Add functions mkdir and rmdir

Author: tarleb

README.md

@@ -113,6 +113,43 @@ Returns:
 - A table of all entries in `directory` without the special entries (`.`
   and `..`).
 
+### mkdir
+
+`mkdir (dirname [, create_parent])`
+
+Create a new directory which is initially empty, or as near to
+empty as the operating system allows. The function throws an
+error if the directory cannot be created, e.g., if the parent
+directory does not exist or if a directory of the same name is
+already present.
+
+If the optional second parameter is provided and truthy, then all
+directories, including parent directories, are created as
+necessary.
+
+Parameters:
+
+`dirname`:
+:   name of the new directory
+
+`create_parent`:
+:   create parent directories if necessary
+
+### rmdir
+
+`rmdir (dirname [, recursive])`
+
+Remove an existing, empty directory. If `recursive` is given,
+then delete the directory and its contents recursively.
+
+Parameters:
+
+`dirname`:
+:   name of the directory to delete
+
+`recursive`:
+:   delete content recursively
+
 ### setenv {#system-setenv}
 
 `setenv (var, value)`

src/Foreign/Lua/Module/System.hs

@@ -42,6 +42,8 @@ pushModule = do
   addFunction "env" env
   addFunction "getenv" getenv
   addFunction "ls" ls
+  addFunction "mkdir" mkdir
+  addFunction "rmdir" rmdir
   addFunction "setenv" setenv
   addFunction "tmpdirname" tmpdirname
   addFunction "with_tmpdir" with_tmpdir
@@ -154,6 +156,25 @@ env = do
 getenv :: String -> Lua (Optional String)
 getenv name = ioToLua (Optional <$> Env.lookupEnv name)
 
+-- | Create a new directory which is initially empty, or as near to
+-- empty as the operating system allows.
+--
+-- If the optional second parameter is `false`, then create the new
+-- directory only if it doesn't exist yet. If the parameter is `true`,
+-- then parent directories are created as necessary.
+mkdir :: FilePath -> Bool -> Lua ()
+mkdir fp createParent =
+  if createParent
+  then ioToLua (Directory.createDirectoryIfMissing True fp)
+  else ioToLua (Directory.createDirectory fp)
+
+-- | Remove an existing directory.
+rmdir :: FilePath -> Bool -> Lua ()
+rmdir fp recursive =
+  if recursive
+  then ioToLua (Directory.removeDirectoryRecursive fp)
+  else ioToLua (Directory.removeDirectory fp)
+
 -- | Set the specified environment variable to a new value.
 setenv :: String -> String -> Lua ()
 setenv name value = ioToLua (Env.setEnv name value)

test/system-module-tests.lua

@@ -9,21 +9,8 @@ assert(type(system.compiler_name) == 'string')
 assert(type(system.compiler_version) == 'table')
 assert(type(system.os) == 'string')
 
-local token = 'Banana'
-function write_read_token (tmpdir)
-  local filename = tmpdir .. '/foo.txt'
-  local fh = io.open(filename, 'w')
-  fh:write(token .. '\n')
-  fh:close()
-  return io.open(filename):read '*l'
-end
-
--- with_tmpdir
-assert(system.with_tmpdir('.', 'foo', write_read_token) == token)
-assert(system.with_tmpdir('foo', write_read_token) == token)
-
--- tmpdirname
-assert(type(system.tmpdirname()) == 'string', "tmpdirname should return a string")
+-- currentdir
+assert(type(system.currentdir()) == 'string')
 
 -- env
 assert(type(system.env()) == 'table')
@@ -35,10 +22,7 @@ assert(#system.ls('.') == #system.ls())
 assert(pcall(system.ls, 'thisdoesnotexist') == false)
 assert(pcall(system.ls, 'README.md') == false)
 
--- currentdir
-assert(type(system.currentdir()) == 'string')
-
--- Complex scripts
+-- mkdir and rmdir
 function in_tmpdir (callback)
   local orig_dir = system.currentdir()
   return system.with_tmpdir(
@@ -52,6 +36,44 @@ function in_tmpdir (callback)
   )
 end
 
+function test_mkdir_rmdir ()
+  -- mkdir
+  assert(not pcall(system.mkdir, '.'), "should not be possible to create `.`")
+  assert(pcall(system.mkdir, 'foo'), "normal dir creation")
+  assert(pcall(system.mkdir, 'foo', true), "dir creation if exists")
+  assert((system.ls())[1] == 'foo')
+  assert(not pcall(system.mkdir, 'bar/baz'),
+         "creation of nested dir")
+  assert(pcall(system.mkdir, 'bar/baz', true),
+         "nested dir creation, including parent directories")
+  assert((system.ls 'bar')[1] == 'baz')
+
+  -- rmdir
+  assert(pcall(system.rmdir, 'foo'), "delete empty directory")
+  assert(not pcall(system.rmdir, 'bar'), "cannot delete non-empty dir")
+  assert(pcall(system.rmdir, 'bar', true), "delete dir recursively")
+  assert(#system.ls() == 0, "dir should be empty")
+end
+in_tmpdir(test_mkdir_rmdir)
+
+-- tmpdirname
+assert(type(system.tmpdirname()) == 'string', "tmpdirname should return a string")
+
+-- with_tmpdir
+local token = 'Banana'
+function write_read_token (tmpdir)
+  local filename = tmpdir .. '/foo.txt'
+  local fh = io.open(filename, 'w')
+  fh:write(token .. '\n')
+  fh:close()
+  return io.open(filename):read '*l'
+end
+
+assert(system.with_tmpdir('.', 'foo', write_read_token) == token)
+assert(system.with_tmpdir('foo', write_read_token) == token)
+
+
+-- Complex scripts
 function create_then_count_files ()
   io.open('README.org', 'w'):close()
   return #system.ls '.'