chore: flat out the file structure

include/furc/front/lexer.hpp

@@ -0,0 +1,47 @@
+#ifndef FURC_FRONT_LEXER_HPP
+#define FURC_FRONT_LEXER_HPP
+
+#include "furc/front/token.hpp"
+
+#include <cstddef>
+#include <deque>
+#include <string_view>
+
+namespace furc {
+
+class lexer {
+public:
+    lexer(std::string_view filepath, std::string_view content)
+      : m_filepath(filepath), m_content(content) {}
+
+    ~lexer() = default;
+
+    lexer(lexer&&) noexcept            = default;
+    lexer& operator=(lexer&&) noexcept = default;
+
+    lexer(const lexer&)            = delete;
+    lexer& operator=(const lexer&) = delete;
+public:
+    token next_token();
+    token peek_token(std::size_t offset = 0);
+private:
+    token get_token();
+
+    void           next();
+    constexpr char get(std::size_t offset = 0) const;
+    void           skip_spaces();
+
+    constexpr token::location location() const;
+private:
+    std::string_view m_filepath;
+    std::string_view m_content;
+    std::size_t      m_cursor    = 0;
+    std::size_t      m_row       = 0;
+    std::size_t      m_lineStart = 0;
+
+    std::deque<token> m_peekToken;
+};
+
+} // namespace furc
+
+#endif // FURC_FRONT_LEXER_HPP