add utf8.reverse

4 files changed, 88 insertions, 0 deletions

diff --git a/core/src/xmake/engine.c b/core/src/xmake/engine.c
index bca1cce65..9ceabd156 100644
--- a/core/src/xmake/engine.c
+++ b/core/src/xmake/engine.c
@@ -287,6 +287,7 @@ tb_int_t xm_utf8_codepoint(lua_State *lua);
 tb_int_t xm_utf8_offset(lua_State *lua);
 tb_int_t xm_utf8_codes(lua_State *lua);
 tb_int_t xm_utf8_sub(lua_State *lua);
+tb_int_t xm_utf8_reverse(lua_State *lua);
 tb_int_t xm_utf8_lastof(lua_State *lua);
 tb_int_t xm_utf8_find(lua_State *lua);
 tb_int_t xm_utf8_width(lua_State *lua);
@@ -604,6 +605,7 @@ static luaL_Reg const g_utf8_functions[] = {
     {"len", xm_utf8_len},
     {"offset", xm_utf8_offset},
     {"sub", xm_utf8_sub},
+    {"reverse", xm_utf8_reverse},
     {"lastof", xm_utf8_lastof},
     {"find", xm_utf8_find},
     {"width", xm_utf8_width},
diff --git a/core/src/xmake/utf8/reverse.c b/core/src/xmake/utf8/reverse.c
new file mode 100644
index 000000000..0c0b7aaf7
--- /dev/null
+++ b/core/src/xmake/utf8/reverse.c
@@ -0,0 +1,57 @@
+/*!A cross-platform build utility based on Lua
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright (C) 2015-present, Xmake Open Source Community.
+ *
+ * @author      ruki
+ * @file        reverse.c
+ *
+ */
+
+/* //////////////////////////////////////////////////////////////////////////////////////
+ * includes
+ */
+#include "utf8.h"
+
+/* //////////////////////////////////////////////////////////////////////////////////////
+ * implementation
+ */
+
+/* utf8.reverse(s)
+ */
+tb_int_t xm_utf8_reverse(lua_State *lua) {
+    size_t len;
+    tb_char_t const* s = luaL_checklstring(lua, 1, &len);
+    if (len == 0) {
+        lua_pushliteral(lua, "");
+        return 1;
+    }
+
+    // do reverse
+    if (len < 1024) {
+        tb_char_t buf[1024 + 1];
+        xm_utf8_reverse_impl(s, len, buf);
+        lua_pushlstring(lua, buf, len);
+    } else {
+        tb_char_t* buf = (tb_char_t*)tb_malloc_bytes(len + 1);
+        if (buf) {
+            xm_utf8_reverse_impl(s, len, buf);
+            lua_pushlstring(lua, buf, len);
+            tb_free(buf);
+        } else {
+            lua_pushnil(lua);
+        }
+    }
+    return 1;
+}
diff --git a/core/src/xmake/utf8/utf8.c b/core/src/xmake/utf8/utf8.c
index ff6c33a1a..ace3a213c 100644
--- a/core/src/xmake/utf8/utf8.c
+++ b/core/src/xmake/utf8/utf8.c
@@ -476,3 +476,31 @@ tb_char_t const* xm_utf8_sub_impl(tb_char_t const* s, tb_size_t len, tb_long_t i
     return s + start_byte - 1;
 }
 
+tb_char_t* xm_utf8_reverse_impl(tb_char_t const* s, tb_size_t len, tb_char_t* buf) {
+    tb_assert_and_check_return_val(s && len && buf, tb_null);
+
+    tb_char_t const* p = s;
+    tb_char_t const* e = s + len;
+    tb_char_t* d = buf + len;
+
+    while (p < e) {
+        xm_utf8_int_t code;
+        tb_char_t const* next = xm_utf8_decode(p, &code, tb_false);
+        
+        // invalid utf8? treat as 1 byte
+        tb_size_t n = 1;
+        if (next) {
+            n = next - p;
+        }
+        
+        // safety check
+        if (p + n > e) n = e - p;
+
+        d -= n;
+        tb_memcpy(d, p, n);
+        p += n;
+    }
+    buf[len] = '\0';
+    return buf;
+}
+
diff --git a/core/src/xmake/utf8/utf8.h b/core/src/xmake/utf8/utf8.h
index fff81f1e5..fe83e8e86 100644
--- a/core/src/xmake/utf8/utf8.h
+++ b/core/src/xmake/utf8/utf8.h
@@ -55,5 +55,6 @@ tb_long_t           xm_utf8_find_impl(tb_char_t const* s, tb_size_t len, tb_char
 tb_long_t           xm_utf8_lastof_impl(tb_char_t const* s, tb_size_t len, tb_char_t const* sub, tb_size_t sublen);
 tb_long_t           xm_utf8_byte_impl(tb_char_t const* s, tb_size_t len, tb_long_t i, tb_long_t j, xm_utf8_codepoint_func_t func, tb_cpointer_t udata);
 tb_char_t const*    xm_utf8_sub_impl(tb_char_t const* s, tb_size_t len, tb_long_t i, tb_long_t j, tb_size_t* psublen);
+tb_char_t*          xm_utf8_reverse_impl(tb_char_t const* s, tb_size_t len, tb_char_t* buf);
 
 #endif