commit 4e9f2d13d5b6fa71ca480394e0b7e75463d4aeec
parent b6ebbb2fee13aa223fdd12921cd0411e02db9dd0
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 14 Oct 1999 17:13:09 -0200
new implementation of hash tables.
Diffstat:
| M | lapi.c | | | 6 | +++--- |
| M | lbuiltin.c | | | 73 | +++++++++++++++++++++++++++++++++++++++++++++++++------------------------ |
| M | lgc.c | | | 19 | +++++++++++-------- |
| M | lobject.h | | | 15 | +++++++++------ |
| M | lstring.c | | | 9 | +++++---- |
| M | lstring.h | | | 4 | +++- |
| M | ltable.c | | | 271 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------- |
| M | ltable.h | | | 15 | +++++++-------- |
| M | lvm.c | | | 4 | ++-- |
9 files changed, 287 insertions(+), 129 deletions(-)
diff --git a/lapi.c b/lapi.c
@@ -1,5 +1,5 @@
/*
-** $Id: lapi.c,v 1.52 1999/10/07 19:04:30 roberto Exp roberto $
+** $Id: lapi.c,v 1.53 1999/10/11 16:13:11 roberto Exp roberto $
** Lua API
** See Copyright Notice in lua.h
*/
@@ -422,11 +422,11 @@ const char *lua_nextvar (const char *varname) {
int luaA_next (const Hash *t, int i) {
- int tsize = nhash(t);
+ int tsize = t->size;
for (; i<tsize; i++) {
Node *n = node(t, i);
if (ttype(val(n)) != LUA_T_NIL) {
- luaA_pushobject(ref(n));
+ luaA_pushobject(key(n));
luaA_pushobject(val(n));
return i+1; /* index to be used next time */
}
diff --git a/lbuiltin.c b/lbuiltin.c
@@ -1,5 +1,5 @@
/*
-** $Id: lbuiltin.c,v 1.65 1999/10/07 19:04:30 roberto Exp roberto $
+** $Id: lbuiltin.c,v 1.66 1999/10/11 16:13:11 roberto Exp roberto $
** Built-in functions
** See Copyright Notice in lua.h
*/
@@ -44,13 +44,13 @@ static void pushtagstring (TaggedString *s) {
static real getsize (const Hash *h) {
real max = 0;
- int i = nhash(h);
+ int i = h->size;
Node *n = h->node;
while (i--) {
- if (ttype(ref(n)) == LUA_T_NUMBER &&
+ if (ttype(key(n)) == LUA_T_NUMBER &&
ttype(val(n)) != LUA_T_NIL &&
- nvalue(ref(n)) > max)
- max = nvalue(ref(n));
+ nvalue(key(n)) > max)
+ max = nvalue(key(n));
n++;
}
return max;
@@ -59,7 +59,7 @@ static real getsize (const Hash *h) {
static real getnarg (const Hash *a) {
TObject index;
- TObject *value;
+ const TObject *value;
/* value = table.n */
ttype(&index) = LUA_T_STRING;
tsvalue(&index) = luaS_new("n");
@@ -337,7 +337,13 @@ static void luaB_nextvar (void) {
static void luaB_next (void) {
const Hash *a = gethash(1);
const TObject *k = luaA_Address(luaL_nonnullarg(2));
- int i = (ttype(k) == LUA_T_NIL) ? 0 : luaH_pos(a, k)+1;
+ int i; /* will get first element after `i' */
+ if (ttype(k) == LUA_T_NIL)
+ i = 0; /* get first */
+ else {
+ i = luaH_pos(a, k)+1;
+ luaL_arg_check(i != 0, 2, "key not found");
+ }
if (luaA_next(a, i) == 0)
lua_pushnil();
}
@@ -408,7 +414,7 @@ static void luaB_foreachi (void) {
stack may be reallocated by the call. Moreover, some C compilers do not
initialize structs, so we must do the assignment after the declaration */
f = *luaA_Address(luaL_functionarg(2));
- luaD_checkstack(3); /* for f, ref, and val */
+ luaD_checkstack(3); /* for f, key, and val */
for (i=1; i<=n; i++) {
*(L->stack.top++) = f;
ttype(L->stack.top) = LUA_T_NUMBER; nvalue(L->stack.top++) = i;
@@ -426,12 +432,12 @@ static void luaB_foreach (void) {
int i;
TObject f; /* see comment in 'foreachi' */
f = *luaA_Address(luaL_functionarg(2));
