add return support

src/ast_list.cc

@@ -646,8 +646,13 @@ ObjectPtr ArgumentsAST::eval(EnvPtr env, ObjectPtr caller) {
   //每次调用函数，都有创建一个新的内部环境
   EnvPtr funcEnv = func->runtimeEnv();
   params->eval(funcEnv, env, children_);
-  auto result = func->block()->eval(funcEnv);
-  return result;
+  try {
+    func->block()->eval(funcEnv);
+  }
+  catch(ASTReturnException &e) {
+    return e.result_;
+  }
+  return nullptr;
 }
 
 ObjectPtr ArgumentsAST::invokeNative(EnvPtr env, NativeFuncPtr func) {
@@ -849,6 +854,25 @@ void NewAST::initInstance(ClassInfoPtr ci, EnvPtr env) {
   }
 }
 
+/*******************return表达式*****************************/
+
+ReturnAST::ReturnAST(): ASTList(ASTKind::LIST_RETURN, false) {}
+
+ObjectPtr ReturnAST::eval(EnvPtr env) {
+  if (children_.empty())
+    throw ASTEvalException("invalid return statement");
+
+  ObjectPtr result = children_[0]->eval(env);
+  throw ASTReturnException(result);
+}
+
+std::string ReturnAST::info() {
+  if (children_.empty())
+    throw ASTEvalException("invalid return statement");
+
+  return "return " + children_[0]->info();
+}
+
 /*******************数组字面量*******************************/
 
 ArrayLiteralAST::ArrayLiteralAST(): ASTList(ASTKind::LIST_ARRAY_LITERAL, false) {}

src/ast_list.h

@@ -361,6 +361,25 @@ class NewAST: public PostfixAST{
 };
 using NewASTPtr = std::shared_ptr<NewAST>;
 
+/*******************return表达式*****************************/
+
+class ReturnAST: public ASTList {
+public:
+  ReturnAST();
+
+  //计算出结果后抛出异常给上层处理
+  ObjectPtr eval(EnvPtr env) override;
+
+  std::string info() override;
+};
+using ReturnASTPtr = std::shared_ptr<ReturnAST>;
+
+class ASTReturnException: public ASTEvalException {
+public:
+  ASTReturnException(ObjectPtr result): ASTEvalException("return"), result_(result) {}
+  ObjectPtr result_;
+};
+
 /*******************数组字面量*******************************/
 
 class ArrayLiteralAST: public ASTList {

src/ast_tree.h

@@ -22,6 +22,7 @@ class ASTEvalException: public ASTException {
   ASTEvalException(const std::string &msg): ASTException(msg) {}
 };
 
+
 /******************************AST迭代器接口*****************************/
 template <typename Item>
 class Iterator {
@@ -73,8 +74,9 @@ enum class ASTKind {
   LIST_CLASS_STMNT = 2018,
   LIST_DOT = 2019,
   LIST_NEW = 2020,
-  LIST_ARRAY_LITERAL = 2021,
-  LIST_ARRAY_REF = 2022 
+  LIST_RETURN = 2021,
+  LIST_ARRAY_LITERAL = 2022,
+  LIST_ARRAY_REF = 2023 
 };
 
 /*********************AST的基类，用于定义接口****************************/

src/parser.cc

@@ -113,6 +113,9 @@ void BasicParser::init() {
         Parser::rule(ASTKind::LIST_WHILE_STMNT)->custom("while", true)\
         ->commomPR(condition)->commomPR(block),
 
+        //return 语句
+        Parser::rule(ASTKind::LIST_RETURN)->custom("return", true)->commomPR(expr),
+
         //普通的算术表达式
         simple
       });

src/parser.h

@@ -25,6 +25,7 @@
  * simple     : expr
  * statement  : "if" condition block EOL {elif} ["else" block]
  *              | "while" condition block
+ *              | "return" expr
  *              | simple
  * elif       : "elif" condition block EOL
  * condition  : expr
@@ -42,6 +43,8 @@
  * 1. program允许以NULL作为分割符，主要是为了if块的“换行{”格式问题，if语句会把program中的
  *    EOL Token吞掉；
  *    一般情况下，应该使用换行或者分号
+ *
+ * 2. simple其实可以被expr替代
  */
 
 class BasicParser {

src/parser_constructor.cc

@@ -94,6 +94,9 @@ ASTreePtr ASTFactory::getListInstance(ASTKind kind) {
     case ASTKind::LIST_NEW:
       result = std::make_shared<NewAST>();
       break;
+    case ASTKind::LIST_RETURN:
+      result = std::make_shared<ReturnAST>();
+      break;
     case ASTKind::LIST_ARRAY_REF:
       result = std::make_shared<ArrayRefAST>();
       break;

testFiles/bar.spr

@@ -0,0 +1,5 @@
+require foo as bar_foo
+
+bar_foo.a = 101
+print(bar_foo.fooInstance.age)
+

testFiles/entry.spr

@@ -0,0 +1,25 @@
+class Foo {
+  a_ = nil
+  b_ = nil
+
+  def init(a, b) {
+    self.a_ = a
+    self.b_ = b
+  }
+
+  def foo() {
+    print(a_ + b_)
+  }  
+
+  def sumAB() {
+    num = a_ + b_
+    return num + 1
+    print("shit")
+  }
+}
+
+f = Foo.new(1, 2)
+f.foo()
+
+h = f.sumAB()
+print(h)

testFiles/foo.spr

@@ -0,0 +1,4 @@
+require bar as barrr
+
+a = 100
+

testFiles/test.spr

@@ -0,0 +1,72 @@
+print("test function")
+def fact(n) {
+  f = 1
+  while n > 0 {
+    f = f * n
+    n = n - 1  
+  }
+  return f
+}
+result = fact(3)
+print("6 succes")
+
+print("test fib")
+def fib(n) {
+  if n < 2 {
+    return n  
+  } 
+  else {
+    return fib(n - 1) + fib(n - 2) 
+  }
+}
+result = fib(10)
+print("55 success")
+
+print("test class")
+class Position {
+  x = y = 0
+
+  def init() {
+
+  }
+
+  def move (nx, ny) {
+    x = nx
+    y = ny   
+  } 
+}
+p = Position.new()
+p.move(3, 4)
+p.x = 10
+print(p.x + p.y)
+print("14 success")
+
+if 1 > 2 {
+  print ("1 > 2")    
+}
+elif 3 < 2{
+  print ("3 < 2")  
+}
+elif 3 < 2 {
+  print ("3 < 2")  
+}
+else {
+  print ("else test successfully")  
+}
+
+true = (1 < 2)
+false = (1 > 2)
+
+if or(true, false) {
+  print("or test successfully");    
+}
+else {
+  print("or test failed")    
+}
+
+if and(true, false) {
+  print("and test failed")  
+}
+else {
+  print("and test successfully")  
+}