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Diffstat (limited to 'src/s3select/rapidjson/example/filterkey/filterkey.cpp')
-rw-r--r-- | src/s3select/rapidjson/example/filterkey/filterkey.cpp | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/src/s3select/rapidjson/example/filterkey/filterkey.cpp b/src/s3select/rapidjson/example/filterkey/filterkey.cpp new file mode 100644 index 000000000..c34a050dc --- /dev/null +++ b/src/s3select/rapidjson/example/filterkey/filterkey.cpp @@ -0,0 +1,135 @@ +// JSON filterkey example with SAX-style API. + +// This example parses JSON text from stdin with validation. +// During parsing, specified key will be filtered using a SAX handler. +// It re-output the JSON content to stdout without whitespace. + +#include "rapidjson/reader.h" +#include "rapidjson/writer.h" +#include "rapidjson/filereadstream.h" +#include "rapidjson/filewritestream.h" +#include "rapidjson/error/en.h" +#include <stack> + +using namespace rapidjson; + +// This handler forwards event into an output handler, with filtering the descendent events of specified key. +template <typename OutputHandler> +class FilterKeyHandler { +public: + typedef char Ch; + + FilterKeyHandler(OutputHandler& outputHandler, const Ch* keyString, SizeType keyLength) : + outputHandler_(outputHandler), keyString_(keyString), keyLength_(keyLength), filterValueDepth_(), filteredKeyCount_() + {} + + bool Null() { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Null() && EndValue(); } + bool Bool(bool b) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Bool(b) && EndValue(); } + bool Int(int i) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Int(i) && EndValue(); } + bool Uint(unsigned u) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Uint(u) && EndValue(); } + bool Int64(int64_t i) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Int64(i) && EndValue(); } + bool Uint64(uint64_t u) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Uint64(u) && EndValue(); } + bool Double(double d) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Double(d) && EndValue(); } + bool RawNumber(const Ch* str, SizeType len, bool copy) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.RawNumber(str, len, copy) && EndValue(); } + bool String (const Ch* str, SizeType len, bool copy) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.String (str, len, copy) && EndValue(); } + + bool StartObject() { + if (filterValueDepth_ > 0) { + filterValueDepth_++; + return true; + } + else { + filteredKeyCount_.push(0); + return outputHandler_.StartObject(); + } + } + + bool Key(const Ch* str, SizeType len, bool copy) { + if (filterValueDepth_ > 0) + return true; + else if (len == keyLength_ && std::memcmp(str, keyString_, len) == 0) { + filterValueDepth_ = 1; + return true; + } + else { + ++filteredKeyCount_.top(); + return outputHandler_.Key(str, len, copy); + } + } + + bool EndObject(SizeType) { + if (filterValueDepth_ > 0) { + filterValueDepth_--; + return EndValue(); + } + else { + // Use our own filtered memberCount + SizeType memberCount = filteredKeyCount_.top(); + filteredKeyCount_.pop(); + return outputHandler_.EndObject(memberCount) && EndValue(); + } + } + + bool StartArray() { + if (filterValueDepth_ > 0) { + filterValueDepth_++; + return true; + } + else + return outputHandler_.StartArray(); + } + + bool EndArray(SizeType elementCount) { + if (filterValueDepth_ > 0) { + filterValueDepth_--; + return EndValue(); + } + else + return outputHandler_.EndArray(elementCount) && EndValue(); + } + +private: + FilterKeyHandler(const FilterKeyHandler&); + FilterKeyHandler& operator=(const FilterKeyHandler&); + + bool EndValue() { + if (filterValueDepth_ == 1) // Just at the end of value after filtered key + filterValueDepth_ = 0; + return true; + } + + OutputHandler& outputHandler_; + const char* keyString_; + const SizeType keyLength_; + unsigned filterValueDepth_; + std::stack<SizeType> filteredKeyCount_; +}; + +int main(int argc, char* argv[]) { + if (argc != 2) { + fprintf(stderr, "filterkey key < input.json > output.json\n"); + return 1; + } + + // Prepare JSON reader and input stream. + Reader reader; + char readBuffer[65536]; + FileReadStream is(stdin, readBuffer, sizeof(readBuffer)); + + // Prepare JSON writer and output stream. + char writeBuffer[65536]; + FileWriteStream os(stdout, writeBuffer, sizeof(writeBuffer)); + Writer<FileWriteStream> writer(os); + + // Prepare Filter + FilterKeyHandler<Writer<FileWriteStream> > filter(writer, argv[1], static_cast<SizeType>(strlen(argv[1]))); + + // JSON reader parse from the input stream, filter handler filters the events, and forward to writer. + // i.e. the events flow is: reader -> filter -> writer + if (!reader.Parse(is, filter)) { + fprintf(stderr, "\nError(%u): %s\n", static_cast<unsigned>(reader.GetErrorOffset()), GetParseError_En(reader.GetParseErrorCode())); + return 1; + } + + return 0; +} |