Backport Lua utf8 library;

CMakeLists.txt

@@ -330,6 +330,7 @@ set(LOVR_SRC
   src/core/zip.c
   src/api/api.c
   src/api/l_lovr.c
+  src/lib/lua/lutf8lib.c
   src/util.c
 )
 

Tupfile.lua

@@ -431,6 +431,7 @@ for spatializer, enabled in pairs(config.spatializers) do
 end
 
 src += 'src/lib/stb/*.c'
+src += 'src/lib/lua/*.c'
 src += (config.modules.audio or config.modules.data) and 'src/lib/miniaudio/*.c' or nil
 src += config.modules.data and 'src/lib/jsmn/*.c' or nil
 src += config.modules.data and 'src/lib/minimp3/*.c' or nil

src/api/api.c

@@ -1,5 +1,6 @@
 #include "api.h"
 #include "util.h"
+#include "lib/lua/lutf8lib.h"
 #include <lua.h>
 #include <lauxlib.h>
 #include <stdlib.h>
@@ -111,6 +112,7 @@ void luax_preload(lua_State* L) {
 #ifndef LOVR_DISABLE_TIMER
     { "lovr.timer", luaopen_lovr_timer },
 #endif
+    { "utf8", luaopen_utf8 },
     { NULL, NULL }
   };
 