- luaD_checkstack(3); /* for f, ref, and val */
- for (i=0; i<a->nhash; i++) {
+ luaD_checkstack(3); /* for f, key, and val */
+ for (i=0; i<a->size; i++) {
const Node *nd = &(a->node[i]);
if (ttype(val(nd)) != LUA_T_NIL) {
*(L->stack.top++) = f;
- *(L->stack.top++) = *ref(nd);
+ *(L->stack.top++) = *key(nd);
*(L->stack.top++) = *val(nd);
luaD_calln(2, 1);
if (ttype(L->stack.top-1) != LUA_T_NIL)
@@ -531,36 +537,37 @@ static int sort_comp (lua_Object f, const TObject *a, const TObject *b) {
}
static void auxsort (Hash *a, int l, int u, lua_Object f) {
+ StkId P = L->stack.top - L->stack.stack; /* temporary place for pivot */
+ L->stack.top++;
+ ttype(L->stack.stack+P) = LUA_T_NIL;
while (l < u) { /* for tail recursion */
- TObject *P;
int i, j;
/* sort elements a[l], a[(l+u)/2] and a[u] */
- if (sort_comp(f, luaH_getint(a, u), luaH_getint(a, l))) /* a[l]>a[u]? */
+ if (sort_comp(f, luaH_getint(a, u), luaH_getint(a, l))) /* a[u]<a[l]? */
swap(a, l, u);
if (u-l == 1) break; /* only 2 elements */
i = (l+u)/2;
- P = luaH_getint(a, i);
- if (sort_comp(f, P, luaH_getint(a, l))) /* a[l]>a[i]? */
+ *(L->stack.stack+P) = *luaH_getint(a, i); /* P = a[i] */
+ if (sort_comp(f, L->stack.stack+P, luaH_getint(a, l))) /* a[i]<a[l]? */
swap(a, l, i);
- else if (sort_comp(f, luaH_getint(a, u), P)) /* a[i]>a[u]? */
+ else if (sort_comp(f, luaH_getint(a, u), L->stack.stack+P)) /* a[u]<a[i]? */
swap(a, i, u);
if (u-l == 2) break; /* only 3 elements */
- P = L->stack.top++;
- *P = *luaH_getint(a, i); /* save pivot on stack (for GC) */
+ *(L->stack.stack+P) = *luaH_getint(a, i); /* save pivot on stack (for GC) */
swap(a, i, u-1); /* put median element as pivot (a[u-1]) */
/* a[l] <= P == a[u-1] <= a[u], only needs to sort from l+1 to u-2 */
i = l; j = u-1;
- for (;;) {
- /* invariant: a[l..i] <= P <= a[j..u] */
- while (sort_comp(f, luaH_getint(a, ++i), P)) /* stop when a[i] >= P */
+ for (;;) { /* invariant: a[l..i] <= P <= a[j..u] */
+ /* repeat i++ until a[i] >= P */
+ while (sort_comp(f, luaH_getint(a, ++i), L->stack.stack+P))
if (i>u) lua_error("invalid order function for sorting");
- while (sort_comp(f, P, luaH_getint(a, --j))) /* stop when a[j] <= P */
+ /* repeat j-- until a[j] <= P */
+ while (sort_comp(f, (L->stack.stack+P), luaH_getint(a, --j)))
if (j<l) lua_error("invalid order function for sorting");
if (j<i) break;
swap(a, i, j);
}
swap(a, u-1, i); /* swap pivot (a[u-1]) with a[i] */
- L->stack.top--; /* remove pivot from stack */
/* a[l..i-1] <= a[i] == P <= a[i+1..u] */
/* adjust so that smaller "half" is in [j..i] and larger one in [l..u] */
if (i-l < u-i) {
@@ -571,6 +578,7 @@ static void auxsort (Hash *a, int l, int u, lua_Object f) {
}
auxsort(a, j, i, f); /* call recursively the smaller one */
} /* repeat the routine for the larger one */
+ L->stack.top--; /* remove pivot from stack */
}
static void luaB_sort (void) {
@@ -608,7 +616,23 @@ static void mem_query (void) {
static void hash_query (void) {
const TObject *o = luaA_Address(luaL_nonnullarg(1));
- lua_pushnumber(luaH_hashindex(o));
+ luaL_arg_check(ttype(o) == LUA_T_STRING, 1, "string expected");
+ lua_pushnumber(tsvalue(o)->hash);
+}
+
+
+static void table_query (void) {
+ const Hash *t = avalue(luaA_Address(luaL_tablearg(1)));
+ int i = luaL_opt_int(2, -1);
+ if (i == -1) {
+ lua_pushnumber(t->size);
