lstring.c File Reference

#include "lprefix.h"
#include <string.h>
#include "lua.h"
#include "ldebug.h"
#include "ldo.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"

Go to the source code of this file.

Macros
#define	lstring_c
#define	LUA_CORE
#define	MEMERRMSG   "not enough memory"
#define	LUAI_HASHLIMIT   5

Functions
int	luaS_eqlngstr (TString *a, TString *b)
unsigned int	luaS_hash (const char *str, size_t l, unsigned int seed)
unsigned int	luaS_hashlongstr (TString *ts)
void	luaS_resize (lua_State *L, int newsize)
void	luaS_clearcache (global_State *g)
void	luaS_init (lua_State *L)
static TString *	createstrobj (lua_State *L, size_t l, int tag, unsigned int h)
TString *	luaS_createlngstrobj (lua_State *L, size_t l)
void	luaS_remove (lua_State *L, TString *ts)
static TString *	internshrstr (lua_State *L, const char *str, size_t l)
TString *	luaS_newlstr (lua_State *L, const char *str, size_t l)
TString *	luaS_new (lua_State *L, const char *str)
Udata *	luaS_newudata (lua_State *L, size_t s)

Macro Definition Documentation

lstring_c

#define lstring_c

Definition at line 7 of file lua-5.3.6/src/lstring.c.

LUA_CORE

#define LUA_CORE

Definition at line 8 of file lua-5.3.6/src/lstring.c.

LUAI_HASHLIMIT

#define LUAI_HASHLIMIT   5

Definition at line 33 of file lua-5.3.6/src/lstring.c.

Referenced by luaS_hash().

MEMERRMSG

#define MEMERRMSG   "not enough memory"

Definition at line 25 of file lua-5.3.6/src/lstring.c.

Referenced by luaS_init().

Function Documentation

createstrobj()

static TString * createstrobj ( lua_State * L, size_t l, int tag, unsigned int h )

static

Definition at line 133 of file lua-5.3.6/src/lstring.c.

                                                                               {
  TString *ts;
  GCObject *o;
  size_t totalsize;  /* total size of TString object */
  totalsize = sizelstring(l);
  o = luaC_newobj(L, tag, totalsize);
  ts = gco2ts(o);
  ts->hash = h;
  ts->extra = 0;
  getstr(ts)[l] = '\0';  /* ending 0 */
  return ts;
}

References TString::extra, gco2ts, getstr, TString::hash, luaC_newobj(), and sizelstring.

Referenced by internshrstr(), and luaS_createlngstrobj().

internshrstr()

static TString * internshrstr ( lua_State * L, const char * str, size_t l )

static

Definition at line 167 of file lua-5.3.6/src/lstring.c.

                                                                       {
  TString *ts;
  global_State *g = G(L);
  unsigned int h = luaS_hash(str, l, g->seed);
  TString **list = &g->strt.hash[lmod(h, g->strt.size)];
  lua_assert(str != NULL);  /* otherwise 'memcmp'/'memcpy' are undefined */
  for (ts = *list; ts != NULL; ts = ts->u.hnext) {
    if (l == ts->shrlen &&
        (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
      /* found! */
      if (isdead(g, ts))  /* dead (but not collected yet)? */
        changewhite(ts);  /* resurrect it */
      return ts;
    }
  }
  if (g->strt.nuse >= g->strt.size && g->strt.size <= MAX_INT/2) {
    luaS_resize(L, g->strt.size * 2);
    list = &g->strt.hash[lmod(h, g->strt.size)];  /* recompute with new size */
  }
  ts = createstrobj(L, l, LUA_TSHRSTR, h);
  memcpy(getstr(ts), str, l * sizeof(char));
  ts->shrlen = cast_byte(l);
  ts->u.hnext = *list;
  *list = ts;
  g->strt.nuse++;
  return ts;
}

References cast_byte, changewhite, createstrobj(), G, getstr, stringtable::hash, TString::hnext, isdead, lmod, lua_assert, LUA_TSHRSTR, luaS_hash(), luaS_resize(), MAX_INT, NULL, stringtable::nuse, global_State::seed, TString::shrlen, stringtable::size, global_State::strt, and TString::u.

