implement visitors

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

@@ -527,4 +527,21 @@ public class EvalVisitor implements Visitor<Value> {
     return null;
   }
 
+  @Override
+  public Value visit(FieldAssignment e) {
+    Value val = this.env.get(e.varName);
+    String fieldNameToUpdate = e.path[e.path.length - 1];
+    
+    // Find the struct that holds the field to be updated
+    Map<String, Value> struct = val.asStruct();
+    for (int i = 0; i < e.path.length - 1; i++) {
+      struct = struct.get(e.path[i]).asStruct();
+    }
+
+    // if we are here, struct contains a reference to the struct that holds the field to be updated
+    struct.put(fieldNameToUpdate, e.expression.welcome(this));
+
+    return null;
+  }
+
 }

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

@@ -865,4 +865,31 @@ public class GenASM implements Visitor<Void> {
     return null;
   }
 
+  @Override
+  public Void visit(FieldAssignment e) {
+    var structDef = this.structs.get(e.structName);
+    int offset = this.env.get(e.varName);
+    String fieldNameToUpdate = e.path[e.path.length - 1];
+
+    // Push the expression onto the stack
+    e.expression.welcome(this);
+    this.ex.write("    pushq %rax\n");
+
+    // move struct address into rax
+    this.ex.write("    movq " + offset + "(%rbp), %rax\n");
+
+    // If there are at least two elements in the path, 
+    // move the address of the next referenced struct into rax
+    for  (int i = 0; i < e.path.length - 1; i++) {
+      structDef = this.structs.get(structDef.fields[Helper.getFieldIndex(structDef, e.path[i])].type.getName());
+      this.ex.write("    movq " + Helper.getFieldOffset(structDef, e.path[i]) + "(%rax), %rax\n");
+    }
+
+    // pop the expression that is ontop of the stack into the field of the struct that has to be updated
+    this.ex.write("    popq " + Helper.getFieldOffset(structDef, fieldNameToUpdate) + "(%rax)\n");
+    this.ex.write("    movq $0, %rax\n"); // clear rax sind an assignment has no result
+
+    return null;
+  }
+
 }

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

@@ -269,4 +269,9 @@ class GetVars implements Visitor<Void> {
   public Void visit(DestructorCall e) {
     return null;
   }
+
+  @Override
+  public Void visit(FieldAssignment e) {
+    return null;
+  }
 }

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

@@ -444,4 +444,17 @@ public class PrettyPrintVisitor implements Visitor<Void> {
     return null;
   }
 
+  @Override
+  public Void visit(FieldAssignment e) {
+    ex.write(e.varName);
+    for (int i = 0; i < e.path.length; i++) {
+      ex.write(".");
+      ex.write(e.path[i]);
+    }
+    ex.write(" = ");
+    e.expression.welcome(this);
+    ex.write(";");
+    return null;
+  }
+
 }

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

@@ -49,4 +49,5 @@ public interface Visitor<R> {
     R visit(ConstructorCall e);
     R visit(NullExpression e);
     R visit(DestructorCall e);
+    R visit(FieldAssignment e);
 }