From f24dabd0897e802d30e8b652f0b633b84c78865b Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sun, 28 Apr 2024 17:57:01 +0200
Subject: rebel-parse: add support for swapped-add-assign operator (`=+`)

---
 crates/rebel-parse/src/ast.rs            | 17 ++++++++++++-----
 crates/rebel-parse/src/grammar/recipe.rs |  7 +++++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/crates/rebel-parse/src/ast.rs b/crates/rebel-parse/src/ast.rs
index e3b93ba..88853d7 100644
--- a/crates/rebel-parse/src/ast.rs
+++ b/crates/rebel-parse/src/ast.rs
@@ -55,14 +55,21 @@ pub enum BodyStmt<'a> {
 }
 
 impl<'a> BodyStmt<'a> {
-	pub(crate) fn assign(dest: TypedExpr<'a>, op: Option<OpBinary>, expr: Expr<'a>) -> Self {
+	pub(crate) fn assign(
+		dest: TypedExpr<'a>,
+		op: Option<OpBinary>,
+		swapped: bool,
+		expr: Expr<'a>,
+	) -> Self {
 		match op {
 			Some(op) => {
 				let dest_expr = dest.expr.clone();
-				BodyStmt::Assign {
-					dest,
-					expr: Expr::binary(dest_expr, op, expr),
-				}
+				let expr = if swapped {
+					Expr::binary(expr, op, dest_expr)
+				} else {
+					Expr::binary(dest_expr, op, expr)
+				};
+				BodyStmt::Assign { dest, expr }
 			}
 			None => BodyStmt::Assign { dest, expr },
 		}
diff --git a/crates/rebel-parse/src/grammar/recipe.rs b/crates/rebel-parse/src/grammar/recipe.rs
index 393b12c..aaa40d2 100644
--- a/crates/rebel-parse/src/grammar/recipe.rs
+++ b/crates/rebel-parse/src/grammar/recipe.rs
@@ -27,8 +27,11 @@ peg::parser! {
 			= body:body_stmt() ++ p(';') { ast::Body(body) }
 
 		pub rule body_stmt() -> ast::BodyStmt<'a>
-			= dest:typed_expr() op:assign_op() expr:expr() {
-				ast::BodyStmt::assign(dest, op, expr)
+			= dest:typed_expr() p2('=', '+') expr:expr() {
+				ast::BodyStmt::assign(dest, Some(Add), true, expr)
+			}
+			/ dest:typed_expr() op:assign_op() expr:expr() {
+				ast::BodyStmt::assign(dest, op, false, expr)
 			}
 			/ expr:expr() {
 				ast::BodyStmt::Expr { expr }
-- 
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