Implement codegen using an Observer

src/codegen/CodegenObserver.cpp

@@ -0,0 +1,20 @@
+//
+// Created by christoph on 21.03.23.
+//
+
+#include "CodegenObserver.h"
+#include <boost/format.hpp>
+#include <iostream>
+
+CodegenObserver::CodegenObserver(const Node &node, std::string &output_string)
+        : PostfixObserver(node), output_string(output_string) {}
+
+void CodegenObserver::action(const Node &node) {
+    const uint8_t opcode = node.compile();
+    const uint8_t INVALID = -1;
+
+    if (opcode != INVALID) {
+        output_string += (boost::format("%x") % static_cast<uint32_t>(opcode)).str(); // uint8_t is always interpreted as char
+        output_string += ' ';
+    }
+}

src/codegen/CodegenObserver.h

@@ -0,0 +1,23 @@
+//
+// Created by christoph on 21.03.23.
+//
+
+#ifndef LOGISIMASSEMBLER_CODEGENOBSERVER_H
+#define LOGISIMASSEMBLER_CODEGENOBSERVER_H
+
+#include "../ast/PostfixObserver.h"
+
+class CodegenObserver : public PostfixObserver {
+public:
+    CodegenObserver(const Node &node, std::string &output_string);
+
+    ~CodegenObserver() override = default;
+
+protected:
+    void action(const Node &node) override;
+
+private:
+    std::string &output_string;
+};
+
+#endif //LOGISIMASSEMBLER_CODEGENOBSERVER_H