mirror of https://github.com/lua/lua
154 lines
3.0 KiB
C
154 lines
3.0 KiB
C
/*
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** tree.c
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** TecCGraf - PUC-Rio
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*/
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char *rcs_tree="$Id: tree.c,v 1.20 1996/03/14 15:56:26 roberto Exp roberto $";
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#include <string.h>
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#include "mem.h"
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#include "lua.h"
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#include "tree.h"
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#include "lex.h"
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#include "hash.h"
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#include "table.h"
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#define NUM_HASHS 64
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typedef struct {
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int size;
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int nuse; /* number of elements (including EMPTYs) */
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TaggedString **hash;
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} stringtable;
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static int initialized = 0;
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static stringtable string_root[NUM_HASHS];
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static TaggedString EMPTY = {LUA_T_STRING, 0, NOT_USED, NOT_USED, 0, 2, {0}};
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static unsigned long hash (char *buff, long size)
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{
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unsigned long h = 0;
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while (size--)
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h = ((h<<5)-h)^(unsigned char)*(buff++);
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return h;
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}
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static void initialize (void)
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{
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initialized = 1;
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luaI_addReserved();
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luaI_initsymbol();
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luaI_initconstant();
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}
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static void grow (stringtable *tb)
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{
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int newsize = luaI_redimension(tb->size);
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TaggedString **newhash = newvector(newsize, TaggedString *);
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int i;
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for (i=0; i<newsize; i++)
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newhash[i] = NULL;
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/* rehash */
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tb->nuse = 0;
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for (i=0; i<tb->size; i++)
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if (tb->hash[i] != NULL && tb->hash[i] != &EMPTY)
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{
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int h = tb->hash[i]->hash%newsize;
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while (newhash[h])
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h = (h+1)%newsize;
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newhash[h] = tb->hash[i];
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tb->nuse++;
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}
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luaI_free(tb->hash);
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tb->size = newsize;
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tb->hash = newhash;
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}
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static TaggedString *insert (char *buff, long size, int tag, stringtable *tb)
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{
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TaggedString *ts;
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unsigned long h = hash(buff, size);
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int i;
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int j = -1;
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if ((Long)tb->nuse*3 >= (Long)tb->size*2)
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{
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if (!initialized)
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initialize();
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grow(tb);
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}
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i = h%tb->size;
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while ((ts = tb->hash[i]) != NULL)
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{
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if (ts == &EMPTY)
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j = i;
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else if (ts->size == size && ts->tag == tag &&
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memcmp(buff, ts->str, size) == 0)
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return ts;
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i = (i+1)%tb->size;
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}
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/* not found */
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lua_pack();
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if (j != -1) /* is there an EMPTY space? */
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i = j;
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else
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tb->nuse++;
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ts = tb->hash[i] = (TaggedString *)luaI_malloc(sizeof(TaggedString)+size-1);
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memcpy(ts->str, buff, size);
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ts->tag = tag;
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ts->size = size;
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ts->marked = 0;
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ts->hash = h;
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ts->varindex = ts->constindex = NOT_USED;
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return ts;
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}
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TaggedString *luaI_createuserdata (char *buff, long size, int tag)
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{
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return insert(buff, size, tag, &string_root[(unsigned)buff[0]%NUM_HASHS]);
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}
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TaggedString *lua_createstring (char *str)
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{
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return luaI_createuserdata(str, strlen(str)+1, LUA_T_STRING);
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}
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/*
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** Garbage collection function.
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** This function traverse the string list freeing unindexed strings
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*/
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Long lua_strcollector (void)
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{
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Long counter = 0;
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int i;
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for (i=0; i<NUM_HASHS; i++)
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{
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stringtable *tb = &string_root[i];
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int j;
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for (j=0; j<tb->size; j++)
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{
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TaggedString *t = tb->hash[j];
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if (t != NULL && t->marked <= 1)
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{
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if (t->marked)
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t->marked = 0;
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else
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{
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luaI_free(t);
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tb->hash[j] = &EMPTY;
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counter++;
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}
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}
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}
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}
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return counter;
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}
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