discord-rpc/src/serialization.h
2017-07-24 10:54:47 -07:00

106 lines
3 KiB
C++

#pragma once
#include <stdint.h>
#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
#include "rapidjson/internal/itoa.h"
// if only there was a standard library function for this
template<size_t Len>
inline size_t StringCopy(char (&dest)[Len], const char* src) {
if (!dest || !src || !Len) {
return 0;
}
size_t copied;
char* out = dest;
for (copied = 1; *src && copied < Len; ++copied) {
*out++ = *src++;
}
*out = 0;
return copied - 1;
}
size_t JsonWriteHandshakeObj(char* dest, size_t maxLen, int version, const char* applicationId);
// Commands
struct DiscordRichPresence;
size_t JsonWriteRichPresenceObj(char* dest, size_t maxLen, int nonce, int pid, const DiscordRichPresence* presence);
size_t JsonWriteSubscribeCommand(char* dest, size_t maxLen, int nonce, const char* evtName);
// I want to use as few allocations as I can get away with, and to do that with RapidJson, you need to supply some of
// your own allocators for stuff rather than use the defaults
class LinearAllocator {
public:
char* buffer_;
char* end_;
LinearAllocator() {
assert(0); // needed for some default case in rapidjson, should not use
}
LinearAllocator(char* buffer, size_t size) : buffer_(buffer), end_(buffer + size) {}
static const bool kNeedFree = false;
void* Malloc(size_t size)
{
char* res = buffer_;
buffer_ += size;
if (buffer_ > end_) {
buffer_ = res;
return nullptr;
}
return res;
}
void* Realloc(void* originalPtr, size_t originalSize, size_t newSize)
{
if (newSize == 0) {
return nullptr;
}
// allocate how much you need in the first place
assert(!originalPtr && !originalSize);
return Malloc(newSize);
}
static void Free(void* ptr) { /* shrug */ }
};
template<int Size>
class FixedLinearAllocator : public LinearAllocator {
public:
char fixedBuffer_[Size];
FixedLinearAllocator() : LinearAllocator(fixedBuffer_, Size) {}
static const bool kNeedFree = false;
};
// wonder why this isn't a thing already, maybe I missed it
class DirectStringBuffer {
public:
typedef typename char Ch;
char* buffer_;
char* end_;
char* current_;
DirectStringBuffer(char* buffer, size_t maxLen)
: buffer_(buffer)
, end_(buffer + maxLen)
, current_(buffer)
{}
void Put(char c)
{
if (current_ < end_) {
*current_++ = c;
}
}
void Flush() {}
size_t GetSize() const
{
return current_ - buffer_;
}
};
using UTF8 = rapidjson::UTF8<char>;
// Writer appears to need about 16 bytes per nested object level (with 64bit size_t)
using WriterAllocator = FixedLinearAllocator<2048>;
constexpr size_t WriterNestingLevels = 2048 / (2 * sizeof(size_t));
using JsonWriter = rapidjson::Writer<DirectStringBuffer, UTF8, UTF8, WriterAllocator, rapidjson::kWriteNoFlags>;
using JsonDocument = rapidjson::GenericDocument<UTF8>;