Create evaluator for minus operator

smnp/runtime/evaluators/expression.py

@@ -2,6 +2,7 @@ from smnp.ast.node.atom import StringLiteral, IntegerLiteral, NoteLiteral, BoolL
 from smnp.ast.node.identifier import FunctionCall
 from smnp.ast.node.list import List
 from smnp.ast.node.map import Map
+from smnp.ast.node.unit import MinusOperator
 from smnp.error.runtime import RuntimeException
 from smnp.runtime.evaluator import Evaluator
 from smnp.type.model import Type
@@ -18,6 +19,7 @@ def expressionEvaluator(doAssert=False):
             from smnp.runtime.evaluators.function import FunctionCallEvaluator
             from smnp.runtime.evaluators.atom import ListEvaluator
             from smnp.runtime.evaluators.atom import MapEvaluator
+            from smnp.runtime.evaluators.minus import MinusEvaluator
             result =  Evaluator.oneOf(
                 Evaluator.forNodes(FunctionCallEvaluator.evaluate, FunctionCall),
                 Evaluator.forNodes(StringEvaluator.evaluate, StringLiteral),
@@ -26,7 +28,8 @@ def expressionEvaluator(doAssert=False):
                 Evaluator.forNodes(BoolEvaluator.evaluate, BoolLiteral),
                 Evaluator.forNodes(TypeEvaluator.evaluate, TypeLiteral),
                 Evaluator.forNodes(ListEvaluator.evaluate, List),
-                Evaluator.forNodes(MapEvaluator.evaluate, Map)
+                Evaluator.forNodes(MapEvaluator.evaluate, Map),
+                Evaluator.forNodes(MinusEvaluator.evaluate, MinusOperator)
                 # Evaluator.forNodes(IdentifierEvaluator.evaluate, Identifier),
                 # Evaluator.forNodes(ListEvaluator.evaluate, List),
                 # Evaluator.forNodes(AccessEvaluator.evaluate, LeftAssociativeOperatorNode),

smnp/runtime/evaluators/minus.py

@@ -0,0 +1,31 @@
+from smnp.error.runtime import RuntimeException
+from smnp.runtime.evaluator import Evaluator, evaluate
+from smnp.type.model import Type
+
+
+class MinusEvaluator(Evaluator):
+
+    @classmethod
+    def evaluator(cls, node, environment):
+        value = evaluate(node.value, environment).value
+        try:
+            return {
+                Type.INTEGER: cls.evaluateForInteger,
+                Type.STRING: cls.evaluateForString,
+                Type.LIST: cls.evaluateForList
+            }[value.type](value.value)
+        except KeyError:
+            raise RuntimeException(f"Type {value.type.name.lower()} does not support '{node.operator.value}' operator", node.pos)
+
+    @classmethod
+    def evaluateForInteger(cls, value):
+
+        return Type.integer(-value)
+
+    @classmethod
+    def evaluateForString(cls, value):
+        return Type.string(value[::-1])
+
+    @classmethod
+    def evaluateForList(cls, value):
+        return Type.list(value[::-1])