1/*
2** $Id: lutf8lib.c,v 1.16.1.1 2017/04/19 17:29:57 roberto Exp $
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#define MAXUNICODE 0x10FFFF
24
25#define iscont(p) ((*(p) & 0xC0) == 0x80)
26
27
28/* from strlib */
29/* translate a relative string position: negative means back from end */
30static lua_Integer u_posrelat (lua_Integer pos, size_t len) {
31 if (pos >= 0) return pos;
32 else if (0u - (size_t)pos > len) return 0;
33 else return (lua_Integer)len + pos + 1;
34}
35
36
37/*
38** Decode one UTF-8 sequence, returning NULL if byte sequence is invalid.
39*/
40static const char *utf8_decode (const char *o, int *val) {
41 static const unsigned int limits[] = {0xFF, 0x7F, 0x7FF, 0xFFFF};
42 const unsigned char *s = (const unsigned char *)o;
43 unsigned int c = s[0];
44 unsigned int res = 0; /* final result */
45 if (c < 0x80) /* ascii? */
46 res = c;
47 else {
48 int count = 0; /* to count number of continuation bytes */
49 while (c & 0x40) { /* still have continuation bytes? */
50 int cc = s[++count]; /* read next byte */
51 if ((cc & 0xC0) != 0x80) /* not a continuation byte? */
52 return NULL; /* invalid byte sequence */
53 res = (res << 6) | (cc & 0x3F); /* add lower 6 bits from cont. byte */
54 c <<= 1; /* to test next bit */
55 }
56 res |= ((c & 0x7F) << (count * 5)); /* add first byte */
57 if (count > 3 || res > MAXUNICODE || res <= limits[count])
58 return NULL; /* invalid byte sequence */
59 s += count; /* skip continuation bytes read */
60 }
61 if (val) *val = res;
62 return (const char *)s + 1; /* +1 to include first byte */
63}
64
65
66/*
67** utf8len(s [, i [, j]]) --> number of characters that start in the
68** range [i,j], or nil + current position if 's' is not well formed in
69** that interval
70*/
71static int utflen (lua_State *L) {
72 int n = 0;
73 size_t len;
74 const char *s = luaL_checklstring(L, 1, &len);
75 lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
76 lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
77 luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2,
78 "initial position out of string");
79 luaL_argcheck(L, --posj < (lua_Integer)len, 3,
80 "final position out of string");
81 while (posi <= posj) {
82 const char *s1 = utf8_decode(s + posi, NULL);
83 if (s1 == NULL) { /* conversion error? */
84 lua_pushnil(L); /* return nil ... */
85 lua_pushinteger(L, posi + 1); /* ... and current position */
86 return 2;
87 }
88 posi = s1 - s;
89 n++;
90 }
91 lua_pushinteger(L, n);
92 return 1;
93}
94
95
96/*
97** codepoint(s, [i, [j]]) -> returns codepoints for all characters
98** that start in the range [i,j]
99*/
100static int codepoint (lua_State *L) {
101 size_t len;
102 const char *s = luaL_checklstring(L, 1, &len);
103 lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
104 lua_Integer pose = u_posrelat(luaL_optinteger(L, 3, posi), len);
105 int n;
106 const char *se;
107 luaL_argcheck(L, posi >= 1, 2, "out of range");
108 luaL_argcheck(L, pose <= (lua_Integer)len, 3, "out of range");
109 if (posi > pose) return 0; /* empty interval; return no values */
110 if (pose - posi >= INT_MAX) /* (lua_Integer -> int) overflow? */
111 return luaL_error(L, "string slice too long");
112 n = (int)(pose - posi) + 1;
113 luaL_checkstack(L, n, "string slice too long");
114 n = 0;
115 se = s + pose;
116 for (s += posi - 1; s < se;) {
117 int code;
118 s = utf8_decode(s, &code);
119 if (s == NULL)
120 return luaL_error(L, "invalid UTF-8 code");
121 lua_pushinteger(L, code);
122 n++;
123 }
124 return n;
125}
126
127
128static void pushutfchar (lua_State *L, int arg) {
129 lua_Integer code = luaL_checkinteger(L, arg);
130 luaL_argcheck(L, 0 <= code && code <= MAXUNICODE, arg, "value out of range");
131 lua_pushfstring(L, "%U", (long)code);
132}
133
134
135/*
136** utfchar(n1, n2, ...) -> char(n1)..char(n2)...
