1 files changed, 588 insertions, 0 deletions

diff --git a/ltable.c b/ltable.c
new file mode 100644
index 00000000..420391fc
--- /dev/null
+++ b/ltable.c
@@ -0,0 +1,588 @@
+/*
+** $Id: ltable.c,v 2.72 2012/09/11 19:37:16 roberto Exp $
+** Lua tables (hash)
+** See Copyright Notice in lua.h
+*/
+
+
+/*
+** Implementation of tables (aka arrays, objects, or hash tables).
+** Tables keep its elements in two parts: an array part and a hash part.
+** Non-negative integer keys are all candidates to be kept in the array
+** part. The actual size of the array is the largest `n' such that at
+** least half the slots between 0 and n are in use.
+** Hash uses a mix of chained scatter table with Brent's variation.
+** A main invariant of these tables is that, if an element is not
+** in its main position (i.e. the `original' position that its hash gives
+** to it), then the colliding element is in its own main position.
+** Hence even when the load factor reaches 100%, performance remains good.
+*/
+
+#include <string.h>
+
+#define ltable_c
+#define LUA_CORE
+
+#include "lua.h"
+
+#include "ldebug.h"
+#include "ldo.h"
+#include "lgc.h"
+#include "lmem.h"
+#include "lobject.h"
+#include "lstate.h"
+#include "lstring.h"
+#include "ltable.h"
+#include "lvm.h"
+
+
+/*
+** max size of array part is 2^MAXBITS
+*/
+#if LUAI_BITSINT >= 32
+#define MAXBITS         30
+#else
+#define MAXBITS         (LUAI_BITSINT-2)
+#endif
+
+#define MAXASIZE        (1 << MAXBITS)
+
+
+#define hashpow2(t,n)           (gnode(t, lmod((n), sizenode(t))))
+
+#define hashstr(t,str)          hashpow2(t, (str)->tsv.hash)
+#define hashboolean(t,p)        hashpow2(t, p)
+
+
+/*
+** for some types, it is better to avoid modulus by power of 2, as
+** they tend to have many 2 factors.
+*/
+#define hashmod(t,n)    (gnode(t, ((n) % ((sizenode(t)-1)|1))))
+
+
+#define hashpointer(t,p)        hashmod(t, IntPoint(p))
+
+
+#define dummynode               (&dummynode_)
+
+#define isdummy(n)              ((n) == dummynode)
+
+static const Node dummynode_ = {
+  {NILCONSTANT},  /* value */
+  {{NILCONSTANT, NULL}}  /* key */
+};
+
+
+/*
+** hash for lua_Numbers
+*/
+static Node *hashnum (const Table *t, lua_Number n) {
+  int i;
+  luai_hashnum(i, n);
+  if (i < 0) {
+    if (cast(unsigned int, i) == 0u - i)  /* use unsigned to avoid overflows */
+      i = 0;  /* handle INT_MIN */
+    i = -i;  /* must be a positive value */
+  }
+  return hashmod(t, i);
+}
+
+
+
+/*
+** returns the `main' position of an element in a table (that is, the index
+** of its hash value)
+*/
+static Node *mainposition (const Table *t, const TValue *key) {
+  switch (ttype(key)) {
+    case LUA_TNUMBER:
+      return hashnum(t, nvalue(key));
+    case LUA_TLNGSTR: {
+      TString *s = rawtsvalue(key);
+      if (s->tsv.extra == 0) {  /* no hash? */
+        s->tsv.hash = luaS_hash(getstr(s), s->tsv.len, s->tsv.hash);
+        s->tsv.extra = 1;  /* now it has its hash */
+      }
+      return hashstr(t, rawtsvalue(key));
+    }
+    case LUA_TSHRSTR:
+      return hashstr(t, rawtsvalue(key));
+    case LUA_TBOOLEAN:
+      return hashboolean(t, bvalue(key));
+    case LUA_TLIGHTUSERDATA:
+      return hashpointer(t, pvalue(key));
+    case LUA_TLCF:
+      return hashpointer(t, fvalue(key));
+    default:
+      return hashpointer(t, gcvalue(key));
+  }
+}
+
+
+/*
+** returns the index for `key' if `key' is an appropriate key to live in
+** the array part of the table, -1 otherwise.
