lua/src/ltablib.c

   1 /*
   2 ** $Id: ltablib.c,v 1.38 2005/10/23 17:38:15 roberto Exp $
   3 ** Library for Table Manipulation
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stddef.h>
   9
  10 #define ltablib_c
  11 #define LUA_LIB
  12
  13 #include "lua.h"
  14
  15 #include "lauxlib.h"
  16 #include "lualib.h"
  17
  18
  19 #define aux_getn(L,n)   (luaL_checktype(L, n, LUA_TTABLE), luaL_getn(L, n))
  20
  21
  22 static int foreachi (lua_State *L) {
  23   int i;
  24   int n = aux_getn(L, 1);
  25   luaL_checktype(L, 2, LUA_TFUNCTION);
  26   for (i=1; i <= n; i++) {
  27     lua_pushvalue(L, 2);  /* function */
  28     lua_pushinteger(L, i);  /* 1st argument */
  29     lua_rawgeti(L, 1, i);  /* 2nd argument */
  30     lua_call(L, 2, 1);
  31     if (!lua_isnil(L, -1))
  32       return 1;
  33     lua_pop(L, 1);  /* remove nil result */
  34   }
  35   return 0;
  36 }
  37
  38
  39 static int foreach (lua_State *L) {
  40   luaL_checktype(L, 1, LUA_TTABLE);
  41   luaL_checktype(L, 2, LUA_TFUNCTION);
  42   lua_pushnil(L);  /* first key */
  43   while (lua_next(L, 1)) {
  44     lua_pushvalue(L, 2);  /* function */
  45     lua_pushvalue(L, -3);  /* key */
  46     lua_pushvalue(L, -3);  /* value */
  47     lua_call(L, 2, 1);
  48     if (!lua_isnil(L, -1))
  49       return 1;
  50     lua_pop(L, 2);  /* remove value and result */
  51   }
  52   return 0;
  53 }
  54
  55
  56 static int maxn (lua_State *L) {
  57   lua_Number max = 0;
  58   luaL_checktype(L, 1, LUA_TTABLE);
  59   lua_pushnil(L);  /* first key */
  60   while (lua_next(L, 1)) {
  61     lua_pop(L, 1);  /* remove value */
  62     if (lua_type(L, -1) == LUA_TNUMBER) {
  63       lua_Number v = lua_tonumber(L, -1);
  64       if (v > max) max = v;
  65     }
  66   }
  67   lua_pushnumber(L, max);
  68   return 1;
  69 }
  70
  71
  72 static int getn (lua_State *L) {
  73   lua_pushinteger(L, aux_getn(L, 1));
  74   return 1;
  75 }
  76
  77
  78 static int setn (lua_State *L) {
  79   luaL_checktype(L, 1, LUA_TTABLE);
  80 #ifndef luaL_setn
  81   luaL_setn(L, 1, luaL_checkint(L, 2));
  82 #else
  83   luaL_error(L, LUA_QL("setn") " is obsolete");
  84 #endif
  85   lua_pushvalue(L, 1);
  86   return 1;
  87 }
  88
  89
  90 static int tinsert (lua_State *L) {
  91   int e = aux_getn(L, 1) + 1;  /* first empty element */
  92   int pos;  /* where to insert new element */
  93   switch (lua_gettop(L)) {
  94     case 2: {  /* called with only 2 arguments */
  95       pos = e;  /* insert new element at the end */
  96       break;
  97     }
  98     case 3: {
  99       int i;
 100       pos = luaL_checkint(L, 2);  /* 2nd argument is the position */
 101       if (pos > e) e = pos;  /* `grow' array if necessary */
 102       for (i = e; i > pos; i--) {  /* move up elements */
 103         lua_rawgeti(L, 1, i-1);
 104         lua_rawseti(L, 1, i);  /* t[i] = t[i-1] */
 105       }
 106       break;
 107     }
 108     default: {
 109       return luaL_error(L, "wrong number of arguments to " LUA_QL("insert"));
 110     }
 111   }
 112   luaL_setn(L, 1, e);  /* new size */
 113   lua_rawseti(L, 1, pos);  /* t[pos] = v */
 114   return 0;
 115 }
 116
 117
 118 static int tremove (lua_State *L) {
 119   int e = aux_getn(L, 1);
 120   int pos = luaL_optint(L, 2, e);
 121   if (e == 0) return 0;  /* table is `empty' */
 122   luaL_setn(L, 1, e - 1);  /* t.n = n-1 */
 123   lua_rawgeti(L, 1, pos);  /* result = t[pos] */
 124   for ( ;pos<e; pos++) {
 125     lua_rawgeti(L, 1, pos+1);
 126     lua_rawseti(L, 1, pos);  /* t[pos] = t[pos+1] */
 127   }
 128   lua_pushnil(L);
 129   lua_rawseti(L, 1, e);  /* t[e] = nil */
 130   return 1;
 131 }
 132
 133
 134 static int tconcat (lua_State *L) {
 135   luaL_Buffer b;
 136   size_t lsep;
 137   int i, last;
 138   const char *sep = luaL_optlstring(L, 2, "", &lsep);
 139   luaL_checktype(L, 1, LUA_TTABLE);
 140   i = luaL_optint(L, 3, 1);
 141   last = luaL_opt(L, luaL_checkint, 4, luaL_getn(L, 1));
 142   luaL_buffinit(L, &b);
 143   for (; i <= last; i++) {
 144     lua_rawgeti(L, 1, i);
 145     luaL_argcheck(L, lua_isstring(L, -1), 1, "table contains non-strings");
 146     luaL_addvalue(&b);
 147     if (i != last)
 148       luaL_addlstring(&b, sep, lsep);
 149   }
 150   luaL_pushresult(&b);
 151   return 1;
 152 }
 153
 154
 155
 156 /*
 157 ** {======================================================
 158 ** Quicksort
 159 ** (based on `Algorithms in MODULA-3', Robert Sedgewick;
 160 **  Addison-Wesley, 1993.)
