| /* |
| ** hash.c |
| ** hash manager for lua |
| */ |
| |
| char *rcs_hash="$Id: hash.c,v 2.25 1995/05/02 18:43:03 roberto Exp $"; |
| |
| #include <string.h> |
| |
| #include "mem.h" |
| #include "opcode.h" |
| #include "hash.h" |
| #include "table.h" |
| #include "lua.h" |
| |
| #define streq(s1,s2) (s1 == s2 || (*(s1) == *(s2) && strcmp(s1,s2)==0)) |
| |
| #define nhash(t) ((t)->nhash) |
| #define nuse(t) ((t)->nuse) |
| #define markarray(t) ((t)->mark) |
| #define nodevector(t) ((t)->node) |
| #define node(t,i) (&(t)->node[i]) |
| #define ref(n) (&(n)->ref) |
| #define val(n) (&(n)->val) |
| |
| |
| #define REHASH_LIMIT 0.70 /* avoid more than this % full */ |
| |
| |
| static Hash *listhead = NULL; |
| |
| |
| |
| /* hash dimensions values */ |
| static Word dimensions[] = |
| {3, 5, 7, 11, 23, 47, 97, 197, 397, 797, 1597, 3203, 6421, |
| 12853, 25717, 51437, 65521, 0}; /* 65521 == last prime < MAX_WORD */ |
| |
| static Word redimension (Word nhash) |
| { |
| Word i; |
| for (i=0; dimensions[i]!=0; i++) |
| { |
| if (dimensions[i] > nhash) |
| return dimensions[i]; |
| } |
| lua_error("table overflow"); |
| return 0; /* to avoid warnings */ |
| } |
| |
| static Word hashindex (Hash *t, Object *ref) /* hash function */ |
| { |
| switch (tag(ref)) |
| { |
| case LUA_T_NIL: |
| lua_error ("unexpected type to index table"); |
| return -1; /* UNREACHEABLE */ |
| case LUA_T_NUMBER: |
| return (((Word)nvalue(ref))%nhash(t)); |
| case LUA_T_STRING: |
| { |
| unsigned long h = tsvalue(ref)->hash; |
| if (h == 0) |
| { |
| char *name = svalue(ref); |
| while (*name) |
| h = ((h<<5)-h)^(unsigned char)*(name++); |
| tsvalue(ref)->hash = h; |
| } |
| return (Word)h%nhash(t); /* make it a valid index */ |
| } |
| case LUA_T_FUNCTION: |
| return (((IntPoint)ref->value.tf)%nhash(t)); |
| case LUA_T_CFUNCTION: |
| return (((IntPoint)fvalue(ref))%nhash(t)); |
| case LUA_T_ARRAY: |
| return (((IntPoint)avalue(ref))%nhash(t)); |
| default: /* user data */ |
| return (((IntPoint)uvalue(ref))%nhash(t)); |
| } |
| } |
| |
| Bool lua_equalObj (Object *t1, Object *t2) |
| { |
| if (tag(t1) != tag(t2)) return 0; |
| switch (tag(t1)) |
| { |
| case LUA_T_NIL: return 1; |
| case LUA_T_NUMBER: return nvalue(t1) == nvalue(t2); |
| case LUA_T_STRING: return streq(svalue(t1), svalue(t2)); |
| case LUA_T_ARRAY: return avalue(t1) == avalue(t2); |
| case LUA_T_FUNCTION: return t1->value.tf == t2->value.tf; |
| case LUA_T_CFUNCTION: return fvalue(t1) == fvalue(t2); |
| default: return uvalue(t1) == uvalue(t2); |
| } |
| } |
| |
| static Word present (Hash *t, Object *ref) |
| { |
| Word h = hashindex(t, ref); |
| while (tag(ref(node(t, h))) != LUA_T_NIL) |
| { |
| if (lua_equalObj(ref, ref(node(t, h)))) |
| return h; |
| h = (h+1) % nhash(t); |
| } |
| return h; |
| } |
| |
| |
| /* |
| ** Alloc a vector node |
| */ |
| static Node *hashnodecreate (Word nhash) |
| { |
| Word i; |
| Node *v = newvector (nhash, Node); |
| for (i=0; i<nhash; i++) |
| tag(ref(&v[i])) = LUA_T_NIL; |
| return v; |
| } |
| |
| /* |
| ** Create a new hash. Return the hash pointer or NULL on error. |
| */ |
| static Hash *hashcreate (Word nhash) |
| { |
| Hash *t = new(Hash); |
| nhash = redimension((Word)((float)nhash/REHASH_LIMIT)); |
| nodevector(t) = hashnodecreate(nhash); |
| nhash(t) = nhash; |
| nuse(t) = 0; |
| markarray(t) = 0; |
| return t; |
| } |
| |
| /* |
| ** Delete a hash |
| */ |
| static void hashdelete (Hash *t) |
| { |
| luaI_free (nodevector(t)); |
| luaI_free(t); |
| } |
| |
| |
| /* |
| ** Mark a hash and check its elements |
| */ |
| void lua_hashmark (Hash *h) |
| { |
| if (markarray(h) == 0) |
| { |
| Word i; |
| markarray(h) = 1; |
| for (i=0; i<nhash(h); i++) |
| { |
| Node *n = node(h,i); |
| if (tag(ref(n)) != LUA_T_NIL) |
| { |
| lua_markobject(&n->ref); |
| lua_markobject(&n->val); |
| } |
| } |
| } |
