1 /*
2 ** $Id: ltablib.c,v 1.93.1.1 2017/04/19 17:20:42 roberto Exp $
3 ** Library for Table Manipulation
4 ** See Copyright Notice in lua.h
5 */
6 
7 #define ltablib_c
8 #define LUA_LIB
9 
10 #include "lprefix.h"
11 
12 
13 #include <limits.h>
14 #include <stddef.h>
15 #include <string.h>
16 
17 #include "lua.h"
18 
19 #include "lauxlib.h"
20 #include "lualib.h"
21 
22 
23 /*
24 ** Operations that an object must define to mimic a table
25 ** (some functions only need some of them)
26 */
27 #define TAB_R	1			/* read */
28 #define TAB_W	2			/* write */
29 #define TAB_L	4			/* length */
30 #define TAB_RW	(TAB_R | TAB_W)		/* read/write */
31 
32 
33 #define aux_getn(L,n,w)	(checktab(L, n, (w) | TAB_L), luaL_len(L, n))
34 
35 
checkfield(lua_State * L,const char * key,int n)36 static int checkfield (lua_State *L, const char *key, int n) {
37   lua_pushstring(L, key);
38   return (lua_rawget(L, -n) != LUA_TNIL);
39 }
40 
41 
42 /*
43 ** Check that 'arg' either is a table or can behave like one (that is,
44 ** has a metatable with the required metamethods)
45 */
checktab(lua_State * L,int arg,int what)46 static void checktab (lua_State *L, int arg, int what) {
47   if (lua_type(L, arg) != LUA_TTABLE) {  /* is it not a table? */
48     int n = 1;  /* number of elements to pop */
49     if (lua_getmetatable(L, arg) &&  /* must have metatable */
50         (!(what & TAB_R) || checkfield(L, "__index", ++n)) &&
51         (!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&
52         (!(what & TAB_L) || checkfield(L, "__len", ++n))) {
53       lua_pop(L, n);  /* pop metatable and tested metamethods */
54     }
55     else
56       luaL_checktype(L, arg, LUA_TTABLE);  /* force an error */
57   }
58 }
59 
60 
61 #if defined(LUA_COMPAT_MAXN)
maxn(lua_State * L)62 static int maxn (lua_State *L) {
63   lua_Number max = 0;
64   luaL_checktype(L, 1, LUA_TTABLE);
65   lua_pushnil(L);  /* first key */
66   while (lua_next(L, 1)) {
67     lua_pop(L, 1);  /* remove value */
68     if (lua_type(L, -1) == LUA_TNUMBER) {
69       lua_Number v = lua_tonumber(L, -1);
70       if (v > max) max = v;
71     }
72   }
73   lua_pushnumber(L, max);
74   return 1;
75 }
76 #endif
77 
78 
tinsert(lua_State * L)79 static int tinsert (lua_State *L) {
80   lua_Integer e = aux_getn(L, 1, TAB_RW) + 1;  /* first empty element */
81   lua_Integer pos;  /* where to insert new element */
82   switch (lua_gettop(L)) {
83     case 2: {  /* called with only 2 arguments */
84       pos = e;  /* insert new element at the end */
85       break;
86     }
87     case 3: {
88       lua_Integer i;
89       pos = luaL_checkinteger(L, 2);  /* 2nd argument is the position */
90       luaL_argcheck(L, 1 <= pos && pos <= e, 2, "position out of bounds");
91       for (i = e; i > pos; i--) {  /* move up elements */
92         lua_geti(L, 1, i - 1);
93         lua_seti(L, 1, i);  /* t[i] = t[i - 1] */
94       }
95       break;
96     }
97     default: {
98       return luaL_error(L, "wrong number of arguments to 'insert'");
99     }
100   }
101   lua_seti(L, 1, pos);  /* t[pos] = v */
102   return 0;
103 }
104 
105 
tremove(lua_State * L)106 static int tremove (lua_State *L) {
107   lua_Integer size = aux_getn(L, 1, TAB_RW);
108   lua_Integer pos = luaL_optinteger(L, 2, size);
109   if (pos != size)  /* validate 'pos' if given */
110     luaL_argcheck(L, 1 <= pos && pos <= size + 1, 1, "position out of bounds");
111   lua_geti(L, 1, pos);  /* result = t[pos] */
112   for ( ; pos < size; pos++) {
113     lua_geti(L, 1, pos + 1);
114     lua_seti(L, 1, pos);  /* t[pos] = t[pos + 1] */
115   }
116   lua_pushnil(L);
117   lua_seti(L, 1, pos);  /* t[pos] = nil */
118   return 1;
119 }
120 
121 
122 /*
123 ** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever
124 ** possible, copy in increasing order, which is better for rehashing.