+*/
+static int arrayindex (const TValue *key) {
+  if (ttisnumber(key)) {
+    lua_Number n = nvalue(key);
+    int k;
+    lua_number2int(k, n);
+    if (luai_numeq(cast_num(k), n))
+      return k;
+  }
+  return -1;  /* `key' did not match some condition */
+}
+
+
+/*
+** returns the index of a `key' for table traversals. First goes all
+** elements in the array part, then elements in the hash part. The
+** beginning of a traversal is signaled by -1.
+*/
+static int findindex (lua_State *L, Table *t, StkId key) {
+  int i;
+  if (ttisnil(key)) return -1;  /* first iteration */
+  i = arrayindex(key);
+  if (0 < i && i <= t->sizearray)  /* is `key' inside array part? */
+    return i-1;  /* yes; that's the index (corrected to C) */
+  else {
+    Node *n = mainposition(t, key);
+    for (;;) {  /* check whether `key' is somewhere in the chain */
+      /* key may be dead already, but it is ok to use it in `next' */
+      if (luaV_rawequalobj(gkey(n), key) ||
+            (ttisdeadkey(gkey(n)) && iscollectable(key) &&
+             deadvalue(gkey(n)) == gcvalue(key))) {
+        i = cast_int(n - gnode(t, 0));  /* key index in hash table */
+        /* hash elements are numbered after array ones */
+        return i + t->sizearray;
+      }
+      else n = gnext(n);
+      if (n == NULL)
+        luaG_runerror(L, "invalid key to " LUA_QL("next"));  /* key not found */
+    }
+  }
+}
+
+
+int luaH_next (lua_State *L, Table *t, StkId key) {
+  int i = findindex(L, t, key);  /* find original element */
+  for (i++; i < t->sizearray; i++) {  /* try first array part */
+    if (!ttisnil(&t->array[i])) {  /* a non-nil value? */
+      setnvalue(key, cast_num(i+1));
+      setobj2s(L, key+1, &t->array[i]);
+      return 1;
+    }
+  }
+  for (i -= t->sizearray; i < sizenode(t); i++) {  /* then hash part */
+    if (!ttisnil(gval(gnode(t, i)))) {  /* a non-nil value? */
+      setobj2s(L, key, gkey(gnode(t, i)));
+      setobj2s(L, key+1, gval(gnode(t, i)));
+      return 1;
+    }
+  }
+  return 0;  /* no more elements */
+}
+
+
+/*
+** {=============================================================
+** Rehash
+** ==============================================================
+*/
+
+
+static int computesizes (int nums[], int *narray) {
+  int i;
+  int twotoi;  /* 2^i */
+  int a = 0;  /* number of elements smaller than 2^i */
+  int na = 0;  /* number of elements to go to array part */
+  int n = 0;  /* optimal size for array part */
+  for (i = 0, twotoi = 1; twotoi/2 < *narray; i++, twotoi *= 2) {
+    if (nums[i] > 0) {
+      a += nums[i];
+      if (a > twotoi/2) {  /* more than half elements present? */
+        n = twotoi;  /* optimal size (till now) */
+        na = a;  /* all elements smaller than n will go to array part */
+      }
+    }
+    if (a == *narray) break;  /* all elements already counted */
+  }
+  *narray = n;
+  lua_assert(*narray/2 <= na && na <= *narray);
+  return na;
+}
+
+
+static int countint (const TValue *key, int *nums) {
+  int k = arrayindex(key);
+  if (0 < k && k <= MAXASIZE) {  /* is `key' an appropriate array index? */
+    nums[luaO_ceillog2(k)]++;  /* count as such */
+    return 1;
+  }
+  else
+    return 0;
+}
+
+
+static int numusearray (const Table *t, int *nums) {
+  int lg;
+  int ttlg;  /* 2^lg */
+  int ause = 0;  /* summation of `nums' */
+  int i = 1;  /* count to traverse all array keys */
+  for (lg=0, ttlg=1; lg<=MAXBITS; lg++, ttlg*=2) {  /* for each slice */
