Create evaluator for sum (sum, subtraction and string concatenation)

smnp/runtime/evaluators/expression.py

@@ -1,3 +1,4 @@
+from smnp.ast.node.expression import Sum
 from smnp.ast.node.factor import NotOperator, Power, Loop
 from smnp.ast.node.identifier import FunctionCall, Assignment
 from smnp.ast.node.term import Product
@@ -19,6 +20,7 @@ def expressionEvaluator(doAssert=False):
         from smnp.runtime.evaluators.assignment import AssignmentEvaluator
         from smnp.runtime.evaluators.product import ProductEvaluator
 
+        from smnp.runtime.evaluators.sum import SumEvaluator
         result = Evaluator.oneOf(
             Evaluator.forNodes(FunctionCallEvaluator.evaluate, FunctionCall),
             Evaluator.forNodes(MinusEvaluator.evaluate, MinusOperator),
@@ -28,6 +30,7 @@ def expressionEvaluator(doAssert=False):
             Evaluator.forNodes(LoopEvaluator.evaluate, Loop),
             Evaluator.forNodes(AssignmentEvaluator.evaluate, Assignment),
             Evaluator.forNodes(ProductEvaluator.evaluate, Product),
+            Evaluator.forNodes(SumEvaluator.evaluate, Sum),
             AtomEvaluator.evaluate
         )(node, environment)
 

smnp/runtime/evaluators/sum.py

@@ -0,0 +1,40 @@
+from smnp.error.runtime import RuntimeException
+from smnp.runtime.evaluator import Evaluator
+from smnp.runtime.evaluators.expression import expressionEvaluator
+from smnp.type.model import Type
+
+
+class SumEvaluator(Evaluator):
+
+    @classmethod
+    def evaluator(cls, node, environment):
+        left = expressionEvaluator(doAssert=True)(node.left, environment).value
+        right = expressionEvaluator(doAssert=True)(node.right, environment).value
+
+        if left.type == right.type == Type.INTEGER:
+            return cls.integerEvaluator(left, node.operator, right)
+
+        if left.type == right.type == Type.STRING:
+            return cls.stringEvaluator(left, node.operator, right)
+
+        raise RuntimeException(f"Operator {node.operator.value} is not supported by {left.type.name.lower()} and {right.type.name.lower()} types", node.operator.pos)
+
+    @classmethod
+    def integerEvaluator(cls, left, operator, right):
+        if operator.value == "+":
+            return Type.integer(left.value + right.value)
+
+        if operator.value == "-":
+            return Type.integer(left.value - right.value)
+
+        raise RuntimeError("This line should never be reached")
+
+    @classmethod
+    def stringEvaluator(cls, left, operator, right):
+        if operator.value == "+":
+            return Type.string(left.value + right.value)
+
+        if operator.value == "-":
+            raise RuntimeException(f"Operator {operator.value} is not supported by string types", operator.pos)
+
+        raise RuntimeError("This line should never be reached")