125 ** "possible" means destination after original range, or smaller
126 ** than origin, or copying to another table.
127 */
tmove(lua_State * L)128 static int tmove (lua_State *L) {
129   lua_Integer f = luaL_checkinteger(L, 2);
130   lua_Integer e = luaL_checkinteger(L, 3);
131   lua_Integer t = luaL_checkinteger(L, 4);
132   int tt = !lua_isnoneornil(L, 5) ? 5 : 1;  /* destination table */
133   checktab(L, 1, TAB_R);
134   checktab(L, tt, TAB_W);
135   if (e >= f) {  /* otherwise, nothing to move */
136     lua_Integer n, i;
137     luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
138                   "too many elements to move");
139     n = e - f + 1;  /* number of elements to move */
140     luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
141                   "destination wrap around");
142     if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) {
143       for (i = 0; i < n; i++) {
144         lua_geti(L, 1, f + i);
145         lua_seti(L, tt, t + i);
146       }
147     }
148     else {
149       for (i = n - 1; i >= 0; i--) {
150         lua_geti(L, 1, f + i);
151         lua_seti(L, tt, t + i);
152       }
153     }
154   }
155   lua_pushvalue(L, tt);  /* return destination table */
156   return 1;
157 }
158 
159 
addfield(lua_State * L,luaL_Buffer * b,lua_Integer i)160 static void addfield (lua_State *L, luaL_Buffer *b, lua_Integer i) {
161   lua_geti(L, 1, i);
162   if (!lua_isstring(L, -1))
163     luaL_error(L, "invalid value (%s) at index %d in table for 'concat'",
164                   luaL_typename(L, -1), i);
165   luaL_addvalue(b);
166 }
167 
168 
tconcat(lua_State * L)169 static int tconcat (lua_State *L) {
170   luaL_Buffer b;
171   lua_Integer last = aux_getn(L, 1, TAB_R);
172   size_t lsep;
173   const char *sep = luaL_optlstring(L, 2, "", &lsep);
174   lua_Integer i = luaL_optinteger(L, 3, 1);
175   last = luaL_optinteger(L, 4, last);
176   luaL_buffinit(L, &b);
177   for (; i < last; i++) {
178     addfield(L, &b, i);
179     luaL_addlstring(&b, sep, lsep);
180   }
181   if (i == last)  /* add last value (if interval was not empty) */
182     addfield(L, &b, i);
183   luaL_pushresult(&b);
184   return 1;
185 }
186 
187 
188 /*
189 ** {======================================================
190 ** Pack/unpack
191 ** =======================================================
192 */
193 
pack(lua_State * L)194 static int pack (lua_State *L) {
195   int i;
196   int n = lua_gettop(L);  /* number of elements to pack */
197   lua_createtable(L, n, 1);  /* create result table */
198   lua_insert(L, 1);  /* put it at index 1 */
199   for (i = n; i >= 1; i--)  /* assign elements */
200     lua_seti(L, 1, i);
201   lua_pushinteger(L, n);
202   lua_setfield(L, 1, "n");  /* t.n = number of elements */
203   return 1;  /* return table */
204 }
205 
206 
unpack(lua_State * L)207 static int unpack (lua_State *L) {
208   lua_Unsigned n;
209   lua_Integer i = luaL_optinteger(L, 2, 1);
210   lua_Integer e = luaL_opt(L, luaL_checkinteger, 3, luaL_len(L, 1));
211   if (i > e) return 0;  /* empty range */
212   n = (lua_Unsigned)e - i;  /* number of elements minus 1 (avoid overflows) */
213   if (n >= (unsigned int)INT_MAX  || !lua_checkstack(L, (int)(++n)))
214     return luaL_error(L, "too many results to unpack");
215   for (; i < e; i++) {  /* push arg[i..e - 1] (to avoid overflows) */
216     lua_geti(L, 1, i);
217   }
218   lua_geti(L, 1, e);  /* push last element */
219   return (int)n;
220 }
221 
222 /* }====================================================== */
223 
224 
225 
226 /*
227 ** {======================================================
228 ** Quicksort
229 ** (based on 'Algorithms in MODULA-3', Robert Sedgewick;
230 **  Addison-Wesley, 1993.)
231 ** =======================================================
232 */
233 
234 
235 /* type for array indices */
236 typedef unsigned int IdxT;
237 
238 
239 /*
240 ** Produce a "random" 'unsigned int' to randomize pivot choice. This
241 ** macro is used only when 'sort' detects a big imbalance in the result
242 ** of a partition. (If you don't want/need this "randomness", ~0 is a
243 ** good choice.)