+    int lc = 0;  /* counter */
+    int lim = ttlg;
+    if (lim > t->sizearray) {
+      lim = t->sizearray;  /* adjust upper limit */
+      if (i > lim)
+        break;  /* no more elements to count */
+    }
+    /* count elements in range (2^(lg-1), 2^lg] */
+    for (; i <= lim; i++) {
+      if (!ttisnil(&t->array[i-1]))
+        lc++;
+    }
+    nums[lg] += lc;
+    ause += lc;
+  }
+  return ause;
+}
+
+
+static int numusehash (const Table *t, int *nums, int *pnasize) {
+  int totaluse = 0;  /* total number of elements */
+  int ause = 0;  /* summation of `nums' */
+  int i = sizenode(t);
+  while (i--) {
+    Node *n = &t->node[i];
+    if (!ttisnil(gval(n))) {
+      ause += countint(gkey(n), nums);
+      totaluse++;
+    }
+  }
+  *pnasize += ause;
+  return totaluse;
+}
+
+
+static void setarrayvector (lua_State *L, Table *t, int size) {
+  int i;
+  luaM_reallocvector(L, t->array, t->sizearray, size, TValue);
+  for (i=t->sizearray; i<size; i++)
+     setnilvalue(&t->array[i]);
+  t->sizearray = size;
+}
+
+
+static void setnodevector (lua_State *L, Table *t, int size) {
+  int lsize;
+  if (size == 0) {  /* no elements to hash part? */
+    t->node = cast(Node *, dummynode);  /* use common `dummynode' */
+    lsize = 0;
+  }
+  else {
+    int i;
+    lsize = luaO_ceillog2(size);
+    if (lsize > MAXBITS)
+      luaG_runerror(L, "table overflow");
+    size = twoto(lsize);
+    t->node = luaM_newvector(L, size, Node);
+    for (i=0; i<size; i++) {
+      Node *n = gnode(t, i);
+      gnext(n) = NULL;
+      setnilvalue(gkey(n));
+      setnilvalue(gval(n));
+    }
+  }
+  t->lsizenode = cast_byte(lsize);
+  t->lastfree = gnode(t, size);  /* all positions are free */
+}
+
+
+void luaH_resize (lua_State *L, Table *t, int nasize, int nhsize) {
+  int i;
+  int oldasize = t->sizearray;
+  int oldhsize = t->lsizenode;
+  Node *nold = t->node;  /* save old hash ... */
+  if (nasize > oldasize)  /* array part must grow? */
+    setarrayvector(L, t, nasize);
+  /* create new hash part with appropriate size */
+  setnodevector(L, t, nhsize);
+  if (nasize < oldasize) {  /* array part must shrink? */
+    t->sizearray = nasize;
+    /* re-insert elements from vanishing slice */
+    for (i=nasize; i<oldasize; i++) {
+      if (!ttisnil(&t->array[i]))
+        luaH_setint(L, t, i + 1, &t->array[i]);
+    }
+    /* shrink array */
+    luaM_reallocvector(L, t->array, oldasize, nasize, TValue);
+  }
+  /* re-insert elements from hash part */
+  for (i = twoto(oldhsize) - 1; i >= 0; i--) {
+    Node *old = nold+i;
+    if (!ttisnil(gval(old))) {
+      /* doesn't need barrier/invalidate cache, as entry was
+         already present in the table */
+      setobjt2t(L, luaH_set(L, t, gkey(old)), gval(old));
+    }
+  }
+  if (!isdummy(nold))
+    luaM_freearray(L, nold, cast(size_t, twoto(oldhsize))); /* free old array */
+}
+
+
+void luaH_resizearray (lua_State *L, Table *t, int nasize) {
+  int nsize = isdummy(t->node) ? 0 : sizenode(t);
+  luaH_resize(L, t, nasize, nsize);
+}
+
+
+static void rehash (lua_State *L, Table *t, const TValue *ek) {
+  int nasize, na;
+  int nums[MAXBITS+1];  /* nums[i] = number of keys with 2^(i-1) < k <= 2^i */
+  int i;
+  int totaluse;
+  for (i=0; i<=MAXBITS; i++) nums[i] = 0;  /* reset counts */
+  nasize = numusearray(t, nums);  /* count keys in array part */
+  totaluse = nasize;  /* all those keys are integer keys */