 161 */
 162
 163
 164 static void set2 (lua_State *L, int i, int j) {
 165   lua_rawseti(L, 1, i);
 166   lua_rawseti(L, 1, j);
 167 }
 168
 169 static int sort_comp (lua_State *L, int a, int b) {
 170   if (!lua_isnil(L, 2)) {  /* function? */
 171     int res;
 172     lua_pushvalue(L, 2);
 173     lua_pushvalue(L, a-1);  /* -1 to compensate function */
 174     lua_pushvalue(L, b-2);  /* -2 to compensate function and `a' */
 175     lua_call(L, 2, 1);
 176     res = lua_toboolean(L, -1);
 177     lua_pop(L, 1);
 178     return res;
 179   }
 180   else  /* a < b? */
 181     return lua_lessthan(L, a, b);
 182 }
 183
 184 static void auxsort (lua_State *L, int l, int u) {
 185   while (l < u) {  /* for tail recursion */
 186     int i, j;
 187     /* sort elements a[l], a[(l+u)/2] and a[u] */
 188     lua_rawgeti(L, 1, l);
 189     lua_rawgeti(L, 1, u);
 190     if (sort_comp(L, -1, -2))  /* a[u] < a[l]? */
 191       set2(L, l, u);  /* swap a[l] - a[u] */
 192     else
 193       lua_pop(L, 2);
 194     if (u-l == 1) break;  /* only 2 elements */
 195     i = (l+u)/2;
 196     lua_rawgeti(L, 1, i);
 197     lua_rawgeti(L, 1, l);
 198     if (sort_comp(L, -2, -1))  /* a[i]<a[l]? */
 199       set2(L, i, l);
 200     else {
 201       lua_pop(L, 1);  /* remove a[l] */
 202       lua_rawgeti(L, 1, u);
 203       if (sort_comp(L, -1, -2))  /* a[u]<a[i]? */
 204         set2(L, i, u);
 205       else
 206         lua_pop(L, 2);
 207     }
 208     if (u-l == 2) break;  /* only 3 elements */
 209     lua_rawgeti(L, 1, i);  /* Pivot */
 210     lua_pushvalue(L, -1);
 211     lua_rawgeti(L, 1, u-1);
 212     set2(L, i, u-1);
 213     /* a[l] <= P == a[u-1] <= a[u], only need to sort from l+1 to u-2 */
 214     i = l; j = u-1;
 215     for (;;) {  /* invariant: a[l..i] <= P <= a[j..u] */
 216       /* repeat ++i until a[i] >= P */
 217       while (lua_rawgeti(L, 1, ++i), sort_comp(L, -1, -2)) {
 218         if (i>u) luaL_error(L, "invalid order function for sorting");
 219         lua_pop(L, 1);  /* remove a[i] */
 220       }
 221       /* repeat --j until a[j] <= P */
 222       while (lua_rawgeti(L, 1, --j), sort_comp(L, -3, -1)) {
 223         if (j<l) luaL_error(L, "invalid order function for sorting");
 224         lua_pop(L, 1);  /* remove a[j] */
 225       }
 226       if (j<i) {
 227         lua_pop(L, 3);  /* pop pivot, a[i], a[j] */
 228         break;
 229       }
 230       set2(L, i, j);
 231     }
 232     lua_rawgeti(L, 1, u-1);
 233     lua_rawgeti(L, 1, i);
 234     set2(L, u-1, i);  /* swap pivot (a[u-1]) with a[i] */
 235     /* a[l..i-1] <= a[i] == P <= a[i+1..u] */
 236     /* adjust so that smaller half is in [j..i] and larger one in [l..u] */
 237     if (i-l < u-i) {
 238       j=l; i=i-1; l=i+2;
 239     }
 240     else {
 241       j=i+1; i=u; u=j-2;
 242     }
 243     auxsort(L, j, i);  /* call recursively the smaller one */
 244   }  /* repeat the routine for the larger one */
 245 }
 246
 247 static int sort (lua_State *L) {
 248   int n = aux_getn(L, 1);
 249   luaL_checkstack(L, 40, "");  /* assume array is smaller than 2^40 */
 250   if (!lua_isnoneornil(L, 2))  /* is there a 2nd argument? */
 251     luaL_checktype(L, 2, LUA_TFUNCTION);
 252   lua_settop(L, 2);  /* make sure there is two arguments */
 253   auxsort(L, 1, n);
 254   return 0;
 255 }
 256
 257 /* }====================================================== */
 258
 259
 260 static const luaL_Reg tab_funcs[] = {
 261   {"concat", tconcat},
 262   {"foreach", foreach},
 263   {"foreachi", foreachi},
 264   {"getn", getn},
 265   {"maxn", maxn},
 266   {"insert", tinsert},
 267   {"remove", tremove},
 268   {"setn", setn},
 269   {"sort", sort},
 270   {NULL, NULL}
 271 };
 272
 273
 274 LUALIB_API int luaopen_table (lua_State *L) {
 275   luaL_register(L, LUA_TABLIBNAME, tab_funcs);
 276   return 1;
 277 }
 278