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