Handle return expressions

Author: mdbrnowski

interpreter.py

@@ -1,4 +1,5 @@
 from copy import deepcopy
+import sys
 
 from generated.MyParser import MyParser
 from generated.MyParserVisitor import MyParserVisitor
@@ -65,7 +66,12 @@ def visitPrint(self, ctx: MyParser.PrintContext):
             print(str(self.visit(ctx.getChild(i))))
 
     def visitReturn(self, ctx: MyParser.ReturnContext):
-        return self.visitChildren(ctx)  # todo
+        if ctx.expression() is not None:
+            return_value = self.visit(ctx.expression())
+            if not isinstance(return_value, Int):
+                raise TypeError
+            sys.exit(return_value.value)
+        sys.exit()
 
     def visitBinaryExpression(self, ctx: MyParser.BinaryExpressionContext):
         a = self.visit(ctx.getChild(0))

test_main.py

@@ -87,3 +87,8 @@ def test_interpreter(name: str, output: str):
     result = runner.invoke(app, ["run", f"tests/interpreter/{name}.txt"])
     assert result.exit_code == 0
     assert result.stdout == "\n".join(map(str, output)) + "\n"
+
+
+def test_interpreter_return():
+    result = runner.invoke(app, ["run", "tests/interpreter/return.txt"])
+    assert result.exit_code == 1

tests/interpreter/return.txt

@@ -0,0 +1,2 @@
+print 0;
+return 1;