From f70b2b4c6c96b315c69f5de65eb7194062980bd0 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sun, 28 Apr 2024 00:20:59 +0200
Subject: rebel-lang: implement simple assignments for REPL

---
 crates/rebel-lang/examples/repl.rs | 33 +++++++++++++++++++++++--------
 crates/rebel-lang/src/scope.rs     | 40 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 63 insertions(+), 10 deletions(-)

diff --git a/crates/rebel-lang/examples/repl.rs b/crates/rebel-lang/examples/repl.rs
index 0e3debc..07c906f 100644
--- a/crates/rebel-lang/examples/repl.rs
+++ b/crates/rebel-lang/examples/repl.rs
@@ -51,6 +51,7 @@ fn main() -> rustyline::Result<()> {
 
 	while let Ok(line) = rl.readline("> ") {
 		rl.add_history_entry(line.as_str())?;
+
 		let tokens = match tokenize::token_stream(&line) {
 			Ok(value) => value,
 			Err(err) => {
@@ -58,21 +59,37 @@ fn main() -> rustyline::Result<()> {
 				continue;
 			}
 		};
-		let expr = match recipe::expr(&tokens) {
+		let stmt = match recipe::body_stmt(&tokens) {
 			Ok(value) => value,
 			Err(err) => {
 				println!("Parse error: {err}");
 				continue;
 			}
 		};
-		match Type::ast_expr_type(&ctx, &expr) {
-			Ok(_) => (),
-			Err(err) => {
-				println!("Type error: {err:?}");
-				continue;
+
+		match &stmt {
+			rebel_parse::ast::BodyStmt::Assign { dest: _, expr } => {
+				match Type::ast_expr_type(&ctx, expr) {
+					Ok(_) => (),
+					Err(err) => {
+						println!("Type error: {err:?}");
+						continue;
+					}
+				};
 			}
-		};
-		let value = match Value::eval(&ctx, &expr) {
+			rebel_parse::ast::BodyStmt::Expr { expr } => {
+				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:?}");
diff --git a/crates/rebel-lang/src/scope.rs b/crates/rebel-lang/src/scope.rs
index bae9678..1d574b3 100644
--- a/crates/rebel-lang/src/scope.rs
+++ b/crates/rebel-lang/src/scope.rs
@@ -5,7 +5,7 @@ use rebel_parse::ast;
 use crate::{
 	func::Func,
 	typing::{Type, TypeFamily},
-	value::Value,
+	value::{self, EvalError, Value},
 };
 
 #[derive(Debug, Default)]
@@ -14,8 +14,44 @@ pub struct Context {
 	pub methods: HashMap<TypeFamily, HashMap<&'static str, Func>>,
 }
 
+impl Context {
+	pub fn run(&mut self, stmt: &ast::BodyStmt) -> value::Result<Value> {
+		match stmt {
+			ast::BodyStmt::Assign { dest, expr } => {
+				let value = Value::eval(self, expr)?;
+				let typ = value.typ().or(Err(EvalError))?;
+
+				// TODO: Handle specified type
+				let ast::TypedExpr {
+					expr: dest_expr,
+					typ: _,
+				} = dest;
+
+				// TODO: Handle other assignable expressions
+				let dest_path = match dest_expr {
+					ast::Expr::Path(path) => path,
+					_ => return Err(EvalError),
+				};
+				let [dest_ident] = dest_path.components[..] else {
+					return Err(EvalError);
+				};
+
+				// TODO: Lexical scoping
+				self.values.0.insert(
+					dest_ident.name.to_owned(),
+					ModuleEntry::Def((typ, (Some(value.clone())))),
+				);
+
+				Ok(value)
+			}
+			ast::BodyStmt::Expr { expr } => Value::eval(self, expr),
+			ast::BodyStmt::Empty => Ok(Value::Unit),
+		}
+	}
+}
+
 #[derive(Debug, Default)]
-pub struct Module(HashMap<String, ModuleEntry>);
+pub struct Module(pub HashMap<String, ModuleEntry>);
 
 impl Module {
 	pub fn lookup(&self, path: &[ast::Ident<'_>]) -> Option<(&Type, Option<&Value>)> {
-- 
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