Simplifies visitor

src/interpreter/Evaluator.java

@@ -5,7 +5,7 @@ import expression.*;
 import java.util.HashMap;
 import java.util.Map;
 
-public class Evaluator extends ExpressionVisitor<Integer> {
+public class Evaluator extends Visitor<Integer> {
 
     final Expression expression;
     final Map<String, Integer> valuation = new HashMap<>();
@@ -19,22 +19,18 @@ public class Evaluator extends ExpressionVisitor<Integer> {
         return visit(expression);
     }
 
-    @Override
     public Integer visitAddition(Addition addition) {
         return visit(addition.leftHandSide) + visit(addition.rightHandSide);
     }
 
-    @Override
     public Integer visitSubtraction(Subtraction subtraction) {
         return visit(subtraction.leftHandSide) - visit(subtraction.rightHandSide);
     }
 
-    @Override
     public Integer visitInt(Int integer) {
         return integer.value;
     }
 
-    @Override
     public Integer visitIdentifier(Identifier identifier) {
         if (valuation.containsKey(identifier.name)) {
             return valuation.get(identifier.name);

src/interpreter/ExpressionVisitor.java

@@ -1,28 +0,0 @@
-package interpreter;
-
-import expression.*;
-import java.lang.reflect.Method;
-
-public abstract class ExpressionVisitor<T> {
-    public T visit(Expression expression) {
-        String methodName = "visit" + expression.getClass().getSimpleName();
-        Method method;
-        try {
-            method = this.getClass().getMethod(methodName, expression.getClass());
-        } catch (NoSuchMethodException e) {
-            throw new RuntimeException(e);
-        }
-        Object result;
-        try {
-            result = method.invoke(this, expression);
-        } catch (Exception e) {
-            throw new RuntimeException(e);
-        }
-        return (T) result;
-    }
-
-    public abstract T visitAddition(Addition addition);
-    public abstract T visitSubtraction(Subtraction subtraction);
-    public abstract T visitInt(Int integer);
-    public abstract T visitIdentifier(Identifier identifier);
-}

src/interpreter/Interpreter.java

@@ -5,7 +5,7 @@ import program.*;
 import java.util.HashMap;
 import java.util.Map;
 
-public class Interpreter extends ProgramVisitor {
+public class Interpreter extends Visitor {
     final Program program;
     final Map<String, Integer> valuation = new HashMap<>();
 
@@ -20,19 +20,16 @@ public class Interpreter extends ProgramVisitor {
         visit(program);
     }
 
-    @Override
     public void visitAssignment(Assignment assignment) {
         Evaluator evaluator = new Evaluator(assignment.expression, valuation);
         valuation.put(assignment.identifier.name, evaluator.eval());
     }
 
-    @Override
     public void visitComposition(Composition composition) {
         visit(composition.first);
         visit(composition.second);
     }
 
-    @Override
     public void visitConditional(Conditional conditional) {
         Evaluator evaluator = new Evaluator(conditional.condition, valuation);
         if (evaluator.eval() != 0) {
@@ -42,7 +39,6 @@ public class Interpreter extends ProgramVisitor {
         }
     }
 
-    @Override
     public void visitLoop(Loop loop) {
         Evaluator evaluator = new Evaluator(loop.condition, valuation);
         if (evaluator.eval() != 0) {

src/interpreter/ProgramVisitor.java

@@ -1,18 +0,0 @@
-package interpreter;
-
-import program.*;
-
-public abstract class ProgramVisitor {
-    public void visit(Program program) {
-        try {
-            this.getClass().getMethod("visit" + program.getClass().getSimpleName(), program.getClass()).invoke(this, program);
-        } catch(Exception ex) {
-            throw new RuntimeException(ex);
-        }
-    }
-
-    public abstract void visitAssignment(Assignment assignment);
-    public abstract void visitComposition(Composition composition);
-    public abstract void visitConditional(Conditional conditional);
-    public abstract void visitLoop(Loop loop);
-}

src/interpreter/Visitor.java

@@ -0,0 +1,12 @@
+package interpreter;
+
+public abstract class Visitor<T> {
+    @SuppressWarnings("unchecked")
+    public T visit(Object object) {
+        try {
+            return (T) this.getClass().getMethod("visit" + object.getClass().getSimpleName(), object.getClass()).invoke(this, object);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+}