mpp: implement container adapter

Previously encode/decode expected the first argument (cont) to
be tnt::Buffer of something with the same API.

This commit introduces contaier adapter, so it is allowed now to
encode to standard contiguous container (std::vector etc) and
encode/decode just by pointer to data.

Fix decode headers while we are here.

src/mpp/ContAdapter.hpp

@@ -0,0 +1,273 @@
+#pragma once
+/*
+ * Copyright 2010-2024 Tarantool AUTHORS: please see AUTHORS file.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above
+ *    copyright notice, this list of conditions and the
+ *    following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above
+ *    copyright notice, this list of conditions and the following
+ *    disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY AUTHORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <cstdint>
+#include <cstring>
+#include <utility>
+
+#include "../Utils/CStr.hpp"
+#include "../Utils/Traits.hpp"
+
+namespace mpp {
+
+namespace encode_details {
+
+/** Common data+size pair that is used for writing of variable-length data. */
+struct WData {
+	const char *data;
+	size_t size;
+};
+
+/** Random struct; used to check whether container has template write method. */
+struct TestWriteStruct {
+	uint32_t a;
+	uint16_t b;
+};
+
+/** Test that container if Buffer-like: has several needed write methods. */
+template <class CONT, class _ = void>
+struct is_write_callable_h : std::false_type {};
+
+template <class CONT>
+struct is_write_callable_h<CONT,
+	std::void_t<decltype(std::declval<CONT>().write(uint8_t{})),
+		    decltype(std::declval<CONT>().write(uint64_t{})),
+		    decltype(std::declval<CONT>().write(TestWriteStruct{})),
+		    decltype(std::declval<CONT>().write({(const char *)0, 1})),
+		    decltype(std::declval<CONT>().write(tnt::CStr<'a', 'b'>{}))
+		   >> : std::true_type {};
+
+template <class CONT>
+constexpr bool is_write_callable_v = is_write_callable_h<CONT>::value;
+
+template <class CONT>
+class BufferWriter {
+public:
+	explicit BufferWriter(CONT& cont_) : cont{cont_} {}
+	void write(WData data) { cont.write({data.data, data.size}); }
+	template <char... C>
+	void write(tnt::CStr<C...> str)
+	{
+		cont.write(std::move(str));
+	}
+	template <class T>
+	void write(T&& t)
+	{
+		cont.write(std::forward<T>(t));
+	}
+
+private:
+	CONT& cont;
+};
+
+template <class CONT>
+class StdContWriter {
+public:
+	static_assert(sizeof(*std::declval<CONT>().data()) == 1);
+	explicit StdContWriter(CONT& cont_) : cont{cont_} {}
+	void write(WData data)
+	{
+		size_t old_size = std::size(cont);
+		cont.resize(old_size + data.size);
+		std::memcpy(std::data(cont) + old_size, data.data, data.size);
+	}
+	template <char... C>
+	void write(tnt::CStr<C...> data)
+	{
+		size_t old_size = std::size(cont);
+		cont.resize(old_size + data.size);
+		std::memcpy(std::data(cont) + old_size, data.data, data.size);
+	}
+
+	template <class T>
+	void write(T&& t)
+	{
+		static_assert(std::is_standard_layout_v<std::remove_reference_t<T>>);
+		size_t old_size = std::size(cont);
+		cont.resize(old_size + sizeof(T));
+		std::memcpy(std::data(cont) + old_size, &t, sizeof(T));
+	}
+
+private:
+	CONT& cont;
+};
+
+template <class C>
+class PtrWriter {
+public:
+	static_assert(sizeof(C) == 1);
+	static_assert(!std::is_const_v<C>);
+	explicit PtrWriter(C *& ptr_) : ptr{ptr_} {}
