mirror of
https://github.com/lua/lua
synced 2024-11-26 14:51:21 +03:00
336 lines
6.7 KiB
C
336 lines
6.7 KiB
C
/*
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** hash.c
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** hash manager for lua
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*/
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char *rcs_hash="$Id: hash.c,v 2.24 1995/02/06 19:34:03 roberto Exp roberto $";
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#include <string.h>
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#include "mem.h"
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#include "opcode.h"
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#include "hash.h"
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#include "table.h"
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#include "lua.h"
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#define streq(s1,s2) (s1 == s2 || (*(s1) == *(s2) && strcmp(s1,s2)==0))
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#define nhash(t) ((t)->nhash)
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#define nuse(t) ((t)->nuse)
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#define markarray(t) ((t)->mark)
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#define nodevector(t) ((t)->node)
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#define node(t,i) (&(t)->node[i])
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#define ref(n) (&(n)->ref)
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#define val(n) (&(n)->val)
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#define REHASH_LIMIT 0.70 /* avoid more than this % full */
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static Hash *listhead = NULL;
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/* hash dimensions values */
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static Word dimensions[] =
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{3, 5, 7, 11, 23, 47, 97, 197, 397, 797, 1597, 3203, 6421,
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12853, 25717, 51437, 65521, 0}; /* 65521 == last prime < MAX_WORD */
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static Word redimension (Word nhash)
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{
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Word i;
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for (i=0; dimensions[i]!=0; i++)
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{
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if (dimensions[i] > nhash)
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return dimensions[i];
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}
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lua_error("table overflow");
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return 0; /* to avoid warnings */
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}
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static Word hashindex (Hash *t, Object *ref) /* hash function */
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{
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switch (tag(ref))
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{
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case LUA_T_NIL:
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lua_error ("unexpected type to index table");
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return -1; /* UNREACHEABLE */
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case LUA_T_NUMBER:
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return (((Word)nvalue(ref))%nhash(t));
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case LUA_T_STRING:
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{
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unsigned long h = tsvalue(ref)->hash;
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if (h == 0)
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{
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char *name = svalue(ref);
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while (*name)
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h = ((h<<5)-h)^(unsigned char)*(name++);
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tsvalue(ref)->hash = h;
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}
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return (Word)h%nhash(t); /* make it a valid index */
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}
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case LUA_T_FUNCTION:
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return (((IntPoint)bvalue(ref))%nhash(t));
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case LUA_T_CFUNCTION:
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return (((IntPoint)fvalue(ref))%nhash(t));
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case LUA_T_ARRAY:
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return (((IntPoint)avalue(ref))%nhash(t));
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default: /* user data */
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return (((IntPoint)uvalue(ref))%nhash(t));
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}
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}
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Bool lua_equalObj (Object *t1, Object *t2)
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{
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if (tag(t1) != tag(t2)) return 0;
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switch (tag(t1))
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{
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case LUA_T_NIL: return 1;
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case LUA_T_NUMBER: return nvalue(t1) == nvalue(t2);
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case LUA_T_STRING: return streq(svalue(t1), svalue(t2));
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case LUA_T_ARRAY: return avalue(t1) == avalue(t2);
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case LUA_T_FUNCTION: return bvalue(t1) == bvalue(t2);
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case LUA_T_CFUNCTION: return fvalue(t1) == fvalue(t2);
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default: return uvalue(t1) == uvalue(t2);
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}
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}
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static Word present (Hash *t, Object *ref)
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{
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Word h = hashindex(t, ref);
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while (tag(ref(node(t, h))) != LUA_T_NIL)
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{
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if (lua_equalObj(ref, ref(node(t, h))))
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return h;
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h = (h+1) % nhash(t);
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}
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return h;
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}
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/*
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** Alloc a vector node
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*/
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static Node *hashnodecreate (Word nhash)
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{
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Word i;
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Node *v = newvector (nhash, Node);
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for (i=0; i<nhash; i++)
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tag(ref(&v[i])) = LUA_T_NIL;
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return v;
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}
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/*
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** Create a new hash. Return the hash pointer or NULL on error.
