1 files changed, 61 insertions, 0 deletions
diff --git a/server/lexer/lexer.hpp b/server/lexer/lexer.hpp
new file mode 100644
index 0000000..d08a2df
--- /dev/null
+++ b/server/lexer/lexer.hpp
@@ -0,0 +1,61 @@
+#pragma once
+
+#include "input.hpp"
+#include "token.hpp"
+#include "token_type.hpp"
+
+#include <functional>
+#include <optional>
+#include <string_view>
+#include <vector>
+
+namespace math::server {
+namespace lexer::details {
+
+// Exposed for testing:
+std::string_view parse_whitespace(const std::string_view&);
+std::optional<double> parse_number(const std::string_view&);
+std::optional<token::Type> parse_const_token(const std::string_view&);
+
+}
+
+class Lexer {
+public:
+    explicit Lexer(const std::string_view& input);
+    explicit Lexer(const lexer::Input& input);
+
+    using Token = lexer::Token;
+    using ParsedToken = lexer::ParsedToken;
+    using Type = Token::Type;
+    using TokenProcessor = std::function<bool (const ParsedToken&)>;
+
+    bool for_each_token(const TokenProcessor& process);
+
+    std::vector<ParsedToken> get_tokens();
+
+    bool has_token() const {
+        return peek_token().has_value();
+    }
+
+    std::optional<ParsedToken> peek_token() const {
+        return m_token_buffer;
+    }
+
+    void drop_token();
+    std::optional<ParsedToken> drop_token_of_type(Type type);
+
+private:
+    std::optional<ParsedToken> parse_whitespace() const;
+    std::optional<ParsedToken> parse_const_token() const;
+    std::optional<ParsedToken> parse_number() const;
+
+    ParsedToken parse_token() const;
+
+    void consume_whitespace();
+    void consume_token();
+
+    lexer::Input m_input;
+    std::optional<ParsedToken> m_token_buffer;
+};
+
+}