ctrump/common/symbol.c

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/* -*- coding:utf-8 -*- 
 Copyright (c) 2009, Fixstars Corporation
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification, 
 are permitted provided that the following conditions are met:
 
   * Redistributions of source code must retain the above copyright notice,
     this list of conditions and the following disclaimer.
 
   * Redistributions in binary form must reproduce the above copyright notice,
     this list of conditions and the following disclaimer in the documentation
     and/or other materials provided with the distribution.
 
   * Neither the name of Fixstars Corporation nor the names of its contributors
     may be used to endorse or promote products derived from this software
     without specific prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include "ctrump/common/symbol.h"
#include "ctrump/common/mempool.h"
#include <stdlib.h>
#include <string.h>

static unsigned int
hash(const char *symstr,
     int symlen)
{
    int h = 0;
    int i;
    for (i=0; i<symlen; i++) {
        int c = symstr[i];

        h = h*997+c;
    }

    return h + (h>>5);
}

static struct table {
    unsigned int table_size;
    struct ctrump_symbol **table;
    struct ctrump_mempool pool;
} table;
static int symbol_id = 0;

void
ctrump_init_symtab(int initial_size)
{
    int i;
    symbol_id = 0;
    table.table_size = initial_size;
    ctrump_mempool_init(&table.pool, 1024);
    table.table = malloc(initial_size * sizeof(struct ctrump_symbol*));
    for (i=0; i<initial_size; i++) {
        table.table[i] = NULL;
    }
}

void
ctrump_destroy_symtab(void)
{
    ctrump_mempool_destroy(&table.pool);
    free(table.table);
}

const struct ctrump_symbol *
ctrump_intern(const char *symstr,
              int symstrlen)
{
    unsigned int h = hash(symstr, symstrlen);
    struct ctrump_symbol **chain_ptr = &table.table[h%table.table_size];
    struct ctrump_symbol *cur = *chain_ptr;
    char *strbuf;

    while (cur) {
        if ((memcmp(cur->symstr, symstr, symstrlen)==0) &&
            cur->symlen == symstrlen) {
            /* find */
            return cur;
        }

        chain_ptr = &cur->chain;
        cur = cur->chain;
    }

    /* alloc entry */
    strbuf = ctrump_mempool_alloc_align(&table.pool, 0, symstrlen+1);
    memcpy(strbuf, symstr, symstrlen);
    strbuf[symstrlen] = '\0';

    cur = ctrump_mempool_alloc(&table.pool, sizeof(struct ctrump_symbol));
    cur->symlen = symstrlen;
    cur->symstr = strbuf;
    cur->chain = NULL;
    cur->hashval = h;
    cur->id = symbol_id++;

    *chain_ptr = cur;

    return cur;
}

int
ctrump_get_current_symbol_num(void)
{
    return symbol_id;
}

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