+  totaluse += numusehash(t, nums, &nasize);  /* count keys in hash part */
+  /* count extra key */
+  nasize += countint(ek, nums);
+  totaluse++;
+  /* compute new size for array part */
+  na = computesizes(nums, &nasize);
+  /* resize the table to new computed sizes */
+  luaH_resize(L, t, nasize, totaluse - na);
+}
+
+
+
+/*
+** }=============================================================
+*/
+
+
+Table *luaH_new (lua_State *L) {
+  Table *t = &luaC_newobj(L, LUA_TTABLE, sizeof(Table), NULL, 0)->h;
+  t->metatable = NULL;
+  t->flags = cast_byte(~0);
+  t->array = NULL;
+  t->sizearray = 0;
+  setnodevector(L, t, 0);
+  return t;
+}
+
+
+void luaH_free (lua_State *L, Table *t) {
+  if (!isdummy(t->node))
+    luaM_freearray(L, t->node, cast(size_t, sizenode(t)));
+  luaM_freearray(L, t->array, t->sizearray);
+  luaM_free(L, t);
+}
+
+
+static Node *getfreepos (Table *t) {
+  while (t->lastfree > t->node) {
+    t->lastfree--;
+    if (ttisnil(gkey(t->lastfree)))
+      return t->lastfree;
+  }
+  return NULL;  /* could not find a free place */
+}
+
+
+
+/*
+** inserts a new key into a hash table; first, check whether key's main
+** position is free. If not, check whether colliding node is in its main
+** position or not: if it is not, move colliding node to an empty place and
+** put new key in its main position; otherwise (colliding node is in its main
+** position), new key goes to an empty position.
+*/
+TValue *luaH_newkey (lua_State *L, Table *t, const TValue *key) {
+  Node *mp;
+  if (ttisnil(key)) luaG_runerror(L, "table index is nil");
+  else if (ttisnumber(key) && luai_numisnan(L, nvalue(key)))
+    luaG_runerror(L, "table index is NaN");
+  mp = mainposition(t, key);
+  if (!ttisnil(gval(mp)) || isdummy(mp)) {  /* main position is taken? */
+    Node *othern;
+    Node *n = getfreepos(t);  /* get a free place */
+    if (n == NULL) {  /* cannot find a free place? */
+      rehash(L, t, key);  /* grow table */
+      /* whatever called 'newkey' take care of TM cache and GC barrier */
+      return luaH_set(L, t, key);  /* insert key into grown table */
+    }
+    lua_assert(!isdummy(n));
+    othern = mainposition(t, gkey(mp));
+    if (othern != mp) {  /* is colliding node out of its main position? */
+      /* yes; move colliding node into free position */
+      while (gnext(othern) != mp) othern = gnext(othern);  /* find previous */
+      gnext(othern) = n;  /* redo the chain with `n' in place of `mp' */
+      *n = *mp;  /* copy colliding node into free pos. (mp->next also goes) */
+      gnext(mp) = NULL;  /* now `mp' is free */
+      setnilvalue(gval(mp));
+    }
+    else {  /* colliding node is in its own main position */
+      /* new node will go into free position */
+      gnext(n) = gnext(mp);  /* chain new position */
+      gnext(mp) = n;
+      mp = n;
+    }
+  }
+  setobj2t(L, gkey(mp), key);
+  luaC_barrierback(L, obj2gco(t), key);
+  lua_assert(ttisnil(gval(mp)));
+  return gval(mp);
+}
+
+
+/*
+** search function for integers
+*/
+const TValue *luaH_getint (Table *t, int key) {
+  /* (1 <= key && key <= t->sizearray) */
+  if (cast(unsigned int, key-1) < cast(unsigned int, t->sizearray))
+    return &t->array[key-1];
+  else {
+    lua_Number nk = cast_num(key);
+    Node *n = hashnum(t, nk);
+    do {  /* check whether `key' is somewhere in the chain */
+      if (ttisnumber(gkey(n)) && luai_numeq(nvalue(gkey(n)), nk))
+        return gval(n);  /* that's it */
+      else n = gnext(n);
