From 5dd99a45adac4b9a583e14dd468dd13b156e2c7e Mon Sep 17 00:00:00 2001
From: Ajay Brahmakshatriya <ajaybr@mit.edu>
Date: Fri, 8 Dec 2023 11:05:56 -0500
Subject: [PATCH] Added support for defer init for dyn_var

---
 include/builder/dyn_var.h          | 20 +++++++++++++++++
 samples/outputs.var_names/sample53 | 10 +++++++++
 samples/outputs/sample53           | 10 +++++++++
 samples/sample53.cpp               | 36 ++++++++++++++++++++++++++++++
 4 files changed, 76 insertions(+)
 create mode 100644 samples/outputs.var_names/sample53
 create mode 100644 samples/outputs/sample53
 create mode 100644 samples/sample53.cpp

diff --git a/include/builder/dyn_var.h b/include/builder/dyn_var.h
index 1d5702f..a09c30e 100644
--- a/include/builder/dyn_var.h
+++ b/include/builder/dyn_var.h
@@ -90,6 +90,13 @@ struct with_name {
 	with_name(const std::string &n, bool wd = false) : name(n), with_decl(wd) {}
 };
 
+// constructor helper to defer the initialization of dyn_var
+// This allows declaring dyn_var outside the context, but initialize
+// them later
+struct defer_init {
+	// No members
+};
+
 template <typename T>
 class dyn_var_impl : public var {
 public:
@@ -226,6 +233,19 @@ class dyn_var_impl : public var {
 		block_var->preferred_name = "";
 		var_name = v.name;
 	}
+
+	dyn_var_impl(const defer_init&) {
+		// Do nothing here
+	}
+	// The function to actually initialize a dyn_var, if it 
+	// has been deferred. It is OKAY to call this even if defer_init
+	// is not used, but is not adviced. This can definitely be called multiple 
+	// times and will produce the same dyn_var based on the static tag at the
+	// time of this call
+	// Currently we don't support init val, but can be added if needed
+	void deferred_init(void) {
+		create_dyn_var(false);
+	}
 	dyn_var_impl(const dyn_var_sentinel_type &a, std::string name = "") {
 		create_dyn_var(true);
 		if (name != "") {
diff --git a/samples/outputs.var_names/sample53 b/samples/outputs.var_names/sample53
new file mode 100644
index 0000000..b049c23
--- /dev/null
+++ b/samples/outputs.var_names/sample53
@@ -0,0 +1,10 @@
+void foo (void) {
+  int obj_0;
+  int x_1 = 0;
+  if (x_1) {
+    obj_0 = 1;
+  } else {
+    obj_0 = 2;
+  }
+}
+
diff --git a/samples/outputs/sample53 b/samples/outputs/sample53
new file mode 100644
index 0000000..0988e23
--- /dev/null
+++ b/samples/outputs/sample53
@@ -0,0 +1,10 @@
+void foo (void) {
+  int var0;
+  int var1 = 0;
+  if (var1) {
+    var0 = 1;
+  } else {
+    var0 = 2;
+  }
+}
+
diff --git a/samples/sample53.cpp b/samples/sample53.cpp
new file mode 100644
index 0000000..6bb8e3c
--- /dev/null
+++ b/samples/sample53.cpp
@@ -0,0 +1,36 @@
+// Include the headers
+#include "blocks/c_code_generator.h"
+#include "builder/dyn_var.h"
+#include "builder/lib/utils.h"
+#include "builder/static_var.h"
+#include <iostream>
+
+// Include the BuildIt types
+using builder::dyn_var;
+using builder::static_var;
+
+
+struct external_object_t {
+	dyn_var<int> member = builder::defer_init();
+};
+
+static void foo(external_object_t &obj) {	
+	// Init not
+	obj.member.deferred_init();
+	
+	dyn_var<int> x = 0;
+	if (x) {
+		obj.member = 1;	
+	} else {
+		obj.member = 2;
+	}	
+}
+
+int main(int argc, char *argv[]) {
+
+	external_object_t obj;
+
+	builder::builder_context context;
+	block::c_code_generator::generate_code(context.extract_function_ast(foo, "foo", obj), std::cout, 0);
+	return 0;
+}