+ lua_pushnumber(t->firstfree - t->node);
+ }
+ else if (i < t->size) {
+ luaA_pushobject(&t->node[i].key);
+ luaA_pushobject(&t->node[i].val);
+ lua_pushnumber(t->node[i].next == NULL ? 0 : t->node[i].next - t->node);
+ }
}
@@ -715,6 +739,7 @@ static const struct luaL_reg builtin_funcs[] = {
{"extra", extra_services},
{"hash", hash_query},
{"querystr", query_strings},
+ {"querytab", table_query},
{"testC", testC},
{"totalmem", mem_query},
#endif
diff --git a/lgc.c b/lgc.c
@@ -1,5 +1,5 @@
/*
-** $Id: lgc.c,v 1.27 1999/10/04 17:51:04 roberto Exp roberto $
+** $Id: lgc.c,v 1.28 1999/10/11 16:13:11 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -51,10 +51,10 @@ static void hashmark (Hash *h) {
if (!h->marked) {
int i;
h->marked = 1;
- for (i=nhash(h)-1; i>=0; i--) {
+ for (i=h->size-1; i>=0; i--) {
Node *n = node(h,i);
- if (ttype(ref(n)) != LUA_T_NIL) {
- markobject(&n->ref);
+ if (ttype(key(n)) != LUA_T_NIL) {
+ markobject(&n->key);
markobject(&n->val);
}
}
@@ -157,11 +157,11 @@ static void collecttable (void) {
}
-static void clear_global_list (void) {
+static void clear_global_list (int limit) {
TaggedString **p = &L->rootglobal;
TaggedString *next;
while ((next = *p) != NULL) {
- if (next->marked) p = &next->nextglobal;
+ if (next->marked >= limit) p = &next->nextglobal;
else *p = next->nextglobal;
}
}
@@ -176,7 +176,7 @@ static void collectstring (int limit) {
TObject o; /* to call userdata 'gc' tag method */
int i;
ttype(&o) = LUA_T_USERDATA;
- clear_global_list();
+ clear_global_list(limit);
for (i=0; i<NUM_HASHS; i++) { /* for each hash table */
stringtable *tb = &L->string_root[i];
int j;
@@ -200,6 +200,8 @@ static void collectstring (int limit) {
}
}
}
+ if ((tb->nuse+1)*6 < tb->size)
+ luaS_grow(tb); /* table is too big; `grow' it to a smaller size */
}
}
@@ -237,7 +239,8 @@ void luaC_collect (int all) {
collectstring(all?MAX_INT:1);
collectproto();
collectclosure();
- luaD_gcIM(&luaO_nilobject); /* GC tag method for nil (signal end of GC) */
+ if (!all)
+ luaD_gcIM(&luaO_nilobject); /* GC tag method for nil (signal end of GC) */
}
diff --git a/lobject.h b/lobject.h
@@ -1,5 +1,5 @@
/*
-** $Id: lobject.h,v 1.31 1999/10/04 17:51:04 roberto Exp roberto $
+** $Id: lobject.h,v 1.32 1999/10/11 16:13:11 roberto Exp roberto $
** Type definitions for Lua objects
** See Copyright Notice in lua.h
*/
@@ -162,27 +162,30 @@ typedef struct Closure {
typedef struct node {
- TObject ref;
+ TObject key;
TObject val;
+ struct node *next; /* for chaining */
} Node;
typedef struct Hash {
+ int htag;
+ Node *node;
+ unsigned int size;
+ Node *firstfree; /* this position is free; all positions after it are full */
struct Hash *next;
int marked;
- Node *node;
- int nhash;
- int nuse;
- int htag;
} Hash;
extern const char *const luaO_typenames[];
+
#define luaO_typename(o) luaO_typenames[-ttype(o)]
extern const TObject luaO_nilobject;
+
#define luaO_equalObj(t1,t2) ((ttype(t1) != ttype(t2)) ? 0 \
: luaO_equalval(t1,t2))
int luaO_equalval (const TObject *t1, const TObject *t2);
diff --git a/lstring.c b/lstring.c
@@ -1,5 +1,5 @@
/*
-** $Id: lstring.c,v 1.22 1999/10/04 17:51:04 roberto Exp roberto $
+** $Id: lstring.c,v 1.23 1999/10/11 16:13:11 roberto Exp roberto $
** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h
*/
