feat: wip: use impl to implement FIX library.

Signed-off-by: Amlal El Mahrouss <amlal@nekernel.org>

1 files changed, 95 insertions, 0 deletions

diff --git a/src/fix/parser_impl.cpp b/src/fix/parser_impl.cpp
new file mode 100644
index 0000000..28c9d0d
--- /dev/null
+++ b/src/fix/parser_impl.cpp
@@ -0,0 +1,95 @@
+/*
+ * File: fix/parser_impl.cpp
+ * Purpose: Financial Information Exchange parser in C++
+ * Author: Amlal El Mahrouss (amlal@nekernel.org)
+ * Copyright 2025, Amlal El Mahrouss, licensed under the Boost Software License.
+ */
+
+#define OCL_FIX_HAS_IMPL
+#include <ocl/fix/parser.hpp>
+
+namespace ocl::fix
+{
+
+	namespace detail
+	{
+		inline const char* begin_fix() noexcept
+		{
+			return "FIX.4.2";
+		}
+	} // namespace detail
+
+	struct visitor::impl final
+	{
+	public:
+		static constexpr int	  soh  = '\x01';
+		static constexpr char	  eq   = '=';
+		static constexpr unsigned base = 10U;
+
+		explicit impl() = default;
+		~impl()			= default;
+
+		impl& operator=(const impl&) = delete;
+		impl(const impl&)			 = delete;
+
+		/// @brief Visits a FIX message and parse it into a range_buffer object.
+		/// @param in The input FIX message as a string.
+		/// @warning This function may throw exceptions.
+		range_buffer visit(const boost::string_view& in)
+		{
+			if (auto begin = detail::begin_fix(); begin != range_buffer::begin)
+				range_buffer::begin = begin;
+
+			range_buffer ret{};
+
+			if (in.empty())
+				return ret;
+
+			std::string key;
+
+			std::size_t off = 0UL;
+
+			while (off < in.size())
+			{
+				std::size_t eq_pos = in.find(eq, off);
+				if (eq_pos == std::string::npos)
+					break;
+
+				std::string tag = in.substr(off, eq_pos - off).to_string();
+
+				std::size_t soh_pos = in.find(soh, eq_pos + 1);
+				if (soh_pos == std::string::npos)
+					soh_pos = in.size();
+
+				std::string value = in.substr(eq_pos + 1, soh_pos - eq_pos - 1).to_string();
+
+				if (ret.magic_.empty())
+				{
+					ret.magic_	   = value;
+					ret.magic_len_ = value.size();
+				}
+
+				ret.message_[tag] = value;
+
+				off = soh_pos + 1;
+			}
+
+			return ret;
+		}
+	};
+
+	/// \brief Alias of visit.
+	range_buffer visitor::operator()(const std::string& in)
+	{
+		return impl_->visit(in);
+	}
+
+	/// @brief Visits a FIX message and parse it into a range_buffer object.
+	/// @param in The input FIX message as a string.
+	/// @warning This function may throw exceptions.
+	range_buffer visitor::visit(const std::string& in)
+	{
+		return impl_->visit(in);
+	}
+
+} // namespace ocl::fix