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if ( new_block == 0 )
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return 0;
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new_block->next = strblock_chain;
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strblock_chain = new_block;
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/* Take future allocations out of the larger remaining space. */
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if ( remaining < nalloc - n )
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{
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storage_start = new_block->data + n;
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storage_finish = new_block->data + nalloc;
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}
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return new_block->data;
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}
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#endif
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}
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static unsigned int hash_keyval( const char * key )
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{
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unsigned int hash = 0;
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unsigned i;
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unsigned int len = strlen( key );
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for ( i = 0; i < len / sizeof( unsigned int ); ++i )
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{
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unsigned int val;
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memcpy( &val, key, sizeof( unsigned int ) );
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hash = hash * 2147059363 + val;
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key += sizeof( unsigned int );
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}
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{
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unsigned int val = 0;
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memcpy( &val, key, len % sizeof( unsigned int ) );
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hash = hash * 2147059363 + val;
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}
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hash += (hash >> 17);
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return hash;
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}
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static void string_set_init(string_set * set)
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{
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set->size = 0;
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set->num = 4;
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set->data = (struct hash_item * *)BJAM_MALLOC( set->num * sizeof( struct hash_item * ) );
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memset( set->data, 0, set->num * sizeof( struct hash_item * ) );
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}
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static void string_set_done(string_set * set)
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{
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BJAM_FREE( set->data );
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}
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static void string_set_resize(string_set *set)
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{
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unsigned i;
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string_set new_set;
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new_set.num = set->num * 2;
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new_set.size = set->size;
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new_set.data = (struct hash_item * *)BJAM_MALLOC( sizeof( struct hash_item * ) * new_set.num );
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memset(new_set.data, 0, sizeof(struct hash_item *) * new_set.num);
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for ( i = 0; i < set->num; ++i )
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{
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while ( set->data[i] )
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{
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struct hash_item * temp = set->data[i];
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unsigned pos = temp->header.hash % new_set.num;
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set->data[i] = temp->header.next;
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temp->header.next = new_set.data[pos];
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new_set.data[pos] = temp;
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}
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}
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BJAM_FREE( set->data );
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*set = new_set;
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}
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static const char * string_set_insert ( string_set * set, const char * string )
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{
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unsigned hash = hash_keyval( string );
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unsigned pos = hash % set->num;
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unsigned l;
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struct hash_item * result;
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for ( result = set->data[pos]; result; result = result->header.next )
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{
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if ( strcmp( result->data, string ) == 0 )
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{
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return result->data;
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}
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}
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if( set->size >= set->num )
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{
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string_set_resize( set );
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pos = hash % set->num;
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}
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l = strlen( string );
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result = (struct hash_item *)allocate( sizeof( struct hash_header ) + l + 1 );
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result->header.hash = hash;
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result->header.next = set->data[pos];
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#ifndef NDEBUG
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result->header.magic = OBJECT_MAGIC;
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#endif
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memcpy( result->data, string, l + 1 );
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assert( hash_keyval( result->data ) == result->header.hash );
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set->data[pos] = result;
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strtotal += l + 1;
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++set->size;
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return result->data;
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}
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static struct hash_item * object_get_item( OBJECT * obj )
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{
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return (struct hash_item *)( (char *)obj - offsetof( struct hash_item, data ) );
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}
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static void object_validate( OBJECT * obj )
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{
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assert( object_get_item( obj )->header.magic == OBJECT_MAGIC );
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}
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/*
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* object_new() - create an object from a string.
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*/
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OBJECT * object_new( const char * string )
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{
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#ifdef BJAM_NO_MEM_CACHE
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int l = strlen( string );
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struct hash_item * m = (struct hash_item *)BJAM_MALLOC( sizeof(struct hash_header) + l + 1 );
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strtotal += l + 1;
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memcpy( m->data, string, l + 1 );
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m->header.magic = OBJECT_MAGIC;
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return (OBJECT *)m->data;
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#else
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if ( ! strhash.data )
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string_set_init( &strhash );
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strcount_in += 1;
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return (OBJECT *)string_set_insert( &strhash, string );
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#endif
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}
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/*
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* object_copy() - return a copy of an object
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*/
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OBJECT * object_copy( OBJECT * obj )
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{
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object_validate( obj );
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#ifdef BJAM_NO_MEM_CACHE
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return object_new( object_str( obj ) );
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#else
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strcount_in += 1;
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return obj;
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#endif
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}
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/*
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* object_free() - free an object
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*/
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void object_free( OBJECT * obj )
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{
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object_validate( obj );
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#ifdef BJAM_NO_MEM_CACHE
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BJAM_FREE( object_get_item( obj ) );
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#endif
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strcount_out += 1;
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}
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/*
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* object_str() - return the
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*/
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const char * object_str( OBJECT * obj )
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{
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object_validate( obj );
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return (const char *)obj;
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}
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/*
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* object_equal() - compare two objects
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*/
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int object_equal( OBJECT * lhs, OBJECT * rhs )
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{
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object_validate( lhs );
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object_validate( rhs );
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#ifdef BJAM_NO_MEM_CACHE
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return strcmp(object_str(lhs), object_str(rhs)) == 0;
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#else
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assert( (lhs == rhs) == ( strcmp(object_str(lhs), object_str(rhs)) == 0 ) );
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return lhs == rhs;
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#endif
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}
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/*
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* object_hash() - returns the hash value of an object
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*/
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unsigned int object_hash( OBJECT * obj )
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{
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object_validate( obj );
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#ifdef BJAM_NO_MEM_CACHE
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return hash_keyval( object_str( obj ) );
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#else
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return object_get_item( obj )->header.hash;
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#endif
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}
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/*
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* object_done() - free string tables.
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*/
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void object_done()
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{
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#ifdef BJAM_NEWSTR_NO_ALLOCATE
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unsigned i;
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for ( i = 0; i < strhash.num; ++i )
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{
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while ( strhash.data[i] )
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{
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struct hash_item * item = strhash.data[i];
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strhash.data[i] = item->header.next;
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BJAM_FREE( item );
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}
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}
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#else
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/* Reclaim string blocks. */
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while ( strblock_chain != 0 )
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{
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strblock * n = strblock_chain->next;
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BJAM_FREE(strblock_chain);
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strblock_chain = n;
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}
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#endif
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string_set_done( &strhash );
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if ( DEBUG_MEM )
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printf( "%dK in strings\n", strtotal / 1024 );
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/* printf( "--- %d strings of %d dangling\n", strcount_in-strcount_out, strcount_in ); */
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}
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