add assignments

src/run.rs

@@ -1,7 +1,7 @@
 use std::{collections::HashMap, fmt::Debug, rc::Rc};
 
 use crate::{
-	ast::{Constant, Expression, Location},
+	ast::{Constant, Expression, Location, Statement},
 	types::{Value, ValueInner},
 };
 
@@ -104,6 +104,43 @@ impl Eval for Expression {
 	}
 }
 
+pub trait Exec {
+	fn exec(&self, scope: &mut Scope);
+}
+
+impl Exec for Statement {
+	fn exec(&self, scope: &mut Scope) {
+		match self {
+			Statement::Assign { target, source } => {
+				let value = source.eval(scope);
+				match target {
+					Location::Variable { name } => {
+						scope.set(name.into(), value);
+					}
+					Location::Field { table, index } => {
+						let table = table.eval(scope);
+						let Some(ValueInner::Table(table)) = table else {
+							panic!("attempt to index non-table value {table:?}")
+						};
+						let index = index.eval(scope);
+						let Some(index) = index else {
+							panic!("attempt to index with a nil value")
+						};
+						table.set(index, value);
+					}
+				};
+			}
+			Statement::Call { callee, args } => {
+				Expression::Call {
+					callee: callee.clone(),
+					args: args.clone(),
+				}
+				.eval(scope);
+			}
+		}
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;
@@ -178,4 +215,18 @@ mod tests {
 			Some(49.into())
 		);
 	}
+
+	#[test]
+	fn test_var_assign() {
+		let mut scope = Scope::default();
+		assert_eq!(scope.get("foo"), None);
+		assert_eq!(scope.get("bar"), None);
+		ast::Statement::Assign {
+			target: ast::Location::Variable { name: "foo".into() },
+			source: Box::new(ast::Expression::Constant(ast::Constant::Number(42))),
+		}
+		.exec(&mut scope);
+		assert_eq!(scope.get("foo"), Some(42.into()));
+		assert_eq!(scope.get("bar"), None);
+	}
 }