244 */
245 #if !defined(l_randomizePivot)		/* { */
246 
247 #include <time.h>
248 
249 /* size of 'e' measured in number of 'unsigned int's */
250 #define sof(e)		(sizeof(e) / sizeof(unsigned int))
251 
252 /*
253 ** Use 'time' and 'clock' as sources of "randomness". Because we don't
254 ** know the types 'clock_t' and 'time_t', we cannot cast them to
255 ** anything without risking overflows. A safe way to use their values
256 ** is to copy them to an array of a known type and use the array values.
257 */
l_randomizePivot(void)258 static unsigned int l_randomizePivot (void) {
259   clock_t c = clock();
260   time_t t = time(NULL);
261   unsigned int buff[sof(c) + sof(t)];
262   unsigned int i, rnd = 0;
263   memcpy(buff, &c, sof(c) * sizeof(unsigned int));
264   memcpy(buff + sof(c), &t, sof(t) * sizeof(unsigned int));
265   for (i = 0; i < sof(buff); i++)
266     rnd += buff[i];
267   return rnd;
268 }
269 
270 #endif					/* } */
271 
272 
273 /* arrays larger than 'RANLIMIT' may use randomized pivots */
274 #define RANLIMIT	100u
275 
276 
set2(lua_State * L,IdxT i,IdxT j)277 static void set2 (lua_State *L, IdxT i, IdxT j) {
278   lua_seti(L, 1, i);
279   lua_seti(L, 1, j);
280 }
281 
282 
283 /*
284 ** Return true iff value at stack index 'a' is less than the value at
285 ** index 'b' (according to the order of the sort).
286 */
sort_comp(lua_State * L,int a,int b)287 static int sort_comp (lua_State *L, int a, int b) {
288   if (lua_isnil(L, 2))  /* no function? */
289     return lua_compare(L, a, b, LUA_OPLT);  /* a < b */
290   else {  /* function */
291     int res;
292     lua_pushvalue(L, 2);    /* push function */
293     lua_pushvalue(L, a-1);  /* -1 to compensate function */
294     lua_pushvalue(L, b-2);  /* -2 to compensate function and 'a' */
295     lua_call(L, 2, 1);      /* call function */
296     res = lua_toboolean(L, -1);  /* get result */
297     lua_pop(L, 1);          /* pop result */
298     return res;
299   }
300 }
301 
302 
303 /*
304 ** Does the partition: Pivot P is at the top of the stack.
305 ** precondition: a[lo] <= P == a[up-1] <= a[up],
306 ** so it only needs to do the partition from lo + 1 to up - 2.
307 ** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
308 ** returns 'i'.
309 */
partition(lua_State * L,IdxT lo,IdxT up)310 static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
311   IdxT i = lo;  /* will be incremented before first use */
312   IdxT j = up - 1;  /* will be decremented before first use */
313   /* loop invariant: a[lo .. i] <= P <= a[j .. up] */
314   for (;;) {
315     /* next loop: repeat ++i while a[i] < P */
316     while (lua_geti(L, 1, ++i), sort_comp(L, -1, -2)) {
317       if (i == up - 1)  /* a[i] < P  but a[up - 1] == P  ?? */
318         luaL_error(L, "invalid order function for sorting");
319       lua_pop(L, 1);  /* remove a[i] */
320     }
321     /* after the loop, a[i] >= P and a[lo .. i - 1] < P */
322     /* next loop: repeat --j while P < a[j] */
323     while (lua_geti(L, 1, --j), sort_comp(L, -3, -1)) {
324       if (j < i)  /* j < i  but  a[j] > P ?? */
325         luaL_error(L, "invalid order function for sorting");
326       lua_pop(L, 1);  /* remove a[j] */
327     }
328     /* after the loop, a[j] <= P and a[j + 1 .. up] >= P */
329     if (j < i) {  /* no elements out of place? */
330       /* a[lo .. i - 1] <= P <= a[j + 1 .. i .. up] */
331       lua_pop(L, 1);  /* pop a[j] */
332       /* swap pivot (a[up - 1]) with a[i] to satisfy pos-condition */
333       set2(L, up - 1, i);
334       return i;
335     }
336     /* otherwise, swap a[i] - a[j] to restore invariant and repeat */
337     set2(L, i, j);
338   }
339 }
340 
341 
342 /*
343 ** Choose an element in the middle (2nd-3th quarters) of [lo,up]
344 ** "randomized" by 'rnd'
345 */
choosePivot(IdxT lo,IdxT up,unsigned int rnd)346 static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
