rebel-lang: repl: add support for multiline input

Only multiline strings are supported, as the validator only checks if
the token stream is valid, not if it is a valid expression.

2 files changed, 32 insertions, 5 deletions

diff --git a/crates/rebel-lang/Cargo.toml b/crates/rebel-lang/Cargo.toml
index 0c2f684..957d31d 100644
--- a/crates/rebel-lang/Cargo.toml
+++ b/crates/rebel-lang/Cargo.toml
@@ -15,4 +15,4 @@ enum-kinds = "0.5.1"
 
 [dev-dependencies]
 clap = { version = "4.0.0", features = ["derive"] }
-rustyline = "14.0.0"
+rustyline = { version = "14.0.0", features = ["derive"] }
diff --git a/crates/rebel-lang/examples/repl.rs b/crates/rebel-lang/examples/repl.rs
index 07c906f..e4c2550 100644
--- a/crates/rebel-lang/examples/repl.rs
+++ b/crates/rebel-lang/examples/repl.rs
@@ -5,6 +5,7 @@ use rebel_lang::{
 	value::{EvalError, Result, Value},
 };
 use rebel_parse::{recipe, tokenize};
+use rustyline::{error::ReadlineError, validate::ValidationResult};
 
 fn intrinsic_array_len(params: &[Value]) -> Result<Value> {
 	assert!(params.len() == 1);
@@ -23,6 +24,24 @@ fn intrinsic_string_len(params: &[Value]) -> Result<Value> {
 	))
 }
 
+#[derive(rustyline::Completer, rustyline::Hinter, rustyline::Highlighter, rustyline::Helper)]
+struct Helper;
+
+impl rustyline::validate::Validator for Helper {
+	fn validate(
+		&self,
+		ctx: &mut rustyline::validate::ValidationContext,
+	) -> rustyline::Result<rustyline::validate::ValidationResult> {
+		let input = ctx.input();
+		let result = match tokenize::token_stream(input) {
+			Ok(_) => ValidationResult::Valid(None),
+			Err(_) => ValidationResult::Incomplete,
+		};
+
+		Ok(result)
+	}
+}
+
 fn main() -> rustyline::Result<()> {
 	let mut ctx = Context::default();
 
@@ -47,12 +66,20 @@ fn main() -> rustyline::Result<()> {
 		},
 	);
 
-	let mut rl = rustyline::DefaultEditor::new()?;
+	let mut rl = rustyline::Editor::<Helper, rustyline::history::DefaultHistory>::new()?;
+	rl.set_helper(Some(Helper));
 
-	while let Ok(line) = rl.readline("> ") {
-		rl.add_history_entry(line.as_str())?;
+	loop {
+		let input = match rl.readline("> ") {
+			Ok(input) => input,
+			Err(ReadlineError::Interrupted) => continue,
+			Err(ReadlineError::WindowResized) => continue,
+			Err(ReadlineError::Eof) => break,
+			Err(err) => panic!("{err}"),
+		};
+		rl.add_history_entry(input.as_str())?;
 
-		let tokens = match tokenize::token_stream(&line) {
+		let tokens = match tokenize::token_stream(&input) {
 			Ok(value) => value,
 			Err(err) => {
 				println!("Tokenize error: {err}");