// Reading a message JSON with Reader (SAX-style API).
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// The JSON should be an object with key-string pairs.
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#include "rapidjson/reader.h"
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#include "rapidjson/error/en.h"
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#include <iostream>
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#include <string>
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#include <map>
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using namespace std;
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using namespace rapidjson;
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typedef map<string, string> MessageMap;
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#if defined(__GNUC__)
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RAPIDJSON_DIAG_PUSH
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RAPIDJSON_DIAG_OFF(effc++)
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#endif
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#ifdef __clang__
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RAPIDJSON_DIAG_PUSH
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RAPIDJSON_DIAG_OFF(switch-enum)
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#endif
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struct MessageHandler
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: public BaseReaderHandler<UTF8<>, MessageHandler> {
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MessageHandler() : messages_(), state_(kExpectObjectStart), name_() {}
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bool StartObject() {
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switch (state_) {
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case kExpectObjectStart:
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state_ = kExpectNameOrObjectEnd;
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return true;
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default:
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return false;
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}
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}
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bool String(const char* str, SizeType length, bool) {
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switch (state_) {
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case kExpectNameOrObjectEnd:
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name_ = string(str, length);
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state_ = kExpectValue;
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return true;
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case kExpectValue:
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messages_.insert(MessageMap::value_type(name_, string(str, length)));
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state_ = kExpectNameOrObjectEnd;
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return true;
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default:
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return false;
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}
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}
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bool EndObject(SizeType) { return state_ == kExpectNameOrObjectEnd; }
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bool Default() { return false; } // All other events are invalid.
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MessageMap messages_;
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enum State {
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kExpectObjectStart,
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kExpectNameOrObjectEnd,
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kExpectValue
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}state_;
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std::string name_;
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};
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#if defined(__GNUC__)
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RAPIDJSON_DIAG_POP
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#endif
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#ifdef __clang__
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RAPIDJSON_DIAG_POP
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#endif
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static void ParseMessages(const char* json, MessageMap& messages) {
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Reader reader;
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MessageHandler handler;
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StringStream ss(json);
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if (reader.Parse(ss, handler))
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messages.swap(handler.messages_); // Only change it if success.
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else {
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ParseErrorCode e = reader.GetParseErrorCode();
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size_t o = reader.GetErrorOffset();
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cout << "Error: " << GetParseError_En(e) << endl;;
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cout << " at offset " << o << " near '" << string(json).substr(o, 10) << "...'" << endl;
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}
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}
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int main() {
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MessageMap messages;
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const char* json1 = "{ \"greeting\" : \"Hello!\", \"farewell\" : \"bye-bye!\" }";
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cout << json1 << endl;
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ParseMessages(json1, messages);
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for (MessageMap::const_iterator itr = messages.begin(); itr != messages.end(); ++itr)
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cout << itr->first << ": " << itr->second << endl;
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cout << endl << "Parse a JSON with invalid schema." << endl;
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const char* json2 = "{ \"greeting\" : \"Hello!\", \"farewell\" : \"bye-bye!\", \"foo\" : {} }";
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cout << json2 << endl;
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ParseMessages(json2, messages);
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return 0;
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}
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