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Telegram/lib_base/base/bytes.h

@@ -0,0 +1,170 @@
+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#pragma once
+
+#include "base/basic_types.h"
+#include <gsl/gsl>
+#include <gsl/byte>
+#include <vector>
+#include <array>
+
+namespace bytes {
+
+using type = gsl::byte;
+using span = gsl::span<type>;
+using const_span = gsl::span<const type>;
+using vector = std::vector<type>;
+
+template <gsl::index Size>
+using array = std::array<type, Size>;
+
+inline span make_detached_span(QByteArray &container) {
+	return gsl::as_writable_bytes(gsl::make_span(container));
+}
+
+template <
+	typename Container,
+	typename = std::enable_if_t<
+		!std::is_const_v<Container>
+		&& !std::is_same_v<Container, QByteArray>>>
+inline span make_span(Container &container) {
+	return gsl::as_writable_bytes(gsl::make_span(container));
+}
+
+template<>
+inline span make_span<span, void>(span &container) {
+	return container;
+}
+
+template <typename Container>
+inline const_span make_span(const Container &container) {
+	return gsl::as_bytes(gsl::make_span(container));
+}
+
+inline const_span make_span(const_span &container) {
+	return container;
+}
+
+template <typename Type, std::ptrdiff_t Extent>
+inline span make_span(gsl::span<Type, Extent> container) {
+	return gsl::as_writable_bytes(container);
+}
+
+template <typename Type, std::ptrdiff_t Extent>
+inline const_span make_span(gsl::span<const Type, Extent> container) {
+	return gsl::as_bytes(container);
+}
+
+template <typename Type>
+inline span make_span(Type *value, std::size_t count) {
+	return gsl::as_writable_bytes(gsl::make_span(value, count));
+}
+
+template <typename Type>
+inline const_span make_span(const Type *value, std::size_t count) {
+	return gsl::as_bytes(gsl::make_span(value, count));
+}
+
+template <typename Type>
+inline span object_as_span(Type *value) {
+	return bytes::make_span(value, 1);
+}
+
+template <typename Type>
+inline const_span object_as_span(const Type *value) {
+	return bytes::make_span(value, 1);
+}
+
+template <typename Container>
+inline vector make_vector(const Container &container) {
+	const auto buffer = bytes::make_span(container);
+	return { buffer.begin(), buffer.end() };
+}
+
+inline void copy(span destination, const_span source) {
+	Expects(destination.size() >= source.size());
+
+	memcpy(destination.data(), source.data(), source.size());
+}
+
+inline void move(span destination, const_span source) {
+	Expects(destination.size() >= source.size());
+
+	memmove(destination.data(), source.data(), source.size());
+}
+
+inline void set_with_const(span destination, type value) {
+	memset(
+		destination.data(),
+		gsl::to_integer<unsigned char>(value),
+		destination.size());
+}
+
+inline int compare(const_span a, const_span b) {
+	const auto aSize = a.size(), bSize = b.size();
+	return (aSize > bSize)
+		? 1
+		: (aSize < bSize)
+		? -1
+		: memcmp(a.data(), b.data(), aSize);
+}
+
+namespace details {
+
+template <typename Arg>
+std::size_t spansLength(Arg &&arg) {
+	return bytes::make_span(arg).size();
+}
+
+template <typename Arg, typename ...Args>
+std::size_t spansLength(Arg &&arg, Args &&...args) {
+	return bytes::make_span(arg).size() + spansLength(args...);
+}
+
+template <typename Arg>
+void spansAppend(span destination, Arg &&arg) {
+	bytes::copy(destination, bytes::make_span(arg));
+}
+
+template <typename Arg, typename ...Args>
+void spansAppend(span destination, Arg &&arg, Args &&...args) {
+	const auto data = bytes::make_span(arg);
+	bytes::copy(destination, data);
+	spansAppend(destination.subspan(data.size()), args...);
+}
+
+} // namespace details
+
+template <
+	typename ...Args,
+	typename = std::enable_if_t<(sizeof...(Args) > 1)>>
+vector concatenate(Args &&...args) {
+	const auto size = details::spansLength(args...);
+	auto result = vector(size);
+	details::spansAppend(make_span(result), args...);
+	return result;
+}
+
+template <typename SpanRange>
+vector concatenate(SpanRange args) {
+	auto size = std::size_t(0);
+	for (const auto &arg : args) {
+		size += bytes::make_span(arg).size();
+	}
+	auto result = vector(size);
+	auto buffer = make_span(result);
+	for (const auto &arg : args) {
+		const auto part = bytes::make_span(arg);
+		bytes::copy(buffer, part);
+		buffer = buffer.subspan(part.size());
+	}
+	return result;
+}
+
+void set_random(span destination);
+
+} // namespace bytes