fix: 修复字符串转义、对象相等比较、除零处理

- 词法分析器：字符串字面量中支持 \n \t \r " \ 转义序列，未知转义序列报告错误并跳过剩余字符串
- 解释器：对象相等比较新增深度比较（键值对逐一比对）
- 解释器：除法和取模运算在除数为零时返回 RuntimeError，避免产生 inf/NaN

Co-Authored-By: Claude <noreply@anthropic.com>

src/interpreter/interpreter.rs

@@ -308,6 +308,12 @@ impl Interpreter {
                         }),
                     },
                     crate::ast::expr::BinaryOp::Div => match (l,r) {
+                        (Value::Number(_), Value::Number(b)) if b == 0.0 => {
+                            Err(RuntimeError::RuntimeError {
+                                message: "Division by zero".to_string(),
+                                token: None,
+                            })
+                        }
                         (Value::Number(a), Value::Number(b)) => Ok(Value::Number(a/b)),
                         _ => Err(RuntimeError::RuntimeError {
                             message: "Invalid '/' operands".to_string(),
@@ -315,6 +321,12 @@ impl Interpreter {
                         }),
                     },
                     crate::ast::expr::BinaryOp::Mod => match (l,r) {
+                        (Value::Number(_), Value::Number(b)) if b == 0.0 => {
+                            Err(RuntimeError::RuntimeError {
+                                message: "Modulo by zero".to_string(),
+                                token: None,
+                            })
+                        }
                         (Value::Number(a), Value::Number(b)) => Ok(Value::Number(a%b)),
                         _ => Err(RuntimeError::RuntimeError {
                             message: "Invalid '%' operands".to_string(),
@@ -423,6 +435,14 @@ impl Interpreter {
                 if x.len() != y.len() { return false; }
                 x.iter().zip(y.iter()).all(|(a,b)| self.is_equal(a,b))
             }
+            (Value::Object(x), Value::Object(y)) => {
+                let x = x.borrow();
+                let y = y.borrow();
+                if x.len() != y.len() { return false; }
+                x.iter().all(|(k, v)| {
+                    y.get(k).map_or(false, |yv| self.is_equal(v, yv))
+                })
+            }
             _ => false,
         }
     }
@@ -1003,6 +1023,40 @@ mod tests {
         assert_bool(&eval_expr("[1] == [1, 2]"), false);
     }
 
+    // =========================================================================
+    // Object equality
+    // =========================================================================
+
+    #[test]
+    fn eval_object_equality_same() {
+        let interp = run("let a = {x: 1, y: 2}; let b = {x: 1, y: 2}; let r = a == b;");
+        assert_bool(&get_var(&interp, "r"), true);
+    }
+
+    #[test]
+    fn eval_object_equality_different_values() {
+        let interp = run("let a = {x: 1}; let b = {x: 2}; let r = a == b;");
+        assert_bool(&get_var(&interp, "r"), false);
+    }
+
+    #[test]
+    fn eval_object_equality_different_keys() {
+        let interp = run("let a = {x: 1}; let b = {y: 1}; let r = a == b;");
+        assert_bool(&get_var(&interp, "r"), false);
+    }
+
+    #[test]
+    fn eval_object_equality_different_size() {
+        let interp = run("let a = {x: 1}; let b = {x: 1, y: 2}; let r = a == b;");
+        assert_bool(&get_var(&interp, "r"), false);
+    }
+
+    #[test]
+    fn eval_object_equality_empty() {
+        let interp = run("let a = {}; let b = {}; let r = a == b;");
+        assert_bool(&get_var(&interp, "r"), true);
+    }
+
     // =========================================================================
     // Strings as indexable
     // =========================================================================
@@ -1119,6 +1173,22 @@ mod tests {
         assert!(result.is_err(), "Expected error for undefined variable");
     }
 
+    #[test]
+    fn error_division_by_zero() {
+        let result = std::panic::catch_unwind(|| {
+            eval_expr("1 / 0");
+        });
+        assert!(result.is_err(), "Expected error for division by zero");
+    }
+
+    #[test]
+    fn error_modulo_by_zero() {
+        let result = std::panic::catch_unwind(|| {
+            eval_expr("1 % 0");
+        });
+        assert!(result.is_err(), "Expected error for modulo by zero");
+    }
+
     #[test]
     fn error_type_mismatch_negate_string() {
         let result = std::panic::catch_unwind(|| {

src/lexer/lexer.rs

@@ -233,7 +233,38 @@ impl Lexer {
         let mut value = String::new();
 
         while !self.is_at_end() && self.peek() != '"' {
-            value.push(self.advance());
+            let c = self.advance();
+            if c == '\\' {
+                // Handle escape sequences
+                if self.is_at_end() {
+                    errors.push(RuntimeError::lex("Unterminated string literal", line, column));
+                    return None;
+                }
+                match self.advance() {
+                    'n' => value.push('\n'),
+                    't' => value.push('\t'),
+                    'r' => value.push('\r'),
+                    '"' => value.push('"'),
+                    '\\' => value.push('\\'),
+                    other => {
+                        errors.push(RuntimeError::lex(
+                            format!("Unknown escape sequence '\\{}'", other),
+                            line,
+                            column,
+                        ));
+                        // Consume the rest of the string to avoid cascading errors
+                        while !self.is_at_end() && self.peek() != '"' {
+                            self.advance();
+                        }
+                        if !self.is_at_end() {
+                            self.advance(); // consume closing "
+                        }
+                        return None;
+                    }
+                }
+            } else {
+                value.push(c);
+            }
         }
 
         if self.is_at_end() {
@@ -451,6 +482,43 @@ mod tests {
         ]);
     }
 
+    #[test]
+    fn string_escape_newline() {
+        let kinds = tokenize("\"a\\nb\"");
+        assert_eq!(kinds, vec![TokenKind::String("a\nb".into())]);
+    }
+
+    #[test]
+    fn string_escape_tab() {
+        let kinds = tokenize("\"a\\tb\"");
+        assert_eq!(kinds, vec![TokenKind::String("a\tb".into())]);
+    }
+
+    #[test]
+    fn string_escape_quote() {
+        let kinds = tokenize("\"he\\\"llo\"");
+        assert_eq!(kinds, vec![TokenKind::String("he\"llo".into())]);
+    }
+
+    #[test]
+    fn string_escape_backslash() {
+        let kinds = tokenize("\"a\\\\b\"");
+        assert_eq!(kinds, vec![TokenKind::String("a\\b".into())]);
+    }
+
+    #[test]
+    fn string_escape_carriage_return() {
+        let kinds = tokenize("\"a\\rb\"");
+        assert_eq!(kinds, vec![TokenKind::String("a\rb".into())]);
+    }
+
+    #[test]
+    fn string_unknown_escape_is_error() {
+        let (_, errors) = tokenize_full("\"\\x\"");
+        assert_eq!(errors.len(), 1);
+        assert!(errors[0].to_string().contains("Unknown escape"));
+    }
+
     // ----- identifiers and keywords -----
 
     #[test]