lutf8lib.c revision 1.7
1/* $NetBSD: lutf8lib.c,v 1.7 2017/04/26 13:17:33 mbalmer Exp $ */ 2 3/* 4** Id: lutf8lib.c,v 1.16 2016/12/22 13:08:50 roberto Exp 5** Standard library for UTF-8 manipulation 6** See Copyright Notice in lua.h 7*/ 8 9#define lutf8lib_c 10#define LUA_LIB 11 12#include "lprefix.h" 13 14 15#ifndef _KERNEL 16#include <assert.h> 17#include <limits.h> 18#include <stdlib.h> 19#include <string.h> 20#endif /* _KERNEL */ 21 22#include "lua.h" 23 24#include "lauxlib.h" 25#include "lualib.h" 26 27#define MAXUNICODE 0x10FFFF 28 29#define iscont(p) ((*(p) & 0xC0) == 0x80) 30 31 32/* from strlib */ 33/* translate a relative string position: negative means back from end */ 34static lua_Integer u_posrelat (lua_Integer pos, size_t len) { 35 if (pos >= 0) return pos; 36 else if (0u - (size_t)pos > len) return 0; 37 else return (lua_Integer)len + pos + 1; 38} 39 40 41/* 42** Decode one UTF-8 sequence, returning NULL if byte sequence is invalid. 43*/ 44static const char *utf8_decode (const char *o, int *val) { 45 static const unsigned int limits[] = {0xFF, 0x7F, 0x7FF, 0xFFFF}; 46 const unsigned char *s = (const unsigned char *)o; 47 unsigned int c = s[0]; 48 unsigned int res = 0; /* final result */ 49 if (c < 0x80) /* ascii? */ 50 res = c; 51 else { 52 int count = 0; /* to count number of continuation bytes */ 53 while (c & 0x40) { /* still have continuation bytes? */ 54 int cc = s[++count]; /* read next byte */ 55 if ((cc & 0xC0) != 0x80) /* not a continuation byte? */ 56 return NULL; /* invalid byte sequence */ 57 res = (res << 6) | (cc & 0x3F); /* add lower 6 bits from cont. byte */ 58 c <<= 1; /* to test next bit */ 59 } 60 res |= ((c & 0x7F) << (count * 5)); /* add first byte */ 61 if (count > 3 || res > MAXUNICODE || res <= limits[count]) 62 return NULL; /* invalid byte sequence */ 63 s += count; /* skip continuation bytes read */ 64 } 65 if (val) *val = res; 66 return (const char *)s + 1; /* +1 to include first byte */ 67} 68 69 70/* 71** utf8len(s [, i [, j]]) --> number of characters that start in the 72** range [i,j], or nil + current position if 's' is not well formed in 73** that interval 74*/ 75static int utflen (lua_State *L) { 76 int n = 0; 77 size_t len; 78 const char *s = luaL_checklstring(L, 1, &len); 79 lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len); 80 lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len); 81 luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2, 82 "initial position out of string"); 83 luaL_argcheck(L, --posj < (lua_Integer)len, 3, 84 "final position out of string"); 85 while (posi <= posj) { 86 const char *s1 = utf8_decode(s + posi, NULL); 87 if (s1 == NULL) { /* conversion error? */ 88 lua_pushnil(L); /* return nil ... */ 89 lua_pushinteger(L, posi + 1); /* ... and current position */ 90 return 2; 91 } 92 posi = s1 - s; 93 n++; 94 } 95 lua_pushinteger(L, n); 96 return 1; 97} 98 99 100/* 101** codepoint(s, [i, [j]]) -> returns codepoints for all characters 102** that start in the range [i,j] 103*/ 104static int codepoint (lua_State *L) { 105 size_t len; 106 const char *s = luaL_checklstring(L, 1, &len); 107 lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len); 108 lua_Integer pose = u_posrelat(luaL_optinteger(L, 3, posi), len); 109 int n; 110 const char *se; 111 luaL_argcheck(L, posi >= 1, 2, "out of range"); 112 luaL_argcheck(L, pose <= (lua_Integer)len, 3, "out of range"); 113 if (posi > pose) return 0; /* empty interval; return no values */ 114 if (pose - posi >= INT_MAX) /* (lua_Integer -> int) overflow? */ 115 return luaL_error(L, "string slice too long"); 116 n = (int)(pose - posi) + 1; 117 luaL_checkstack(L, n, "string slice too long"); 118 n = 0; 119 se = s + pose; 120 for (s += posi - 1; s < se;) { 121 int code; 122 s = utf8_decode(s, &code); 123 if (s == NULL) 124 return luaL_error(L, "invalid UTF-8 code"); 125 lua_pushinteger(L, code); 126 n++; 127 } 128 return n; 129} 130 131 132static void pushutfchar (lua_State *L, int arg) { 133 lua_Integer code = luaL_checkinteger(L, arg); 134 luaL_argcheck(L, 0 <= code && code <= MAXUNICODE, arg, "value out of range"); 135 lua_pushfstring(L, "%U", (long)code); 136} 137 138 139/* 140** utfchar(n1, n2, ...) -> char(n1)..char(n2)... 