Add an api function to get vtable address from version info.

LUA_API.rst

@@ -1168,6 +1168,10 @@ and are only documented here for completeness:
 
   Sets the global address ``name``. Returns the value of ``getAddress`` before the change.
 
+* ``dfhack.internal.getVTable(name)``
+
+  Returns the pre-extracted vtable address ``name``, or *nil*.
+
 * ``dfhack.internal.getBase()``
 
   Returns the base address of the process.

Lua API.html

@@ -1326,6 +1326,9 @@ global environment, persistent between calls to the script.</p>
 <li><p class="first"><tt class="docutils literal">dfhack.internal.setAddress(name, value)</tt></p>
 <p>Sets the global address <tt class="docutils literal">name</tt>. Returns the value of <tt class="docutils literal">getAddress</tt> before the change.</p>
 </li>
+<li><p class="first"><tt class="docutils literal">dfhack.internal.getVTable(name)</tt></p>
+<p>Returns the pre-extracted vtable address <tt class="docutils literal">name</tt>, or <em>nil</em>.</p>
+</li>
 <li><p class="first"><tt class="docutils literal">dfhack.internal.getBase()</tt></p>
 <p>Returns the base address of the process.</p>
 </li>

library/LuaApi.cpp

@@ -1080,6 +1080,17 @@ static int internal_setAddress(lua_State *L)
     return 1;
 }
 
+static int internal_getVTable(lua_State *L)
+{
+    const char *name = luaL_checkstring(L, 1);
+    uint32_t addr = (uint32_t)Core::getInstance().vinfo->getVTable(name);
+    if (addr)
+        lua_pushnumber(L, addr);
+    else
+        lua_pushnil(L);
+    return 1;
+}
+
 static int internal_getMemRanges(lua_State *L)
 {
     std::vector<DFHack::t_memrange> ranges;
@@ -1200,6 +1211,7 @@ static int internal_diffscan(lua_State *L)
 static const luaL_Reg dfhack_internal_funcs[] = {
     { "getAddress", internal_getAddress },
     { "setAddress", internal_setAddress },
+    { "getVTable", internal_getVTable },
     { "getMemRanges", internal_getMemRanges },
     { "memmove", internal_memmove },
     { "memcmp", internal_memcmp },