rocksdb/third-party/rapidjson/prettywriter.h
Igor Canadi a0e9ee5965 Add rapidjson to RocksDB
Summary:
This diff adds rapidjson (https://code.google.com/p/rapidjson/) to RocksDB repository. First step to adding JSON is to add a JSON parser :)

I'm not sure if rapidjson is the right choice. I only considered folly as an alternative. Using folly JSON parser has serious downsides. I tried extracting folly::json from the folly library. However, it depends on folly::dynamic, which basically depends on everything else. I would prefer to avoid adding complete folly library as RocksDB dependency. Folly has a lot of its own dependencies (https://github.com/facebook/folly) and also looks like open source world has some trouble installing it (https://groups.google.com/forum/#!forum/facebook-folly -- 60% of the posts are compile errors). We can discuss this if you think otherwise.

RapidJSON does not have any dependencies whatsoever. No boost, no STL. We don't need to compile it since it's all header files. The performance results are also impressive: https://code.google.com/p/rapidjson/wiki/Performance. However, I'll make sure to write code in a way that we can easily switch JSON implementations going forward. Quora thread has some alternatives: http://www.quora.com/What-is-the-best-C-JSON-library

Test Plan: none

Reviewers: dhruba, haobo, yhchiang, sdong, jamesgpearce

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D18729
2014-05-15 16:07:05 -07:00

157 lines
5 KiB
C++

#ifndef RAPIDJSON_PRETTYWRITER_H_
#define RAPIDJSON_PRETTYWRITER_H_
#include "writer.h"
namespace rapidjson {
//! Writer with indentation and spacing.
/*!
\tparam Stream Type of ouptut stream.
\tparam Encoding Encoding of both source strings and output.
\tparam Allocator Type of allocator for allocating memory of stack.
*/
template<typename Stream, typename Encoding = UTF8<>, typename Allocator = MemoryPoolAllocator<> >
class PrettyWriter : public Writer<Stream, Encoding, Allocator> {
public:
typedef Writer<Stream, Encoding, Allocator> Base;
typedef typename Base::Ch Ch;
//! Constructor
/*! \param stream Output stream.
\param allocator User supplied allocator. If it is null, it will create a private one.
\param levelDepth Initial capacity of
*/
PrettyWriter(Stream& stream, Allocator* allocator = 0, size_t levelDepth = Base::kDefaultLevelDepth) :
Base(stream, allocator, levelDepth), indentChar_(' '), indentCharCount_(4) {}
//! Set custom indentation.
/*! \param indentChar Character for indentation. Must be whitespace character (' ', '\t', '\n', '\r').
\param indentCharCount Number of indent characters for each indentation level.
\note The default indentation is 4 spaces.
*/
PrettyWriter& SetIndent(Ch indentChar, unsigned indentCharCount) {
RAPIDJSON_ASSERT(indentChar == ' ' || indentChar == '\t' || indentChar == '\n' || indentChar == '\r');
indentChar_ = indentChar;
indentCharCount_ = indentCharCount;
return *this;
}
//@name Implementation of Handler.
//@{
PrettyWriter& Null() { PrettyPrefix(kNullType); Base::WriteNull(); return *this; }
PrettyWriter& Bool(bool b) { PrettyPrefix(b ? kTrueType : kFalseType); Base::WriteBool(b); return *this; }
PrettyWriter& Int(int i) { PrettyPrefix(kNumberType); Base::WriteInt(i); return *this; }
PrettyWriter& Uint(unsigned u) { PrettyPrefix(kNumberType); Base::WriteUint(u); return *this; }
PrettyWriter& Int64(int64_t i64) { PrettyPrefix(kNumberType); Base::WriteInt64(i64); return *this; }
PrettyWriter& Uint64(uint64_t u64) { PrettyPrefix(kNumberType); Base::WriteUint64(u64); return *this; }
PrettyWriter& Double(double d) { PrettyPrefix(kNumberType); Base::WriteDouble(d); return *this; }
PrettyWriter& String(const Ch* str, SizeType length, bool copy = false) {
(void)copy;
PrettyPrefix(kStringType);
Base::WriteString(str, length);
return *this;
}
PrettyWriter& StartObject() {
PrettyPrefix(kObjectType);
new (Base::level_stack_.template Push<typename Base::Level>()) typename Base::Level(false);
Base::WriteStartObject();
return *this;
}
PrettyWriter& EndObject(SizeType memberCount = 0) {
(void)memberCount;
RAPIDJSON_ASSERT(Base::level_stack_.GetSize() >= sizeof(typename Base::Level));
RAPIDJSON_ASSERT(!Base::level_stack_.template Top<typename Base::Level>()->inArray);
bool empty = Base::level_stack_.template Pop<typename Base::Level>(1)->valueCount == 0;
if (!empty) {
Base::stream_.Put('\n');
WriteIndent();
}
Base::WriteEndObject();
return *this;
}
PrettyWriter& StartArray() {
PrettyPrefix(kArrayType);
new (Base::level_stack_.template Push<typename Base::Level>()) typename Base::Level(true);
Base::WriteStartArray();
return *this;
}
PrettyWriter& EndArray(SizeType memberCount = 0) {
(void)memberCount;
RAPIDJSON_ASSERT(Base::level_stack_.GetSize() >= sizeof(typename Base::Level));
RAPIDJSON_ASSERT(Base::level_stack_.template Top<typename Base::Level>()->inArray);
bool empty = Base::level_stack_.template Pop<typename Base::Level>(1)->valueCount == 0;
if (!empty) {
Base::stream_.Put('\n');
WriteIndent();
}
Base::WriteEndArray();
return *this;
}
//@}
//! Simpler but slower overload.
PrettyWriter& String(const Ch* str) { return String(str, internal::StrLen(str)); }
protected:
void PrettyPrefix(Type type) {
(void)type;
if (Base::level_stack_.GetSize() != 0) { // this value is not at root
typename Base::Level* level = Base::level_stack_.template Top<typename Base::Level>();
if (level->inArray) {
if (level->valueCount > 0) {
Base::stream_.Put(','); // add comma if it is not the first element in array
Base::stream_.Put('\n');
}
else
Base::stream_.Put('\n');
WriteIndent();
}
else { // in object
if (level->valueCount > 0) {
if (level->valueCount % 2 == 0) {
Base::stream_.Put(',');
Base::stream_.Put('\n');
}
else {
Base::stream_.Put(':');
Base::stream_.Put(' ');
}
}
else
Base::stream_.Put('\n');
if (level->valueCount % 2 == 0)
WriteIndent();
}
if (!level->inArray && level->valueCount % 2 == 0)
RAPIDJSON_ASSERT(type == kStringType); // if it's in object, then even number should be a name
level->valueCount++;
}
else
RAPIDJSON_ASSERT(type == kObjectType || type == kArrayType);
}
void WriteIndent() {
size_t count = (Base::level_stack_.GetSize() / sizeof(typename Base::Level)) * indentCharCount_;
PutN(Base::stream_, indentChar_, count);
}
Ch indentChar_;
unsigned indentCharCount_;
};
} // namespace rapidjson
#endif // RAPIDJSON_RAPIDJSON_H_