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"use strict";
const lua = require('./lua.js');
const lauxlib = require('./lauxlib.js');
const MAXUNICODE = 0x10FFFF;
const iscont = function(p) {
let c = p & 0xC0;
return c === 0x80;
};
/* translate a relative string position: negative means back from end */
const u_posrelat = function(pos, len) {
if (pos >= 0) return pos;
else if (0 - pos > len) return 0;
else return len + pos + 1;
};
/*
** Decode one UTF-8 sequence, returning NULL if byte sequence is invalid.
*/
const limits = [0xFF, 0x7F, 0x7FF, 0xFFFF];
const utf8_decode = function(s, pos) {
let c = s[pos];
let res = 0; /* final result */
if (c < 0x80) /* ascii? */
res = c;
else {
let count = 0; /* to count number of continuation bytes */
while (c & 0x40) { /* still have continuation bytes? */
let cc = s[pos + (++count)]; /* read next byte */
if ((cc & 0xC0) !== 0x80) /* not a continuation byte? */
return null; /* invalid byte sequence */
res = (res << 6) | (cc & 0x3F); /* add lower 6 bits from cont. byte */
c <<= 1; /* to test next bit */
}
res |= ((c & 0x7F) << (count * 5)); /* add first byte */
if (count > 3 || res > MAXUNICODE || res <= limits[count])
return null; /* invalid byte sequence */
pos += count; /* skip continuation bytes read */
}
return {
code: res,
pos: pos + 1
};
};
/*
** utf8len(s [, i [, j]]) --> number of characters that start in the
** range [i,j], or nil + current position if 's' is not well formed in
** that interval
*/
const utflen = function(L) {
let n = 0;
let s = lauxlib.luaL_checkstring(L, 1);
let len = s.length;
let posi = u_posrelat(lauxlib.luaL_optinteger(L, 2, 1), len);
let posj = u_posrelat(lauxlib.luaL_optinteger(L, 3, -1), len);
lauxlib.luaL_argcheck(L, 1 <= posi && --posi <= len, 2, lua.to_luastring("initial position out of string"));
lauxlib.luaL_argcheck(L, --posj < len, 3, lua.to_luastring("final position out of string"));
while (posi <= posj) {
let dec = utf8_decode(s, posi);
if (dec === null) { /* conversion error? */
lua.lua_pushnil(L); /* return nil ... */
lua.lua_pushinteger(L, posi + 1); /* ... and current position */
return 2;
}
posi = dec.pos;
n++;
}
lua.lua_pushinteger(L, n);
return 1;
};
const pushutfchar = function(L, arg) {
let code = lauxlib.luaL_checkinteger(L, arg);
lauxlib.luaL_argcheck(L, 0 <= code && code <= MAXUNICODE, arg, lua.to_luastring("value out of range", true));
lua.lua_pushstring(L, lua.to_luastring(String.fromCodePoint(code)));
};
/*
** utfchar(n1, n2, ...) -> char(n1)..char(n2)...
*/
const utfchar = function(L) {
let n = lua.lua_gettop(L); /* number of arguments */
if (n === 1) /* optimize common case of single char */
pushutfchar(L, 1);
else {
let b = new lauxlib.luaL_Buffer();
lauxlib.luaL_buffinit(L, b);
for (let i = 1; i <= n; i++) {
pushutfchar(L, i);
lauxlib.luaL_addvalue(b);
}
lauxlib.luaL_pushresult(b);
}
return 1;
};
