Exporting Natspec documentation to a JSON interface

- Adding a getDocumentation() function to solidity compiler stack
  so that we can obtain the natspec interface for a contract

- Adding libjsoncpp as a dependency of libsolidity. This is done
  in a dirty way, using libjsonrpc-cpp s an intermediate dependency
  for the moment. Will fix soon.

- Start of a test file for Natspec exporting to JSON

solidityNatspecJSON.cpp

@@ -0,0 +1,77 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum 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.
+
+	cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+ */
+/**
+ * @author Lefteris Karapetsas <lefteris@ethdev.com>
+ * @date 2014
+ * Unit tests for the solidity compiler JSON Interface output.
+ */
+
+#include <boost/test/unit_test.hpp>
+#include <libsolidity/CompilerStack.h>
+#include <jsonrpc/json/json.h>
+
+namespace dev
+{
+namespace solidity
+{
+namespace test
+{
+
+class DocumentationChecker
+{
+public:
+	void checkNatspec(std::string const& _code, std::string const& _expectedDocumentationString)
+	{
+		m_compilerStack.parse(_code);
+		auto generatedDocumentationString = m_compilerStack.getDocumentation();
+		Json::Value generatedDocumentation;
+		m_reader.parse(generatedDocumentationString, generatedDocumentation);
+		Json::Value expectedDocumentation;
+		m_reader.parse(_expectedDocumentationString, expectedDocumentation);
+		BOOST_CHECK_MESSAGE(expectedDocumentation == generatedDocumentation,
+							"Expected " << _expectedDocumentationString <<
+							"\n but got:\n" << generatedDocumentationString);
+	}
+
+private:
+	CompilerStack m_compilerStack;
+	Json::Reader m_reader;
+};
+
+BOOST_FIXTURE_TEST_SUITE(SolidityNatspecJSON, DocumentationChecker)
+
+BOOST_AUTO_TEST_CASE(basic_test)
+{
+	char const* sourceCode = "contract test {\n"
+	"  /// Multiplies `a` by 7\n"
+	"  function mul(uint a) returns(uint d) { return a * 7; }\n"
+	"}\n";
+
+	char const* natspec = "{"
+	"\"methods\":{"
+	"    \"mul\":{ \"user\": \" Multiplies `a` by 7\"}"
+	"}}";
+
+	checkNatspec(sourceCode, natspec);
+}
+
+
+BOOST_AUTO_TEST_SUITE_END()
+
+}
+}
+}