295 lines
8.8 KiB
C++
295 lines
8.8 KiB
C++
// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
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// This code is based on Lua 5.x implementation licensed under MIT License; see lua_LICENSE.txt for details
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#include "lualib.h"
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#include "lcommon.h"
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#define MAXUNICODE 0x10FFFF
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#define iscont(p) ((*(p)&0xC0) == 0x80)
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// from strlib
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// translate a relative string position: negative means back from end
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static int u_posrelat(int pos, size_t len)
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{
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if (pos >= 0)
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return pos;
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else if (0u - (size_t)pos > len)
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return 0;
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else
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return (int)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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static const char* utf8_decode(const char* o, int* val)
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{
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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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res = c;
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else
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{
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int count = 0; // to count number of continuation bytes
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while (c & 0x40)
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{ // 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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}
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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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}
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if (val)
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*val = res;
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return (const char*)s + 1; // +1 to include first byte
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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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static int utflen(lua_State* L)
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{
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int n = 0;
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size_t len;
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const char* s = luaL_checklstring(L, 1, &len);
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int posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
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int posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
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luaL_argcheck(L, 1 <= posi && --posi <= (int)len, 2, "initial position out of string");
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luaL_argcheck(L, --posj < (int)len, 3, "final position out of string");
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while (posi <= posj)
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{
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const char* s1 = utf8_decode(s + posi, NULL);
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if (s1 == NULL)
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{ // 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 = (int)(s1 - s);
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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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/*
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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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static int codepoint(lua_State* L)
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{
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size_t len;
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const char* s = luaL_checklstring(L, 1, &len);
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int posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
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int pose = u_posrelat(luaL_optinteger(L, 3, posi), len);
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int n;
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const char* se;
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luaL_argcheck(L, posi >= 1, 2, "out of range");
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luaL_argcheck(L, pose <= (int)len, 3, "out of range");
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if (posi > pose)
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return 0; // empty interval; return no values
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if (pose - posi >= INT_MAX) // (int -> int) overflow?
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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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n = 0;
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se = s + pose;
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for (s += posi - 1; s < se;)
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{
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int code;
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s = utf8_decode(s, &code);
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if (s == NULL)
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luaL_error(L, "invalid UTF-8 code");
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lua_pushinteger(L, code);
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n++;
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}
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return n;
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}
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// from Lua 5.3 lobject.h
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#define UTF8BUFFSZ 8
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// from Lua 5.3 lobject.c, copied verbatim + static
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static int luaO_utf8esc(char* buff, unsigned long x)
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{
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int n = 1; // number of bytes put in buffer (backwards)
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LUAU_ASSERT(x <= 0x10FFFF);
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if (x < 0x80) // ascii?
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buff[UTF8BUFFSZ - 1] = cast_to(char, x);
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else
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{ // need continuation bytes
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unsigned int mfb = 0x3f; // maximum that fits in first byte
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do
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{ // add continuation bytes
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buff[UTF8BUFFSZ - (n++)] = cast_to(char, 0x80 | (x & 0x3f));
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x >>= 6; // remove added bits
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mfb >>= 1; // now there is one less bit available in first byte
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} while (x > mfb); // still needs continuation byte?
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buff[UTF8BUFFSZ - n] = cast_to(char, (~mfb << 1) | x); // add first byte
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}
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return n;
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}
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// lighter replacement for pushutfchar; doesn't push any string onto the stack
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static int buffutfchar(lua_State* L, int arg, char* buff, const char** charstr)
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{
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int 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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int l = luaO_utf8esc(buff, cast_to(long, code));
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*charstr = buff + UTF8BUFFSZ - l;
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return l;
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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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** This version avoids the need to make more invasive upgrades elsewhere (like
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** implementing the %U escape in lua_pushfstring) and avoids pushing string
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** objects for each codepoint in the multi-argument case. -Jovanni
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*/
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static int utfchar(lua_State* L)
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{
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char buff[UTF8BUFFSZ];
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const char* charstr;
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int n = lua_gettop(L); // number of arguments
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if (n == 1)
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{ // optimize common case of single char
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int l = buffutfchar(L, 1, buff, &charstr);
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lua_pushlstring(L, charstr, l);
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}
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else
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{
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luaL_Buffer b;
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luaL_buffinit(L, &b);
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for (int i = 1; i <= n; i++)
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{
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int l = buffutfchar(L, i, buff, &charstr);
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luaL_addlstring(&b, charstr, l, -1);
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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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static int byteoffset(lua_State* L)
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{
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size_t len;
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const char* s = luaL_checklstring(L, 1, &len);
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int n = luaL_checkinteger(L, 2);
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int posi = (n >= 0) ? 1 : (int)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 <= (int)len, 3, "position out of range");
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if (n == 0)
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{
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// find beginning of current byte sequence
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while (posi > 0 && iscont(s + posi))
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posi--;
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}
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else
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{
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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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{
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while (n < 0 && posi > 0)
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{ // move back
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do
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{ // 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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}
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else
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{
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n--; // do not move for 1st character
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while (n > 0 && posi < (int)len)
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{
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do
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{ // 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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static int iter_aux(lua_State* L)
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{
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size_t len;
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const char* s = luaL_checklstring(L, 1, &len);
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int 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 < (int)len)
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{
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n++; // skip current byte
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while (iscont(s + n))
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n++; // and its continuations
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}
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if (n >= (int)len)
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return 0; // no more codepoints
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else
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{
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int code;
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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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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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return 2;
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}
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}
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static int iter_codes(lua_State* L)
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{
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luaL_checkstring(L, 1);
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lua_pushcfunction(L, iter_aux, NULL);
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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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// 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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{"char", utfchar},
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{"len", utflen},
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{"codes", iter_codes},
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{NULL, NULL},
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};
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int luaopen_utf8(lua_State* L)
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{
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luaL_register(L, LUA_UTF8LIBNAME, funcs);
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lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT) / sizeof(char) - 1);
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lua_setfield(L, -2, "charpattern");
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return 1;
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}
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