/*
** offset(s, n, [i]) -> index where n-th character counting from
** position 'i' starts; 0 means character at 'i'.
*/
const byteoffset = function(L) {
let s = lauxlib.luaL_checkstring(L, 1);
let n = lauxlib.luaL_checkinteger(L, 2);
let posi = n >= 0 ? 1 : s.length + 1;
posi = u_posrelat(lauxlib.luaL_optinteger(L, 3, posi), s.length);
lauxlib.luaL_argcheck(L, 1 <= posi && --posi <= s.length, 3, lua.to_luastring("position out of range", true));
if (n === 0) {
/* find beginning of current byte sequence */
while (posi > 0 && iscont(s[posi])) posi--;
} else {
if (iscont(s[posi]))
lauxlib.luaL_error(L, lua.to_luastring("initial position is a continuation byte", true));
if (n < 0) {
while (n < 0 && posi > 0) { /* move back */
do { /* find beginning of previous character */
posi--;
} while (posi > 0 && iscont(s[posi]));
n++;
}
} else {
n--; /* do not move for 1st character */
while (n > 0 && posi < s.length) {
do { /* find beginning of next character */
posi++;
} while (iscont(s[posi])); /* (cannot pass final '\0') */
n--;
}
}
}
if (n === 0) /* did it find given character? */
lua.lua_pushinteger(L, posi + 1);
else /* no such character */
lua.lua_pushnil(L);
return 1;
};
/*
** codepoint(s, [i, [j]]) -> returns codepoints for all characters
** that start in the range [i,j]
*/
const codepoint = function(L) {
let s = lauxlib.luaL_checkstring(L, 1);
let posi = u_posrelat(lauxlib.luaL_optinteger(L, 2, 1), s.length);
let pose = u_posrelat(lauxlib.luaL_optinteger(L, 3, posi), s.length);
lauxlib.luaL_argcheck(L, posi >= 1, 2, lua.to_luastring("out of range", true));
lauxlib.luaL_argcheck(L, pose <= s.length, 3, lua.to_luastring("out of range", true));
if (posi > pose) return 0; /* empty interval; return no values */
if (pose - posi >= Number.MAX_SAFE_INTEGER)
return lauxlib.luaL_error(L, lua.to_luastring("string slice too long", true));
let n = (pose - posi) + 1;
lauxlib.luaL_checkstack(L, n, lua.to_luastring("string slice too long", true));
n = 0;
for (posi -= 1; posi < pose;) {
let dec = utf8_decode(s, posi);
if (dec === null)
return lauxlib.luaL_error(L, lua.to_luastring("invalid UTF-8 code", true));
lua.lua_pushinteger(L, dec.code);
posi = dec.pos;
n++;
}
return n;
};
const iter_aux = function(L) {
let s = lauxlib.luaL_checkstring(L, 1);
let len = s.length;
let n = lua.lua_tointeger(L, 2) - 1;
if (n < 0) /* first iteration? */
n = 0; /* start from here */
else if (n < len) {
n++; /* skip current byte */
while (iscont(s[n])) n++; /* and its continuations */
}
if (n >= len)
return 0; /* no more codepoints */
else {
let dec = utf8_decode(s, n);
if (dec === null || iscont(s[dec.pos]))
return lauxlib.luaL_error(L, lua.to_luastring("invalid UTF-8 code", true));
lua.lua_pushinteger(L, n + 1);
lua.lua_pushinteger(L, dec.code);
return 2;
}
};
const iter_codes = function(L) {
lauxlib.luaL_checkstring(L, 1);
lua.lua_pushcfunction(L, iter_aux);
lua.lua_pushvalue(L, 1);
lua.lua_pushinteger(L, 0);
return 3;
};
const funcs = {
"char": utfchar,
"codepoint": codepoint,
"codes": iter_codes,
"len": utflen,
"offset": byteoffset
};
/* pattern to match a single UTF-8 character */
const UTF8PATT = [ 91, 0, 45, 127, 194, 45, 244, 93, 91, 128, 45, 191, 93, 42 ];
const luaopen_utf8 = function(L) {
lauxlib.luaL_newlib(L, funcs);
lua.lua_pushstring(L, UTF8PATT);
lua.lua_setfield(L, -2, lua.to_luastring("charpattern", true));
return 1;
};
module.exports.luaopen_utf8 = luaopen_utf8;
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