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st.c

Go to the documentation of this file.

/* This is a public domain general purpose hash table package written by Peter Moore @ UCB. */

/* static       char    sccsid[] = "@(#) st.c 5.1 89/12/14 Crucible"; */

#include "config.h"
#include "defines.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "st.h"

#ifdef _WIN32
#include <malloc.h>
#endif

typedef struct st_table_entry st_table_entry;

struct st_table_entry {
    unsigned int hash;
    st_data_t key;
    st_data_t record;
    st_table_entry *next;
};

#define ST_DEFAULT_MAX_DENSITY 5
#define ST_DEFAULT_INIT_TABLE_SIZE 11

    /*
     * DEFAULT_MAX_DENSITY is the default for the largest we allow the
     * average number of items per bin before increasing the number of
     * bins
     *
     * DEFAULT_INIT_TABLE_SIZE is the default for the number of bins
     * allocated initially
     *
     */
static int numcmp(long, long);
static int numhash(long);
static struct st_hash_type type_numhash = {
    numcmp,
    numhash,
};

/* extern int strcmp(const char *, const char *); */
static int strhash(const char *);
static struct st_hash_type type_strhash = {
    strcmp,
    strhash,
};

#ifdef RUBY_PLATFORM
#define xmalloc ruby_xmalloc
#define xcalloc ruby_xcalloc
#define xrealloc ruby_xrealloc
#define xfree ruby_xfree

void *xmalloc(long);
void *xcalloc(long, long);
void *xrealloc(void *, long);
void xfree(void *);
#endif

static void rehash(st_table *);

#define alloc(type) (type*)xmalloc((unsigned)sizeof(type))
#define Calloc(n,s) (char*)xcalloc((n),(s))

#define EQUAL(table,x,y) ((x)==(y) || (*table->type->compare)((x),(y)) == 0)

#define do_hash(key,table) (unsigned int)(*(table)->type->hash)((key))
#define do_hash_bin(key,table) (do_hash(key, table)%(table)->num_bins)

/*
 * MINSIZE is the minimum size of a dictionary.
 */

#define MINSIZE 8

/*
Table of prime numbers 2^n+a, 2<=n<=30.
*/
static long primes[] = {
        8 + 3,
        16 + 3,
        32 + 5,
        64 + 3,
        128 + 3,
        256 + 27,
        512 + 9,
        1024 + 9,
        2048 + 5,
        4096 + 3,
        8192 + 27,
        16384 + 43,
        32768 + 3,
        65536 + 45,
        131072 + 29,
        262144 + 3,
        524288 + 21,
        1048576 + 7,
        2097152 + 17,
        4194304 + 15,
        8388608 + 9,
        16777216 + 43,
        33554432 + 35,
        67108864 + 15,
        134217728 + 29,
        268435456 + 3,
        536870912 + 11,
        1073741824 + 85,
        0
};

static int
new_size(size)
    int size;
{
    int i;

#if 0
    for (i=3; i<31; i++) {
        if ((1<<i) > size) return 1<<i;
    }
    return -1;
#else
    int newsize;

    for (i = 0, newsize = MINSIZE;
         i < sizeof(primes)/sizeof(primes[0]);
         i++, newsize <<= 1)
    {
        if (newsize > size) return primes[i];
    }
    /* Ran out of polynomials */
    return -1;                  /* should raise exception */
#endif
}

#ifdef HASH_LOG
static int collision = 0;
static int init_st = 0;

static void
stat_col()
{
    FILE *f = fopen("/tmp/col", "w");
    fprintf(f, "collision: %d\n", collision);
    fclose(f);
}
#endif

st_table*
st_init_table_with_size(type, size)
    struct st_hash_type *type;
    int size;
{
    st_table *tbl;

#ifdef HASH_LOG
    if (init_st == 0) {
        init_st = 1;
        atexit(stat_col);
    }
#endif

    size = new_size(size);      /* round up to prime number */

    tbl = alloc(st_table);
    tbl->type = type;
    tbl->num_entries = 0;
    tbl->num_bins = size;
    tbl->bins = (st_table_entry **)Calloc(size, sizeof(st_table_entry*));

    return tbl;
}

st_table*
st_init_table(type)
    struct st_hash_type *type;
{
    return st_init_table_with_size(type, 0);
}

st_table*
st_init_numtable(void)
{
    return st_init_table(&type_numhash);
}

st_table*
st_init_numtable_with_size(size)
    int size;
{
    return st_init_table_with_size(&type_numhash, size);
}

st_table*
st_init_strtable(void)
{
    return st_init_table(&type_strhash);
}

st_table*
st_init_strtable_with_size(size)
    int size;
{
    return st_init_table_with_size(&type_strhash, size);
}

void
st_free_table(table)
    st_table *table;
{
    register st_table_entry *ptr, *next;
    int i;

    for(i = 0; i < table->num_bins; i++) {
        ptr = table->bins[i];
        while (ptr != 0) {
            next = ptr->next;
            free(ptr);
            ptr = next;
        }
    }
    free(table->bins);
    free(table);
}

