Add new JSON API for better abstraction and for supporting strict JSON parsing

1 files changed, 109 insertions, 0 deletions

diff --git a/libdevcore/JSON.cpp b/libdevcore/JSON.cpp
new file mode 100644
index 00000000..079d4d51
--- /dev/null
+++ b/libdevcore/JSON.cpp
@@ -0,0 +1,109 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/** @file JSON.cpp
+ * @author Alexander Arlt <alexander.arlt@arlt-labs.com>
+ * @date 2018
+ */
+
+#include "JSON.h"
+
+#include <sstream>
+#include <map>
+#include <memory>
+
+using namespace std;
+
+namespace dev
+{
+
+namespace
+{
+
+/// StreamWriterBuilder that can be constructed with specific settings
+class StreamWriterBuilder: public Json::StreamWriterBuilder
+{
+public:
+	explicit StreamWriterBuilder(map<string, string> const& _settings)
+	{
+		for (auto const& iter :_settings)
+			this->settings_[iter.first] = iter.second;
+	}
+};
+
+/// CharReaderBuilder with strict-mode settings
+class StrictModeCharReaderBuilder: public Json::CharReaderBuilder
+{
+public:
+	StrictModeCharReaderBuilder()
+	{
+		Json::CharReaderBuilder::strictMode(&this->settings_);
+	}
+};
+
+/// Serialise the JSON object (@a _input) with specific builder (@a _builder)
+/// \param _input JSON input string
+/// \param _builder StreamWriterBuilder that is used to create new Json::StreamWriter
+/// \return serialized json object
+string print(Json::Value const& _input, Json::StreamWriterBuilder const& _builder)
+{
+	stringstream stream;
+	unique_ptr<Json::StreamWriter> writer(_builder.newStreamWriter());
+	writer->write(_input, &stream);
+	return stream.str();
+}
+
+/// Parse a JSON string (@a _input) with specified builder (@ _builder) and writes resulting JSON object to (@a _json)
+/// \param _builder CharReaderBuilder that is used to create new Json::CharReaders
+/// \param _input JSON input string
+/// \param _json [out] resulting JSON object
+/// \param _errs [out] Formatted error messages
+/// \return \c true if the document was successfully parsed, \c false if an error occurred.
+bool parse(Json::CharReaderBuilder& _builder, string const& _input, Json::Value& _json, string* _errs)
+{
+	unique_ptr<Json::CharReader> reader(_builder.newCharReader());
+	return reader->parse(_input.c_str(), _input.c_str() + _input.length(), &_json, _errs);
+}
+
+} // end anonymous namespace
+
+string jsonPrettyPrint(Json::Value const& _input)
+{
+	static map<string, string> settings{{"indentation", "  "}};
+	static StreamWriterBuilder writerBuilder(settings);
+	return print(_input, writerBuilder);
+}
+
+string jsonCompactPrint(Json::Value const& _input)
+{
+	static map<string, string> settings{{"indentation", ""}};
+	static StreamWriterBuilder writerBuilder(settings);
+	return print(_input, writerBuilder);
+}
+
+bool jsonParseStrict(string const& _input, Json::Value& _json, string* _errs /* = nullptr */)
+{
+	static StrictModeCharReaderBuilder readerBuilder;
+	return parse(readerBuilder, _input, _json, _errs);
+}
+
+bool jsonParse(string const& _input, Json::Value& _json, string *_errs /* = nullptr */)
+{
+	static Json::CharReaderBuilder readerBuilder;
+	return parse(readerBuilder, _input, _json, _errs);
+}
+
+} // namespace dev