feat: 添加赋值运算符支持，更新解析器、解释器和词法分析器以处理相关语法

examples/assign_op.ast

@@ -0,0 +1,15 @@
+let a = 1
+a += 2
+print("a=", a)
+
+let b = 2
+b -= 1
+print("b=", b)
+
+let c = 5
+c *= 5
+print("c=", c)
+
+let d = 10
+c /= 5
+print("d=", d)

src/ast/expr.rs

@@ -11,6 +11,7 @@ pub enum Expr {
     /// 赋值表达式：a = b
     Assign {
         name: String,
+        op: AssignOp,
         value: Box<Expr>,
     },
 
@@ -24,6 +25,7 @@ pub enum Expr {
     Set {
         object: Box<Expr>,
         name: String,
+        op: AssignOp,
         value: Box<Expr>,
     },
 
@@ -47,6 +49,7 @@ pub enum Expr {
     IndexSet {
         array: Box<Expr>,
         index: Box<Expr>,
+        op: AssignOp,
         value: Box<Expr>,
     },
 
@@ -118,3 +121,12 @@ pub enum LogicalOp {
     And,
     Or,
 }
+
+#[derive(Debug, Clone, Copy)]
+pub enum AssignOp {
+    Equal,      // =
+    PlusEqual,  // +=
+    MinusEqual, // -=
+    StarEqual,  // *=
+    SlashEqual, // /=
+}

src/interpreter/interpreter.rs

@@ -141,8 +141,15 @@ impl Interpreter {
                     }),
                 }
             }
-            Expr::Assign { name, value } => {
-                let val = self.evaluate(*value)?;
+            Expr::Assign { name, op, value } => {
+                let rhs = self.evaluate(*value)?;
+                let val = match op {
+                    AssignOp::Equal => rhs,
+                    _ => {
+                        let current = self.env.borrow().get(&name).ok_or_else(|| RuntimeError::RuntimeError { message: format!("Undefined variable '{}'", name), token: None })?;
+                        self.apply_assign_op(current.clone(), rhs, op)?
+                    }
+                };
                 if !self.env.borrow_mut().assign(&name, val.clone()) {
                     return Err(RuntimeError::RuntimeError {
                         message: format!("Undefined variable '{}'", name),
@@ -169,11 +176,19 @@ impl Interpreter {
                     }),
                 }
             }
-            Expr::Set { object, name, value } => {
+            Expr::Set { object, name, op,  value } => {
                 let obj = self.evaluate(*object)?;
+                let rhs = self.evaluate(*value)?;
                 match obj {
                     Value::Object(map) => {
-                        let val = self.evaluate(*value)?;
+                        let val = match op {
+                            AssignOp::Equal => rhs,
+                            _ => {
+                                let map_borrow = map.borrow();
+                                let current = map_borrow.get(&name).ok_or_else(|| RuntimeError::RuntimeError { message: format!("Property '{}' does not exist", name), token: None })?;
+                                self.apply_assign_op(current.clone(), rhs, op)?
+                            }
+                        };
                         map.borrow_mut().insert(name, val.clone());
                         Ok(val)
                     }
@@ -208,10 +223,10 @@ impl Interpreter {
                     }),
                 }
             }
-            Expr::IndexSet { array, index, value } => {
+            Expr::IndexSet { array, index, op, value } => {
                 let arr = self.evaluate(*array)?;
                 let idx = self.evaluate(*index)?;
-                let val = self.evaluate(*value)?;
+                let rhs = self.evaluate(*value)?;
                 let i = self.as_array_index(&idx)?;
                 match arr {
                     Value::Array(vec) => {
@@ -222,6 +237,13 @@ impl Interpreter {
                                 token: None,
                             });
                         }
+                        let val = match op {
+                            AssignOp::Equal => rhs,
+                            _ => {
+                                let current = vec[i].clone();
+                                self.apply_assign_op(current, rhs, op)?
+                            }
+                        };
                         vec[i] = val.clone();
                         Ok(val)
                     }
@@ -398,6 +420,32 @@ impl Interpreter {
         }
     }
 
