Enable creating custom methods

smnp/runtime/evaluator.py

@@ -1,3 +1,4 @@
+from smnp.ast.node.extend import ExtendNode
 from smnp.ast.node.function import FunctionDefinitionNode
 from smnp.ast.node.program import Program
 from smnp.error.runtime import RuntimeException
@@ -68,9 +69,11 @@ def evaluate(node, environment):
     from smnp.runtime.evaluators.expression import expressionEvaluator
 
     from smnp.runtime.evaluators.function import FunctionDefinitionEvaluator
+    from smnp.runtime.evaluators.extend import ExtendEvaluator
     result = Evaluator.oneOf(
         Evaluator.forNodes(ProgramEvaluator.evaluate, Program),
         Evaluator.forNodes(FunctionDefinitionEvaluator.evaluate, FunctionDefinitionNode),
+        Evaluator.forNodes(ExtendEvaluator.evaluate, ExtendNode),
         expressionEvaluator()
     )(node, environment)
 

smnp/runtime/evaluators/extend.py

@@ -0,0 +1,25 @@
+from smnp.runtime.evaluator import Evaluator
+from smnp.runtime.evaluators.function import argumentsNodeToMethodSignature
+from smnp.runtime.evaluators.type import TypeEvaluator
+
+
+class ExtendEvaluator(Evaluator):
+
+    @classmethod
+    def evaluator(cls, node, environment):
+        type = TypeEvaluator.evaluate(node.type, environment).value #TODO check if it isn't necessary to verify 'result' attr of EvaluatioNResult
+        variable = node.variable.value
+        cls._evaluateExtend(node.methods, environment, type, variable)
+
+    @classmethod
+    def _evaluateExtend(cls, node, environment, type, variable):
+        for child in node.children:
+            cls._evaluateMethodDefinition(child, environment, type, variable)
+
+    @classmethod
+    def _evaluateMethodDefinition(cls, node, environment, type, variable):
+        name = node.name.value
+        signature = argumentsNodeToMethodSignature(node.arguments)
+        arguments = [arg.variable.value for arg in node.arguments]
+        body = node.body
+        environment.addCustomMethod(type, variable, name, signature, arguments, body)

smnp/runtime/evaluators/type.py

@@ -0,0 +1,10 @@
+from smnp.runtime.evaluator import Evaluator
+from smnp.type.model import Type
+from smnp.type.value import Value
+
+
+class TypeEvaluator(Evaluator):
+
+    @classmethod
+    def evaluator(cls, node, environment):
+        return Value(Type.TYPE, node.type)