1/*
2** $Id: lutf8lib.c $
3** Standard library for UTF-8 manipulation
4** See Copyright Notice in lua.h
5*/
6
7#define lutf8lib_c
8#define LUA_LIB
9
10#include "lprefix.h"
11
12
13#include <assert.h>
14#include <limits.h>
15#include <stdlib.h>
16#include <string.h>
17
18#include "lua.h"
19
20#include "lauxlib.h"
21#include "lualib.h"
22
23
24#define MAXUNICODE 0x10FFFFu
25
26#define MAXUTF 0x7FFFFFFFu
27
28/*
29** Integer type for decoded UTF-8 values; MAXUTF needs 31 bits.
30*/
31#if (UINT_MAX >> 30) >= 1
32typedef unsigned int utfint;
33#else
34typedef unsigned long utfint;
35#endif
36
37
38#define iscont(p) ((*(p) & 0xC0) == 0x80)
39
40
41/* from strlib */
42/* translate a relative string position: negative means back from end */
43static lua_Integer u_posrelat (lua_Integer pos, size_t len) {
44 if (pos >= 0) return pos;
45 else if (0u - (size_t)pos > len) return 0;
46 else return (lua_Integer)len + pos + 1;
47}
48
49
50/*
51** Decode one UTF-8 sequence, returning NULL if byte sequence is
52** invalid. The array 'limits' stores the minimum value for each
53** sequence length, to check for overlong representations. Its first
54** entry forces an error for non-ascii bytes with no continuation
55** bytes (count == 0).
56*/
57static const char *utf8_decode (const char *s, utfint *val, int strict) {
58 static const utfint limits[] =
59 {~(utfint)0, 0x80, 0x800, 0x10000u, 0x200000u, 0x4000000u};
60 unsigned int c = (unsigned char)s[0];
61 utfint res = 0; /* final result */
62 if (c < 0x80) /* ascii? */
63 res = c;
64 else {
65 int count = 0; /* to count number of continuation bytes */
66 for (; c & 0x40; c <<= 1) { /* while it needs continuation bytes... */
67 unsigned int cc = (unsigned char)s[++count]; /* read next byte */
68 if ((cc & 0xC0) != 0x80) /* not a continuation byte? */
69 return NULL; /* invalid byte sequence */
70 res = (res << 6) | (cc & 0x3F); /* add lower 6 bits from cont. byte */
71 }
72 res |= ((utfint)(c & 0x7F) << (count * 5)); /* add first byte */
73 if (count > 5 || res > MAXUTF || res < limits[count])
74 return NULL; /* invalid byte sequence */
75 s += count; /* skip continuation bytes read */
76 }
77 if (strict) {
78 /* check for invalid code points; too large or surrogates */
79 if (res > MAXUNICODE || (0xD800u <= res && res <= 0xDFFFu))
80 return NULL;
81 }
82 if (val) *val = res;
83 return s + 1; /* +1 to include first byte */
84}
85
86
87/*
88** utf8len(s [, i [, j [, lax]]]) --> number of characters that
89** start in the range [i,j], or nil + current position if 's' is not
90** well formed in that interval
91*/
92static int utflen (lua_State *L) {
93 lua_Integer n = 0; /* counter for the number of characters */
94 size_t len; /* string length in bytes */
95 const char *s = luaL_checklstring(L, 1, &len);
96 lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
97 lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
98 int lax = lua_toboolean(L, 4);
99 luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2,
100 "initial position out of bounds");
101 luaL_argcheck(L, --posj < (lua_Integer)len, 3,
102 "final position out of bounds");
103 while (posi <= posj) {
104 const char *s1 = utf8_decode(s + posi, NULL, !lax);
105 if (s1 == NULL) { /* conversion error? */
106 luaL_pushfail(L); /* return fail ... */
107 lua_pushinteger(L, posi + 1); /* ... and current position */
108 return 2;
109 }
110 posi = s1 - s;
111 n++;
112 }
113 lua_pushinteger(L, n);
114 return 1;
115}
116
117
118/*
119** codepoint(s, [i, [j [, lax]]]) -> returns codepoints for all
120** characters that start in the range [i,j]
121*/
122static int codepoint (lua_State *L) {
123 size_t len;
124 const char *s = luaL_checklstring(L, 1, &len);
125 lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
126 lua_Integer pose = u_posrelat(luaL_optinteger(L, 3, posi), len);
127 int lax = lua_toboolean(L, 4);
128 int n;
129 const char *se;
130 luaL_argcheck(L, posi >= 1, 2, "out of bounds");
131 luaL_argcheck(L, pose <= (lua_Integer)len, 3, "out of bounds");
132 if (posi > pose) return 0; /* empty interval; return no values */
133 if (pose - posi >= INT_MAX) /* (lua_Integer -> int) overflow? */
134 return luaL_error(L, "string slice too long");
135 n = (int)(pose - posi) + 1; /* upper bound for number of returns */
136 luaL_checkstack(L, n, "string slice too long");
137 n = 0; /* count the number of returns */
138 se = s + pose; /* string end */
139 for (s += posi - 1; s < se;) {
140 utfint code;
141 s = utf8_decode(s, &code, !lax);
142 if (s == NULL)
143 return luaL_error(L, "invalid UTF-8 code");
144 lua_pushinteger(L, code);
145 n++;
146 }
147 return n;
148}
149
150
151static void pushutfchar (lua_State *L, int arg) {
152 lua_Unsigned code = (lua_Unsigned)luaL_checkinteger(L, arg);
153 luaL_argcheck(L, code <= MAXUTF, arg, "value out of range");
154 lua_pushfstring(L, "%U", (long)code);
155}
156
157
158/*
159** utfchar(n1, n2, ...) -> char(n1)..char(n2)...
