Implement assignment as binop

README.md

@@ -16,7 +16,7 @@
   - [x] Logical boolean operators
 - [x] Variables
   - [x] Declaration
-  - [ ] Assignment
+  - [x] Assignment
 - [ ] While loop `while X { ... }`
 - [ ] If else statement `if X { ... } else { ... }`
   - [ ] If Statement

src/interpreter.rs

@@ -48,6 +48,19 @@ impl Interpreter {
     }
 
     fn resolve_binop(&mut self, bo: BinOpType, lhs: Expr, rhs: Expr) -> Value {
+        // Treat assignment separate from the other expressions
+        if matches!(bo, BinOpType::Assign) {
+            match lhs {
+                Expr::Ident(name) => {
+                    let rhs = self.resolve_expr(rhs);
+                    self.vartable.insert(name, rhs.clone());
+                    return rhs;
+                }
+                _ => panic!("Runtime error: Left hand side of assignment must be an identifier"),
+            }
+        }
+        
+
         let lhs = self.resolve_expr(lhs);
         let rhs = self.resolve_expr(rhs);
 
@@ -69,6 +82,7 @@ impl Interpreter {
                 BinOpType::Ge => Value::I64(if lhs >= rhs { 1 } else { 0 }),
                 BinOpType::Lt => Value::I64(if lhs < rhs { 1 } else { 0 }),
                 BinOpType::Le => Value::I64(if lhs <= rhs { 1 } else { 0 }),
+                BinOpType::Assign => unreachable!(),
             },
             // _ => panic!("Value types are not compatible"),
         }

src/lexer.rs

@@ -228,6 +228,8 @@ impl Token {
             Token::Lt => BinOpType::Lt,
             Token::Le => BinOpType::Le,
 
+            Token::Assign => BinOpType::Assign,
+
             _ => return None,
         })
     }

src/parser.rs

@@ -52,6 +52,9 @@ pub enum BinOpType {
 
     /// Check less or equal
     Le,
+
+    /// Assign to a variable
+    Assign,
 }
 
 /// Types for unary operators
@@ -239,14 +242,15 @@ impl BinOpType {
     /// See: https://en.cppreference.com/w/c/language/operator_precedence
     fn precedence(&self) -> u8 {
         match self {
-            BinOpType::BOr => 0,
+            BinOpType::Assign => 0,
-            BinOpType::BXor => 1,
+            BinOpType::BOr => 1,
-            BinOpType::BAnd => 2,
+            BinOpType::BXor => 2,
-            BinOpType::Equ | BinOpType::Neq => 3,
+            BinOpType::BAnd => 3,
-            BinOpType::Gt | BinOpType::Ge | BinOpType::Lt | BinOpType::Le => 4,
+            BinOpType::Equ | BinOpType::Neq => 4,
-            BinOpType::Shl | BinOpType::Shr => 5,
+            BinOpType::Gt | BinOpType::Ge | BinOpType::Lt | BinOpType::Le => 5,
-            BinOpType::Add | BinOpType::Sub => 6,
+            BinOpType::Shl | BinOpType::Shr => 6,
-            BinOpType::Mul | BinOpType::Div | BinOpType::Mod => 7,
+            BinOpType::Add | BinOpType::Sub => 7,
+            BinOpType::Mul | BinOpType::Div | BinOpType::Mod => 8,
         }
     }
 }