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** $Id: lutf8lib.c,v 1.16 2016/12/22 13:08:50 roberto Exp $
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** Standard library for UTF-8 manipulation
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** See Copyright Notice in lua.h
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#define MAXUNICODE 0x10FFFF
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#define iscont(p) ((*(p) & 0xC0) == 0x80)
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/* translate a relative string position: negative means back from end */
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static lua_Integer u_posrelat (lua_Integer pos, size_t len) {
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if (pos >= 0) return pos;
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else if (0u - (size_t)pos > len) return 0;
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else return (lua_Integer)len + pos + 1;
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** Decode one UTF-8 sequence, returning NULL if byte sequence is invalid.
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static const char *utf8_decode (const char *o, int *val) {
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static const unsigned int limits[] = {0xFF, 0x7F, 0x7FF, 0xFFFF};
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const unsigned char *s = (const unsigned char *)o;
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unsigned int c = s[0];
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unsigned int res = 0; /* final result */
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if (c < 0x80) /* ascii? */
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int count = 0; /* to count number of continuation bytes */
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while (c & 0x40) { /* still have continuation bytes? */
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int cc = s[++count]; /* read next byte */
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if ((cc & 0xC0) != 0x80) /* not a continuation byte? */
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return NULL; /* invalid byte sequence */
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res = (res << 6) | (cc & 0x3F); /* add lower 6 bits from cont. byte */
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c <<= 1; /* to test next bit */
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res |= ((c & 0x7F) << (count * 5)); /* add first byte */
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if (count > 3 || res > MAXUNICODE || res <= limits[count])
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return NULL; /* invalid byte sequence */
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s += count; /* skip continuation bytes read */
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return (const char *)s + 1; /* +1 to include first byte */
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** utf8len(s [, i [, j]]) --> number of characters that start in the
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** range [i,j], or nil + current position if 's' is not well formed in
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static int utflen (lua_State *L) {
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const char *s = luaL_checklstring(L, 1, &len);
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lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
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lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
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luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2,
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"initial position out of string");
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luaL_argcheck(L, --posj < (lua_Integer)len, 3,
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"final position out of string");
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while (posi <= posj) {
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const char *s1 = utf8_decode(s + posi, NULL);
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if (s1 == NULL) { /* conversion error? */
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lua_pushnil(L); /* return nil ... */
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lua_pushinteger(L, posi + 1); /* ... and current position */
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lua_pushinteger(L, n);
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** codepoint(s, [i, [j]]) -> returns codepoints for all characters
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** that start in the range [i,j]
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static int codepoint (lua_State *L) {
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const char *s = luaL_checklstring(L, 1, &len);
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lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
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lua_Integer pose = u_posrelat(luaL_optinteger(L, 3, posi), len);
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luaL_argcheck(L, posi >= 1, 2, "out of range");
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luaL_argcheck(L, pose <= (lua_Integer)len, 3, "out of range");
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if (posi > pose) return 0; /* empty interval; return no values */
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if (pose - posi >= INT_MAX) /* (lua_Integer -> int) overflow? */
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return luaL_error(L, "string slice too long");
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n = (int)(pose - posi) + 1;
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luaL_checkstack(L, n, "string slice too long");
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for (s += posi - 1; s < se;) {
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s = utf8_decode(s, &code);
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return luaL_error(L, "invalid UTF-8 code");
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lua_pushinteger(L, code);
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static void pushutfchar (lua_State *L, int arg) {
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lua_Integer code = luaL_checkinteger(L, arg);
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luaL_argcheck(L, 0 <= code && code <= MAXUNICODE, arg, "value out of range");
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lua_pushfstring(L, "%U", (long)code);
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** utfchar(n1, n2, ...) -> char(n1)..char(n2)...
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static int utfchar (lua_State *L) {
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int n = lua_gettop(L); /* number of arguments */
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if (n == 1) /* optimize common case of single char */
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luaL_buffinit(L, &b);
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for (i = 1; i <= n; i++) {
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** offset(s, n, [i]) -> index where n-th character counting from
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** position 'i' starts; 0 means character at 'i'.
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static int byteoffset (lua_State *L) {
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const char *s = luaL_checklstring(L, 1, &len);
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lua_Integer n = luaL_checkinteger(L, 2);
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lua_Integer posi = (n >= 0) ? 1 : len + 1;
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posi = u_posrelat(luaL_optinteger(L, 3, posi), len);
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luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 3,
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"position out of range");
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/* find beginning of current byte sequence */
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while (posi > 0 && iscont(s + posi)) posi--;
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if (iscont(s + posi))
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luaL_error(L, "initial position is a continuation byte");
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while (n < 0 && posi > 0) { /* move back */
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do { /* find beginning of previous character */
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} while (posi > 0 && iscont(s + posi));
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n--; /* do not move for 1st character */
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while (n > 0 && posi < (lua_Integer)len) {
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do { /* find beginning of next character */
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} while (iscont(s + posi)); /* (cannot pass final '\0') */
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if (n == 0) /* did it find given character? */
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lua_pushinteger(L, posi + 1);
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else /* no such character */
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static int iter_aux (lua_State *L) {
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const char *s = luaL_checklstring(L, 1, &len);
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lua_Integer n = lua_tointeger(L, 2) - 1;
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if (n < 0) /* first iteration? */
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n = 0; /* start from here */
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else if (n < (lua_Integer)len) {
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n++; /* skip current byte */
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while (iscont(s + n)) n++; /* and its continuations */
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if (n >= (lua_Integer)len)
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return 0; /* no more codepoints */
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const char *next = utf8_decode(s + n, &code);
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if (next == NULL || iscont(next))
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return luaL_error(L, "invalid UTF-8 code");
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lua_pushinteger(L, n + 1);
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lua_pushinteger(L, code);
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static int iter_codes (lua_State *L) {
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luaL_checkstring(L, 1);
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lua_pushcfunction(L, iter_aux);
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lua_pushinteger(L, 0);
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/* pattern to match a single UTF-8 character */
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#define UTF8PATT "[\0-\x7F\xC2-\xF4][\x80-\xBF]*"
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static const luaL_Reg funcs[] = {
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{"offset", byteoffset},
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{"codepoint", codepoint},
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{"codes", iter_codes},
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{"charpattern", NULL},
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LUAMOD_API int luaopen_utf8 (lua_State *L) {
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luaL_newlib(L, funcs);
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lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT)/sizeof(char) - 1);
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lua_setfield(L, -2, "charpattern");
added
removed
uspace/lib/lua/src/lutf8lib.c
