Rewrite of the buffer code + proper UTF-8 support

This patch rewrites much of the code in src/buffer.rs to (utlimately),
be less buggy. It also changed getchar() to have proper support for
UTF-8 characters. The autocomplete function was also enhanced to support
completions with filenames that have spaces in their paths. It handles
these by placing a backslash ('\') before each space in the filename.
There is not yet any completion support with quote ('), nor double-quote
characters ("). The buffer is still navigable with arrow keys, so
arbitrary deletions and insertions are still possible. Deletions and
insertions with multi-width UTF-8 characters work as expected.

Signed-off-by: Rory Dudley <rory@netc.lu>

1 files changed, 45 insertions, 13 deletions

diff --git a/src/main.rs b/src/main.rs
index 8cfd680..a73c2c4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,7 +6,7 @@ mod path;
 mod poem;
 use poem::{read::Readable, recite::Reciteable, Poem};
 mod compose;
-use buffer::{getline, STDIN};
+use buffer::{getline, Key, STDIN};
 use compose::Environment;
 use termios::{tcsetattr, Termios, ECHO, ECHOE, ICANON, TCSANOW};
 
@@ -27,8 +27,11 @@ use termios::{tcsetattr, Termios, ECHO, ECHOE, ICANON, TCSANOW};
 /// ```
 fn repl(
     away: &mut Arc<Mutex<bool>>,
-    buffer: &mut Arc<Mutex<Vec<u8>>>,
+    buffer: &mut Arc<Mutex<Vec<char>>>,
     pos: &mut Arc<Mutex<usize>>,
+    comp_pos: &mut Arc<Mutex<usize>>,
+    comp_len: &mut Arc<Mutex<usize>>,
+    last_key: &mut Arc<Mutex<Key>>,
     env: &mut Environment,
 ) {
     // Setup termios flags
@@ -39,9 +42,6 @@ fn repl(
 
     // Main shell loop
     loop {
-        // Clear the buffer
-        buffer.lock().unwrap().clear();
-
         // Get the prompt
         let prompt = match env::var("PS1") {
             Ok(val) => val,
@@ -60,7 +60,7 @@ fn repl(
         tcsetattr(STDIN, TCSANOW, &mut termios).unwrap();
 
         // Wait for user input
-        let bytes = getline(buffer, pos);
+        let bytes = getline(buffer, pos, comp_pos, comp_len, last_key);
 
         // Check if we've reached EOF (i.e. <C-d>)
         if bytes == 0 {
@@ -69,9 +69,7 @@ fn repl(
         }
 
         // Convert buffer to a string and trim it
-        let poetry = String::from_utf8_lossy(&buffer.lock().unwrap())
-            .trim()
-            .to_string();
+        let poetry = buffer.lock().unwrap().iter().collect::<String>();
 
         // Skip parsing if there is no poetry
         if poetry.is_empty() {
@@ -86,7 +84,7 @@ fn repl(
         *away.lock().unwrap() = true;
 
         // Parse the poem
-        let poem = Poem::read(poetry, env);
+        let poem = Poem::read(poetry.to_string(), env);
         let poem = match poem {
             Ok(poem) => poem,
             Err(e) => {
@@ -151,17 +149,43 @@ fn main() {
     // Compose the environment for dwvsh
     let mut env = compose::env();
 
-    // Handle signals
+    // Set when we are not on the buffer
     let mut away = Arc::new(Mutex::new(true));
-    let mut buffer: Arc<Mutex<Vec<u8>>> = Arc::new(Mutex::new(vec![]));
+
+    // Any text in the current buffer
+    let mut buffer: Arc<Mutex<Vec<char>>> = Arc::new(Mutex::new(Vec::new()));
+
+    // Position in the buffer. Subject to change based on input from the user. Typing a character
+    // increments the position, while backspacing will decrement it. The user may also move it
+    // manually using the arrow keys to insert or delete at an arbitrary location in the buffer.
     let mut pos: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
+
+    // Position in the autocomplete list. This value gets reset if a new autocomplete list is
+    // generated (for instance, if the user preses '/' to start autocomplete in a new directory).
+    let mut comp_pos: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
+
+    // Keep track of the length of the last buffer from [crate::buffer::comp].
+    let mut comp_len: Arc<Mutex<usize>> = Arc::new(Mutex::new(0));
+
+    // Keep track of the last key for autocomplete, as we may need to add or sub additionally from
+    // [comp_pos] before calling [crate::buffer::comp] (i.e. swapping directions (tab vs. shift +
+    // tab)).
+    let mut last_key: Arc<Mutex<Key>> = Arc::new(Mutex::new(Key::Ignored));
+
+    // Handle signals
     unsafe {
         let away = Arc::clone(&away);
         let buffer = Arc::clone(&buffer);
         let pos = Arc::clone(&pos);
+        let comp_pos = Arc::clone(&comp_pos);
+        let comp_len = Arc::clone(&comp_len);
+        let last_key = Arc::clone(&last_key);
         signal_hook::low_level::register(signal_hook::consts::SIGINT, move || {
             buffer.lock().unwrap().clear();
             *pos.lock().unwrap() = 0;
+            *comp_pos.lock().unwrap() = 0;
+            *comp_len.lock().unwrap() = 0;
+            *last_key.lock().unwrap() = Key::Ignored;
             if *away.lock().unwrap() {
                 println!();
             } else {
@@ -180,5 +204,13 @@ fn main() {
     options(&mut env);
 
     // Begin evaluating commands
-    repl(&mut away, &mut buffer, &mut pos, &mut env);
+    repl(
+        &mut away,
+        &mut buffer,
+        &mut pos,
+        &mut comp_pos,
+        &mut comp_len,
+        &mut last_key,
+        &mut env,
+    );
 }