add in memory read and write for file2

CMakeLists.txt

@@ -28,6 +28,8 @@ add_library(solanaceae_file2
 	./solanaceae/file/file2.hpp
 	./solanaceae/file/file2_std.hpp
 	./solanaceae/file/file2_std.cpp
+	./solanaceae/file/file2_mem.hpp
+	./solanaceae/file/file2_mem.cpp
 )
 
 target_include_directories(solanaceae_file2 PUBLIC .)

solanaceae/file/file2_mem.cpp

@@ -0,0 +1,59 @@
+#include "./file2_mem.hpp"
+
+File2MemW::File2MemW(std::vector<uint8_t>& mem) : File2I(true, false), _mem(mem) {
+}
+
+File2MemW::~File2MemW(void) {
+}
+
+bool File2MemW::isGood(void) {
+	// TODO: are there any error cases?
+	return true;
+}
+
+bool File2MemW::write(const ByteSpan data, int64_t pos) {
+	if (pos != -1) { // only support streaming
+		return false;
+	}
+
+	if (data.empty()) {
+		return false; // true instead?
+	}
+
+	_mem.insert(_mem.cend(), data.cbegin(), data.cend());
+
+	return isGood();
+}
+
+std::variant<ByteSpan, std::vector<uint8_t>> File2MemW::read(uint64_t size, int64_t pos) {
+	return {};
+}
+
+File2MemR::File2MemR(ByteSpan mem) : File2I(false, true), _mem(mem) {
+}
+
+File2MemR::~File2MemR(void) {
+}
+
+bool File2MemR::isGood(void) {
+	// TODO: return false if eof?
+	return true;
+}
+
+bool File2MemR::write(const ByteSpan data, int64_t pos) {
+	return false;
+}
+
+std::variant<ByteSpan, std::vector<uint8_t>> File2MemR::read(uint64_t size, int64_t pos) {
+	if (_read_pos >= _mem.size) {
+		return {};
+	}
+
+	ByteSpan ret {
+		_mem.ptr + _read_pos,
+		std::min(size, _mem.size - _read_pos)
+	};
+	_read_pos += ret.size;
+	return ret;
+}
+

solanaceae/file/file2_mem.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+#include "./file2.hpp"
+
+// write to vector or read from span
+// no seeking for now (could make sense for read)
+
+struct File2MemW : public File2I {
+	std::vector<uint8_t>& _mem;
+
+	File2MemW(std::vector<uint8_t>& mem);
+	virtual ~File2MemW(void);
+
+	bool isGood(void) override;
+
+	bool write(const ByteSpan data, int64_t pos = -1) override;
+	std::variant<ByteSpan, std::vector<uint8_t>> read(uint64_t size, int64_t pos = -1) override;
+};
+
+struct File2MemR : public File2I {
+	ByteSpan _mem;
+	int64_t _read_pos{0};
+
+	File2MemR(ByteSpan mem);
+	virtual ~File2MemR(void);
+
+	bool isGood(void) override;
+
+	bool write(const ByteSpan data, int64_t pos = -1) override;
+	std::variant<ByteSpan, std::vector<uint8_t>> read(uint64_t size, int64_t pos = -1) override;
+};
+