v1.4.4

source/extern/lua/lstring.c

@@ -0,0 +1,226 @@
+/*
+** $Id: lstring.c,v 2.49 2015/06/01 16:34:37 roberto Exp $
+** String table (keeps all strings handled by Lua)
+** See Copyright Notice in lua.h
+*/
+
+#define lstring_c
+#define LUA_CORE
+
+#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"
+
+
+#define MEMERRMSG       "not enough memory"
+
+
+/*
+** Lua will use at most ~(2^LUAI_HASHLIMIT) bytes from a string to
+** compute its hash
+*/
+#if !defined(LUAI_HASHLIMIT)
+#define LUAI_HASHLIMIT		5
+#endif
+
+
+/*
+** equality for long strings
+*/
+int luaS_eqlngstr (TString *a, TString *b) {
+  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 */
+}
+
+
+unsigned int luaS_hash (const char *str, size_t l, unsigned int seed) {
+  unsigned int h = seed ^ cast(unsigned int, l);
+  size_t l1;
+  size_t step = (l >> LUAI_HASHLIMIT) + 1;
+  for (l1 = l; l1 >= step; l1 -= step)
+    h = h ^ ((h<<5) + (h>>2) + cast_byte(str[l1 - 1]));
+  return h;
+}
+
+
+/*
+** resizes the string table
+*/
+void luaS_resize (lua_State *L, int newsize) {
+  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;
+}
+
+
+/*
+** Clear API string cache. (Entries cannot be empty, so fill them with
+** a non-collectable string.)
+*/
+void luaS_clearcache (global_State *g) {
+  int i;
+  for (i = 0; i < STRCACHE_SIZE; i++) {
+    if (iswhite(g->strcache[i][0]))  /* will entry be collected? */
+      g->strcache[i][0] = g->memerrmsg;  /* replace it with something fixed */
+  }
+}
+
+
+/*
+** Initialize the string table and the string cache
+*/
+void luaS_init (lua_State *L) {
+  global_State *g = G(L);
+  int i;
+  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_SIZE; i++)  /* fill cache with valid strings */
+    g->strcache[i][0] = g->memerrmsg;
+}
+
+
+
+/*
+** creates a new string object
+*/
+static TString *createstrobj (lua_State *L, const char *str, size_t l,
+                              int tag, unsigned int h) {
+  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;
+  memcpy(getaddrstr(ts), str, l * sizeof(char));
+  getaddrstr(ts)[l] = '\0';  /* ending 0 */
+  return ts;
+}
+
+
+void luaS_remove (lua_State *L, TString *ts) {
+  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--;
+}
+
+
+/*
+** checks whether short string exists and reuses it or creates a new one
+*/
+static TString *internshrstr (lua_State *L, const char *str, size_t l) {
+  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)];
+  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, str, l, LUA_TSHRSTR, h);
+  ts->shrlen = cast_byte(l);
+  ts->u.hnext = *list;
+  *list = ts;
+  g->strt.nuse++;
+  return ts;
+}
+
+
+/*
+** new string (with explicit length)
+*/
+TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
+  if (l <= LUAI_MAXSHORTLEN)  /* short string? */
+    return internshrstr(L, str, l);
+  else {
+    TString *ts;
+    if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char))
+      luaM_toobig(L);
+    ts = createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
+    ts->u.lnglen = l;
+    return ts;
+  }
+}
+
+
+/*
+** Create or reuse a zero-terminated string, first checking in the
+** cache (using the string address as a key). The cache can contain
+** only zero-terminated strings, so it is safe to use 'strcmp' to
+** check hits.
+*/
+TString *luaS_new (lua_State *L, const char *str) {
+  unsigned int i = point2uint(str) % STRCACHE_SIZE;  /* hash */
+  TString **p = G(L)->strcache[i];
+  if (strcmp(str, getstr(p[0])) == 0)  /* hit? */
+    return p[0];  /* that it is */
+  else {  /* normal route */
+    TString *s = luaS_newlstr(L, str, strlen(str));
+    p[0] = s;
+    return s;
+  }
+}
+
+
+Udata *luaS_newudata (lua_State *L, size_t s) {
+  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;
+}
+