Early work on tab completion

src/prompt/comp.rs

@@ -0,0 +1,86 @@
+use rustyline::completion::{Candidate, Completer};
+
+use crate::{expand::cmdsub::expand_cmdsub_string, parse::lex::KEYWORDS, prelude::*};
+
+use super::readline::SynHelper;
+
+impl<'a> Completer for SynHelper<'a> {
+	type Candidate = String;
+	fn complete( &self, line: &str, pos: usize, ctx: &rustyline::Context<'_>,) -> rustyline::Result<(usize, Vec<Self::Candidate>)> {
+		let mut shenv = self.shenv.clone();
+		let mut comps = vec![];
+		shenv.new_input(line);
+		let mut token_stream = Lexer::new(line.to_string(), &mut shenv).lex();
+		if let Some(comp_token) = token_stream.pop() {
+			let raw = comp_token.as_raw(&mut shenv);
+			let is_cmd = if let Some(token) = token_stream.pop() {
+				match token.rule() {
+					TkRule::Sep => true,
+					_ if KEYWORDS.contains(&token.rule()) => true,
+					_ => false
+				}
+			} else {
+				true
+			};
+			if let TkRule::Ident | TkRule::Whitespace = comp_token.rule() {
+				if is_cmd {
+					let cmds = shenv.meta().path_cmds();
+					comps.extend(cmds.iter().map(|cmd| cmd.to_string()));
+					comps.retain(|cmd| cmd.starts_with(&raw));
+					if !comps.is_empty() && comps.len() > 1 {
+						if get_bin_path("fzf", &self.shenv).is_some() {
+							if let Some(mut selection) = fzf_comp(&comps, &mut shenv) {
+								while selection.starts_with(&raw) {
+									selection = selection.strip_prefix(&raw).unwrap().to_string();
+								}
+								comps = vec![selection];
+							}
+						}
+					} else if let Some(mut comp) = comps.pop() {
+						while comp.starts_with(&raw) {
+							comp = comp.strip_prefix(&raw).unwrap().to_string();
+						}
+						comps = vec![comp];
+					}
+					return Ok((pos,comps))
+				} else {
+					let (start, matches) = self.file_comp.complete(line, pos, ctx)?;
+					comps.extend(matches.iter().map(|c| c.display().to_string()));
+
+					if !comps.is_empty() && comps.len() > 1 {
+						if get_bin_path("fzf", &self.shenv).is_some() {
+							if let Some(selection) = fzf_comp(&comps, &mut shenv) {
+								return Ok((start, vec![selection]))
+							} else {
+								return Ok((start, comps))
+							}
+						} else {
+							return Ok((start, comps))
+						}
+					} else if let Some(comp) = comps.pop() {
+						// Slice off the already typed bit
+						return Ok((start, vec![comp]))
+					}
+				}
+			}
+		}
+		Ok((pos,comps))
+	}
+}
+
+pub fn fzf_comp(comps: &[String], shenv: &mut ShEnv) -> Option<String> {
+	// All of the fzf wrapper libraries suck
+	// So we gotta do this now
+	let echo_args = comps.join("\n");
+	let echo = format!("echo \"{echo_args}\"");
+	let fzf = "fzf --height=~30% --layout=reverse --border --border-label=completion";
+	let command = format!("{echo} | {fzf}");
+
+	shenv.ctx_mut().set_flag(ExecFlags::NO_EXPAND); // Prevent any pesky shell injections with filenames like '$(rm -rf /)'
+	let selection = expand_cmdsub_string(&command, shenv).ok()?;
+	if selection.is_empty() {
+		None
+	} else {
+		Some(selection.trim().to_string())
+	}
+}

src/prompt/mod.rs

@@ -5,6 +5,7 @@ use rustyline::{config::Configurer, history::{DefaultHistory, History}, ColorMod
 pub mod readline;
 pub mod highlight;
 pub mod validate;
+pub mod comp;
 
 fn init_rl<'a>(shenv: &'a mut ShEnv) -> Editor<SynHelper<'a>, DefaultHistory> {
 	let hist_path = std::env::var("FERN_HIST").unwrap_or_default();

src/prompt/readline.rs

@@ -1,11 +1,10 @@
-use rustyline::{completion::{Completer, FilenameCompleter}, hint::{Hint, Hinter}, history::{History, SearchDirection}, Helper};
+use rustyline::{completion::{Candidate, Completer, FilenameCompleter}, hint::{Hint, Hinter}, history::{History, SearchDirection}, Helper};
 
 use crate::prelude::*;
 
 pub struct SynHelper<'a> {
-	file_comp: FilenameCompleter,
+	pub file_comp: FilenameCompleter,
 	pub shenv: &'a mut ShEnv,
-	pub commands: Vec<String>
 }
 
 impl<'a> Helper for SynHelper<'a> {}
@@ -15,7 +14,6 @@ impl<'a> SynHelper<'a> {
 		Self {
 			file_comp: FilenameCompleter::new(),
 			shenv,
-			commands: vec![]
 		}
 	}
 
@@ -35,12 +33,6 @@ impl<'a> SynHelper<'a> {
 
 
 
-impl<'a> Completer for SynHelper<'a> {
-	type Candidate = String;
-	fn complete( &self, line: &str, pos: usize, ctx: &rustyline::Context<'_>,) -> rustyline::Result<(usize, Vec<Self::Candidate>)> {
-		Ok((0,vec![]))
-	}
-}
 
 pub struct SynHint {
 	text: String,