From e92e7d2183cbf57f2b93a4b6216b2e81c57ee0ef Mon Sep 17 00:00:00 2001
From: ChUrl <christoph.urlacher@protonmail.com>
Date: Tue, 21 Mar 2023 15:48:42 +0100
Subject: [PATCH] Implement codegen using an Observer

---
 src/ast/PostfixObserver.cpp     | 18 ++++++++++++++++++
 src/ast/PostfixObserver.h       | 23 +++++++++++++++++++++++
 src/codegen/CodegenObserver.cpp | 20 ++++++++++++++++++++
 src/codegen/CodegenObserver.h   | 23 +++++++++++++++++++++++
 4 files changed, 84 insertions(+)
 create mode 100644 src/ast/PostfixObserver.cpp
 create mode 100644 src/ast/PostfixObserver.h
 create mode 100644 src/codegen/CodegenObserver.cpp
 create mode 100644 src/codegen/CodegenObserver.h

diff --git a/src/ast/PostfixObserver.cpp b/src/ast/PostfixObserver.cpp
new file mode 100644
index 0000000..7f8a9fb
--- /dev/null
+++ b/src/ast/PostfixObserver.cpp
@@ -0,0 +1,18 @@
+//
+// Created by christoph on 20.03.23.
+//
+
+#include "PostfixObserver.h"
+
+PostfixObserver::PostfixObserver(const Node &root) : Observer(root) {}
+
+// TODO: Shouldn't be recursive
+void PostfixObserver::traverse(const Node &node) {
+    for (const auto &child : node.getChildren()) {
+        depth++;
+        traverse(*child);
+        depth--;
+    }
+
+    action(node);
+}
diff --git a/src/ast/PostfixObserver.h b/src/ast/PostfixObserver.h
new file mode 100644
index 0000000..2e1964a
--- /dev/null
+++ b/src/ast/PostfixObserver.h
@@ -0,0 +1,23 @@
+//
+// Created by christoph on 20.03.23.
+//
+
+#ifndef LOGISIMASSEMBLER_POSTFIXOBSERVER_H
+#define LOGISIMASSEMBLER_POSTFIXOBSERVER_H
+
+#include "Observer.h"
+
+class PostfixObserver : public Observer {
+public:
+    PostfixObserver(const Node &root);
+
+    ~PostfixObserver() override = default;
+
+protected:
+    void traverse(const Node &node) override;
+
+protected:
+    uint32_t depth = 0;
+};
+
+#endif //LOGISIMASSEMBLER_PREFIXOBSERVER_H
diff --git a/src/codegen/CodegenObserver.cpp b/src/codegen/CodegenObserver.cpp
new file mode 100644
index 0000000..1b9640c
--- /dev/null
+++ b/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 += ' ';
+    }
+}
diff --git a/src/codegen/CodegenObserver.h b/src/codegen/CodegenObserver.h
new file mode 100644
index 0000000..9f916d9
--- /dev/null
+++ b/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