implement variable assignment

src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java

@@ -52,6 +52,13 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     }
   }
 
+  @Override
+  public Node visitVariable_assignment(KlangParser.Variable_assignmentContext ctx) {
+    String name = ctx.IDENT().getText();
+    Expression expression = (Expression) this.visit(ctx.expression());
+    return new VariableAssignment(name, expression);
+  }
+
   @Override
   public Node visitMultiplicationExpression(KlangParser.MultiplicationExpressionContext ctx) {
     Node left = this.visit(ctx.atom(0));

src/main/java/de/hsrm/compiler/Klang/nodes/statements/VariableAssignment.java

@@ -0,0 +1,21 @@
+package de.hsrm.compiler.Klang.nodes.statements;
+
+import de.hsrm.compiler.Klang.nodes.expressions.Expression;
+import de.hsrm.compiler.Klang.visitors.Visitor;
+
+public class VariableAssignment extends Statement {
+
+    public String name;
+    public Expression expression;
+
+    public VariableAssignment(String name, Expression expression) {
+        this.name = name;
+        this.expression = expression;
+    }
+
+    @Override
+    public <R> R welcome(Visitor<R> v) {
+        return v.visit(this);
+    }
+
+}

src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java

@@ -85,6 +85,13 @@ public class EvalVisitor implements Visitor<Value> {
     return null;
   }
 
+  @Override
+  public Value visit(VariableAssignment e) {
+    Value result = e.expression.welcome(this);
+    this.env.put(e.name, result);
+    return result;
+  }
+
   @Override
   public Value visit(Block e) {
     Value result = null;

src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java

@@ -125,6 +125,14 @@ public class PrettyPrintVisitor implements Visitor<Void> {
         return null;
     }
 
+    @Override
+    public Void visit(VariableAssignment e) {
+        ex.write(e.name + " = ");
+        e.expression.welcome(this);
+        ex.write(";");
+        return null;
+    }
+
     @Override
     public Void visit(Block e) {
         ex.write("{");
@@ -171,7 +179,7 @@ public class PrettyPrintVisitor implements Visitor<Void> {
             }
             arg.welcome(this);
         }
-        ex.write(");");
+        ex.write(")");
         return null;
     }
 

src/main/java/de/hsrm/compiler/Klang/visitors/Visitor.java

@@ -15,6 +15,7 @@ public interface Visitor<R> {
     R visit(ModuloExpression e);
     R visit(IfStatement e);
     R visit(PrintStatement e);
+    R visit(VariableAssignment e);
     R visit(Block e);
     R visit(FunctionDefinition e);
     R visit(FunctionCall e);