Add FileSelection dialog type

This patch adds the FileSelection struct representing a file selection
dialog.  It can be displayed using the backend’s show_file_selection
function.

Currently, we only support file open dialogs (i. e.  choosing an
existing file).  Support for save dialogs should be added in the future.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/backends/dialog.rs b/src/backends/dialog.rs
index 8061d98..668cf57 100644
--- a/src/backends/dialog.rs
+++ b/src/backends/dialog.rs
@@ -3,7 +3,7 @@
 
 use std::process;
 
-use crate::{Choice, Error, Input, Message, Password, Question, Result};
+use crate::{Choice, Error, FileSelection, Input, Message, Password, Question, Result};
 
 /// The `dialog` backend.
 ///
@@ -160,4 +160,11 @@ impl super::Backend for Dialog {
         self.execute(args, vec![], &question.title)
             .and_then(|output| get_choice(output.status))
     }
+
+    fn show_file_selection(&self, file_selection: &FileSelection) -> Result<Option<String>> {
+        let dir = file_selection.path_to_string().ok_or("path not valid")?;
+        let args = vec!["--fselect", &dir];
+        self.execute(args, vec![], &file_selection.title)
+            .and_then(get_stderr)
+    }
 }