src/lib/lua/lutf8lib.c

@@ -0,0 +1,331 @@
+/*
+** $Id: lutf8lib.c $
+** Standard library for UTF-8 manipulation
+**
+** Copyright © 1994–2021 Lua.org, PUC-Rio.
+**
+** Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+** associated documentation files (the "Software"), to deal in the Software without restriction,
+** including without limitation the rights to use, copy, modify, merge, publish, distribute,
+** sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+** furnished to do so, subject to the following conditions:
+**
+** The above copyright notice and this permission notice shall be included in all copies or
+** substantial portions of the Software.
+**
+** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+** NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+** NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+** DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#define lutf8lib_c
+#define LUA_LIB
+
+
+#include <assert.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "lua.h"
+
+#include "lauxlib.h"
+#include "lualib.h"
+
+
+#define MAXUNICODE      0x10FFFFu
+
+#define MAXUTF          0x7FFFFFFFu
+
+#define UTF8BUFFSZ      8
+
+/*
+** Integer type for decoded UTF-8 values; MAXUTF needs 31 bits.
+*/
+#if (UINT_MAX >> 30) >= 1
+typedef unsigned int utfint;
+#else
+typedef unsigned long utfint;
+#endif
+
+
+#define iscont(p)       ((*(p) & 0xC0) == 0x80)
+
+
+/* from strlib */
+/* translate a relative string position: negative means back from end */
+static lua_Integer u_posrelat (lua_Integer pos, size_t len) {
+  if (pos >= 0) return pos;
+  else if (0u - (size_t)pos > len) return 0;
+  else return (lua_Integer)len + pos + 1;
+}
+
+
+/*
+** Decode one UTF-8 sequence, returning NULL if byte sequence is
+** invalid.  The array 'limits' stores the minimum value for each
+** sequence length, to check for overlong representations. Its first
+** entry forces an error for non-ascii bytes with no continuation
+** bytes (count == 0).
+*/
+static const char *utf8_decode (const char *s, utfint *val, int strict) {
+  static const utfint limits[] =
+        {~(utfint)0, 0x80, 0x800, 0x10000u, 0x200000u, 0x4000000u};
+  unsigned int c = (unsigned char)s[0];
+  utfint res = 0;  /* final result */
+  if (c < 0x80)  /* ascii? */
+    res = c;
+  else {
+    int count = 0;  /* to count number of continuation bytes */
+    for (; c & 0x40; c <<= 1) {  /* while it needs continuation bytes... */
+      unsigned int cc = (unsigned char)s[++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 */
+    }
+    res |= ((utfint)(c & 0x7F) << (count * 5));  /* add first byte */
+    if (count > 5 || res > MAXUTF || res < limits[count])
+      return NULL;  /* invalid byte sequence */
+    s += count;  /* skip continuation bytes read */
+  }
+  if (strict) {
+    /* check for invalid code points; too large or surrogates */
+    if (res > MAXUNICODE || (0xD800u <= res && res <= 0xDFFFu))
+      return NULL;
+  }
+  if (val) *val = res;
+  return s + 1;  /* +1 to include first byte */
+}
+
+
+/*
+** utf8len(s [, i [, j [, lax]]]) --> number of characters that
+** start in the range [i,j], or nil + current position if 's' is not
+** well formed in that interval
+*/
+static int utflen (lua_State *L) {
+  lua_Integer n = 0;  /* counter for the number of characters */
+  size_t len;  /* string length in bytes */
+  const char *s = luaL_checklstring(L, 1, &len);
+  lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
+  lua_Integer posj = u_posrelat(luaL_optinteger(L, 3, -1), len);
+  int lax = lua_toboolean(L, 4);
+  luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 2,
+                   "initial position out of bounds");
+  luaL_argcheck(L, --posj < (lua_Integer)len, 3,
+                   "final position out of bounds");
+  while (posi <= posj) {
+    const char *s1 = utf8_decode(s + posi, NULL, !lax);
+    if (s1 == NULL) {  /* conversion error? */
+      lua_pushnil(L);  /* return nil ... */
+      lua_pushinteger(L, posi + 1);  /* ... and current position */
+      return 2;
+    }
+    posi = s1 - s;
+    n++;
+  }
+  lua_pushinteger(L, n);
+  return 1;
+}
+
+
+/*
+** codepoint(s, [i, [j [, lax]]]) -> returns codepoints for all
+** characters that start in the range [i,j]
+*/
+static int codepoint (lua_State *L) {
+  size_t len;
+  const char *s = luaL_checklstring(L, 1, &len);
+  lua_Integer posi = u_posrelat(luaL_optinteger(L, 2, 1), len);
+  lua_Integer pose = u_posrelat(luaL_optinteger(L, 3, posi), len);
+  int lax = lua_toboolean(L, 4);
+  int n;
+  const char *se;
+  luaL_argcheck(L, posi >= 1, 2, "out of bounds");
+  luaL_argcheck(L, pose <= (lua_Integer)len, 3, "out of bounds");
+  if (posi > pose) return 0;  /* empty interval; return no values */
+  if (pose - posi >= INT_MAX)  /* (lua_Integer -> int) overflow? */
