be/src/util/json-util.h

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// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// under the License.

#ifndef IMPALA_UTIL_JSON_UTIL_H
#define IMPALA_UTIL_JSON_UTIL_H

#include <rapidjson/document.h>
#include <rapidjson/rapidjson.h>

#include "util/pretty-printer.h"
#include "util/template-util.h"

namespace google {
namespace protobuf {
class Message;
}
} // namespace google

namespace impala {

/// ToJsonValue() converts 'value' into a rapidjson::Value in 'out_val'. The type of
/// 'out_val' depends on the value of 'type'. If type != TUnit::NONE and 'value' is
/// numeric, 'value' will be set to a string which is the pretty-printed representation of
/// 'value' (e.g. conversion to MB etc). Otherwise the value is directly copied into
/// 'out_val'.
template <typename T>
ENABLE_IF_NOT_ARITHMETIC(T, void)
ToJsonValue(const T& value, const TUnit::type unit, rapidjson::Document* document,
    rapidjson::Value* out_val) {
  *out_val = value;
}

/// Specialisation for std::string which requires explicit use of 'document's allocator to
/// copy into out_val.
template <>
void ToJsonValue<std::string>(const std::string& value, const TUnit::type unit,
    rapidjson::Document* document, rapidjson::Value* out_val);

/// Does pretty-printing if 'value' is numeric, and type is not NONE, otherwise constructs
/// a json object containing 'value' as a literal.
template <typename T>
ENABLE_IF_ARITHMETIC(T, void)
ToJsonValue(const T& value, const TUnit::type unit, rapidjson::Document* document,
    rapidjson::Value* out_val) {
  if (unit != TUnit::NONE) {
    const std::string& s = PrettyPrinter::Print(value, unit);
    ToJsonValue(s, unit, document, out_val);
  } else {
    *out_val = value;
  }
}

/// Uses reflection to append the fields from the protobuf 'pb' to the JSON object 'obj'.
/// Recursively adds nested arrays and objects, i.e. makes a verbatim copy of 'pb'.
/// 'document' must be the document containing 'obj'.
/// Care must be taken when converting protobufs that may contain sensitive data, e.g.
/// strings, so as to not leak it. Strings are automatically redacted if redaction
/// is enabled.
void ProtobufToJson(const google::protobuf::Message& pb, rapidjson::Document* document,
    rapidjson::Value* obj);
} // namespace impala

#endif