256 lines
7.1 KiB
JavaScript
256 lines
7.1 KiB
JavaScript
"use strict";
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const {
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lua_gettop,
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lua_pushcfunction,
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lua_pushfstring,
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lua_pushinteger,
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lua_pushnil,
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lua_pushstring,
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lua_pushvalue,
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lua_setfield,
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lua_tointeger
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} = require('./lua.js');
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const {
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luaL_Buffer,
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luaL_addvalue,
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luaL_argcheck,
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luaL_buffinit,
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luaL_checkinteger,
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luaL_checkstack,
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luaL_checkstring,
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luaL_error,
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luaL_newlib,
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luaL_optinteger,
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luaL_pushresult
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} = require('./lauxlib.js');
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const {
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luastring_of,
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to_luastring
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} = require("./fengaricore.js");
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const MAXUNICODE = 0x10FFFF;
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const iscont = function(p) {
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let c = p & 0xC0;
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return c === 0x80;
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};
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/* translate a relative string position: negative means back from end */
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const u_posrelat = function(pos, len) {
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if (pos >= 0) return pos;
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else if (0 - pos > len) return 0;
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else return len + pos + 1;
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};
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/*
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** Decode one UTF-8 sequence, returning NULL if byte sequence is invalid.
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*/
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const limits = [0xFF, 0x7F, 0x7FF, 0xFFFF];
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const utf8_decode = function(s, pos) {
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let c = s[pos];
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let res = 0; /* final result */
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if (c < 0x80) /* ascii? */
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res = c;
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else {
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let count = 0; /* to count number of continuation bytes */
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while (c & 0x40) { /* still have continuation bytes? */
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let cc = s[pos + (++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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}
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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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pos += count; /* skip continuation bytes read */
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}
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return {
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code: res,
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pos: pos + 1
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};
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};
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/*
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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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** that interval
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*/
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const utflen = function(L) {
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let n = 0;
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let s = luaL_checkstring(L, 1);
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let len = s.length;
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let posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
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let posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
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luaL_argcheck(L, 1 <= posi && --posi <= len, 2, "initial position out of string");
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luaL_argcheck(L, --posj < len, 3, "final position out of string");
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while (posi <= posj) {
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let dec = utf8_decode(s, posi);
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if (dec === 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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return 2;
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}
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posi = dec.pos;
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n++;
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}
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lua_pushinteger(L, n);
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return 1;
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};
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const p_U = to_luastring("%U");
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const pushutfchar = function(L, arg) {
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let 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, p_U, code);
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};
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/*
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** utfchar(n1, n2, ...) -> char(n1)..char(n2)...
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*/
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const utfchar = function(L) {
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let n = lua_gettop(L); /* number of arguments */
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if (n === 1) /* optimize common case of single char */
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pushutfchar(L, 1);
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else {
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let b = new luaL_Buffer();
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luaL_buffinit(L, b);
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for (let i = 1; i <= n; i++) {
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pushutfchar(L, i);
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luaL_addvalue(b);
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}
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luaL_pushresult(b);
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}
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return 1;
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};
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/*
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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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*/
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const byteoffset = function(L) {
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let s = luaL_checkstring(L, 1);
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let n = luaL_checkinteger(L, 2);
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let posi = n >= 0 ? 1 : s.length + 1;
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posi = u_posrelat(luaL_optinteger(L, 3, posi), s.length);
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luaL_argcheck(L, 1 <= posi && --posi <= s.length, 3, "position out of range");
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if (n === 0) {
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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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} else {
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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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if (n < 0) {
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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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posi--;
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} while (posi > 0 && iscont(s[posi]));
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n++;
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}
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} else {
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n--; /* do not move for 1st character */
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while (n > 0 && posi < s.length) {
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do { /* find beginning of next character */
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posi++;
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} while (iscont(s[posi])); /* (cannot pass final '\0') */
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n--;
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}
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}
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}
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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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lua_pushnil(L);
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return 1;
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};
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/*
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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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*/
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const codepoint = function(L) {
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let s = luaL_checkstring(L, 1);
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let posi = u_posrelat(luaL_optinteger(L, 2, 1), s.length);
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let pose = u_posrelat(luaL_optinteger(L, 3, posi), s.length);
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luaL_argcheck(L, posi >= 1, 2, "out of range");
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luaL_argcheck(L, pose <= s.length, 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 >= Number.MAX_SAFE_INTEGER)
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return luaL_error(L, "string slice too long");
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let n = (pose - posi) + 1;
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luaL_checkstack(L, n, "string slice too long");
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n = 0;
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for (posi -= 1; posi < pose;) {
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let dec = utf8_decode(s, posi);
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if (dec === null)
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return luaL_error(L, "invalid UTF-8 code");
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lua_pushinteger(L, dec.code);
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posi = dec.pos;
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n++;
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}
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return n;
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};
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const iter_aux = function(L) {
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let s = luaL_checkstring(L, 1);
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let len = s.length;
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let 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 < 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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}
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if (n >= len)
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return 0; /* no more codepoints */
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else {
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let dec = utf8_decode(s, n);
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if (dec === null || iscont(s[dec.pos]))
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return luaL_error(L, to_luastring("invalid UTF-8 code"));
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lua_pushinteger(L, n + 1);
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lua_pushinteger(L, dec.code);
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return 2;
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}
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};
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const iter_codes = function(L) {
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luaL_checkstring(L, 1);
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lua_pushcfunction(L, iter_aux);
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lua_pushvalue(L, 1);
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lua_pushinteger(L, 0);
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return 3;
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};
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const funcs = {
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"char": utfchar,
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"codepoint": codepoint,
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"codes": iter_codes,
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"len": utflen,
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"offset": byteoffset
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};
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/* pattern to match a single UTF-8 character */
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const UTF8PATT = luastring_of(91, 0, 45, 127, 194, 45, 244, 93, 91, 128, 45, 191, 93, 42);
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const luaopen_utf8 = function(L) {
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luaL_newlib(L, funcs);
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lua_pushstring(L, UTF8PATT);
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lua_setfield(L, -2, to_luastring("charpattern", true));
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return 1;
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};
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module.exports.luaopen_utf8 = luaopen_utf8;
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