From 572f779e70367ba6f5ed5b9dac68565d9d6f3598 Mon Sep 17 00:00:00 2001
From: servostar <sven.vogel123@web.de>
Date: Wed, 8 May 2024 10:26:57 +0200
Subject: [PATCH] added codegen backend

---
 src/codegen/backend.c | 86 +++++++++++++++++++++++++++++++++++++++++++
 src/codegen/backend.h | 40 ++++++++++++++++++++
 src/main.c            |  3 ++
 3 files changed, 129 insertions(+)
 create mode 100644 src/codegen/backend.c
 create mode 100644 src/codegen/backend.h

diff --git a/src/codegen/backend.c b/src/codegen/backend.c
new file mode 100644
index 0000000..bb9a8e2
--- /dev/null
+++ b/src/codegen/backend.c
@@ -0,0 +1,86 @@
+//
+// Created by servostar on 5/8/24.
+//
+
+#include <codegen/backend.h>
+#include <stdlib.h>
+
+#define TRUE 1
+#define FALSE 0
+
+static CodegenResult __new_result(enum CodegenErrorCode code, char* message) {
+    const CodegenResult result = {
+        .code = code,
+        .message =  message
+    };
+    return result;
+}
+
+static struct Codegen_Lib_t {
+    CodegenFunction codegen_function;
+    InitCodegenBackend init_function;
+    DeinitCodegenBackend deinit_function;
+    unsigned char initialized;
+} CodegenLib;
+
+static CodegenResult __unimplemented() {
+    return __new_result(Unimplemented, "Backend not set");
+}
+
+static CodegenResult __default_codegen_function(AST_NODE_PTR _ptr, void** _out) {
+    return __unimplemented();
+}
+
+static CodegenResult __default_backend_init(void) {
+    return __unimplemented();
+}
+
+static CodegenResult __default_backend_deinit(void) {
+    return __unimplemented();
+}
+
+static void __deinit(void) {
+    if (CodegenLib.initialized && CodegenLib.deinit_function) {
+        CodegenLib.deinit_function();
+    }
+}
+
+void CG_init(void) {
+    CodegenLib.codegen_function = __default_codegen_function;
+    CodegenLib.init_function = __default_backend_init;
+    CodegenLib.deinit_function = __default_backend_deinit;
+
+    atexit(__deinit);
+}
+
+void CG_set_codegen_backend(InitCodegenBackend init, DeinitCodegenBackend deinit, CodegenFunction codegen) {
+    CodegenLib.codegen_function = codegen;
+    CodegenLib.init_function = init;
+    CodegenLib.deinit_function = deinit;
+}
+
+CodegenResult CG_codegen(const AST_NODE_PTR ast, void** output) {
+    if (ast == NULL) {
+        return __new_result(InvalidAST, "AST is NULL");
+    }
+
+    if (output == NULL) {
+        return __new_result(NoOutputStorage, "Output pointer is NULL");
+    }
+
+    if (CodegenLib.codegen_function == NULL) {
+        return __new_result(NoBackend, "No code generation backend");
+    }
+
+    if (!CodegenLib.initialized && CodegenLib.init_function) {
+        const CodegenResult result = CodegenLib.init_function();
+
+        if (result.code != Sucess) {
+            return result;
+        }
+
+        CodegenLib.initialized = TRUE;
+    }
+
+    return CodegenLib.codegen_function(ast, output);
+}
\ No newline at end of file
diff --git a/src/codegen/backend.h b/src/codegen/backend.h
new file mode 100644
index 0000000..f63191d
--- /dev/null
+++ b/src/codegen/backend.h
@@ -0,0 +1,40 @@
+//
+// Created by servostar on 5/8/24.
+//
+
+#ifndef LIB_H
+#define LIB_H
+
+#include <ast/ast.h>
+
+enum CodegenErrorCode {
+    Sucess,
+    Unimplemented,
+    InvalidAST,
+    NoBackend,
+    NoOutputStorage,
+    Error
+};
+
+typedef struct CodegenResult_t {
+    const enum CodegenErrorCode code;
+    const char* message;
+} CodegenResult;
+
+// parses a syntax tree into intermediate representation
+// and creates backend specific data structure
+// returns a success code
+typedef CodegenResult (*CodegenFunction) (const AST_NODE_PTR, void**);
+
+typedef CodegenResult (*InitCodegenBackend) (void);
+
+typedef CodegenResult (*DeinitCodegenBackend) (void);
+
+void CG_init(void);
+
+// Should only be called from a backend implementation
+void CG_set_codegen_backend(InitCodegenBackend init, DeinitCodegenBackend deinit, CodegenFunction codegen);
+
+CodegenResult CG_codegen(AST_NODE_PTR, void**);
+
+#endif //LIB_H
diff --git a/src/main.c b/src/main.c
index 0b56d88..905d37f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,6 +2,7 @@
 #include <sys/log.h>
 #include <yacc/parser.tab.h>
 #include <ast/ast.h>
+#include <codegen/backend.h>
 #include <gc/gc.h>
 
 #define LOG_LEVEL LOG_LEVEL_DEBUG
@@ -48,6 +49,8 @@ void setup(void)
     // actual setup
     AST_init();
 
+    CG_init();
+
     GC_init();
 
     DEBUG("finished starting up gemstone...");