+	void write(WData data)
+	{
+		std::memcpy(ptr, data.data, data.size);
+		ptr += data.size;
+	}
+	template <char... D>
+	void write(tnt::CStr<D...> data)
+	{
+		std::memcpy(ptr, data.data, data.size);
+		ptr += data.size;
+	}
+
+	template <class T>
+	void write(T&& t)
+	{
+		static_assert(std::is_standard_layout_v<std::remove_reference_t<T>>);
+		std::memcpy(ptr, &t, sizeof(t));
+		ptr += sizeof(t);
+	}
+
+private:
+	C *& ptr;
+};
+
+template <class CONT>
+auto
+wr(CONT& cont)
+{
+	if constexpr (is_write_callable_v<CONT>)
+		return BufferWriter<CONT>{cont};
+	else if constexpr (tnt::is_resizable_v<CONT> && tnt::is_contiguous_v<CONT>)
+		return StdContWriter<CONT>{cont};
+	else if constexpr (std::is_pointer_v<CONT>)
+		return PtrWriter<std::remove_pointer_t<CONT>>{cont};
+	else
+		static_assert(tnt::always_false_v<CONT>);
+}
+
+} // namespace encode_details
+
+namespace decode_details {
+
+/** Common data+size pair that is used for reading of variable-length data. */
+struct RData {
+	char *data;
+	size_t size;
+};
+
+/** Struct that when used as read argument, means skipping of 'size' data. */
+struct Skip {
+	size_t size;
+};
+
+/** Random struct; used to check whether container has template read method. */
+struct TestReadStruct {
+	uint8_t a;
+	uint64_t b;
+};
+
+/** Test that container if Buffer-like: has several needed read methods. */
+template <class CONT, class _ = void>
+struct is_read_callable_h : std::false_type {};
+
+template <class CONT>
+struct is_read_callable_h<CONT,
+	std::void_t<decltype(std::declval<CONT>().read(*(uint8_t*)0)),
+		    decltype(std::declval<CONT>().read(*(uint64_t*)0)),
+		    decltype(std::declval<CONT>().read(*(TestReadStruct*)0)),
+		    decltype(std::declval<CONT>().read({(char *)0, 1})),
+		    decltype(std::declval<CONT>().template get<uint8_t>()),
+		    decltype(std::declval<CONT>().read({1}))
+		   >> : std::true_type {};
+
+template <class CONT>
+constexpr bool is_read_callable_v = is_read_callable_h<CONT>::value;
+
+template <class CONT>
+class BufferReader {
+public:
+	explicit BufferReader(CONT& cont_) : cont{cont_} {}
+	void read(RData data) { cont.read({data.data, data.size}); }
+	void read(Skip data) { cont.read({data.size}); }
+	template <class T>
+	void read(T&& t)
+	{
+		cont.read(std::forward<T>(t));
+	}
+	template <class T>
+	T get()
+	{
+		return cont.template get<T>();
+	}
+
+private:
+	CONT& cont;
+};
+
+template <class C>
+class PtrReader {
+public:
+	static_assert(sizeof(C) == 1);
+	explicit PtrReader(C *& ptr_) : ptr{ptr_} {}
+	void read(RData data)
+	{
+		std::memcpy(data.data, ptr, data.size);
+		ptr += data.size;
+	}
+	void read(Skip data) { ptr += data.size; }
+
+	template <class T>
+	void read(T& t)
+	{
+		static_assert(std::is_standard_layout_v<std::remove_reference_t<T>>);
+		std::memcpy(&t, ptr, sizeof(t));
+		ptr += sizeof(t);
+	}
+	template <class T>
+	T get()
+	{
+		static_assert(std::is_standard_layout_v<std::remove_reference_t<T>>);
+		T t;
+		std::memcpy(&t, ptr, sizeof(t));
+		return t;
+	}
+
+private:
+	C *& ptr;
+};
+
+template <class CONT>
+auto
+rd(CONT& cont)
+{
+	if constexpr (is_read_callable_v<CONT>)
+		return BufferReader<CONT>{cont};
+	else if constexpr (std::is_pointer_v<CONT>)
+		return PtrReader<std::remove_pointer_t<CONT>>{cont};
+	else
+		static_assert(tnt::always_false_v<CONT>);
+}
+
+} // namespace decode_details
+
+} // namespace mpp

