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/* Copyright (C) 1999-2020 by The D Language Foundation, All Rights Reserved
* http://www.digitalmars.com
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
* https://github.com/D-Programming-Language/dmd/blob/master/src/root/stringtable.c
*/
#include "dsystem.h" // uint{8|16|32}_t, memcpy()
#include "root.h"
#include "rmem.h" // mem
#include "stringtable.h"
#include "hash.h"
#define POOL_BITS 12
#define POOL_SIZE (1U << POOL_BITS)
struct StringEntry
{
uint32_t hash;
uint32_t vptr;
};
uint32_t StringTable::allocValue(const char *s, size_t length, void *ptrvalue)
{
const size_t nbytes = sizeof(StringValue) + length + 1;
if (!npools || nfill + nbytes > POOL_SIZE)
{
pools = (uint8_t **)mem.xrealloc(pools, ++npools * sizeof(pools[0]));
pools[npools - 1] = (uint8_t *)mem.xmalloc(nbytes > POOL_SIZE ? nbytes : POOL_SIZE);
nfill = 0;
}
StringValue *sv = (StringValue *)&pools[npools - 1][nfill];
sv->ptrvalue = ptrvalue;
sv->length = length;
::memcpy(sv->lstring(), s, length);
sv->lstring()[length] = 0;
const uint32_t vptr = (uint32_t)(npools << POOL_BITS | nfill);
nfill += nbytes + (-nbytes & 7); // align to 8 bytes
return vptr;
}
StringValue *StringTable::getValue(uint32_t vptr)
{
if (!vptr) return NULL;
const size_t idx = (vptr >> POOL_BITS) - 1;
const size_t off = vptr & (POOL_SIZE - 1);
return (StringValue *)&pools[idx][off];
}
static size_t nextpow2(size_t val)
{
size_t res = 1;
while (res < val)
res <<= 1;
return res;
}
static const double loadFactor = 0.8;
void StringTable::_init(size_t size)
{
size = nextpow2((size_t)(size / loadFactor));
if (size < 32) size = 32;
table = (StringEntry *)mem.xcalloc(size, sizeof(table[0]));
tabledim = size;
pools = NULL;
npools = nfill = 0;
count = 0;
}
void StringTable::reset(size_t size)
{
for (size_t i = 0; i < npools; ++i)
mem.xfree(pools[i]);
mem.xfree(table);
mem.xfree(pools);
table = NULL;
pools = NULL;
_init(size);
}
StringTable::~StringTable()
{
for (size_t i = 0; i < npools; ++i)
mem.xfree(pools[i]);
mem.xfree(table);
mem.xfree(pools);
table = NULL;
pools = NULL;
}
size_t StringTable::findSlot(hash_t hash, const char *s, size_t length)
{
// quadratic probing using triangular numbers
// http://stackoverflow.com/questions/2348187/moving-from-linear-probing-to-quadratic-probing-hash-collisons/2349774#2349774
for (size_t i = hash & (tabledim - 1), j = 1; ;++j)
{
StringValue *sv;
if (!table[i].vptr ||
(table[i].hash == hash &&
(sv = getValue(table[i].vptr))->length == length &&
::memcmp(s, sv->lstring(), length) == 0))
return i;
i = (i + j) & (tabledim - 1);
}
}
StringValue *StringTable::lookup(const char *s, size_t length)
{
const hash_t hash = calcHash(s, length);
const size_t i = findSlot(hash, s, length);
// printf("lookup %.*s %p\n", (int)length, s, table[i].value ?: NULL);
return getValue(table[i].vptr);
}
StringValue *StringTable::update(const char *s, size_t length)
{
const hash_t hash = calcHash(s, length);
size_t i = findSlot(hash, s, length);
if (!table[i].vptr)
{
if (++count > tabledim * loadFactor)
{
grow();
i = findSlot(hash, s, length);
}
table[i].hash = hash;
table[i].vptr = allocValue(s, length, NULL);
}
// printf("update %.*s %p\n", (int)length, s, table[i].value ?: NULL);
return getValue(table[i].vptr);
}
StringValue *StringTable::insert(const char *s, size_t length, void *ptrvalue)
{
const hash_t hash = calcHash(s, length);
size_t i = findSlot(hash, s, length);
if (table[i].vptr)
return NULL; // already in table
if (++count > tabledim * loadFactor)
{
grow();
i = findSlot(hash, s, length);
}
table[i].hash = hash;
table[i].vptr = allocValue(s, length, ptrvalue);
// printf("insert %.*s %p\n", (int)length, s, table[i].value ?: NULL);
return getValue(table[i].vptr);
}
void StringTable::grow()
{
const size_t odim = tabledim;
StringEntry *otab = table;
tabledim *= 2;
table = (StringEntry *)mem.xcalloc(tabledim, sizeof(table[0]));
for (size_t i = 0; i < odim; ++i)
{
StringEntry *se = &otab[i];
if (!se->vptr) continue;
StringValue *sv = getValue(se->vptr);
table[findSlot(se->hash, sv->lstring(), sv->length)] = *se;
}
mem.xfree(otab);
}
/********************************
* Walk the contents of the string table,
* calling fp for each entry.
* Params:
* fp = function to call. Returns !=0 to stop
* Returns:
* last return value of fp call
*/
int StringTable::apply(int (*fp)(StringValue *))
{
for (size_t i = 0; i < tabledim; ++i)
{
StringEntry *se = &table[i];
if (!se->vptr) continue;
StringValue *sv = getValue(se->vptr);
int result = (*fp)(sv);
if (result)
return result;
}
return 0;
}
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