Lua: add `pandoc.system` module (#5468)

The `system` Lua module provides utility functions to interact with the
operating- and file system. E.g.

    print(pandoc.system.get_current_directory())

or

    pandoc.system.with_temporary_directory('tikz', function (dir)
      -- write and compile a TikZ file with pdflatex
    end)

2 files changed, 36 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Lua/Module/System.hs b/src/Text/Pandoc/Lua/Module/System.hs
new file mode 100644
index 000000000..5149c2112
--- /dev/null
+++ b/src/Text/Pandoc/Lua/Module/System.hs
@@ -0,0 +1,34 @@
+{- |
+   Module      : Text.Pandoc.Lua.Module.System
+   Copyright   : © 2019 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+   Stability   : alpha
+
+Pandoc's system Lua module.
+-}
+module Text.Pandoc.Lua.Module.System
+  ( pushModule
+  ) where
+
+import Prelude
+import Foreign.Lua (Lua, NumResults)
+import Foreign.Lua.Module.System (arch, env, getwd, os,
+                                  with_env, with_tmpdir, with_wd)
+import Text.Pandoc.Lua.Util (addFunction, addField)
+
+import qualified Foreign.Lua as Lua
+
+-- | Push the pandoc.system module on the Lua stack.
+pushModule :: Lua NumResults
+pushModule = do
+  Lua.newtable
+  addField "arch" arch
+  addField "os" os
+  addFunction "environment" env
+  addFunction "get_current_directory" getwd
+  addFunction "with_environment" with_env
+  addFunction "with_temp_directory" with_tmpdir
+  addFunction "with_working_directory" with_wd
+  return 1
diff --git a/src/Text/Pandoc/Lua/Packages.hs b/src/Text/Pandoc/Lua/Packages.hs
index fdfa2238a..5f2751f52 100644
--- a/src/Text/Pandoc/Lua/Packages.hs
+++ b/src/Text/Pandoc/Lua/Packages.hs
@@ -25,6 +25,7 @@ import Text.Pandoc.Class (readDataFile, runIO, setUserDataDir)
 import qualified Foreign.Lua as Lua
 import Text.Pandoc.Lua.Module.Pandoc as Pandoc
 import Text.Pandoc.Lua.Module.MediaBag as MediaBag
+import Text.Pandoc.Lua.Module.System as System
 import Text.Pandoc.Lua.Module.Utils as Utils
 
 -- | Parameters used to create lua packages/modules.
@@ -52,6 +53,7 @@ pandocPackageSearcher pkgParams pkgName =
     "pandoc"          -> let datadir = luaPkgDataDir pkgParams
                          in pushWrappedHsFun (Pandoc.pushModule datadir)
     "pandoc.mediabag" -> pushWrappedHsFun MediaBag.pushModule
+    "pandoc.system"   -> pushWrappedHsFun System.pushModule
     "pandoc.utils"    -> let datadir = luaPkgDataDir pkgParams
                          in pushWrappedHsFun (Utils.pushModule datadir)
     _ -> searchPureLuaLoader