Add option to include lua files (#14)

* feat: add include option to build table

allows to copy lua files into LUADIR while installing, for providing
loader wrappers or type annotations. behaves like `modules` key: can be
an array (file will be copied without renaming) or a `from => to` table

Author: alemidev

README.md

@@ -44,6 +44,12 @@ build = {
     -- Optional: if set to `false` pass `--no-default-features` to cargo
     default_features = false,
 
+    -- Optional: copy additional files to lua dir, can specify source path
+    include = {
+        "file.lua",
+        ["path/to/another/file.lua"] = "another-file.lua",
+    },
+
     -- Optional: pass additional features
     features = {"extra", "features"}
 }

src/luarocks/build/rust-mlua.lua

@@ -84,6 +84,21 @@ function mlua.run(rockspec, no_install)
                 return nil, "Failed installing " .. src .. " in " .. dst .. ": " .. err
             end
         end
+
+        local cwd = dir.path(dir.dir_name(rockspec.local_abs_filename), rockspec.name)
+        local luadir = path.lua_dir(rockspec.name, rockspec.version)
+
+        fs.make_dir(dir.dir_name(luadir))
+        for from, to in pairs(rockspec.build.include) do
+            if type(from) == "number" then
+                from = to
+            end
+            to = dir.path(luadir, to)
+            local ok, err = fs.copy(dir.path(cwd, from), to, "exec")
+            if not ok then
+                return nil, "Failed copying " .. from .. " in " .. to .. ": " .. err
+            end
+        end
     end
 
     return true