Affectation de variable

src/parser.rs

@@ -1,4 +1,4 @@
-use crate::expr::{Binary, Expr, Grouping, Unary, Variable};
+use crate::expr::{Assign, Binary, Expr, Grouping, Unary, Variable};
 use crate::expr::Literal::{LiteralBool, LiteralNumber, LiteralString};
 use crate::token::Token;
 use crate::token_type::TokenType;
@@ -92,11 +92,28 @@ impl Parser {
         }
     }
 
-    fn expression(&mut self) -> Result<Expr,ParseError> {
-        self.equality()
+    fn expression(&mut self) -> Result<Expr, ParseError> {
+        self.assignment()
     }
 
-    fn equality(&mut self) -> Result<Expr,ParseError> {
+    fn assignment(&mut self) -> Result<Expr, ParseError> {
+        let expr = self.equality()?;
+
+        if self.match_token(&[TokenType::Equal]) {
+            let value = Box::new(self.assignment()?);       // l'assignation a une associativité par la droite
+
+            match expr {
+                Expr::VariableExpr(v) => {
+                    Ok( Expr::AssignExpr(Assign { name: v.name, value }))
+                }
+                _ => Err(ParseError { message: String::from("Invalid assignment target") })
+            }
+        } else {
+            Ok(expr)
+        }
+    }
+
+    fn equality(&mut self) -> Result<Expr, ParseError> {
         let mut expr: Expr = self.comparison()?;
 
         while self.match_token( &[TokenType::BangEqual, TokenType::EqualEqual]) {
@@ -112,7 +129,7 @@ impl Parser {
         return Ok(expr);
     }
 
-    fn comparison(&mut self) -> Result<Expr,ParseError> {
+    fn comparison(&mut self) -> Result<Expr, ParseError> {
         let mut expr = self.term()?;
 
         while self.match_token(&[TokenType::Greater, TokenType::GreaterEqual, TokenType::Less, TokenType::LessEqual]) {