Implement a per-save lua init script.

Lua API.html

@@ -404,7 +404,10 @@ <h1 class="title">DFHack Lua API</h1>
 <li><a class="reference internal" href="#sort" id="id54">sort</a></li>
 </ul>
 </li>
-<li><a class="reference internal" href="#scripts" id="id55">Scripts</a></li>
+<li><a class="reference internal" href="#scripts" id="id55">Scripts</a><ul>
+<li><a class="reference internal" href="#save-init-script" id="id56">Save init script</a></li>
+</ul>
+</li>
 </ul>
 </div>
 <p>The current version of DFHack has extensive support for
@@ -1034,6 +1037,9 @@ <h2><a class="toc-backref" href="#id18">C++ function wrappers</a></h2>
 <li><p class="first"><tt class="docutils literal">dfhack.getHackPath()</tt></p>
 <p>Returns the dfhack directory path, i.e. <tt class="docutils literal"><span class="pre">&quot;.../df/hack/&quot;</span></tt>.</p>
 </li>
+<li><p class="first"><tt class="docutils literal">dfhack.getSavePath()</tt></p>
+<p>Returns the path to the current save directory, or <em>nil</em> if no save loaded.</p>
+</li>
 <li><p class="first"><tt class="docutils literal">dfhack.getTickCount()</tt></p>
 <p>Returns the tick count in ms, exactly as DF ui uses.</p>
 </li>
@@ -3064,6 +3070,25 @@ <h1><a class="toc-backref" href="#id55">Scripts</a></h1>
 </li>
 </ul>
 <p>Note that this function lets errors propagate to the caller.</p>
+<div class="section" id="save-init-script">
+<h2><a class="toc-backref" href="#id56">Save init script</a></h2>
+<p>If a save directory contains a file called <tt class="docutils literal">raw/init.lua</tt>, it is
+automatically loaded and executed every time the save is loaded. It
+can also define the following functions to be called by dfhack:</p>
+<ul>
+<li><p class="first"><tt class="docutils literal">function onStateChange(op) ... end</tt></p>
+<p>Automatically called from the regular onStateChange event as long
+as the save is still loaded. This avoids the need to install a hook
+into the global <tt class="docutils literal">dfhack.onStateChange</tt> table, with associated
+cleanup concerns.</p>
+</li>
+<li><p class="first"><tt class="docutils literal">function onUnload() ... end</tt></p>
+<p>Called when the save containing the script is unloaded. This function
+should clean up any global hooks installed by the script.</p>
+</li>
+</ul>
+<p>Within the init script, the path to the save directory is available as <tt class="docutils literal">SAVE_PATH</tt>.</p>
+</div>
 </div>
 </div>
 </body>

Lua API.rst

@@ -741,6 +741,10 @@ can be omitted.
 
   Returns the dfhack directory path, i.e. ``".../df/hack/"``.
 
+* ``dfhack.getSavePath()``
+
+  Returns the path to the current save directory, or *nil* if no save loaded.
+
 * ``dfhack.getTickCount()``
 
   Returns the tick count in ms, exactly as DF ui uses.
@@ -2993,3 +2997,24 @@ from other scripts) in any context, via the same function the core uses:
   The ``name`` argument should be the name stem, as would be used on the command line.
 
 Note that this function lets errors propagate to the caller.
+
+Save init script
+================
+
+If a save directory contains a file called ``raw/init.lua``, it is
+automatically loaded and executed every time the save is loaded. It
+can also define the following functions to be called by dfhack:
+
+* ``function onStateChange(op) ... end``
+
+  Automatically called from the regular onStateChange event as long
+  as the save is still loaded. This avoids the need to install a hook
+  into the global ``dfhack.onStateChange`` table, with associated
+  cleanup concerns.
+
+* ``function onUnload() ... end``
+
+  Called when the save containing the script is unloaded. This function
+  should clean up any global hooks installed by the script.
+
+Within the init script, the path to the save directory is available as ``SAVE_PATH``.

library/LuaTools.cpp

@@ -1551,6 +1551,10 @@ void DFHack::Lua::Notification::bind(lua_State *state, const char *name)
 
 void OpenDFHackApi(lua_State *state);
 
+namespace DFHack { namespace Lua { namespace Core {
+    static void InitCoreContext();
+}}}
+
 lua_State *DFHack::Lua::Open(color_ostream &out, lua_State *state)
 {
     if (!state)
@@ -1654,6 +1658,10 @@ lua_State *DFHack::Lua::Open(color_ostream &out, lua_State *state)
     lua_dup(state);
     lua_rawseti(state, LUA_REGISTRYINDEX, LUA_RIDX_GLOBALS);
 
+    // Init core-context specific stuff before loading dfhack.lua
+    if (IsCoreContext(state))
+        Lua::Core::InitCoreContext();
+
     // load dfhack.lua
     Require(out, state, "dfhack");
 
@@ -1829,8 +1837,12 @@ void DFHack::Lua::Core::Init(color_ostream &out)
 
     State = luaL_newstate();
 
+    // Calls InitCoreContext after checking IsCoreContext
     Lua::Open(out, State);
+}
 
+static void Lua::Core::InitCoreContext()
+{
     lua_newtable(State);
     lua_rawsetp(State, LUA_REGISTRYINDEX, &DFHACK_TIMEOUTS_TOKEN);
 

library/lua/dfhack.lua

@@ -328,9 +328,11 @@ end
 
 -- Command scripts
 
-dfhack.internal.scripts = dfhack.internal.scripts or {}
+local internal = dfhack.internal
 
-local scripts = dfhack.internal.scripts
+internal.scripts = internal.scripts or {}
+
+local scripts = internal.scripts
 local hack_path = dfhack.getHackPath()
 
 function dfhack.run_script(name,...)
@@ -349,5 +351,42 @@ function dfhack.run_script(name,...)
     return f(...)
 end
 
+-- Per-save init file
+
+function dfhack.getSavePath()
+    if dfhack.isWorldLoaded() then
+        return dfhack.getDFPath() .. '/data/save/' .. df.global.world.cur_savegame.save_dir
+    end
+end
+
+if dfhack.is_core_context then
+    dfhack.onStateChange.DFHACK_PER_SAVE = function(op)
+        if op == SC_WORLD_LOADED or op == SC_WORLD_UNLOADED then
+            if internal.save_init then
+                if internal.save_init.onUnload then
+                    safecall(internal.save_init.onUnload)
+                end
+                internal.save_init = nil
+            end
+
+            local path = dfhack.getSavePath()
+
+            if path and op == SC_WORLD_LOADED then
+                local env = setmetatable({ SAVE_PATH = path }, { __index = base_env })
+                local f,perr = loadfile(path..'/raw/init.lua', 't', env)
+                if f == nil then
+                    if not string.match(perr, 'No such file or directory') then
+                        dfhack.printerr(perr)
+                    end
+                elseif safecall(f) then
+                    internal.save_init = env
+                end
+            end
+        elseif internal.save_init and internal.save_init.onStateChange then
+            safecall(internal.save_init.onStateChange, op)
+        end
+    end
+end
+
 -- Feed the table back to the require() mechanism.
 return dfhack