[Feature] Add UTF8 `sub` and `len` variants for rspamd_text

diff --git a/src/lua/lua_text.c b/src/lua/lua_text.c
index 7ce7440c79c80662cc97007e74daf5386a20af32..b45ee1743da571cb80839b723e884829fcc1d1f8 100644 (file)
--- a/src/lua/lua_text.c
+++ b/src/lua/lua_text.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Vsevolod Stakhov
+ * Copyright 2025 Vsevolod Stakhov
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,6 +72,12 @@ LUA_FUNCTION_DEF(text, byte);
  * @return {number} length of string in **bytes**
  */
 LUA_FUNCTION_DEF(text, len);
+/***
+ * @method rspamd_text:len_utf8()
+ * Returns length of a string
+ * @return {number} length of string in **bytes**
+ */
+LUA_FUNCTION_DEF(text, len_utf8);
 /***
  * @method rspamd_text:str()
  * Converts text to string by copying its content
@@ -105,6 +111,12 @@ LUA_FUNCTION_DEF(text, span);
  * @return {rspamd_text} new rspamd_text with span (must be careful when using with owned texts...)
  */
 LUA_FUNCTION_DEF(text, sub);
+/***
+ * @method rspamd_text:sub_utf8(start[, len])
+ * Returns a substring for lua_text similar to string.sub from Lua using UTF8 points
+ * @return {rspamd_text} new rspamd_text with span (must be careful when using with owned texts...)
+ */
+LUA_FUNCTION_DEF(text, sub_utf8);
 /***
  * @method rspamd_text:lines([stringify])
  * Returns an iter over all lines as rspamd_text objects or as strings if `stringify` is true
@@ -238,12 +250,14 @@ static const struct luaL_reg textlib_f[] = {
 
 static const struct luaL_reg textlib_m[] = {
        LUA_INTERFACE_DEF(text, len),
+       LUA_INTERFACE_DEF(text, len_utf8),
        LUA_INTERFACE_DEF(text, str),
        LUA_INTERFACE_DEF(text, ptr),
        LUA_INTERFACE_DEF(text, take_ownership),
        LUA_INTERFACE_DEF(text, save_in_file),
        LUA_INTERFACE_DEF(text, span),
        LUA_INTERFACE_DEF(text, sub),
+       LUA_INTERFACE_DEF(text, sub_utf8),
        LUA_INTERFACE_DEF(text, lines),
        LUA_INTERFACE_DEF(text, split),
        LUA_INTERFACE_DEF(text, at),
@@ -1538,8 +1552,7 @@ lua_text_exclude_chars(lua_State *L)
                        pat++;
                        patlen--;
                }
-               for (; patlen > 0 && BITOP(byteset, *(unsigned char *) pat, |=); pat++, patlen--)
-                       ;
+               for (; patlen > 0 && BITOP(byteset, *(unsigned char *) pat, |=); pat++, patlen--);
 
                p = t->start;
                end = t->start + t->len;
@@ -1762,6 +1775,91 @@ lua_text_strtoul(lua_State *L)
        return 1;
 }
 
+static int
+lua_text_len_utf8(lua_State *L)
+{
+       LUA_TRACE_POINT;
+       struct rspamd_lua_text *t = lua_check_text(L, 1);
+       if (t != NULL) {
+               const char *s = t->start;
+               int32_t count = 0, i = 0;
+               UChar32 c;
+               while (i < t->len) {
+                       U8_NEXT(s, i, t->len, c);
+                       if (c < 0) {
+                               lua_pushnil(L);
+                               return 1;
+                       }
+                       count++;
+               }
+
+               lua_pushinteger(L, count);
+               return 1;
+       }
+       else {
+               return luaL_error(L, "invalid arguments");
+       }
+}
+
+static int
+lua_text_sub_utf8(lua_State *L)
+{
+       LUA_TRACE_POINT;
+       struct rspamd_lua_text *t = lua_check_text(L, 1);
+       if (t == NULL) {
+               return luaL_error(L, "invalid arguments");
+       }
+
+       UChar32 c;
+
+       int32_t start = luaL_checkinteger(L, 2);
+       int32_t finish = luaL_optinteger(L, 3, -1);
+
+       int32_t len_utf8 = 0;
+       int32_t i = 0;
+       while (i < t->len) {
+               U8_NEXT(t->start, i, t->len, c);
+               if (c < 0) {
+                       lua_pushnil(L);
+                       return 1;
+               }
+
+               len_utf8++;
+       }
+
+       start = relative_pos_start(start, len_utf8);
+       finish = relative_pos_end(finish, len_utf8);
+
+       if (start > finish) {
+               lua_new_text(L, "", 0, TRUE);
+               return 1;
+       }
+
+       const char *sub_start = t->start;
+       const char *sub_end = t->start;
+       int32_t char_pos = 0, remain, utf8_idx = 0;
+
+       while (char_pos < t->len && utf8_idx < start - 1) {
+               U8_NEXT(t->start, char_pos, t->len, c);
+               sub_start = &t->start[char_pos];
+               utf8_idx++;
+       }
+
+       remain = (t->start + t->len) - sub_start;
+       char_pos = 0;
+
+       while (char_pos < remain && utf8_idx < finish) {
+               U8_NEXT(sub_start, char_pos, remain, c);
+               sub_end = &sub_start[char_pos];
+               utf8_idx++;
+       }
+
+       /* Copy as we have no other options to make it safe */
+       lua_new_text(L, sub_start, sub_end - sub_start, TRUE);
+
+       return 1;
+}
+
 /* Used to distinguish lua text metatable */
 static const unsigned int rspamd_lua_text_cookie = 0x2b21ef6fU;