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path: root/crates/rebel-lang/examples/repl.rs
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use rebel_lang::{
	func::{Func, FuncDef, FuncType},
	scope::Context,
	typing::{ArrayLen, Type, TypeFamily},
	value::{EvalError, Result, Value},
};
use rebel_parse::{recipe, tokenize};
use reedline::{DefaultPrompt, DefaultPromptSegment, Reedline, Signal, ValidationResult};

fn intrinsic_array_len(params: &[Value]) -> Result<Value> {
	assert!(params.len() == 1);
	let Value::Array(array) = &params[0] else {
		panic!();
	};
	Ok(Value::Integer(array.len().try_into().or(Err(EvalError))?))
}
fn intrinsic_string_len(params: &[Value]) -> Result<Value> {
	assert!(params.len() == 1);
	let Value::Str(string) = &params[0] else {
		panic!();
	};
	Ok(Value::Integer(
		string.chars().count().try_into().or(Err(EvalError))?,
	))
}

struct Validator;

impl reedline::Validator for Validator {
	fn validate(&self, line: &str) -> ValidationResult {
		if tokenize::token_stream(line).is_ok() {
			ValidationResult::Complete
		} else {
			ValidationResult::Incomplete
		}
	}
}

fn main() {
	let mut ctx = Context::default();

	ctx.methods.entry(TypeFamily::Array).or_default().insert(
		"len",
		Func {
			typ: FuncType {
				params: vec![Type::Array(Box::new(Type::Free), ArrayLen::Dynamic)],
				ret: Type::Int,
			},
			def: Some(FuncDef::Intrinsic(intrinsic_array_len)),
		},
	);
	ctx.methods.entry(TypeFamily::Str).or_default().insert(
		"len",
		Func {
			typ: FuncType {
				params: vec![Type::Str],
				ret: Type::Int,
			},
			def: Some(FuncDef::Intrinsic(intrinsic_string_len)),
		},
	);

	let mut rl = Reedline::create().with_validator(Box::new(Validator));
	let prompt = DefaultPrompt::new(DefaultPromptSegment::Empty, DefaultPromptSegment::Empty);

	loop {
		let input = match rl.read_line(&prompt).unwrap() {
			Signal::Success(input) => input,
			Signal::CtrlC => continue,
			Signal::CtrlD => break,
		};

		let tokens = match tokenize::token_stream(&input) {
			Ok(value) => value,
			Err(err) => {
				println!("Tokenize error: {err}");
				continue;
			}
		};
		let stmt = match recipe::body_stmt(&tokens) {
			Ok(value) => value,
			Err(err) => {
				println!("Parse error: {err}");
				continue;
			}
		};

		match &stmt {
			rebel_parse::ast::BodyStmt::Assign { dest: _, expr } => {
				match expr.validate() {
					Ok(_) => (),
					Err(err) => {
						println!("Validation error: {err:?}");
						continue;
					}
				};
				match Type::ast_expr_type(&ctx, expr) {
					Ok(_) => (),
					Err(err) => {
						println!("Type error: {err:?}");
						continue;
					}
				};
			}
			rebel_parse::ast::BodyStmt::Expr { expr } => {
				match expr.validate() {
					Ok(_) => (),
					Err(err) => {
						println!("Validation error: {err:?}");
						continue;
					}
				};
				match Type::ast_expr_type(&ctx, expr) {
					Ok(_) => (),
					Err(err) => {
						println!("Type error: {err:?}");
						continue;
					}
				};
			}
			rebel_parse::ast::BodyStmt::Empty => {}
		}

		let value = match ctx.run(&stmt) {
			Ok(value) => value,
			Err(err) => {
				println!("Eval error: {err:?}");
				continue;
			}
		};
		let typ = match value.typ() {
			Ok(typ) => typ,
			Err(err) => {
				println!("Post-eval type error: {err:?}. This should not happen.");
				continue;
			}
		};
		println!("{value}: {typ}");
	}
}