feat: basic lexer + parser with basic example

src/main.cpp

@@ -1,8 +1,55 @@
 #include <iostream>
+#include <fstream>
 #include <print>
+#include "lexer.hpp"
+#include "ast.hpp"
+
+void dump_tokens(const char* filename, Lexer* lexer)
+{
+    while (lexer->NextToken()) {
+        std::print("{}:{}:{}: ", filename, lexer->token().line_number, lexer->token().offset_start);
+        if (lexer->token().token == Id)
+            std::println("id = {}", lexer->token().string);
+        else if (lexer->token().token == IntLiteral)
+            std::println("int = {}", lexer->token().int_number);
+        else 
+            std::println("token = {}", (char)lexer->token().token);
+    }
+}
 
 int main(int argc, char** argv)
 {
-    std::println("Hello, World!");
+    for (int i = 0; i < argc; ++i) {
+        std::println("arg#{}: {}", i, argv[i]);
+    }
+    char* filename;
+    if (argc > 1) {
+        filename = (++argv)[0];
+    } else {
+        fprintf(stderr, "ERROR: Input file is required.\n");
+        return 1;
+    }
+
+    std::ifstream f(filename);
+    if (!f.is_open()) {
+        fprintf(stderr, "ERROR: Failed to open input file: %s\n", filename);
+        return 1;
+    }
+
+    std::string content((std::istreambuf_iterator<char>(f)), std::istreambuf_iterator<char>());
+
+    f.close();
+
+    // std::println("{}", content);
+
+    Lexer lexer(filename, StringView(content.c_str(), content.size()));
+    
+    // dump_tokens(filename, &lexer);
+
+    AstParser parser(&lexer);
+
+    auto node = parser.ParseStatement();
+    ExternNode* extrn = reinterpret_cast<ExternNode*>(node);
+
     return 0;
 }