chore: flat out the file structure

include/furc/front/parser.hpp

@@ -0,0 +1,51 @@
+#ifndef FURC_FRONT_PARSER_HPP
+#define FURC_FRONT_PARSER_HPP
+
+#include "furc/front/ast.hpp"
+#include "furc/front/lexer.hpp"
+#include "furlang/arena.hpp"
+
+#include <stdexcept>
+
+namespace furc {
+
+class parser {
+public:
+    parser(lexer&& lexer, furlang::arena& arena)
+      : m_lexer(std::move(lexer)), m_arena(&arena) {}
+
+    ~parser() = default;
+
+    parser(parser&&) noexcept            = default;
+    parser& operator=(parser&&) noexcept = default;
+
+    parser(const parser&)            = delete;
+    parser& operator=(const parser&) = delete;
+public:
+    ast parse();
+private:
+    stmt_node* parse_stmt();
+    decl_node* parse_decl();
+    expr_node* parse_expr();
+
+    ast_type       parse_type();
+    comp_stmt_node parse_comp();
+
+    expr_node* parse_expr_primary();
+    expr_node* parse_expr_unary();
+    expr_node* parse_expr_right(expr_node* lhs, std::uint32_t precedence = 15);
+private:
+    template <typename... Types>
+    token eat_token(Types... types) {
+        auto token = m_lexer.next_token();
+        if (((token.type == types) || ...)) return token;
+        throw std::runtime_error("unexpected token");
+    }
+private:
+    lexer           m_lexer;
+    furlang::arena* m_arena;
+};
+
+} // namespace furc
+
+#endif // FURC_FRONT_PARSER_HPP