Move output to separate module

src/output.rs

@@ -0,0 +1,56 @@
+use app::PagingMode;
+use errors::*;
+use std::io::{self, Write};
+use std::process::{Child, Command, Stdio};
+
+pub enum OutputType {
+    Pager(Child),
+    Stdout(io::Stdout),
+}
+
+impl OutputType {
+    pub fn from_mode(mode: PagingMode) -> Self {
+        use self::PagingMode::*;
+        match mode {
+            Always => OutputType::try_pager(false),
+            QuitIfOneScreen => OutputType::try_pager(true),
+            _ => OutputType::stdout(),
+        }
+    }
+
+    /// Try to launch the pager. Fall back to stdout in case of errors.
+    fn try_pager(quit_if_one_screen: bool) -> Self {
+        let mut args = vec!["--RAW-CONTROL-CHARS", "--no-init"];
+        if quit_if_one_screen {
+            args.push("--quit-if-one-screen");
+        }
+        Command::new("less")
+            .args(&args)
+            .stdin(Stdio::piped())
+            .spawn()
+            .map(OutputType::Pager)
+            .unwrap_or_else(|_| OutputType::stdout())
+    }
+
+    fn stdout() -> Self {
+        OutputType::Stdout(io::stdout())
+    }
+
+    pub fn handle(&mut self) -> Result<&mut Write> {
+        Ok(match *self {
+            OutputType::Pager(ref mut command) => command
+                .stdin
+                .as_mut()
+                .chain_err(|| "Could not open stdin for pager")?,
+            OutputType::Stdout(ref mut handle) => handle,
+        })
+    }
+}
+
+impl Drop for OutputType {
+    fn drop(&mut self) {
+        if let OutputType::Pager(ref mut command) = *self {
+            let _ = command.wait();
+        }
+    }
+}