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/*
** tree.c
** TecCGraf - PUC-Rio
*/
char *rcs_tree="$Id: tree.c,v 1.23 1997/03/31 14:02:58 roberto Exp roberto $";
#include <string.h>
#include "luamem.h"
#include "lua.h"
#include "tree.h"
#include "lex.h"
#include "hash.h"
#include "table.h"
#include "fallback.h"
#define NUM_HASHS 64
typedef struct {
int size;
int nuse; /* number of elements (including EMPTYs) */
TaggedString **hash;
} stringtable;
static int initialized = 0;
static stringtable string_root[NUM_HASHS];
static TaggedString EMPTY = {LUA_T_STRING, 0, NOT_USED, NOT_USED, 0, 2, {0}};
static unsigned long hash (char *buff, long size)
{
unsigned long h = 0;
while (size--)
h = ((h<<5)-h)^(unsigned char)*(buff++);
return h;
}
static void initialize (void)
{
initialized = 1;
luaI_addReserved();
luaI_initsymbol();
luaI_initconstant();
luaI_initfallbacks();
}
static void grow (stringtable *tb)
{
int newsize = luaI_redimension(tb->size);
TaggedString **newhash = newvector(newsize, TaggedString *);
int i;
for (i=0; i<newsize; i++)
newhash[i] = NULL;
/* rehash */
tb->nuse = 0;
for (i=0; i<tb->size; i++)
if (tb->hash[i] != NULL && tb->hash[i] != &EMPTY)
{
int h = tb->hash[i]->hash%newsize;
while (newhash[h])
h = (h+1)%newsize;
newhash[h] = tb->hash[i];
tb->nuse++;
}
luaI_free(tb->hash);
tb->size = newsize;
tb->hash = newhash;
}
static TaggedString *insert (char *buff, long size, int tag, stringtable *tb)
{
TaggedString *ts;
unsigned long h = hash(buff, size);
int i;
int j = -1;
if ((Long)tb->nuse*3 >= (Long)tb->size*2)
{
if (!initialized)
initialize();
grow(tb);
}
i = h%tb->size;
while ((ts = tb->hash[i]) != NULL)
{
if (ts == &EMPTY)
j = i;
else if (ts->size == size && ts->tag == tag &&
memcmp(buff, ts->str, size) == 0)
return ts;
i = (i+1)%tb->size;
}
/* not found */
lua_pack();
if (j != -1) /* is there an EMPTY space? */
i = j;
else
tb->nuse++;
ts = tb->hash[i] = (TaggedString *)luaI_malloc(sizeof(TaggedString)+size-1);
memcpy(ts->str, buff, size);
ts->tag = tag;
ts->size = size;
ts->marked = 0;
ts->hash = h;
ts->varindex = ts->constindex = NOT_USED;
return ts;
}
TaggedString *luaI_createuserdata (char *buff, long size, int tag)
{
return insert(buff, size, tag, &string_root[(unsigned)buff[0]%NUM_HASHS]);
}
TaggedString *lua_createstring (char *str)
{
return luaI_createuserdata(str, strlen(str)+1, LUA_T_STRING);
}
void luaI_strcallIM (void)
{
int i;
TObject o;
ttype(&o) = LUA_T_USERDATA;
for (i=0; i<NUM_HASHS; i++) {
stringtable *tb = &string_root[i];
int j;
for (j=0; j<tb->size; j++) {
TaggedString *t = tb->hash[j];
if (t != NULL && t->tag != LUA_T_STRING && t->marked == 0) {
tsvalue(&o) = t;
luaI_gcIM(&o);
}
}
}
}
/*
** Garbage collection function.
** This function traverse the string list freeing unindexed strings
*/
Long lua_strcollector (void)
{
Long counter = 0;
int i;
for (i=0; i<NUM_HASHS; i++)
{
stringtable *tb = &string_root[i];
int j;
for (j=0; j<tb->size; j++)
{
TaggedString *t = tb->hash[j];
if (t != NULL && t->marked <= 1)
{
if (t->marked)
t->marked = 0;
else
{
luaI_free(t);
tb->hash[j] = &EMPTY;
counter++;
}
}
}
}
return counter;
}
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