+    } while (n);
+    return luaO_nilobject;
+  }
+}
+
+
+/*
+** search function for short strings
+*/
+const TValue *luaH_getstr (Table *t, TString *key) {
+  Node *n = hashstr(t, key);
+  lua_assert(key->tsv.tt == LUA_TSHRSTR);
+  do {  /* check whether `key' is somewhere in the chain */
+    if (ttisshrstring(gkey(n)) && eqshrstr(rawtsvalue(gkey(n)), key))
+      return gval(n);  /* that's it */
+    else n = gnext(n);
+  } while (n);
+  return luaO_nilobject;
+}
+
+
+/*
+** main search function
+*/
+const TValue *luaH_get (Table *t, const TValue *key) {
+  switch (ttype(key)) {
+    case LUA_TSHRSTR: return luaH_getstr(t, rawtsvalue(key));
+    case LUA_TNIL: return luaO_nilobject;
+    case LUA_TNUMBER: {
+      int k;
+      lua_Number n = nvalue(key);
+      lua_number2int(k, n);
+      if (luai_numeq(cast_num(k), n)) /* index is int? */
+        return luaH_getint(t, k);  /* use specialized version */
+      /* else go through */
+    }
+    default: {
+      Node *n = mainposition(t, key);
+      do {  /* check whether `key' is somewhere in the chain */
+        if (luaV_rawequalobj(gkey(n), key))
+          return gval(n);  /* that's it */
+        else n = gnext(n);
+      } while (n);
+      return luaO_nilobject;
+    }
+  }
+}
+
+
+/*
+** beware: when using this function you probably need to check a GC
+** barrier and invalidate the TM cache.
+*/
+TValue *luaH_set (lua_State *L, Table *t, const TValue *key) {
+  const TValue *p = luaH_get(t, key);
+  if (p != luaO_nilobject)
+    return cast(TValue *, p);
+  else return luaH_newkey(L, t, key);
+}
+
+
+void luaH_setint (lua_State *L, Table *t, int key, TValue *value) {
+  const TValue *p = luaH_getint(t, key);
+  TValue *cell;
+  if (p != luaO_nilobject)
+    cell = cast(TValue *, p);
+  else {
+    TValue k;
+    setnvalue(&k, cast_num(key));
+    cell = luaH_newkey(L, t, &k);
+  }
+  setobj2t(L, cell, value);
+}
+
+
+static int unbound_search (Table *t, unsigned int j) {
+  unsigned int i = j;  /* i is zero or a present index */
+  j++;
+  /* find `i' and `j' such that i is present and j is not */
+  while (!ttisnil(luaH_getint(t, j))) {
+    i = j;
+    j *= 2;
+    if (j > cast(unsigned int, MAX_INT)) {  /* overflow? */
+      /* table was built with bad purposes: resort to linear search */
+      i = 1;
+      while (!ttisnil(luaH_getint(t, i))) i++;
+      return i - 1;
+    }
+  }
+  /* now do a binary search between them */
+  while (j - i > 1) {
+    unsigned int m = (i+j)/2;
+    if (ttisnil(luaH_getint(t, m))) j = m;
+    else i = m;
+  }
+  return i;
+}
+
+
+/*
+** Try to find a boundary in table `t'. A `boundary' is an integer index
+** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).
+*/
+int luaH_getn (Table *t) {
+  unsigned int j = t->sizearray;
+  if (j > 0 && ttisnil(&t->array[j - 1])) {
+    /* there is a boundary in the array part: (binary) search for it */
+    unsigned int i = 0;
+    while (j - i > 1) {
+      unsigned int m = (i+j)/2;
+      if (ttisnil(&t->array[m - 1])) j = m;
+      else i = m;
+    }
+    return i;
+  }
+  /* else must find a boundary in hash part */
+  else if (isdummy(t->node))  /* hash part is empty? */
+    return j;  /* that is easy... */
+  else return unbound_search(t, j);
+}
+
+
+
+#if defined(LUA_DEBUG)
+
+Node *luaH_mainposition (const Table *t, const TValue *key) {
+  return mainposition(t, key);
+}
+
+int luaH_isdummy (Node *n) { return isdummy(n); }
+
+#endif