1 files changed, 59 insertions, 0 deletions
diff --git a/src/buffer.rs b/src/buffer.rs
new file mode 100644
index 0000000..48e2d85
--- /dev/null
+++ b/src/buffer.rs
@@ -0,0 +1,59 @@
+use std::io::{self, Read, Write};
+use std::sync::{Arc, Mutex};
+
+// STDIN is file descriptor (fd) 0 on Linux and other UN*X-likes
+pub const STDIN: i32 = 0;
+
+/// Retrieve a single byte of input
+///
+/// Requires some setup beforehand (see beginning of repl())
+fn getchar() -> u8 {
+    let mut b = [0; 1];
+    io::stdout().lock().flush().unwrap();
+    io::stdin().read_exact(&mut b).unwrap();
+    b[0]
+}
+
+/// Handle user input at the repl prompt
+///
+/// This is required instead of io::stdin().read_line(), because certain
+/// keys like `<tab>` and `<up>` have special functions (cycle through
+/// autocomplete options, and history, respectively). It leverages
+/// [getchar] to read each character as the user inputs it. This also
+/// means special cases for handling backspace, newlines, etc. Assumes
+/// that (ICANON and ECHO) are off. See the beginning of [crate::repl]
+/// for more details.
+pub fn getline(buffer: &mut Arc<Mutex<Vec<u8>>>) -> usize {
+    loop {
+        let c = getchar();
+        match c {
+            // enter/return
+            b'\n' => break,
+
+            // tab
+            b'\t' => {
+                print!(" ");
+                buffer.lock().unwrap().push(b' ');
+            }
+
+            // ctrl-d
+            4 => return 0,
+
+            // backspace
+            127 => {
+                buffer.lock().unwrap().pop();
+                print!("\u{8} \u{8}");
+            }
+
+            // everything else
+            _ => {
+                print!("{}", c as char);
+                buffer.lock().unwrap().push(c);
+            }
+        }
+    }
+
+    println!();
+    buffer.lock().unwrap().push(b'\n');
+    buffer.lock().unwrap().len()
+}