@@ -48,6 +48,7 @@ void luaS_freeall (void) {
luaM_free(L->string_root[i].hash);
}
luaM_free(L->string_root);
+ LUA_ASSERT(init_hash[0] == NULL, "init_hash corrupted");
}
@@ -59,8 +60,8 @@ static unsigned long hash_s (const char *s, long l) {
}
-static void grow (stringtable *tb) {
- int ns = luaO_redimension(tb->size*2); /* new size */
+void luaS_grow (stringtable *tb) {
+ int ns = luaO_redimension(tb->nuse*2); /* new size */
TaggedString **newhash = luaM_newvector(ns, TaggedString *);
int i;
for (i=0; i<ns; i++) newhash[i] = NULL;
@@ -122,7 +123,7 @@ static void newentry (stringtable *tb, TaggedString *ts, int h) {
tb->hash = luaM_newvector(1, TaggedString *); /* so, `clone' it */
tb->hash[0] = NULL;
}
- grow(tb);
+ luaS_grow(tb);
h = ts->hash%tb->size; /* new hash position */
}
ts->nexthash = tb->hash[h]; /* chain new entry */
diff --git a/lstring.h b/lstring.h
@@ -1,5 +1,5 @@
/*
-** $Id: lstring.h,v 1.9 1999/10/04 17:51:04 roberto Exp roberto $
+** $Id: lstring.h,v 1.10 1999/10/11 16:13:11 roberto Exp roberto $
** String table (keep all strings handled by Lua)
** See Copyright Notice in lua.h
*/
@@ -9,6 +9,7 @@
#include "lobject.h"
+#include "lstate.h"
#define NUM_HASHSTR 31 /* a prime not in array `dimensions' */
@@ -25,6 +26,7 @@
void luaS_init (void);
+void luaS_grow (stringtable *tb);
TaggedString *luaS_createudata (void *udata, int tag);
void luaS_freeall (void);
void luaS_free (TaggedString *ts);
diff --git a/ltable.c b/ltable.c
@@ -1,10 +1,23 @@
/*
-** $Id: ltable.c,v 1.24 1999/09/22 14:38:45 roberto Exp roberto $
+** $Id: ltable.c,v 1.25 1999/10/04 17:51:04 roberto Exp roberto $
** Lua tables (hash)
** See Copyright Notice in lua.h
*/
+/*
+** Implementation of tables (aka arrays, objects, or hash tables);
+** 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.
+** In other words, there are collisions only when two elements have the
+** same main position (i.e. the same hash values for that table size).
+** Because of that, the load factor of these tables can be 100% without
+** performance penalties.
+*/
+
+
#include "lauxlib.h"
#include "lmem.h"
#include "lobject.h"
@@ -15,93 +28,104 @@
#define gcsize(n) (1+(n/16))
-#define nuse(t) ((t)->nuse)
-#define nodevector(t) ((t)->node)
#define TagDefault LUA_T_ARRAY;
-static long int hashindex (const TObject *ref) {
- long int h;
- switch (ttype(ref)) {
+/*
+** returns the `main' position of an element in a table (that is, the index
+** of its hash value)
+*/
+static Node *luaH_mainposition (const Hash *t, const TObject *key) {
+ unsigned long h;
+ switch (ttype(key)) {
case LUA_T_NUMBER:
- h = (long int)nvalue(ref);
+ h = (unsigned long)(long)nvalue(key);
break;
case LUA_T_STRING: case LUA_T_USERDATA:
- h = (IntPoint)tsvalue(ref);
+ h = tsvalue(key)->hash;
break;
case LUA_T_ARRAY:
- h = (IntPoint)avalue(ref);
+ h = (IntPoint)avalue(key);
break;
case LUA_T_PROTO:
- h = (IntPoint)tfvalue(ref);
+ h = (IntPoint)tfvalue(key);
break;
case LUA_T_CPROTO:
- h = (IntPoint)fvalue(ref);
+ h = (IntPoint)fvalue(key);
break;
case LUA_T_CLOSURE:
- h = (IntPoint)clvalue(ref);
+ h = (IntPoint)clvalue(key);
break;
default:
lua_error("unexpected type to index table");
h = 0; /* to avoid warnings */
}
- return (h >= 0 ? h : -(h+1));
+ return &t->node[h%t->size];
}
-Node *luaH_present (const Hash *t, const TObject *key) {