141*/ 142static int utfchar (lua_State *L) { 143 int n = lua_gettop(L); /* number of arguments */ 144 if (n == 1) /* optimize common case of single char */ 145 pushutfchar(L, 1); 146 else { 147 int i; 148 luaL_Buffer b; 149 luaL_buffinit(L, &b); 150 for (i = 1; i <= n; i++) { 151 pushutfchar(L, i); 152 luaL_addvalue(&b); 153 } 154 luaL_pushresult(&b); 155 } 156 return 1; 157} 158 159 160/* 161** offset(s, n, [i]) -> index where n-th character counting from 162** position 'i' starts; 0 means character at 'i'. 163*/ 164static int byteoffset (lua_State *L) { 165 size_t len; 166 const char *s = luaL_checklstring(L, 1, &len); 167 lua_Integer n = luaL_checkinteger(L, 2); 168 lua_Integer posi = (n >= 0) ? 1 : len + 1; 169 posi = u_posrelat(luaL_optinteger(L, 3, posi), len); 170 luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 3, 171 "position out of range"); 172 if (n == 0) { 173 /* find beginning of current byte sequence */ 174 while (posi > 0 && iscont(s + posi)) posi--; 175 } 176 else { 177 if (iscont(s + posi)) 178 luaL_error(L, "initial position is a continuation byte"); 179 if (n < 0) { 180 while (n < 0 && posi > 0) { /* move back */ 181 do { /* find beginning of previous character */ 182 posi--; 183 } while (posi > 0 && iscont(s + posi)); 184 n++; 185 } 186 } 187 else { 188 n--; /* do not move for 1st character */ 189 while (n > 0 && posi < (lua_Integer)len) { 190 do { /* find beginning of next character */ 191 posi++; 192 } while (iscont(s + posi)); /* (cannot pass final '\0') */ 193 n--; 194 } 195 } 196 } 197 if (n == 0) /* did it find given character? */ 198 lua_pushinteger(L, posi + 1); 199 else /* no such character */ 200 lua_pushnil(L); 201 return 1; 202} 203 204 205static int iter_aux (lua_State *L) { 206 size_t len; 207 const char *s = luaL_checklstring(L, 1, &len); 208 lua_Integer n = lua_tointeger(L, 2) - 1; 209 if (n < 0) /* first iteration? */ 210 n = 0; /* start from here */ 211 else if (n < (lua_Integer)len) { 212 n++; /* skip current byte */ 213 while (iscont(s + n)) n++; /* and its continuations */ 214 } 215 if (n >= (lua_Integer)len) 216 return 0; /* no more codepoints */ 217 else { 218 int code; 219 const char *next = utf8_decode(s + n, &code); 220 if (next == NULL || iscont(next)) 221 return luaL_error(L, "invalid UTF-8 code"); 222 lua_pushinteger(L, n + 1); 223 lua_pushinteger(L, code); 224 return 2; 225 } 226} 227 228 229static int iter_codes (lua_State *L) { 230 luaL_checkstring(L, 1); 231 lua_pushcfunction(L, iter_aux); 232 lua_pushvalue(L, 1); 233 lua_pushinteger(L, 0); 234 return 3; 235} 236 237 238/* pattern to match a single UTF-8 character */ 239#define UTF8PATT "[\0-\x7F\xC2-\xF4][\x80-\xBF]*" 240 241 242static const luaL_Reg funcs[] = { 243 {"offset", byteoffset}, 244 {"codepoint", codepoint}, 245 {"char", utfchar}, 246 {"len", utflen}, 247 {"codes", iter_codes}, 248 /* placeholders */ 249 {"charpattern", NULL}, 250 {NULL, NULL} 251}; 252 253 254LUAMOD_API int luaopen_utf8 (lua_State *L) { 255 luaL_newlib(L, funcs); 256 lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT)/sizeof(char) - 1); 257 lua_setfield(L, -2, "charpattern"); 258 return 1; 259} 260 261