Add basic lua expression support to memview

Currently just supports basic field accesses (world.x, screen.y.z).
No support for world.x - 4, etc.

Closes #976

library/lua/utils.lua

@@ -652,4 +652,25 @@ function df_shortcut_env()
     return env
 end
 
+df_env = df_shortcut_env()
+
+function df_expr_to_ref(expr)
+    expr = expr:gsub('%["(.-)"%]', function(field) return '.' .. field end)
+        :gsub('%[\'(.-)\'%]', function(field) return '.' .. field end)
+    local parts = split_string(expr, '%.')
+    local obj = df_env[parts[1]]
+    for i = 2, #parts do
+        if i == #parts and type(obj[parts[i]]) ~= 'userdata' then
+            obj = obj:_field(parts[i])
+        else
+            obj = obj[parts[i]]
+        end
+    end
+    return obj
+end
+
+function addressof(obj)
+    return select(2, obj:sizeof())
+end
+
 return _ENV

plugins/devel/CMakeLists.txt

@@ -10,7 +10,7 @@ DFHACK_PLUGIN(dumpmats dumpmats.cpp)
 DFHACK_PLUGIN(eventExample eventExample.cpp)
 DFHACK_PLUGIN(frozen frozen.cpp)
 DFHACK_PLUGIN(kittens kittens.cpp)
-DFHACK_PLUGIN(memview memview.cpp)
+DFHACK_PLUGIN(memview memview.cpp memutils.cpp LINK_LIBRARIES lua)
 DFHACK_PLUGIN(nestboxes nestboxes.cpp)
 DFHACK_PLUGIN(notes notes.cpp)
 DFHACK_PLUGIN(onceExample onceExample.cpp)

plugins/devel/memutils.cpp

@@ -0,0 +1,71 @@
+#include <string>
+
+#include "Core.h"
+#include "LuaTools.h"
+#include "LuaWrapper.h"
+
+using namespace DFHack;
+using namespace DFHack::LuaWrapper;
+using namespace std;
+
+namespace memutils {
+    static lua_State *state;
+    static color_ostream_proxy *out;
+
+    struct initializer {
+        Lua::StackUnwinder *unwinder;
+        initializer()
+        {
+            if (!out)
+                out = new color_ostream_proxy(Core::getInstance().getConsole());
+            if (!state)
+                state = Lua::Open(*out);
+            unwinder = new Lua::StackUnwinder(state);
+        }
+        ~initializer()
+        {
+            delete unwinder;
+        }
+    };
+
+    struct cleaner {
+        ~cleaner()
+        {
+            if (state)
+            {
+                lua_close(state);
+                state = NULL;
+            }
+            if (out)
+            {
+                delete out;
+                out = NULL;
+            }
+        }
+    };
+
+    static cleaner g_cleaner;
+
+    void *lua_expr_to_addr(const char *expr)
+    {
+        initializer init;
+        Lua::PushModulePublic(*out, state, "utils", "df_expr_to_ref");
+        lua_pushstring(state, expr);
+        if (!Lua::SafeCall(*out, state, 1, 1))
+        {
+            out->printerr("Failed to evaluate %s\n", expr);
+            return NULL;
+        }
+
+        Lua::PushModulePublic(*out, state, "utils", "addressof");
+        lua_swap(state);
+        if (!Lua::SafeCall(*out, state, 1, 1) || !lua_isinteger(state, -1))
+        {
+            out->printerr("Failed to get address: %s\n", expr);
+            return NULL;
+        }
+
+        auto addr = uintptr_t(lua_tointeger(state, -1));
+        return (void*)addr;
+    }
+}

plugins/devel/memutils.h

@@ -0,0 +1,3 @@
+namespace memutils {
+    void *lua_expr_to_addr(const char *expr);
+}

plugins/devel/memview.cpp

@@ -8,6 +8,8 @@
 #include <vector>
 #include <sstream>
 
+#include "memutils.h"
+
 using std::vector;
 using std::string;
 using namespace DFHack;
@@ -138,7 +140,19 @@ command_result memview (color_ostream &out, vector <string> & parameters)
 {
     mymutex->lock();
     Core::getInstance().p->getMemRanges(memdata.ranges);
-    memdata.addr=(void *)convert(parameters[0],true);
+    if (parameters.empty())
+    {
+        memdata.addr = 0;
+    }
+    else if (toLower(parameters[0].substr(0, 2)) == "0x")
+    {
+        memdata.addr = (void *)convert(parameters[0],true);
+    }
+    else
+    {
+        memdata.addr = memutils::lua_expr_to_addr(parameters[0].c_str());
+    }
+
     if(memdata.addr==0)
     {
         Deinit();