From fce7d2b9bf30e09b615dbd77b4dd7db94d623bfb Mon Sep 17 00:00:00 2001
From: Robin Krahl <robin.krahl@ireas.org>
Date: Tue, 8 Jan 2019 03:49:42 +0000
Subject: Add question dialog boxes

---
 examples/question.rs   | 12 ++++++++++
 src/backends/dialog.rs | 33 +++++++++++++++++++++++----
 src/backends/mod.rs    |  3 +++
 src/lib.rs             | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 104 insertions(+), 4 deletions(-)
 create mode 100644 examples/question.rs

diff --git a/examples/question.rs b/examples/question.rs
new file mode 100644
index 0000000..d9c0e91
--- /dev/null
+++ b/examples/question.rs
@@ -0,0 +1,12 @@
+// Copyright (C) 2019 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: MIT
+
+use std::io::Result;
+
+use dialog::DialogBox;
+
+fn main() -> Result<()> {
+    let choice = dialog::Question::new("Do you want to continue?").show()?;
+    println!("The user chose: {:?}", choice);
+    Ok(())
+}
diff --git a/src/backends/dialog.rs b/src/backends/dialog.rs
index 8cde8cc..fb0f73f 100644
--- a/src/backends/dialog.rs
+++ b/src/backends/dialog.rs
@@ -5,7 +5,7 @@ use std::io;
 use std::io::Result;
 use std::process;
 
-use crate::{Input, Message};
+use crate::{Choice, Input, Message, Question};
 
 /// The `dialog` backend.
 ///
@@ -87,6 +87,25 @@ fn require_success(status: process::ExitStatus) -> Result<()> {
     }
 }
 
+fn get_choice(status: process::ExitStatus) -> Result<Choice> {
+    if let Some(code) = status.code() {
+        match code {
+            0 => Ok(Choice::Yes),
+            1 => Ok(Choice::No),
+            255 => Ok(Choice::Cancel),
+            code => Err(io::Error::new(
+                io::ErrorKind::Other,
+                format!("Could not execute dialog: {}", code),
+            )),
+        }
+    } else {
+        Err(io::Error::new(
+            io::ErrorKind::Other,
+            "dialog was terminated by a signal",
+        ))
+    }
+}
+
 fn get_stderr(output: process::Output) -> Result<Option<String>> {
     if output.status.success() {
         String::from_utf8(output.stderr)
@@ -99,10 +118,10 @@ fn get_stderr(output: process::Output) -> Result<Option<String>> {
             match code {
                 0 => Ok(None),
                 1 => Ok(None),
-                -1 => Ok(None),
-                _ => Err(io::Error::new(
+                255 => Ok(None),
+                code => Err(io::Error::new(
                     io::ErrorKind::Other,
-                    "Could not execute dialog",
+                    format!("Could not execute dialog: {}", code),
                 )),
             }
         } else {
@@ -131,4 +150,10 @@ impl super::Backend for Dialog {
             .and_then(|output| require_success(output.status))
             .map(|_| ())
     }
+
+    fn show_question(&self, question: &Question) -> Result<Choice> {
+        let args = vec!["--yesno", &question.text];
+        self.execute(args, vec![], &question.title)
+            .and_then(|output| get_choice(output.status))
+    }
 }
diff --git a/src/backends/mod.rs b/src/backends/mod.rs
index 1abb8d1..12a178b 100644
--- a/src/backends/mod.rs
+++ b/src/backends/mod.rs
@@ -22,4 +22,7 @@ pub trait Backend {
 
     /// Shows the given message dialog.
     fn show_message(&self, message: &super::Message) -> Result<()>;
+
+    /// Shows the given question dialog and returns the choice.
+    fn show_question(&self, question: &super::Question) -> Result<super::Choice>;
 }
diff --git a/src/lib.rs b/src/lib.rs
index 0c9d9f9..b51a3cc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,7 @@
 //! are:
 //! - [`Input`][]: a text input dialog
 //! - [`Message`][]: a simple message box
+//! - [`Question`][]: a question dialog box
 //!
 //! These dialog boxes can be displayed using various backends:
 //! - [`Dialog`][]: uses `dialog` to display ncurses-based dialog boxes (requires the external
@@ -64,6 +65,7 @@
 //! [`Dialog`]: backends/struct.Dialog.html
 //! [`Input`]: struct.Input.html
 //! [`Message`]: struct.Message.html
+//! [`Question`]: struct.Question.html
 //! [`default_backend`]: fn.default_backend.html
 //! [`show`]: trait.DialogBox.html#method.show
 //! [`show_with`]: trait.DialogBox.html#method.show_with
@@ -203,6 +205,64 @@ impl DialogBox for Input {
     }
 }
 
+/// A user choise in a dialog box.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Choice {
+    /// The yes button.
+    Yes,
+    /// The no button.
+    No,
+    /// The cancel button or a cancelled dialog.
+    Cancel,
+}
+
+/// A question dialog box.
+///
+/// This dialog box displays a text and an optional title and has a yes and a no button.  The
+/// output is the button presed by the user, or Cancel if the dialog has been cancelled.
+///
+/// # Example
+///
+/// ```no_run
+/// use dialog::DialogBox;
+///
+/// let choice = dialog::Question::new("Do you want to continue?")
+///     .title("Question")
+///     .show()
+///     .expect("Could not display dialog box");
+/// println!("The user chose: {:?}", choice);
+/// ```
+pub struct Question {
+    text: String,
+    title: Option<String>,
+}
+
+impl Question {
+    /// Creates a new question dialog with the given text.
+    pub fn new(text: impl Into<String>) -> Question {
+        Question {
+            text: text.into(),
+            title: None,
+        }
+    }
+
+    /// Sets the title of this question dialog box.
+    ///
+    /// This method returns a reference to `self` to enable chaining.
+    pub fn title(&mut self, title: impl Into<String>) -> &mut Question {
+        self.title = Some(title.into());
+        self
+    }
+}
+
+impl DialogBox for Question {
+    type Output = Choice;
+
+    fn show_with(&self, backend: &impl backends::Backend) -> Result<Self::Output> {
+        backend.show_question(self)
+    }
+}
+
 /// Creates a new instance of the default backend.
 ///
 /// The current implementation always returns a [`Dialog`][] instance.
-- 
cgit v1.2.1