#define PTR_NOT_EQUAL(table, ptr, hash_val, key) \
((ptr) != 0 && (ptr->hash != (hash_val) || !EQUAL((table), (key), (ptr)->key)))

#ifdef HASH_LOG
#define COLLISION collision++
#else
#define COLLISION
#endif

#define FIND_ENTRY(table, ptr, hash_val, bin_pos) do {\
    bin_pos = hash_val%(table)->num_bins;\
    ptr = (table)->bins[bin_pos];\
    if (PTR_NOT_EQUAL(table, ptr, hash_val, key)) {\
        COLLISION;\
        while (PTR_NOT_EQUAL(table, ptr->next, hash_val, key)) {\
            ptr = ptr->next;\
        }\
        ptr = ptr->next;\
    }\
} while (0)

int
st_lookup(table, key, value)
    st_table *table;
    register st_data_t key;
    st_data_t *value;
{
    unsigned int hash_val, bin_pos;
    register st_table_entry *ptr;

    hash_val = do_hash(key, table);
    FIND_ENTRY(table, ptr, hash_val, bin_pos);

    if (ptr == 0) {
        return 0;
    }
    else {
        if (value != 0)  *value = ptr->record;
        return 1;
    }
}

#define ADD_DIRECT(table, key, value, hash_val, bin_pos)\
do {\
    st_table_entry *entry;\
    if (table->num_entries/(table->num_bins) > ST_DEFAULT_MAX_DENSITY) {\
        rehash(table);\
        bin_pos = hash_val % table->num_bins;\
    }\
    \
    entry = alloc(st_table_entry);\
    \
    entry->hash = hash_val;\
    entry->key = key;\
    entry->record = value;\
    entry->next = table->bins[bin_pos];\
    table->bins[bin_pos] = entry;\
    table->num_entries++;\
} while (0)

int
st_insert(table, key, value)
    register st_table *table;
    register st_data_t key;
    st_data_t value;
{
    unsigned int hash_val, bin_pos;
    register st_table_entry *ptr;

    hash_val = do_hash(key, table);
    FIND_ENTRY(table, ptr, hash_val, bin_pos);

    if (ptr == 0) {
        ADD_DIRECT(table, key, value, hash_val, bin_pos);
        return 0;
    }
    else {
        ptr->record = value;
        return 1;
    }
}

void
st_add_direct(table, key, value)
    st_table *table;
    st_data_t key;
    st_data_t value;
{
    unsigned int hash_val, bin_pos;

    hash_val = do_hash(key, table);
    bin_pos = hash_val % table->num_bins;
    ADD_DIRECT(table, key, value, hash_val, bin_pos);
}

static void
rehash(table)
    register st_table *table;
{
    register st_table_entry *ptr, *next, **new_bins;
    int i, old_num_bins = table->num_bins, new_num_bins;
    unsigned int hash_val;

    new_num_bins = new_size(old_num_bins+1);
    new_bins = (st_table_entry**)Calloc(new_num_bins, sizeof(st_table_entry*));

    for(i = 0; i < old_num_bins; i++) {
        ptr = table->bins[i];
        while (ptr != 0) {
            next = ptr->next;
            hash_val = ptr->hash % new_num_bins;
            ptr->next = new_bins[hash_val];
            new_bins[hash_val] = ptr;
            ptr = next;
        }
    }
    free(table->bins);
    table->num_bins = new_num_bins;
    table->bins = new_bins;
}

st_table*
st_copy(old_table)
    st_table *old_table;
{
    st_table *new_table;
    st_table_entry *ptr, *entry;
    int i, num_bins = old_table->num_bins;

    new_table = alloc(st_table);
    if (new_table == 0) {
        return 0;
    }

    *new_table = *old_table;
    new_table->bins = (st_table_entry**)
        Calloc((unsigned)num_bins, sizeof(st_table_entry*));