| } |
| |
| |
| static void call_fallbacks (void) |
| { |
| Hash *curr_array; |
| Object t; |
| tag(&t) = LUA_T_ARRAY; |
| for (curr_array = listhead; curr_array; curr_array = curr_array->next) |
| if (markarray(curr_array) != 1) |
| { |
| avalue(&t) = curr_array; |
| luaI_gcFB(&t); |
| } |
| tag(&t) = LUA_T_NIL; |
| luaI_gcFB(&t); /* end of list */ |
| } |
| |
| |
| /* |
| ** Garbage collection to arrays |
| ** Delete all unmarked arrays. |
| */ |
| Long lua_hashcollector (void) |
| { |
| Hash *curr_array = listhead, *prev = NULL; |
| Long counter = 0; |
| call_fallbacks(); |
| while (curr_array != NULL) |
| { |
| Hash *next = curr_array->next; |
| if (markarray(curr_array) != 1) |
| { |
| if (prev == NULL) listhead = next; |
| else prev->next = next; |
| hashdelete(curr_array); |
| ++counter; |
| } |
| else |
| { |
| markarray(curr_array) = 0; |
| prev = curr_array; |
| } |
| curr_array = next; |
| } |
| return counter; |
| } |
| |
| |
| /* |
| ** Create a new array |
| ** This function inserts the new array in the array list. It also |
| ** executes garbage collection if the number of arrays created |
| ** exceed a pre-defined range. |
| */ |
| Hash *lua_createarray (Word nhash) |
| { |
| Hash *array; |
| lua_pack(); |
| array = hashcreate(nhash); |
| array->next = listhead; |
| listhead = array; |
| return array; |
| } |
| |
| |
| /* |
| ** Re-hash |
| */ |
| static void rehash (Hash *t) |
| { |
| Word i; |
| Word nold = nhash(t); |
| Node *vold = nodevector(t); |
| nhash(t) = redimension(nhash(t)); |
| nodevector(t) = hashnodecreate(nhash(t)); |
| for (i=0; i<nold; i++) |
| { |
| Node *n = vold+i; |
| if (tag(ref(n)) != LUA_T_NIL && tag(val(n)) != LUA_T_NIL) |
| *node(t, present(t, ref(n))) = *n; /* copy old node to new hahs */ |
| } |
| luaI_free(vold); |
| } |
| |
| /* |
| ** If the hash node is present, return its pointer, otherwise return |
| ** null. |
| */ |
| Object *lua_hashget (Hash *t, Object *ref) |
| { |
| Word h = present(t, ref); |
| if (tag(ref(node(t, h))) != LUA_T_NIL) return val(node(t, h)); |
| else return NULL; |
| } |
| |
| |
| /* |
| ** If the hash node is present, return its pointer, otherwise create a new |
| ** node for the given reference and also return its pointer. |
| */ |
| Object *lua_hashdefine (Hash *t, Object *ref) |
| { |
| Word h; |
| Node *n; |
| h = present(t, ref); |
| n = node(t, h); |
| if (tag(ref(n)) == LUA_T_NIL) |
| { |
| nuse(t)++; |
| if ((float)nuse(t) > (float)nhash(t)*REHASH_LIMIT) |
| { |
| rehash(t); |
| h = present(t, ref); |
| n = node(t, h); |
| } |
| *ref(n) = *ref; |
| tag(val(n)) = LUA_T_NIL; |
| } |
| return (val(n)); |
| } |
| |
| |
| /* |
| ** Internal function to manipulate arrays. |
| ** Given an array object and a reference value, return the next element |
| ** in the hash. |
| ** This function pushs the element value and its reference to the stack. |
| */ |
| static void hashnext (Hash *t, Word i) |
| { |
| if (i >= nhash(t)) |
| { |
| lua_pushnil(); lua_pushnil(); |
| return; |
| } |
| while (tag(ref(node(t,i))) == LUA_T_NIL || tag(val(node(t,i))) == LUA_T_NIL) |
| { |
| if (++i >= nhash(t)) |
| { |
| lua_pushnil(); lua_pushnil(); |
| return; |
| } |
| } |
| luaI_pushobject(ref(node(t,i))); |
| luaI_pushobject(val(node(t,i))); |
| } |
| |
| void lua_next (void) |
| { |
| Hash *t; |
| lua_Object o = lua_getparam(1); |
| lua_Object r = lua_getparam(2); |
| if (o == LUA_NOOBJECT || r == LUA_NOOBJECT) |
| lua_error ("too few arguments to function `next'"); |
| if (lua_getparam(3) != LUA_NOOBJECT) |
| lua_error ("too many arguments to function `next'"); |
| if (!lua_istable(o)) |
| lua_error ("first argument of function `next' is not a table"); |
| t = avalue(luaI_Address(o)); |
| if (lua_isnil(r)) |
| { |
| hashnext(t, 0); |
| } |
| else |
| { |
| Word h = present (t, luaI_Address(r)); |
| hashnext(t, h+1); |
| } |
| } |