160*/
161static int utfchar (lua_State *L) {
162 int n = lua_gettop(L); /* number of arguments */
163 if (n == 1) /* optimize common case of single char */
164 pushutfchar(L, 1);
165 else {
166 int i;
167 luaL_Buffer b;
168 luaL_buffinit(L, &b);
169 for (i = 1; i <= n; i++) {
170 pushutfchar(L, i);
171 luaL_addvalue(&b);
172 }
173 luaL_pushresult(&b);
174 }
175 return 1;
176}
177
178
179/*
180** offset(s, n, [i]) -> index where n-th character counting from
181** position 'i' starts; 0 means character at 'i'.
182*/
183static int byteoffset (lua_State *L) {
184 size_t len;
185 const char *s = luaL_checklstring(L, 1, &len);
186 lua_Integer n = luaL_checkinteger(L, 2);
187 lua_Integer posi = (n >= 0) ? 1 : len + 1;
188 posi = u_posrelat(luaL_optinteger(L, 3, posi), len);
189 luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 3,
190 "position out of bounds");
191 if (n == 0) {
192 /* find beginning of current byte sequence */
193 while (posi > 0 && iscont(s + posi)) posi--;
194 }
195 else {
196 if (iscont(s + posi))
197 return luaL_error(L, "initial position is a continuation byte");
198 if (n < 0) {
199 while (n < 0 && posi > 0) { /* move back */
200 do { /* find beginning of previous character */
201 posi--;
202 } while (posi > 0 && iscont(s + posi));
203 n++;
204 }
205 }
206 else {
207 n--; /* do not move for 1st character */
208 while (n > 0 && posi < (lua_Integer)len) {
209 do { /* find beginning of next character */
210 posi++;
211 } while (iscont(s + posi)); /* (cannot pass final '\0') */
212 n--;
213 }
214 }
215 }
216 if (n == 0) /* did it find given character? */
217 lua_pushinteger(L, posi + 1);
218 else /* no such character */
219 luaL_pushfail(L);
220 return 1;
221}
222
223
224static int iter_aux (lua_State *L, int strict) {
225 size_t len;
226 const char *s = luaL_checklstring(L, 1, &len);
227 lua_Unsigned n = (lua_Unsigned)lua_tointeger(L, 2);
228 if (n < len) {
229 while (iscont(s + n)) n++; /* skip continuation bytes */
230 }
231 if (n >= len) /* (also handles original 'n' being negative) */
232 return 0; /* no more codepoints */
233 else {
234 utfint code;
235 const char *next = utf8_decode(s + n, &code, strict);
236 if (next == NULL)
237 return luaL_error(L, "invalid UTF-8 code");
238 lua_pushinteger(L, n + 1);
239 lua_pushinteger(L, code);
240 return 2;
241 }
242}
243
244
245static int iter_auxstrict (lua_State *L) {
246 return iter_aux(L, 1);
247}
248
249static int iter_auxlax (lua_State *L) {
250 return iter_aux(L, 0);
251}
252
253
254static int iter_codes (lua_State *L) {
255 int lax = lua_toboolean(L, 2);
256 luaL_checkstring(L, 1);
257 lua_pushcfunction(L, lax ? iter_auxlax : iter_auxstrict);
258 lua_pushvalue(L, 1);
259 lua_pushinteger(L, 0);
260 return 3;
261}
262
263
264/* pattern to match a single UTF-8 character */
265#define UTF8PATT "[\0-\x7F\xC2-\xFD][\x80-\xBF]*"
266
267
268static const luaL_Reg funcs[] = {
269 {"offset", byteoffset},
270 {"codepoint", codepoint},
271 {"char", utfchar},
272 {"len", utflen},
273 {"codes", iter_codes},
274 /* placeholders */
275 {"charpattern", NULL},
276 {NULL, NULL}
277};
278
279
280LUAMOD_API int luaopen_utf8 (lua_State *L) {
281 luaL_newlib(L, funcs);
282 lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT)/sizeof(char) - 1);
283 lua_setfield(L, -2, "charpattern");
284 return 1;
285}
286
287