    if (new_table->bins == 0) {
        free(new_table);
        return 0;
    }

    for(i = 0; i < num_bins; i++) {
        new_table->bins[i] = 0;
        ptr = old_table->bins[i];
        while (ptr != 0) {
            entry = alloc(st_table_entry);
            if (entry == 0) {
                free(new_table->bins);
                free(new_table);
                return 0;
            }
            *entry = *ptr;
            entry->next = new_table->bins[i];
            new_table->bins[i] = entry;
            ptr = ptr->next;
        }
    }
    return new_table;
}

int
st_delete(table, key, value)
    register st_table *table;
    register st_data_t *key;
    st_data_t *value;
{
    unsigned int hash_val;
    st_table_entry *tmp;
    register st_table_entry *ptr;

    hash_val = do_hash_bin(*key, table);
    ptr = table->bins[hash_val];

    if (ptr == 0) {
        if (value != 0) *value = 0;
        return 0;
    }

    if (EQUAL(table, *key, ptr->key)) {
        table->bins[hash_val] = ptr->next;
        table->num_entries--;
        if (value != 0) *value = ptr->record;
        *key = ptr->key;
        free(ptr);
        return 1;
    }

    for(; ptr->next != 0; ptr = ptr->next) {
        if (EQUAL(table, ptr->next->key, *key)) {
            tmp = ptr->next;
            ptr->next = ptr->next->next;
            table->num_entries--;
            if (value != 0) *value = tmp->record;
            *key = tmp->key;
            free(tmp);
            return 1;
        }
    }

    return 0;
}

int
st_delete_safe(table, key, value, never)
    register st_table *table;
    register st_data_t *key;
    st_data_t *value;
    st_data_t never;
{
    unsigned int hash_val;
    register st_table_entry *ptr;

    hash_val = do_hash_bin(*key, table);
    ptr = table->bins[hash_val];

    if (ptr == 0) {
        if (value != 0) *value = 0;
        return 0;
    }

    for(; ptr != 0; ptr = ptr->next) {
        if ((ptr->key != never) && EQUAL(table, ptr->key, *key)) {
            table->num_entries--;
            *key = ptr->key;
            if (value != 0) *value = ptr->record;
            ptr->key = ptr->record = never;
            return 1;
        }
    }

    return 0;
}

static int
delete_never(key, value, never)
    st_data_t key, value, never;
{
    if (value == never) return ST_DELETE;
    return ST_CONTINUE;
}

void
st_cleanup_safe(table, never)
    st_table *table;
    st_data_t never;
{
    int num_entries = table->num_entries;

    st_foreach(table, delete_never, never);
    table->num_entries = num_entries;
}

void
st_foreach(table, func, arg)
    st_table *table;
    int (*func)();
    st_data_t arg;
{
    st_table_entry *ptr, *last, *tmp;
    enum st_retval retval;
    int i;

    for(i = 0; i < table->num_bins; i++) {
        last = 0;
        for(ptr = table->bins[i]; ptr != 0;) {
            retval = (*func)(ptr->key, ptr->record, arg, 0);
            switch (retval) {
            case ST_CHECK:      /* check if hash is modified during iteration */
                tmp = 0;
                if (i < table->num_bins) {
                    for (tmp = table->bins[i]; tmp; tmp=tmp->next) {
                        if (tmp == ptr) break;
                    }
                }
                if (!tmp) {
                    /* call func with error notice */
                    retval = (*func)(0, 0, arg, 1);
                    return;
                }
                /* fall through */
            case ST_CONTINUE:
                last = ptr;
                ptr = ptr->next;
                break;
            case ST_STOP:
                return;
            case ST_DELETE:
                tmp = ptr;
                if (last == 0) {
                    table->bins[i] = ptr->next;
                }
                else {
                    last->next = ptr->next;
                }
                ptr = ptr->next;
                free(tmp);
                table->num_entries--;
            }
        }
    }
}

static int
strhash(string)
    register const char *string;
{
    register int c;

#ifdef HASH_ELFHASH
    register unsigned int h = 0, g;

    while ((c = *string++) != '\0') {
        h = ( h << 4 ) + c;
        if ( g = h & 0xF0000000 )
            h ^= g >> 24;
        h &= ~g;
    }
    return h;
#elif HASH_PERL
    register int val = 0;

    while ((c = *string++) != '\0') {
        val += c;
        val += (val << 10);
        val ^= (val >> 6);
    }
    val += (val << 3);
    val ^= (val >> 11);

    return val + (val << 15);
#else
    register int val = 0;

    while ((c = *string++) != '\0') {
        val = val*997 + c;
    }

    return val + (val>>5);
#endif
}

static int
numcmp(x, y)
    long x, y;
{
    return x != y;
}

static int
numhash(n)
    long n;
{
    return n;
}

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