Implement AST Observer and AST printer

src/ast/Observer.cpp

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+//
+// Created by christoph on 21.03.23.
+//
+
+#include "Observer.h"
+
+Observer::Observer(const Node &root) : root(root) {}
+
+void Observer::traverse() {
+    traverse(root);
+}

src/ast/Observer.h

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+//
+// Created by christoph on 21.03.23.
+//
+
+#ifndef LOGISIMASSEMBLER_OBSERVER_H
+#define LOGISIMASSEMBLER_OBSERVER_H
+
+#include "Node.h"
+#include <memory>
+
+class Observer {
+public:
+    Observer(const Node &root);
+
+    virtual ~Observer() = default;
+
+    void traverse();
+
+protected:
+    virtual void traverse(const Node &node) = 0;
+
+    virtual void action(const Node &node) = 0;
+
+private:
+    const Node &root;
+};
+
+#endif //LOGISIMASSEMBLER_OBSERVER_H

src/ast/PrefixObserver.cpp

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+//
+// Created by christoph on 20.03.23.
+//
+
+#include "PrefixObserver.h"
+
+PrefixObserver::PrefixObserver(const Node &root) : Observer(root) {}
+
+// TODO: Shouldn't be recursive
+void PrefixObserver::traverse(const Node &node) {
+    action(node);
+
+    for (const auto &child : node.getChildren()) {
+        depth++;
+        traverse(*child);
+        depth--;
+    }
+}

src/ast/PrefixObserver.h

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+//
+// Created by christoph on 20.03.23.
+//
+
+#ifndef LOGISIMASSEMBLER_PREFIXOBSERVER_H
+#define LOGISIMASSEMBLER_PREFIXOBSERVER_H
+
+#include "Observer.h"
+
+class PrefixObserver : public Observer {
+public:
+    PrefixObserver(const Node &root);
+
+    ~PrefixObserver() override = default;
+
+protected:
+    void traverse(const Node &node) override;
+
+protected:
+    uint32_t depth = 0;
+};
+
+#endif //LOGISIMASSEMBLER_PREFIXOBSERVER_H

src/codegen/PrintObserver.cpp

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+//
+// Created by christoph on 21.03.23.
+//
+
+#include <iostream>
+#include "PrintObserver.h"
+
+PrintObserver::PrintObserver(const Node &node) : PrefixObserver(node) {}
+
+void PrintObserver::action(const Node &node) {
+    // Print a simple indent guide
+    std::string depth_padding(depth * 2, '|');
+    if (depth > 0) {
+        for (uint32_t i = 0; i < depth_padding.length(); ++i) {
+            if (i % 2 == 1) {
+                depth_padding[i] = ' ';
+            }
+        }
+        depth_padding[(depth * 2) - 1] = '-';
+    }
+
+    std::cout << depth_padding << typeid(node).name() << std::endl;
+}

src/codegen/PrintObserver.h

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+//
+// Created by christoph on 21.03.23.
+//
+
+#ifndef LOGISIMASSEMBLER_PRINTOBSERVER_H
+#define LOGISIMASSEMBLER_PRINTOBSERVER_H
+
+#include "../ast/PrefixObserver.h"
+
+class PrintObserver : public PrefixObserver {
+public:
+    PrintObserver(const Node &node);
+
+    ~PrintObserver() override = default;
+
+protected:
+    void action(const Node &node) override;
+};
+
+#endif //LOGISIMASSEMBLER_PRINTOBSERVER_H