+    fn apply_assign_op(&self, left: Value, right: Value, op: AssignOp) -> Result<Value, RuntimeError> {
+        match op {
+            AssignOp::Equal => Ok(right),
+            AssignOp::PlusEqual => {
+                let left_num = self.as_number(&left)?;
+                let right_num = self.as_number(&right)?;
+                Ok(Value::Number(left_num + right_num))
+            }
+            AssignOp::MinusEqual => {
+                let left_num = self.as_number(&left)?;
+                let right_num = self.as_number(&right)?;
+                Ok(Value::Number(left_num - right_num))
+            }
+            AssignOp::StarEqual => {
+                let left_num = self.as_number(&left)?;
+                let right_num = self.as_number(&right)?;
+                Ok(Value::Number(left_num * right_num))
+            }
+            AssignOp::SlashEqual => {
+                let left_num = self.as_number(&left)?;
+                let right_num = self.as_number(&right)?;
+                Ok(Value::Number(left_num / right_num))
+            }
+        }
+    }
+
     fn as_number(&self, val: &Value) -> Result<f64, RuntimeError> {
         if let Value::Number(n) = val {
             Ok(*n)

src/lexer/lexer.rs

@@ -56,9 +56,27 @@ impl Lexer {
             ',' => TokenKind::Comma,
             ';' => TokenKind::Semicolon,
 
-            '+' => TokenKind::Plus,
-            '-' => TokenKind::Minus,
-            '*' => TokenKind::Star,
+            '+' => {
+                if self.match_char('=') {
+                    TokenKind::PlusEqual
+                } else {
+                    TokenKind::Plus
+                }
+            }
+            '-' => {
+                if self.match_char('=') {
+                    TokenKind::MinusEqual
+                } else {
+                    TokenKind::Minus
+                }
+            }
+            '*' => {
+                if self.match_char('=') {
+                    TokenKind::StarEqual
+                } else {
+                    TokenKind::Star
+                }
+            }
             '.' => TokenKind::Dot,
             ':' => TokenKind::Colon,
             '[' => TokenKind::LeftBracket,
@@ -71,6 +89,8 @@ impl Lexer {
                         self.advance();
                     }
                     return None;
+                } else if self.match_char('=') {
+                    TokenKind::SlashEqual
                 } else {
                     TokenKind::Slash
                 }

src/lexer/token.rs

@@ -16,6 +16,7 @@ pub enum TokenKind {
     Less, LessEqual,
     EqualEqual, BangEqual,
     AndAnd, OrOr,
+    PlusEqual, MinusEqual, StarEqual, SlashEqual,
 
     // 字面量
     Identifier(String),

src/parser/parser.rs

@@ -202,12 +202,26 @@ impl Parser {
     fn assignment(&mut self) -> Expr {
         let expr = self.logical_or();
 
-        if self.match_kind(&[TokenKind::Equal]) {
+        let op = if self.match_kind(&[TokenKind::Equal]) {
+            Some(AssignOp::Equal)
+        } else if self.match_kind(&[TokenKind::PlusEqual]) {
+            Some(AssignOp::PlusEqual)
+        } else if self.match_kind(&[TokenKind::MinusEqual]) {
+            Some(AssignOp::MinusEqual)
+        } else if self.match_kind(&[TokenKind::StarEqual]) {
+            Some(AssignOp::StarEqual)
+        } else if self.match_kind(&[TokenKind::SlashEqual]) {
+            Some(AssignOp::SlashEqual)
+        } else {
+            None
+        };
+
+        if let Some(op) = op {
             let value = self.assignment();
             return match expr {
-                Expr::Variable(name) => Expr::Assign { name, value: Box::new(value) },
-                Expr::Get { object, name } => Expr::Set { object, name, value: Box::new(value) },
-                Expr::IndexGet { array, index } => Expr::IndexSet { array, index, value: Box::new(value) },
+                Expr::Variable(name) => Expr::Assign { name, op, value: Box::new(value) },
+                Expr::Get { object, name } => Expr::Set { object, name, op, value: Box::new(value) },
+                Expr::IndexGet { array, index } => Expr::IndexSet { array, index, op, value: Box::new(value) },
                 _ => panic!("Invalid assignment target."),
             };
         }