Referenced by luaS_newlstr().

luaS_clearcache()

void luaS_clearcache

(

global_State *

g

)

Definition at line 103 of file lua-5.3.6/src/lstring.c.

                                       {
  int i, j;
  for (i = 0; i < STRCACHE_N; i++)
    for (j = 0; j < STRCACHE_M; j++) {
    if (iswhite(g->strcache[i][j]))  /* will entry be collected? */
      g->strcache[i][j] = g->memerrmsg;  /* replace it with something fixed */
    }
}

References iswhite, global_State::memerrmsg, global_State::strcache, STRCACHE_M, and STRCACHE_N.

Referenced by atomic(), and atomic().

luaS_createlngstrobj()

TString * luaS_createlngstrobj	(	lua_State *	L,
		size_t	l )

Definition at line 147 of file lua-5.3.6/src/lstring.c.

                                                       {
  TString *ts = createstrobj(L, l, LUA_TLNGSTR, G(L)->seed);
  ts->u.lnglen = l;
  return ts;
}

References createstrobj(), G, TString::lnglen, LUA_TLNGSTR, and TString::u.

Referenced by LoadString(), loadStringN(), luaS_newlstr(), and luaV_concat().

luaS_eqlngstr()

int luaS_eqlngstr	(	TString *	a,
		TString *	b )

Definition at line 40 of file lua-5.3.6/src/lstring.c.

                                           {
  size_t len = a->u.lnglen;
  lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR);
  return (a == b) ||  /* same instance or... */
    ((len == b->u.lnglen) &&  /* equal length and ... */
     (memcmp(getstr(a), getstr(b), len) == 0));  /* equal contents */
}

References getstr, TString::lnglen, lua_assert, LUA_TLNGSTR, and TString::u.

luaS_hash()

unsigned int luaS_hash	(	const char *	str,
		size_t	l,
		unsigned int	seed )

Definition at line 49 of file lua-5.3.6/src/lstring.c.

                                                                      {
  unsigned int h = seed ^ cast(unsigned int, l);
  size_t step = (l >> LUAI_HASHLIMIT) + 1;
  for (; l >= step; l -= step)
    h ^= ((h<<5) + (h>>2) + cast_byte(str[l - 1]));
  return h;
}

References cast, cast_byte, and LUAI_HASHLIMIT.

Referenced by internshrstr(), and luaS_hashlongstr().

luaS_hashlongstr()

unsigned int luaS_hashlongstr

(

TString *

ts

)

Definition at line 58 of file lua-5.3.6/src/lstring.c.

                                            {
  lua_assert(ts->tt == LUA_TLNGSTR);
  if (ts->extra == 0) {  /* no hash? */
    ts->hash = luaS_hash(getstr(ts), ts->u.lnglen, ts->hash);
    ts->extra = 1;  /* now it has its hash */
  }
  return ts->hash;
}

References TString::extra, getstr, TString::hash, TString::lnglen, lua_assert, LUA_TLNGSTR, luaS_hash(), and TString::u.

Referenced by mainposition(), and mainposition().

luaS_init()

void luaS_init

(

lua_State *

L

)

Definition at line 116 of file lua-5.3.6/src/lstring.c.

                              {
  global_State *g = G(L);
  int i, j;
  luaS_resize(L, MINSTRTABSIZE);  /* initial size of string table */
  /* pre-create memory-error message */
  g->memerrmsg = luaS_newliteral(L, MEMERRMSG);
  luaC_fix(L, obj2gco(g->memerrmsg));  /* it should never be collected */
  for (i = 0; i < STRCACHE_N; i++)  /* fill cache with valid strings */
    for (j = 0; j < STRCACHE_M; j++)
      g->strcache[i][j] = g->memerrmsg;
}

References G, luaC_fix(), luaS_newliteral, luaS_resize(), global_State::memerrmsg, MEMERRMSG, MINSTRTABSIZE, obj2gco, global_State::strcache, STRCACHE_M, and STRCACHE_N.

Referenced by f_luaopen(), and f_luaopen().

luaS_new()

TString * luaS_new	(	lua_State *	L,
		const char *	str )

Definition at line 219 of file lua-5.3.6/src/lstring.c.