347   IdxT r4 = (up - lo) / 4;  /* range/4 */
348   IdxT p = rnd % (r4 * 2) + (lo + r4);
349   lua_assert(lo + r4 <= p && p <= up - r4);
350   return p;
351 }
352 
353 
354 /*
355 ** QuickSort algorithm (recursive function)
356 */
auxsort(lua_State * L,IdxT lo,IdxT up,unsigned int rnd)357 static void auxsort (lua_State *L, IdxT lo, IdxT up,
358                                    unsigned int rnd) {
359   while (lo < up) {  /* loop for tail recursion */
360     IdxT p;  /* Pivot index */
361     IdxT n;  /* to be used later */
362     /* sort elements 'lo', 'p', and 'up' */
363     lua_geti(L, 1, lo);
364     lua_geti(L, 1, up);
365     if (sort_comp(L, -1, -2))  /* a[up] < a[lo]? */
366       set2(L, lo, up);  /* swap a[lo] - a[up] */
367     else
368       lua_pop(L, 2);  /* remove both values */
369     if (up - lo == 1)  /* only 2 elements? */
370       return;  /* already sorted */
371     if (up - lo < RANLIMIT || rnd == 0)  /* small interval or no randomize? */
372       p = (lo + up)/2;  /* middle element is a good pivot */
373     else  /* for larger intervals, it is worth a random pivot */
374       p = choosePivot(lo, up, rnd);
375     lua_geti(L, 1, p);
376     lua_geti(L, 1, lo);
377     if (sort_comp(L, -2, -1))  /* a[p] < a[lo]? */
378       set2(L, p, lo);  /* swap a[p] - a[lo] */
379     else {
380       lua_pop(L, 1);  /* remove a[lo] */
381       lua_geti(L, 1, up);
382       if (sort_comp(L, -1, -2))  /* a[up] < a[p]? */
383         set2(L, p, up);  /* swap a[up] - a[p] */
384       else
385         lua_pop(L, 2);
386     }
387     if (up - lo == 2)  /* only 3 elements? */
388       return;  /* already sorted */
389     lua_geti(L, 1, p);  /* get middle element (Pivot) */
390     lua_pushvalue(L, -1);  /* push Pivot */
391     lua_geti(L, 1, up - 1);  /* push a[up - 1] */
392     set2(L, p, up - 1);  /* swap Pivot (a[p]) with a[up - 1] */
393     p = partition(L, lo, up);
394     /* a[lo .. p - 1] <= a[p] == P <= a[p + 1 .. up] */
395     if (p - lo < up - p) {  /* lower interval is smaller? */
396       auxsort(L, lo, p - 1, rnd);  /* call recursively for lower interval */
397       n = p - lo;  /* size of smaller interval */
398       lo = p + 1;  /* tail call for [p + 1 .. up] (upper interval) */
399     }
400     else {
401       auxsort(L, p + 1, up, rnd);  /* call recursively for upper interval */
402       n = up - p;  /* size of smaller interval */
403       up = p - 1;  /* tail call for [lo .. p - 1]  (lower interval) */
404     }
405     if ((up - lo) / 128 > n) /* partition too imbalanced? */
406       rnd = l_randomizePivot();  /* try a new randomization */
407   }  /* tail call auxsort(L, lo, up, rnd) */
408 }
409 
410 
sort(lua_State * L)411 static int sort (lua_State *L) {
412   lua_Integer n = aux_getn(L, 1, TAB_RW);
413   if (n > 1) {  /* non-trivial interval? */
414     luaL_argcheck(L, n < INT_MAX, 1, "array too big");
415     if (!lua_isnoneornil(L, 2))  /* is there a 2nd argument? */
416       luaL_checktype(L, 2, LUA_TFUNCTION);  /* must be a function */
417     lua_settop(L, 2);  /* make sure there are two arguments */
418     auxsort(L, 1, (IdxT)n, 0);
419   }
420   return 0;
421 }
422 
423 /* }====================================================== */
424 
425 
426 static const luaL_Reg tab_funcs[] = {
427   {"concat", tconcat},
428 #if defined(LUA_COMPAT_MAXN)
429   {"maxn", maxn},
430 #endif
431   {"insert", tinsert},
432   {"pack", pack},
433   {"unpack", unpack},
434   {"remove", tremove},
435   {"move", tmove},
436   {"sort", sort},
437   {NULL, NULL}
438 };
439 
440 
luaopen_table(lua_State * L)441 LUAMOD_API int luaopen_table (lua_State *L) {
442   luaL_newlib(L, tab_funcs);
443 #if defined(LUA_COMPAT_UNPACK)
444   /* _G.unpack = table.unpack */
445   lua_getfield(L, -1, "unpack");
446   lua_setglobal(L, "unpack");
447 #endif
448   return 1;
449 }
450 
451