dindexer/src/pq/resultset.cpp

/* Copyright 2015, Michele Santullo
 * This file is part of "dindexer".
 *
 * "dindexer" 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.
 *
 * "dindexer" 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 "dindexer".  If not, see <http://www.gnu.org/licenses/>.
 */

#include "pq/resultset.hpp"
#include "resultinfo.hpp"
#include "pq/databaseexception.hpp"
#include <libpq-fe.h>
#include <map>
#include <cassert>
#include <ciso646>
#include <boost/lexical_cast.hpp>
#include <algorithm>
#include <boost/bind.hpp>

namespace pq {
	struct Row::LocalData {
		LocalData ( const PGresult* parResult, std::size_t parRow, const std::map<std::string, int>* parCols, std::size_t parColCount ) :
			result(parResult),
			columns(parCols),
			row_index(parRow),
			col_count(parColCount)
		{
			assert((result and columns) or (not (result or columns)));
		}

		const PGresult* const result;
		const std::map<std::string, int>* const columns;
		const std::size_t row_index;
		const std::size_t col_count;
	};

	struct ResultSet::LocalData {
		explicit LocalData ( PGresult* parResult ) :
			result(parResult)
		{
		}

		PGresult* result;
		std::map<std::string, int> columns;
	};

	Row::Row (const ResultInfo& parResult, std::size_t parRow) :
		m_localData(new LocalData(parResult.result, parRow, parResult.column_mappings, (parResult.column_mappings ? parResult.column_mappings->size() : 0)))
	{
		assert(not m_localData->result or static_cast<std::size_t>(std::max(0, PQnfields(m_localData->result))) == m_localData->col_count);
	}

	Row::Row (Row&& parOther) :
		m_localData(std::move(parOther.m_localData))
	{
	}

	//Row::Row (const Row& parOther) :
	//	m_localData(new LocalData(parOther.m_localData->result, parOther.m_localData->row_index, parOther.m_localData->columns, parOther.m_localData->col_count))
	//{
	//}

	Row::~Row() noexcept {
	}

	std::string Row::operator[] (const std::string& parIndex) const {
		assert(m_localData->columns);
		const auto num_index_it = m_localData->columns->find(parIndex);
		if (num_index_it == m_localData->columns->end())
			throw DatabaseException("Error retrieving column", "Requested column \"" + parIndex + "\" doesn't exist", __FILE__, __LINE__);

		const int num_index = num_index_it->second;
		return PQgetvalue(m_localData->result, static_cast<int>(m_localData->row_index), num_index);
	}

	std::size_t Row::size() const {
		return m_localData->col_count;
	}

	bool Row::empty() const {
		return size() == 0;
	}

	std::string Row::operator[] (std::size_t parIndex) const {
		if (parIndex >= m_localData->col_count) {
			std::ostringstream oss;
			oss << "Requested column at index " << parIndex << " is out of range (column count is " << m_localData->col_count << ')';
			throw DatabaseException("Error retrieving column", oss.str(), __FILE__, __LINE__);
		}

		return PQgetvalue(m_localData->result, static_cast<int>(m_localData->row_index), static_cast<int>(parIndex));
	}

	Row::const_iterator Row::begin() const {
		return boost::make_transform_iterator(
			boost::counting_iterator<std::size_t>(0),
			boost::bind(static_cast<std::string (Row::*)(std::size_t) const>(&Row::operator[]), this, _1)
		);
	}

	Row::const_iterator Row::end() const {
		return boost::make_transform_iterator(
			boost::counting_iterator<std::size_t>(m_localData->col_count),
			boost::bind(static_cast<std::string (Row::*)(std::size_t) const>(&Row::operator[]), this, _1)
		);
	}


	ResultSet::ResultSet (ResultInfo& parResult) :
		m_localData(new LocalData(parResult.result))
	{
		const auto result = m_localData->result;
		const int column_count = PQnfields(result);
		std::string col_name;
		for (int z = 0; z < column_count; ++z) {
			m_localData->columns[PQfname(result, z)] = z;
		}
	}

	ResultSet::ResultSet (ResultSet&& parOther) :
		m_localData(std::move(parOther.m_localData))
	{
	}

	ResultSet::~ResultSet() noexcept {
		if (m_localData->result) {
			PQclear(m_localData->result);
			m_localData->result = nullptr;
		}
	}

	Row ResultSet::operator[] (std::size_t parIndex) const {
		ResultInfo info;
		info.result = m_localData->result;
		info.column_mappings = &m_localData->columns;

		if (parIndex >= size())
			throw DatabaseException("Out of range", "Column index " + boost::lexical_cast<std::string>(parIndex) + " is out of range (column count is " + boost::lexical_cast<std::string>(size()) + ')', __FILE__, __LINE__);

		return Row(info, parIndex);
	}

	std::size_t ResultSet::size() const {
		assert(m_localData->result);
		const auto retval = PQntuples(m_localData->result);
		assert(retval >= 0);
		return static_cast<std::size_t>(std::max(0, retval));
	}

	bool ResultSet::empty() const {
		return size() == 0;
	}

	ResultSet::const_iterator ResultSet::begin() const {
		return boost::make_transform_iterator(
			boost::counting_iterator<std::size_t>(0),
			boost::bind(static_cast<Row (ResultSet::*)(std::size_t) const>(&ResultSet::operator[]), this, _1)
		);
	}

	ResultSet::const_iterator ResultSet::end() const {
		return boost::make_transform_iterator(
			boost::counting_iterator<std::size_t>(size()),
			boost::bind(static_cast<Row (ResultSet::*)(std::size_t) const>(&ResultSet::operator[]), this, _1)
		);
	}
} //namespace pq