Handle unary minus

Author: mdbrnowski

interpreter.py

@@ -71,7 +71,7 @@ def visitTransposeExpression(self, ctx: MyParser.TransposeExpressionContext):
         return self.visitChildren(ctx)  # todo
 
     def visitMinusExpression(self, ctx: MyParser.MinusExpressionContext):
-        return self.visitChildren(ctx)  # todo
+        return -self.visit(ctx.getChild(1))
 
     def visitSingleExpression(self, ctx: MyParser.SingleExpressionContext):
         return self.visit(ctx.getChild(0))

test_main.py

@@ -68,10 +68,10 @@ def test_sem_errors(name: str, line_numbers: list[int], additional: str):
 @pytest.mark.parametrize(
     "name,output",
     [
-        ("simple_math", [23, 35, 1, 1.0, 1]),
+        ("simple_math", [23, 35, 1, 1.0, 1, -2]),
     ],
 )
 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.strip() == "\n".join(map(str, output))
+    assert result.stdout == "\n".join(map(str, output)) + "\n"

tests/interpreter/simple_math.txt

@@ -1,2 +1,3 @@
 print 3 + 4 * 5, (3 + 4) * 5;
-print 2 / 2, 1.0 * 1.0, 2 - 1;
+print 2 / 2, 1.0 * 1.0, 2 - 1;
+print -1 * 2;

utils/values.py

@@ -29,6 +29,9 @@ def __truediv__(self, other):
             return Float(self.value / other.value)
         raise TypeError()
 
+    def __neg__(self):
+        return Int(-self.value)
+
 
 class Float(Value):
     def __init__(self, value):
@@ -54,6 +57,9 @@ def __truediv__(self, other):
             return Float(self.value / other.value)
         raise TypeError()
 
+    def __neg__(self):
+        return Float(-self.value)
+
 
 class String(Value):
     def __init__(self, value):