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*/
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static Hash *hashcreate (Word nhash)
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{
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Hash *t = new(Hash);
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nhash = redimension((Word)((float)nhash/REHASH_LIMIT));
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nodevector(t) = hashnodecreate(nhash);
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nhash(t) = nhash;
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nuse(t) = 0;
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markarray(t) = 0;
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return t;
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}
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/*
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** Delete a hash
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*/
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static void hashdelete (Hash *t)
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{
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luaI_free (nodevector(t));
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luaI_free(t);
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}
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/*
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** Mark a hash and check its elements
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*/
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void lua_hashmark (Hash *h)
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{
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if (markarray(h) == 0)
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{
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Word i;
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markarray(h) = 1;
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for (i=0; i<nhash(h); i++)
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{
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Node *n = node(h,i);
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if (tag(ref(n)) != LUA_T_NIL)
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{
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lua_markobject(&n->ref);
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lua_markobject(&n->val);
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}
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}
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}
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}
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static void call_fallbacks (void)
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{
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Hash *curr_array;
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Object t;
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tag(&t) = LUA_T_ARRAY;
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for (curr_array = listhead; curr_array; curr_array = curr_array->next)
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if (markarray(curr_array) != 1)
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{
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avalue(&t) = curr_array;
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luaI_gcFB(&t);
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}
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tag(&t) = LUA_T_NIL;
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luaI_gcFB(&t); /* end of list */
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}
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/*
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** Garbage collection to arrays
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** Delete all unmarked arrays.
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*/
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Long lua_hashcollector (void)
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{
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Hash *curr_array = listhead, *prev = NULL;
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Long counter = 0;
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call_fallbacks();
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while (curr_array != NULL)
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{
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Hash *next = curr_array->next;
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if (markarray(curr_array) != 1)
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{
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if (prev == NULL) listhead = next;
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else prev->next = next;
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hashdelete(curr_array);
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++counter;
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}
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else
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{
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markarray(curr_array) = 0;
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prev = curr_array;
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}
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curr_array = next;
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}
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return counter;
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}
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/*
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** Create a new array
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** This function inserts the new array in the array list. It also
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** executes garbage collection if the number of arrays created
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** exceed a pre-defined range.
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*/
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Hash *lua_createarray (Word nhash)
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{
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Hash *array;
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lua_pack();
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array = hashcreate(nhash);
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array->next = listhead;
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listhead = array;
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return array;
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}
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/*
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** Re-hash
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*/
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static void rehash (Hash *t)
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{
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Word i;
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Word nold = nhash(t);
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Node *vold = nodevector(t);
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nhash(t) = redimension(nhash(t));
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nodevector(t) = hashnodecreate(nhash(t));
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for (i=0; i<nold; i++)
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{
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Node *n = vold+i;
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if (tag(ref(n)) != LUA_T_NIL && tag(val(n)) != LUA_T_NIL)
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*node(t, present(t, ref(n))) = *n; /* copy old node to new hahs */
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}
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luaI_free(vold);
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}
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/*
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** If the hash node is present, return its pointer, otherwise return
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** null.
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*/
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Object *lua_hashget (Hash *t, Object *ref)
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{
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Word h = present(t, ref);
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if (tag(ref(node(t, h))) != LUA_T_NIL) return val(node(t, h));
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else return NULL;
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}
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/*
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** If the hash node is present, return its pointer, otherwise create a new
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** node for the given reference and also return its pointer.
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*/
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Object *lua_hashdefine (Hash *t, Object *ref)
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{
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Word h;
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Node *n;
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h = present(t, ref);
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n = node(t, h);
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if (tag(ref(n)) == LUA_T_NIL)
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{
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nuse(t)++;
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if ((float)nuse(t) > (float)nhash(t)*REHASH_LIMIT)
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{
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rehash(t);
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h = present(t, ref);
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n = node(t, h);
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}
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*ref(n) = *ref;
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tag(val(n)) = LUA_T_NIL;
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}
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return (val(n));
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}
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/*
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** Internal function to manipulate arrays.
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** Given an array object and a reference value, return the next element
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** in the hash.
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** This function pushs the element value and its reference to the stack.
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*/
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static void hashnext (Hash *t, Word i)
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{
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if (i >= nhash(t))
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{
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lua_pushnil(); lua_pushnil();
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return;
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}
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while (tag(ref(node(t,i))) == LUA_T_NIL || tag(val(node(t,i))) == LUA_T_NIL)
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{
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if (++i >= nhash(t))
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{
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lua_pushnil(); lua_pushnil();
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return;
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}
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}
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luaI_pushobject(ref(node(t,i)));
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luaI_pushobject(val(node(t,i)));
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}
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void lua_next (void)
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{
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Hash *t;
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lua_Object o = lua_getparam(1);
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lua_Object r = lua_getparam(2);
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if (o == LUA_NOOBJECT || r == LUA_NOOBJECT)
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lua_error ("too few arguments to function `next'");
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if (lua_getparam(3) != LUA_NOOBJECT)
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lua_error ("too many arguments to function `next'");
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if (!lua_istable(o))
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lua_error ("first argument of function `next' is not a table");
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t = avalue(luaI_Address(o));
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if (lua_isnil(r))
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{
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hashnext(t, 0);
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}
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else
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{
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Word h = present (t, luaI_Address(r));
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hashnext(t, h+1);
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}
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}
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