Accept non-string subjects with no __len metamethod in Lua 5.1.

1 files changed, 8 insertions, 6 deletions

diff --git a/src/algo.h b/src/algo.h
index bff1f67..80391bf 100644
--- a/src/algo.h
+++ b/src/algo.h
@@ -135,12 +135,14 @@ static void check_subject (lua_State *L, int pos, TArgExec *argE)
     argE->text = lua_touserdata (L, -1);
     lua_pop (L, 1);
 #if LUA_VERSION_NUM == 501
-    if (!luaL_callmeta (L, pos, "__len"))
-      luaL_argerror (L, pos, "subject has no valid __len metamethod");
-    if (lua_type (L, -1) != LUA_TNUMBER)
-      luaL_argerror (L, pos, "subject's length is not a number");
-    argE->textlen = lua_tointeger (L, -1);
-    lua_pop (L, 1);
+    if (luaL_callmeta (L, pos, "__len")) {
+      if (lua_type (L, -1) != LUA_TNUMBER)
+        luaL_argerror (L, pos, "subject's length is not a number");
+      argE->textlen = lua_tointeger (L, -1);
+      lua_pop (L, 1);
+    }
+    else
+      argE->textlen = lua_objlen (L, pos);
 #else
     argE->textlen = luaL_len (L, pos);
 #endif