1 files changed, 91 insertions, 0 deletions
diff --git a/third_party/rust/termion/src/screen.rs b/third_party/rust/termion/src/screen.rs
new file mode 100644
index 0000000000..822399e27c
--- /dev/null
+++ b/third_party/rust/termion/src/screen.rs
@@ -0,0 +1,91 @@
+//! Managing switching between main and alternate screen buffers.
+//!
+//! Note that this implementation uses xterm's new escape sequences for screen switching and thus
+//! only works for xterm compatible terminals (which should be most terminals nowadays).
+//!
+//! # Example
+//!
+//! ```rust
+//! use termion::screen::AlternateScreen;
+//! use std::io::{Write, stdout};
+//!
+//! fn main() {
+//!     {
+//!         let mut screen = AlternateScreen::from(stdout());
+//!         write!(screen, "Writing to alternate screen!").unwrap();
+//!         screen.flush().unwrap();
+//!     }
+//!     println!("Writing to main screen.");
+//! }
+//! ```
+
+use std::io::{self, Write};
+use std::ops;
+use std::fmt;
+
+/// Switch to the main screen buffer of the terminal.
+pub struct ToMainScreen;
+
+impl fmt::Display for ToMainScreen {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, csi!("?1049l"))
+    }
+}
+
+/// Switch to the alternate screen buffer of the terminal.
+pub struct ToAlternateScreen;
+
+impl fmt::Display for ToAlternateScreen {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, csi!("?1049h"))
+    }
+}
+
+/// A terminal restorer, which wraps a type implementing Write, and causes all writes to be written
+/// to an alternate screen.
+///
+/// This is achieved by switching the terminal to the alternate screen on creation and
+/// automatically switching it back to the original screen on drop.
+pub struct AlternateScreen<W: Write> {
+    /// The output target.
+    output: W,
+}
+
+impl<W: Write> AlternateScreen<W> {
+    /// Create an alternate screen wrapper struct for the provided output and switch the terminal
+    /// to the alternate screen.
+    pub fn from(mut output: W) -> Self {
+        write!(output, "{}", ToAlternateScreen).expect("switch to alternate screen");
+        AlternateScreen { output: output }
+    }
+}
+
+impl<W: Write> Drop for AlternateScreen<W> {
+    fn drop(&mut self) {
+        write!(self, "{}", ToMainScreen).expect("switch to main screen");
+    }
+}
+
+impl<W: Write> ops::Deref for AlternateScreen<W> {
+    type Target = W;
+
+    fn deref(&self) -> &W {
+        &self.output
+    }
+}
+
+impl<W: Write> ops::DerefMut for AlternateScreen<W> {
+    fn deref_mut(&mut self) -> &mut W {
+        &mut self.output
+    }
+}
+
+impl<W: Write> Write for AlternateScreen<W> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.output.write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.output.flush()
+    }
+}