- const int tsize = nhash(t);
- const long int h = hashindex(key);
- int h1 = h%tsize;
- Node *n = node(t, h1);
- /* keep looking until an entry with "ref" equal to key or nil */
- while ((ttype(ref(n)) == ttype(key)) ? !luaO_equalval(key, ref(n))
- : ttype(ref(n)) != LUA_T_NIL) {
- h1 += (h&(tsize-2)) + 1; /* double hashing */
- if (h1 >= tsize) h1 -= tsize;
- n = node(t, h1);
- }
- return n;
+const TObject *luaH_get (const Hash *t, const TObject *key) {
+ Node *n = luaH_mainposition(t, key);
+ do {
+ if (luaO_equalObj(key, &n->key))
+ return &n->val;
+ n = n->next;
+ } while (n);
+ return &luaO_nilobject;
+}
+
+
+int luaH_pos (const Hash *t, const TObject *key) {
+ const TObject *v = luaH_get(t, key);
+ return (v == &luaO_nilobject) ? -1 : /* key not found */
+ ((const char *)v - (const char *)(&t->node[0].val))/sizeof(Node);
}
+
static Node *hashnodecreate (int nhash) {
- Node *const v = luaM_newvector(nhash, Node);
+ Node *v = luaM_newvector(nhash, Node);
int i;
- for (i=0; i<nhash; i++)
- ttype(ref(&v[i])) = ttype(val(&v[i])) = LUA_T_NIL;
+ for (i=0; i<nhash; i++) {
+ ttype(key(&v[i])) = ttype(val(&v[i])) = LUA_T_NIL;
+ v[i].next = NULL;
+ }
return v;
}
-Hash *luaH_new (int nhash) {
- Hash *const t = luaM_new(Hash);
- nhash = luaO_redimension(nhash*3/2);
- nodevector(t) = hashnodecreate(nhash);
- nhash(t) = nhash;
- nuse(t) = 0;
+static void setnodevector (Hash *t, int size) {
+ t->node = hashnodecreate(size);
+ t->size = size;
+ t->firstfree = &t->node[size-1]; /* first free position to be used */
+ L->nblocks += gcsize(size);
+}
+
+
+Hash *luaH_new (int size) {
+ Hash *t = luaM_new(Hash);
+ setnodevector(t, luaO_redimension(size+1));
t->htag = TagDefault;
t->next = L->roottable;
L->roottable = t;
t->marked = 0;
- L->nblocks += gcsize(nhash);
return t;
}
void luaH_free (Hash *t) {
- L->nblocks -= gcsize(t->nhash);
- luaM_free(nodevector(t));
+ L->nblocks -= gcsize(t->size);
+ luaM_free(t->node);
luaM_free(t);
}
-static int newsize (Hash *t) {
- Node *const v = t->node;
- const int size = nhash(t);
+static int newsize (const Hash *t) {
+ Node *v = t->node;
+ int size = t->size;
int realuse = 0;
int i;
for (i=0; i<size; i++) {
@@ -112,57 +136,158 @@ static int newsize (Hash *t) {
}
-static void rehash (Hash *t) {
- const int nold = nhash(t);
- Node *const vold = nodevector(t);
- const int nnew = newsize(t);
- int i;
- nodevector(t) = hashnodecreate(nnew);
- nhash(t) = nnew;
- nuse(t) = 0;
- for (i=0; i<nold; i++) {
- Node *n = vold+i;
- if (ttype(val(n)) != LUA_T_NIL) {
- *luaH_present(t, ref(n)) = *n; /* copy old node to new hash */
- nuse(t)++;
- }
+#ifdef DEBUG
+/* check invariant of a table */
+static int listfind (const Node *m, const Node *n) {
+ do {
+ if (m==n) return 1;
+ m = m->next;
+ } while (m);
+ return 0;
+}
+
+static int check_invariant (const Hash *t, int filled) {
+ Node *n;
+ for (n=t->node; n<t->firstfree; n++) {
+ TObject *key = &n->key;
+ LUA_ASSERT(ttype(key) == LUA_T_NIL || n == luaH_mainposition(t, key),
+ "all elements before firstfree are empty or in their main positions");
+ }
+ if (!filled)
+ LUA_ASSERT(ttype(&(n++)->key) == LUA_T_NIL, "firstfree must be empty");
+ else
+ LUA_ASSERT(n == t->node, "table cannot have empty places");
+ for (; n<t->node+t->size; n++) {
