parser -> preprocesser + parser

I've decided to split the module parsing into two modules, one for the
preprocessing stage which only deals with tokens and the parsing stage
which generates bytecode.

Makefile

@@ -35,7 +35,7 @@ VM_OUT=$(DIST)/ovm.out
 ## ASSEMBLY setup
 ASM_DIST=$(DIST)/asm
 ASM_SRC=asm
-ASM_CODE:=$(addprefix $(ASM_SRC)/, lexer.cpp)
+ASM_CODE:=$(addprefix $(ASM_SRC)/, lexer.cpp, preprocesser.cpp)
 ASM_OBJECTS:=$(ASM_CODE:$(ASM_SRC)/%.cpp=$(ASM_DIST)/%.o)
 ASM_DEPS:=$(ASM_OBJECTS:%.o=%.d) $(ASM_DIST)/main.d
 ASM_CFLAGS=$(CPPFLAGS)

asm/preprocesser.cpp

@@ -0,0 +1,13 @@
+/* Copyright (C) 2024 Aryadev Chavali
+
+ * You may distribute and modify this code under the terms of the
+ * GPLv2 license.  You should have received a copy of the GPLv2
+ * license with this file.  If not, please write to:
+ * aryadev@aryadevchavali.com.
+
+ * Created: 2024-04-14
+ * Author: Aryadev Chavali
+ * Description: Preprocessor which occurs after lexing before parsing.
+ */
+
+#include "./preprocesser.hpp"

asm/preprocesser.hpp

@@ -0,0 +1,39 @@
+/* Copyright (C) 2024 Aryadev Chavali
+
+ * You may distribute and modify this code under the terms of the GPLv2
+ * license.  You should have received a copy of the GPLv2 license with
+ * this file.  If not, please write to: aryadev@aryadevchavali.com.
+
+ * Created: 2024-04-14
+ * Author: Aryadev Chavali
+ * Description: Preprocessor which occurs after lexing before parsing.
+ */
+
+#ifndef PREPROCESSER_HPP
+#define PREPROCESSER_HPP
+
+#include <tuple>
+
+#include "./lexer.hpp"
+
+enum pp_err_t
+{
+  OK = 0,
+  EXPECTED_NAME,
+  EXPECTED_STRING,
+  EXPECTED_END,
+  FILE_NONEXISTENT,
+  FILE_PARSE_ERROR,
+  UNKNOWN_NAME,
+};
+
+std::pair<std::vector<token_t>, pp_err_t>
+preprocesser(const std::vector<token_t> &);
+
+std::pair<std::vector<token_t>, pp_err_t>
+preprocess_macro_blocks(const std::vector<token_t> &);
+
+std::pair<std::vector<token_t>, pp_err_t>
+preprocess_use_blocks(const std::vector<token_t> &);
+
+#endif