src/mpp/Dec.hpp

@@ -33,12 +33,19 @@
 #include <cassert>
 #include <functional>
 #include <cstdint>
+#include <cstring>
+#include <tuple>
 #include <utility>
+#include <variant>
 
+#include "BSwap.hpp"
 #include "ClassRule.hpp"
+#include "ContAdapter.hpp"
 #include "Constants.hpp"
 #include "Rules.hpp"
 #include "Spec.hpp"
+#include "../Utils/CStr.hpp"
+#include "../Utils/Traits.hpp"
 
 namespace mpp {
 
@@ -60,7 +67,7 @@ constexpr bool is_any_putable_v =
 /**
  * If it is true, the object of type T will not be decoded - raw data will
  * be saved to it.
- * 
+ *
  * Now it supports only a pair of iterators (probably, wrapped with
  * mpp::as_raw). The check implicilty implies that BUF is an iterator, not
  * buffer - it would be strange to pass a pair of buffer to decoder.
@@ -411,7 +418,7 @@ auto read_value(BUF& buf)
 	using RULE = rule_by_family_t<FAMILY>;
 	if constexpr (SUBRULE == SIMPLEX_SUBRULE) {
 		typename RULE::simplex_value_t tag;
-		buf.read(tag);
+		rd(buf).read(tag);
 		assert(tag >= rule_simplex_tag_range_v<RULE>.first);
 		assert(tag <= rule_simplex_tag_range_v<RULE>.last);
 		[[maybe_unused]] typename RULE::simplex_value_t val =
@@ -427,12 +434,12 @@ auto read_value(BUF& buf)
 			return val;
 	} else {
 		uint8_t tag;
-		buf.read(tag);
+		rd(buf).read(tag);
 		assert(tag == RULE::complex_tag + SUBRULE);
 		using TYPES = typename RULE::complex_types;
 		using V = std::tuple_element_t<SUBRULE, TYPES>;
 		under_uint_t<V> u;
-		buf.read(u);
+		rd(buf).read(u);
 		V val = bswap<V>(u);
 		return val;
 	}
@@ -445,7 +452,7 @@ auto read_item(BUF& buf, ITEM& item)
 	auto val = read_value<FAMILY, SUBRULE>(buf);
 	if constexpr (RULE::has_ext) {
 		int8_t ext_type;
-		buf.read(ext_type);
+		rd(buf).read(ext_type);
 		item.ext_type = ext_type;
 	}
 	if constexpr (RULE::has_data) {
@@ -468,11 +475,11 @@ auto read_item(BUF& buf, ITEM& item)
 			if (size > std::size(item))
 				size = std::size(item);
 		}
-		buf.read({std::data(item), size});
+		rd(buf).read({std::data(item), size});
 		if constexpr (tnt::is_limited_v<ITEM> ||
 			      !tnt::is_resizable_v<ITEM>) {
 			if (size < size_t(val))
-				buf.read({size_t(val) - size});
+				rd(buf).read({size_t(val) - size});
 		}
 	} else if constexpr (RULE::has_children) {
 		if constexpr (tnt::is_clearable_v<ITEM>)
@@ -743,7 +750,7 @@ decode_jump(BUF& buf, T... t)
 {
 	static_assert(path_item_type(PATH::last()) != PIT_BAD);
 	static constexpr auto jumps = JumpsBuilder<PATH, BUF, T...>::build();
-	uint8_t tag = buf.template get<uint8_t>();
+	uint8_t tag = rd(buf).template get<uint8_t>();
 	return jumps.data[tag](buf, t...);
 }
 
@@ -922,10 +929,10 @@ bool jump_skip(BUF& buf, T... t)
 
 	if constexpr (RULE::has_ext) {
 		int8_t ext_type;
-		buf.read(ext_type);
+		rd(buf).read(ext_type);
 	}
 	if constexpr (RULE::has_data) {
-		buf.read({size_t(val)});
+		rd(buf).read({size_t(val)});
 	}
 	if constexpr (RULE::has_children) {
 		auto& arg = std::get<sizeof...(T) - 1>(std::tie(t...));
@@ -1116,7 +1123,7 @@ bool jump_find_key([[maybe_unused]] K k, tnt::iseq<>, BUF& buf, T... t)
 	static_assert(path_item_type(PATH::last()) == PIT_DYN_KEY);
 	using NEXT_PATH = path_push_t<PATH, PIT_DYN_SKIP>;
 	if constexpr (FAMILY == MP_STR)
-		buf.read({k});
+		rd(buf).read({k});
 	return decode_impl<NEXT_PATH>(buf, t..., size_t(1));
 }
 
@@ -1143,7 +1150,7 @@ bool jump_find_key(K k, tnt::iseq<I, J...>, BUF& buf, T... t)
 
 	if (compare_key<FAMILY>(k, key, buf)) {
 		if constexpr (FAMILY == MP_STR)
-			buf.read({k});
+			rd(buf).read({k});
 		return decode_impl<NEXT_PATH>(buf, t...);
 	}
 
@@ -1274,7 +1281,7 @@ bool broken_msgpack_jump(BUF&, T...)
 
 template <class BUF, class... T>
 bool
-decode(BUF& buf, T&&... t)
+decode(BUF&& buf, T&&... t)
 {
 	// TODO: Guard
 	bool res = decode_details::decode(buf, std::forward<T>(t)...);