+ TObject *key = &n->key;
+ Node *mp = luaH_mainposition(t, key);
+ LUA_ASSERT(ttype(key) != LUA_T_NIL,
+ "cannot exist empty elements after firstfree");
+ LUA_ASSERT(n == mp || luaH_mainposition(t, &mp->key) == mp,
+ "either an element or its colliding element is in its main position");
+ LUA_ASSERT(listfind(mp,n), "element is in its main position list");
}
- L->nblocks += gcsize(nnew)-gcsize(nold);
- luaM_free(vold);
+ return 1;
}
+#endif
-void luaH_set (Hash *t, const TObject *ref, const TObject *val) {
- Node *const n = luaH_present(t, ref);
- *val(n) = *val;
- if (ttype(ref(n)) == LUA_T_NIL) { /* new node? */
- *ref(n) = *ref; /* set key */
- nuse(t)++; /* count it */
- if ((long)nuse(t)*3L > (long)nhash(t)*2L) /* check size */
- rehash(t);
+/*
+** the rehash is done in two stages: first, we insert only the elements whose
+** main position is free, to avoid needless collisions. In the second stage,
+** we insert the other elements.
+*/
+static void rehash (Hash *t) {
+ int oldsize = t->size;
+ Node *nold = t->node;
+ int i;
+ LUA_ASSERT(check_invariant(t, 1), "invalid table");
+ L->nblocks -= gcsize(oldsize);
+ setnodevector(t, newsize(t)); /* create new array of nodes */
+ /* first loop; set only elements that can go in their main positions */
+ for (i=0; i<oldsize; i++) {
+ Node *old = nold+i;
+ if (ttype(&old->val) == LUA_T_NIL)
+ old->next = NULL; /* `remove' it for next loop */
+ else {
+ Node *mp = luaH_mainposition(t, &old->key); /* new main position */
+ if (ttype(&mp->key) == LUA_T_NIL) { /* is it empty? */
+ mp->key = old->key; /* put element there */
+ mp->val = old->val;
+ old->next = NULL; /* `remove' it for next loop */
+ }
+ else /* it will be copied in next loop */
+ old->next = mp; /* to be used in next loop */
+ }
}
+ /* update `firstfree' */
+ while (ttype(&t->firstfree->key) != LUA_T_NIL) t->firstfree--;
+ /* second loop; update elements with colision */
+ for (i=0; i<oldsize; i++) {
+ Node *old = nold+i;
+ if (old->next) { /* wasn't already `removed'? */
+ Node *mp = old->next; /* main position */
+ Node *e = t->firstfree; /* actual position */
+ e->key = old->key; /* put element in the free position */
+ e->val = old->val;
+ e->next = mp->next; /* chain actual position in main position's list */
+ mp->next = e;
+ do { /* update `firstfree' */
+ t->firstfree--;
+ } while (ttype(&t->firstfree->key) != LUA_T_NIL);
+ }
+ }
+ LUA_ASSERT(check_invariant(t, 0), "invalid table");
+ luaM_free(nold); /* free old array */
}
-int luaH_pos (const Hash *t, const TObject *r) {
- Node *const n = luaH_present(t, r);
- luaL_arg_check(ttype(val(n)) != LUA_T_NIL, 2, "key not found");
- return n-(t->node);
+/*
+** sets a pair key-value in a hash table; first, check whether key is
+** already present; if not, 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 pair
+** in its main position; otherwise (colliding node is in its main position),
+** new pair goes to an empty position.
+** Tricky point: the only place where an old element is moved is when
+** we move the colliding node to an empty place; nevertheless, its old
+** value is still in that position until we set the value for the new
+** pair; therefore, even when `val' points to an element of this table
+** (this happens when we use `luaH_move'), there is no problem.
