rebel-parse, rebel-lang: distinguish let statements and simple assignments

2 files changed, 29 insertions, 5 deletions

diff --git a/crates/rebel-parse/src/ast/mod.rs b/crates/rebel-parse/src/ast/mod.rs
index ebf7241..4fa8e63 100644
--- a/crates/rebel-parse/src/ast/mod.rs
+++ b/crates/rebel-parse/src/ast/mod.rs
@@ -53,8 +53,12 @@ impl<'a> Block<'a> {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum BlockStmt<'a> {
-	Assign {
+	Let {
 		dest: Box<TypedPat<'a>>,
+		expr: Option<Box<Expr<'a>>>,
+	},
+	Assign {
+		dest: Box<Pat<'a>>,
 		expr: Box<Expr<'a>>,
 	},
 	Expr {
@@ -64,15 +68,22 @@ pub enum BlockStmt<'a> {
 }
 
 impl<'a> BlockStmt<'a> {
+	pub(crate) fn let_assign(dest: TypedPat<'a>, expr: Option<Expr<'a>>) -> Self {
+		BlockStmt::Let {
+			dest: Box::new(dest),
+			expr: expr.map(Box::new),
+		}
+	}
+
 	pub(crate) fn assign(
-		dest: TypedPat<'a>,
+		dest: Pat<'a>,
 		op: Option<OpBinary>,
 		swapped: bool,
 		expr: Expr<'a>,
 	) -> Self {
 		let expr = match op {
 			Some(op) => {
-				let dest_expr = match &dest.pat {
+				let dest_expr = match &dest {
 					Pat::Path(path) => Expr::Path(path.clone()),
 				};
 				if swapped {
@@ -91,6 +102,13 @@ impl<'a> BlockStmt<'a> {
 
 	pub fn validate(&self) -> Result<(), ValidationError> {
 		match self {
+			BlockStmt::Let { dest: _, expr } => {
+				// TODO: Destination validation
+				if let Some(expr) = expr {
+					expr.validate()?;
+				}
+				Ok(())
+			}
 			BlockStmt::Assign { dest: _, expr } => {
 				// TODO: Destination validation
 				expr.validate()
diff --git a/crates/rebel-parse/src/grammar/recipe.rs b/crates/rebel-parse/src/grammar/recipe.rs
index 6b96c85..c9fe1e2 100644
--- a/crates/rebel-parse/src/grammar/recipe.rs
+++ b/crates/rebel-parse/src/grammar/recipe.rs
@@ -34,10 +34,16 @@ peg::parser! {
 			= block:block_stmt() ++ p(';') { ast::Block(block) }
 
 		pub rule block_stmt() -> ast::BlockStmt<'a>
-			= dest:typed_pat() op:assign_op() expr:expr() {
+			= [Token::Keyword(Keyword::Let)] dest:typed_pat() p('=') expr:expr() {
+				ast::BlockStmt::let_assign(dest, Some(expr))
+			}
+			/ [Token::Keyword(Keyword::Let)] dest:typed_pat() {
+				ast::BlockStmt::let_assign(dest, None)
+			}
+			/ dest:pat() op:assign_op() expr:expr() {
 				ast::BlockStmt::assign(dest, op, false, expr)
 			}
-			/ dest:typed_pat() p2('=', '+') expr:expr() {
+			/ dest:pat() p2('=', '+') expr:expr() {
 				ast::BlockStmt::assign(dest, Some(Add), true, expr)
 			}
 			/ expr:expr() {