                                                  {
  unsigned int i = point2uint(str) % STRCACHE_N;  /* hash */
  int j;
  TString **p = G(L)->strcache[i];
  for (j = 0; j < STRCACHE_M; j++) {
    if (strcmp(str, getstr(p[j])) == 0)  /* hit? */
      return p[j];  /* that is it */
  }
  /* normal route */
  for (j = STRCACHE_M - 1; j > 0; j--)
    p[j] = p[j - 1];  /* move out last element */
  /* new element is first in the list */
  p[0] = luaS_newlstr(L, str, strlen(str));
  return p[0];
}

References G, getstr, luaS_newlstr(), point2uint, STRCACHE_M, and STRCACHE_N.

luaS_newlstr()

TString * luaS_newlstr	(	lua_State *	L,
		const char *	str,
		size_t	l )

Definition at line 199 of file lua-5.3.6/src/lstring.c.

                                                                {
  if (l <= LUAI_MAXSHORTLEN)  /* short string? */
    return internshrstr(L, str, l);
  else {
    TString *ts;
    if (l >= (MAX_SIZE - sizeof(TString))/sizeof(char))
      luaM_toobig(L);
    ts = luaS_createlngstrobj(L, l);
    memcpy(getstr(ts), str, l * sizeof(char));
    return ts;
  }
}

References getstr, internshrstr(), LUAI_MAXSHORTLEN, luaM_toobig(), luaS_createlngstrobj(), and MAX_SIZE.

Referenced by luaS_new().

luaS_newudata()

Udata * luaS_newudata	(	lua_State *	L,
		size_t	s )

Definition at line 236 of file lua-5.3.6/src/lstring.c.

                                              {
  Udata *u;
  GCObject *o;
  if (s > MAX_SIZE - sizeof(Udata))
    luaM_toobig(L);
  o = luaC_newobj(L, LUA_TUSERDATA, sizeludata(s));
  u = gco2u(o);
  u->len = s;
  u->metatable = NULL;
  setuservalue(L, u, luaO_nilobject);
  return u;
}

References gco2u, Udata::len, LUA_TUSERDATA, luaC_newobj(), luaM_toobig(), luaO_nilobject, MAX_SIZE, Udata::metatable, NULL, s, setuservalue, and sizeludata.

luaS_remove()

void luaS_remove	(	lua_State *	L,
		TString *	ts )

Definition at line 154 of file lua-5.3.6/src/lstring.c.

                                             {
  stringtable *tb = &G(L)->strt;
  TString **p = &tb->hash[lmod(ts->hash, tb->size)];
  while (*p != ts)  /* find previous element */
    p = &(*p)->u.hnext;
  *p = (*p)->u.hnext;  /* remove element from its list */
  tb->nuse--;
}

References G, TString::hash, stringtable::hash, TString::hnext, lmod, stringtable::nuse, stringtable::size, and TString::u.

Referenced by freeobj(), and freeobj().

luaS_resize()

void luaS_resize	(	lua_State *	L,
		int	newsize )

Definition at line 71 of file lua-5.3.6/src/lstring.c.

                                             {
  int i;
  stringtable *tb = &G(L)->strt;
  if (newsize > tb->size) {  /* grow table if needed */
    luaM_reallocvector(L, tb->hash, tb->size, newsize, TString *);
    for (i = tb->size; i < newsize; i++)
      tb->hash[i] = NULL;
  }
  for (i = 0; i < tb->size; i++) {  /* rehash */
    TString *p = tb->hash[i];
    tb->hash[i] = NULL;
    while (p) {  /* for each node in the list */
      TString *hnext = p->u.hnext;  /* save next */
      unsigned int h = lmod(p->hash, newsize);  /* new position */
      p->u.hnext = tb->hash[h];  /* chain it */
      tb->hash[h] = p;
      p = hnext;
    }
  }
  if (newsize < tb->size) {  /* shrink table if needed */
    /* vanishing slice should be empty */
    lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
    luaM_reallocvector(L, tb->hash, tb->size, newsize, TString *);
  }
  tb->size = newsize;
}

References G, TString::hash, stringtable::hash, TString::hnext, lmod, lua_assert, luaM_reallocvector, NULL, stringtable::size, and TString::u.

Referenced by internshrstr(), and luaS_init().