+*/
+void luaH_set (Hash *t, const TObject *key, const TObject *val) {
+ Node *mp = luaH_mainposition(t, key);
+ Node *n = mp;
+ do { /* check whether `key' is somewhere in the chain */
+ if (luaO_equalObj(key, &n->key)) {
+ n->val = *val; /* update value */
+ return; /* that's all */
+ }
+ else n = n->next;
+ } while (n);
+ /* `key' not found; must insert it */
+ if (ttype(&mp->key) != LUA_T_NIL) { /* main position is not free? */
+ Node *othern; /* main position of colliding node */
+ n = t->firstfree; /* get a free place */
+ /* is colliding node out of its main position? (can only happens if
+ its position if after "firstfree") */
+ if (mp > n && (othern=luaH_mainposition(t, &mp->key)) != mp) {
+ /* yes; move colliding node into free position */
+ while (othern->next != mp) othern = othern->next; /* find previous */
+ othern->next = n; /* redo the chain with `n' in place of `mp' */
+ *n = *mp; /* copy colliding node into free pos. (mp->next also goes) */
+ mp->next = NULL; /* now `mp' is free */
+ }
+ else { /* colliding node is in its own main position */
+ /* new node will go into free position */
+ n->next = mp->next; /* chain new position */
+ mp->next = n;
+ mp = n;
+ }
+ }
+ mp->key = *key;
+ mp->val = *val;
+ for (;;) { /* check free places */
+ if (ttype(&(t->firstfree)->key) == LUA_T_NIL)
+ return; /* OK; table still has a free place */
+ else if (t->firstfree == t->node) break; /* cannot decrement from here */
+ else (t->firstfree)--;
+ }
+ rehash(t); /* no more free places */
}
-void luaH_setint (Hash *t, int ref, const TObject *val) {
+void luaH_setint (Hash *t, int key, const TObject *val) {
TObject index;
ttype(&index) = LUA_T_NUMBER;
- nvalue(&index) = ref;
+ nvalue(&index) = key;
luaH_set(t, &index, val);
}
-TObject *luaH_getint (const Hash *t, int ref) {
+const TObject *luaH_getint (const Hash *t, int key) {
TObject index;
ttype(&index) = LUA_T_NUMBER;
- nvalue(&index) = ref;
+ nvalue(&index) = key;
return luaH_get(t, &index);
}
diff --git a/ltable.h b/ltable.h
@@ -1,5 +1,5 @@
/*
-** $Id: ltable.h,v 1.12 1999/08/16 20:52:00 roberto Exp roberto $
+** $Id: ltable.h,v 1.13 1999/10/04 17:51:04 roberto Exp roberto $
** Lua tables (hash)
** See Copyright Notice in lua.h
*/
@@ -11,20 +11,19 @@
#define node(t,i) (&(t)->node[i])
-#define ref(n) (&(n)->ref)
+#define key(n) (&(n)->key)
#define val(n) (&(n)->val)
-#define nhash(t) ((t)->nhash)
-#define luaH_get(t,ref) (val(luaH_present((t), (ref))))
#define luaH_move(t,from,to) (luaH_setint(t, to, luaH_getint(t, from)))
Hash *luaH_new (int nhash);
void luaH_free (Hash *t);
-Node *luaH_present (const Hash *t, const TObject *key);
-void luaH_set (Hash *t, const TObject *ref, const TObject *val);
+const TObject *luaH_get (const Hash *t, const TObject *key);
+void luaH_set (Hash *t, const TObject *key, const TObject *val);
int luaH_pos (const Hash *t, const TObject *r);
-void luaH_setint (Hash *t, int ref, const TObject *val);
-TObject *luaH_getint (const Hash *t, int ref);
+void luaH_setint (Hash *t, int key, const TObject *val);
+const TObject *luaH_getint (const Hash *t, int key);
+unsigned long luaH_hash (const TObject *key); /* exported only for debugging */
#endif
diff --git a/lvm.c b/lvm.c
@@ -1,5 +1,5 @@
/*
-** $Id: lvm.c,v 1.61 1999/09/06 13:55:09 roberto Exp roberto $
+** $Id: lvm.c,v 1.62 1999/09/17 16:53:54 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
@@ -107,7 +107,7 @@ void luaV_gettable (void) {
int tg = table->value.a->htag;
im = luaT_getim(tg, IM_GETTABLE);
if (ttype(im) == LUA_T_NIL) { /* and does not have a "gettable" method */
- TObject *h = luaH_get(avalue(table), table+1);
+ const TObject *h = luaH_get(avalue(table), table+1);
if (ttype(h) == LUA_T_NIL &&
(ttype(im=luaT_getim(tg, IM_INDEX)) != LUA_T_NIL)) {
/* result is nil and there is an "index" tag method */
