Simplify llDumpList2String() implementation, remove hard limits

Author: HaroldCindy

VM/src/lll.cpp

@@ -7,6 +7,7 @@
 #include "ltable.h"
 #include "lapi.h"
 #include "llsl.h"
+#include "lstrbuf.h"
 #include "mono_strings.h"
 #include "lgcgraph.h"
 
@@ -392,22 +393,19 @@ static int ll_dumplist2string(lua_State *L)
         return 1;
     }
 
-    lua_checkstack(L, 4);
+    const char *sep = nullptr;
+    size_t sep_size = 0;
+    sep = lua_tolstring(L, 2, &sep_size);
+
+    lua_checkstack(L, 5);
 
-    // Assume at least 1 character per item + separator length for our initial capacity.
-    // This is essentially a minimum but gets us in the right ballpark without counting everything
-    // StringBuilder will allocate more as needed.
-    // Set the max capacity to 64k (the max script size) + a little slop.
-    static const int max_size = 65 * 1024;
-    bool first = true;
-    lua_pushstring(L, "");
+    auto *strbuf = luaYB_push(L);
     for(int i=0; i<len; ++i)
     {
-        if (first)
-            lua_pushstring(L, "");
-        else
-            lua_pushvalue(L, 2);
-        first = false;
+        if (i != 0)
+        {
+            luaYB_appendmem(L, strbuf, sep, sep_size);
+        }
 
         // Unlike (string)list_val, this doesn't keep negative zero.
         lua_pushcfunction(L, lsl_cast_list_elem_poszero, "lsl_cast_list_elem_poszero");
@@ -418,13 +416,10 @@ static int ll_dumplist2string(lua_State *L)
         if (lua_type(L, -1) == LUA_TNIL)
             luaL_errorL(L, "non-LSL value in list");
 
-        lua_concat(L, 3);
-        if (lua_strlen(L, 3) > max_size)
-        {
-            luaD_throw(L, LUA_ERRMEM);
-        }
+        luaYB_addvalue(L, strbuf);
     }
 
+    luaYB_pushresult(L, strbuf);
     return 1;
 }
 

tests/conformance/list_operations.lsl

@@ -81,6 +81,8 @@ default
         checkTruth("huge indices2", (string)llList2List(NUMBERS, 201, 200) == "0123456789");
         checkTruth("huge indices3", (string)llList2List(NUMBERS, 1, 200) == "123456789");
         checkTruth("llDumpList2String", llDumpList2String(l, "|") == "1|1.100000|foo|00000000-0000-0000-0000-000000000000|<1.000000, 2.000000, 3.000000>|<1.000000, 2.000000, 3.000000, 4.000000>");
+        checkTruth("llDumpList2String", llDumpList2String([], "|") == "");
+        checkTruth("llDumpList2String", llDumpList2String([1], "|") == "1");
 
         list nums = [1, 2, 3, 4, 5, 6];
         checkTruth("deletelist1", (string)llDeleteSubList(nums, 1, 2) == "1456");