137*/
138static int utfchar (lua_State *L) {
139 int n = lua_gettop(L); /* number of arguments */
140 if (n == 1) /* optimize common case of single char */
141 pushutfchar(L, 1);
142 else {
143 int i;
144 luaL_Buffer b;
145 luaL_buffinit(L, &b);
146 for (i = 1; i <= n; i++) {
147 pushutfchar(L, i);
148 luaL_addvalue(&b);
149 }
150 luaL_pushresult(&b);
151 }
152 return 1;
153}
154
155
156/*
157** offset(s, n, [i]) -> index where n-th character counting from
158** position 'i' starts; 0 means character at 'i'.
159*/
160static int byteoffset (lua_State *L) {
161 size_t len;
162 const char *s = luaL_checklstring(L, 1, &len);
163 lua_Integer n = luaL_checkinteger(L, 2);
164 lua_Integer posi = (n >= 0) ? 1 : len + 1;
165 posi = u_posrelat(luaL_optinteger(L, 3, posi), len);
166 luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 3,
167 "position out of range");
168 if (n == 0) {
169 /* find beginning of current byte sequence */
170 while (posi > 0 && iscont(s + posi)) posi--;
171 }
172 else {
173 if (iscont(s + posi))
174 return luaL_error(L, "initial position is a continuation byte");
175 if (n < 0) {
176 while (n < 0 && posi > 0) { /* move back */
177 do { /* find beginning of previous character */
178 posi--;
179 } while (posi > 0 && iscont(s + posi));
180 n++;
181 }
182 }
183 else {
184 n--; /* do not move for 1st character */
185 while (n > 0 && posi < (lua_Integer)len) {
186 do { /* find beginning of next character */
187 posi++;
188 } while (iscont(s + posi)); /* (cannot pass final '\0') */
189 n--;
190 }
191 }
192 }
193 if (n == 0) /* did it find given character? */
194 lua_pushinteger(L, posi + 1);
195 else /* no such character */
196 lua_pushnil(L);
197 return 1;
198}
199
200
201static int iter_aux (lua_State *L) {
202 size_t len;
203 const char *s = luaL_checklstring(L, 1, &len);
204 lua_Integer n = lua_tointeger(L, 2) - 1;
205 if (n < 0) /* first iteration? */
206 n = 0; /* start from here */
207 else if (n < (lua_Integer)len) {
208 n++; /* skip current byte */
209 while (iscont(s + n)) n++; /* and its continuations */
210 }
211 if (n >= (lua_Integer)len)
212 return 0; /* no more codepoints */
213 else {
214 int code;
215 const char *next = utf8_decode(s + n, &code);
216 if (next == NULL || iscont(next))
217 return luaL_error(L, "invalid UTF-8 code");
218 lua_pushinteger(L, n + 1);
219 lua_pushinteger(L, code);
220 return 2;
221 }
222}
223
224
225static int iter_codes (lua_State *L) {
226 luaL_checkstring(L, 1);
227 lua_pushcfunction(L, iter_aux);
228 lua_pushvalue(L, 1);
229 lua_pushinteger(L, 0);
230 return 3;
231}
232
233
234/* pattern to match a single UTF-8 character */
235#define UTF8PATT "[\0-\x7F\xC2-\xF4][\x80-\xBF]*"
236
237
238static const luaL_Reg funcs[] = {
239 {"offset", byteoffset},
240 {"codepoint", codepoint},
241 {"char", utfchar},
242 {"len", utflen},
243 {"codes", iter_codes},
244 /* placeholders */
245 {"charpattern", NULL},
246 {NULL, NULL}
247};
248
249
250LUAMOD_API int luaopen_utf8 (lua_State *L) {
251 luaL_newlib(L, funcs);
252 lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT)/sizeof(char) - 1);
253 lua_setfield(L, -2, "charpattern");
254 return 1;
255}
256
257