1 files changed, 114 insertions, 0 deletions
diff --git a/cli/repl.rs b/cli/repl.rs
new file mode 100644
index 000000000..55bf4a114
--- /dev/null
+++ b/cli/repl.rs
@@ -0,0 +1,114 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use rustyline;
+
+use crate::msg::ErrorKind;
+use std::error::Error;
+
+use crate::deno_dir::DenoDir;
+use crate::errors::new as deno_error;
+use crate::errors::DenoResult;
+use std::path::PathBuf;
+
+#[cfg(not(windows))]
+use rustyline::Editor;
+
+// Work around the issue that on Windows, `struct Editor` does not implement the
+// `Send` trait, because it embeds a windows HANDLE which is a type alias for
+// *mut c_void. This value isn't actually a pointer and there's nothing that
+// can be mutated through it, so hack around it. TODO: a prettier solution.
+#[cfg(windows)]
+use std::ops::{Deref, DerefMut};
+
+#[cfg(windows)]
+struct Editor<T: rustyline::Helper> {
+  inner: rustyline::Editor<T>,
+}
+
+#[cfg(windows)]
+unsafe impl<T: rustyline::Helper> Send for Editor<T> {}
+
+#[cfg(windows)]
+impl<T: rustyline::Helper> Editor<T> {
+  pub fn new() -> Editor<T> {
+    Editor {
+      inner: rustyline::Editor::<T>::new(),
+    }
+  }
+}
+
+#[cfg(windows)]
+impl<T: rustyline::Helper> Deref for Editor<T> {
+  type Target = rustyline::Editor<T>;
+
+  fn deref(&self) -> &rustyline::Editor<T> {
+    &self.inner
+  }
+}
+
+#[cfg(windows)]
+impl<T: rustyline::Helper> DerefMut for Editor<T> {
+  fn deref_mut(&mut self) -> &mut rustyline::Editor<T> {
+    &mut self.inner
+  }
+}
+
+pub struct Repl {
+  editor: Editor<()>,
+  history_file: PathBuf,
+}
+
+impl Repl {
+  pub fn new(history_file: PathBuf) -> Self {
+    let mut repl = Self {
+      editor: Editor::<()>::new(),
+      history_file,
+    };
+
+    repl.load_history();
+    repl
+  }
+
+  fn load_history(&mut self) {
+    debug!("Loading REPL history: {:?}", self.history_file);
+    self
+      .editor
+      .load_history(&self.history_file.to_str().unwrap())
+      .map_err(|e| debug!("Unable to load history file: {:?} {}", self.history_file, e))
+      // ignore this error (e.g. it occurs on first load)
+      .unwrap_or(())
+  }
+
+  fn save_history(&mut self) -> DenoResult<()> {
+    self
+      .editor
+      .save_history(&self.history_file.to_str().unwrap())
+      .map(|_| debug!("Saved REPL history to: {:?}", self.history_file))
+      .map_err(|e| {
+        eprintln!("Unable to save REPL history: {:?} {}", self.history_file, e);
+        deno_error(ErrorKind::Other, e.description().to_string())
+      })
+  }
+
+  pub fn readline(&mut self, prompt: &str) -> DenoResult<String> {
+    self
+      .editor
+      .readline(&prompt)
+      .map(|line| {
+        self.editor.add_history_entry(line.as_ref());
+        line
+      }).map_err(|e| deno_error(ErrorKind::Other, e.description().to_string()))
+    // Forward error to TS side for processing
+  }
+}
+
+impl Drop for Repl {
+  fn drop(&mut self) {
+    self.save_history().unwrap();
+  }
+}
+
+pub fn history_path(dir: &DenoDir, history_file: &str) -> PathBuf {
+  let mut p: PathBuf = dir.root.clone();
+  p.push(history_file);
+  p
+}