+    return luaL_error(L, "string slice too long");
+  n = (int)(pose -  posi) + 1;  /* upper bound for number of returns */
+  luaL_checkstack(L, n, "string slice too long");
+  n = 0;  /* count the number of returns */
+  se = s + pose;  /* string end */
+  for (s += posi - 1; s < se;) {
+    utfint code;
+    s = utf8_decode(s, &code, !lax);
+    if (s == NULL)
+      return luaL_error(L, "invalid UTF-8 code");
+    lua_pushinteger(L, code);
+    n++;
+  }
+  return n;
+}
+
+
+static int utf8esc (char *buff, unsigned long x) {
+  int n = 1;  /* number of bytes put in buffer (backwards) */
+  lua_assert(x <= 0x7FFFFFFFu);
+  if (x < 0x80)  /* ascii? */
+    buff[UTF8BUFFSZ - 1] = (char) x;
+  else {  /* need continuation bytes */
+    unsigned int mfb = 0x3f;  /* maximum that fits in first byte */
+    do {  /* add continuation bytes */
+      buff[UTF8BUFFSZ - (n++)] = (char) (0x80 | (x & 0x3f));
+      x >>= 6;  /* remove added bits */
+      mfb >>= 1;  /* now there is one less bit available in first byte */
+    } while (x > mfb);  /* still needs continuation byte? */
+    buff[UTF8BUFFSZ - n] = (char) ((~mfb << 1) | x);  /* add first byte */
+  }
+  return n;
+}
+
+
+static void pushutfchar (lua_State *L, int arg) {
+  utfint code = (utfint)luaL_checkinteger(L, arg);
+  luaL_argcheck(L, code <= MAXUTF, arg, "value out of range");
+
+  char buff[UTF8BUFFSZ];
+  int l = utf8esc(buff, (long) code);
+  lua_pushlstring(L, buff + UTF8BUFFSZ - l, l);
+}
+
+
+/*
+** utfchar(n1, n2, ...)  -> char(n1)..char(n2)...
+*/
+static int utfchar (lua_State *L) {
+  int n = lua_gettop(L);  /* number of arguments */
+  if (n == 1)  /* optimize common case of single char */
+    pushutfchar(L, 1);
+  else {
+    int i;
+    luaL_Buffer b;
+    luaL_buffinit(L, &b);
+    for (i = 1; i <= n; i++) {
+      pushutfchar(L, i);
+      luaL_addvalue(&b);
+    }
+    luaL_pushresult(&b);
+  }
+  return 1;
+}
+
+
+/*
+** offset(s, n, [i])  -> index where n-th character counting from
+**   position 'i' starts; 0 means character at 'i'.
+*/
+static int byteoffset (lua_State *L) {
+  size_t len;
+  const char *s = luaL_checklstring(L, 1, &len);
+  lua_Integer n  = luaL_checkinteger(L, 2);
+  lua_Integer posi = (n >= 0) ? 1 : len + 1;
+  posi = u_posrelat(luaL_optinteger(L, 3, posi), len);
+  luaL_argcheck(L, 1 <= posi && --posi <= (lua_Integer)len, 3,
+                   "position out of bounds");
+  if (n == 0) {
+    /* find beginning of current byte sequence */
+    while (posi > 0 && iscont(s + posi)) posi--;
+  }
+  else {
+    if (iscont(s + posi))
+      return luaL_error(L, "initial position is a continuation byte");
+    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 < (lua_Integer)len) {
+         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_pushinteger(L, posi + 1);
+  else  /* no such character */
+    lua_pushnil(L);
+  return 1;
+}
+
+
+static int iter_aux (lua_State *L, int strict) {
+  size_t len;
+  const char *s = luaL_checklstring(L, 1, &len);
+  unsigned int n = (unsigned int) lua_tointeger(L, 2);
+  if (n < len) {
+    while (iscont(s + n)) n++;  /* skip continuation bytes */
+  }
+  if (n >= len)  /* (also handles original 'n' being negative) */
+    return 0;  /* no more codepoints */
+  else {
+    utfint code;
+    const char *next = utf8_decode(s + n, &code, strict);
+    if (next == NULL)
+      return luaL_error(L, "invalid UTF-8 code");
+    lua_pushinteger(L, n + 1);
+    lua_pushinteger(L, code);
+    return 2;
+  }
+}
+
+
+static int iter_auxstrict (lua_State *L) {
+  return iter_aux(L, 1);
+}
+
+static int iter_auxlax (lua_State *L) {
+  return iter_aux(L, 0);
+}
+
+
+static int iter_codes (lua_State *L) {
+  int lax = lua_toboolean(L, 2);
+  luaL_checkstring(L, 1);
+  lua_pushcfunction(L, lax ? iter_auxlax : iter_auxstrict);
+  lua_pushvalue(L, 1);
+  lua_pushinteger(L, 0);
+  return 3;
+}
+
+
+/* pattern to match a single UTF-8 character */
+#define UTF8PATT        "[%z\x01-\x7F\xC2-\xFD][\x80-\xBF]*"
+
+
+static const luaL_Reg funcs[] = {
+  {"offset", byteoffset},
+  {"codepoint", codepoint},
+  {"char", utfchar},
+  {"len", utflen},
+  {"codes", iter_codes},
+  /* placeholders */
+  {"charpattern", NULL},
+  {NULL, NULL}
+};
+
+
+int luaopen_utf8 (lua_State *L) {
+  lua_createtable(L, sizeof(funcs) / sizeof(funcs[0]), 0);
+  const luaL_Reg* f;
+  for (f = funcs; f->name; f++) {
+    if (f->func) {
+      lua_pushcfunction(L, f->func);
+    } else {
+      lua_pushboolean(L, 0);
+    }
+    lua_setfield(L, -2, f->name);
+  }
+  lua_pushlstring(L, UTF8PATT, sizeof(UTF8PATT)/sizeof(char) - 1);
+  lua_setfield(L, -2, "charpattern");
+  return 1;
+}

src/lib/lua/lutf8lib.h

@@ -0,0 +1,3 @@
+struct lua_State;
+
+int luaopen_utf8(struct lua_State *L);