attribute_collector.hpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2017 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#ifndef MAPNIK_ATTRIBUTE_COLLECTOR_HPP
#define MAPNIK_ATTRIBUTE_COLLECTOR_HPP

// mapnik
#include <mapnik/transform/transform_processor.hpp>
#include <mapnik/util/noncopyable.hpp>
#include <mapnik/attribute.hpp>
#include <mapnik/symbolizer.hpp>
#include <mapnik/expression.hpp>  // for expression_ptr, etc
#include <mapnik/expression_node.hpp>
#include <mapnik/parse_path.hpp>  // for path_processor_type
#include <mapnik/path_expression.hpp>  // for path_expression_ptr
#include <mapnik/text/placements/base.hpp>  // for text_placements
#include <mapnik/image_scaling.hpp>
#include <mapnik/group/group_symbolizer_properties.hpp>
#include <mapnik/group/group_rule.hpp>
#include <mapnik/util/conversions.hpp>
#include <mapnik/util/variant.hpp>

#pragma GCC diagnostic push
#include <mapnik/warning_ignore.hpp>
#include <boost/algorithm/string/replace.hpp>
#pragma GCC diagnostic pop

// stl
#include <set>
#include <functional> // std::ref

namespace mapnik {

template <typename Container>
struct expression_attributes
{
    explicit expression_attributes(Container& names)
        : names_(names) {}

    void operator() (attribute const& attr) const
    {
        names_.emplace(attr.name());
    }

    template <typename Tag>
    void operator() (binary_node<Tag> const& x) const
    {
        util::apply_visitor(*this, x.left);
        util::apply_visitor(*this, x.right);
    }

    template <typename Tag>
    void operator() (unary_node<Tag> const& x) const
    {
        util::apply_visitor(*this, x.expr);
    }

    void operator() (regex_match_node const& x) const
    {
        util::apply_visitor(*this, x.expr);
    }

    void operator() (regex_replace_node const& x) const
    {
        util::apply_visitor(*this, x.expr);
    }

    template <typename T>
    void operator() (T const&) const {}

private:
    Container& names_;
};

class group_attribute_collector : public util::noncopyable
{
private:
    std::set<std::string>& names_;
    bool expand_index_columns_;
public:
    group_attribute_collector(std::set<std::string>& names,
                              bool expand_index_columns)
        : names_(names),
          expand_index_columns_(expand_index_columns) {}

    void operator() (group_symbolizer const& sym);
};

template <typename Container>
struct extract_attribute_names
{
    explicit extract_attribute_names(Container& names)
        : names_(names),
          f_attr_(names) {}

    void operator() (mapnik::expression_ptr const& expr) const
    {
        if (expr)
        {
            util::apply_visitor(f_attr_, *expr);
        }
    }
    void operator() (mapnik::transform_type const& expr) const
    {
        if (expr)
        {
            transform_processor_type::collect_attributes(names_, *expr);
        }
    }

    void operator() (mapnik::text_placements_ptr const& expr) const
    {
        if (expr)
        {
            expression_set::const_iterator it;
            expression_set expressions;
            // TODO - optimize (dane)
            expr->add_expressions(expressions);
            for (it=expressions.begin(); it != expressions.end(); ++it)
            {
                if (*it) util::apply_visitor(f_attr_, **it);
            }
        }
    }

    void operator() (mapnik::path_expression_ptr const& expr) const
    {
        if (expr)
        {
            path_processor_type::collect_attributes(*expr,names_);
        }
    }

    template <typename T>
    void operator() (T const&) const {}

private:
    Container& names_;
    expression_attributes<std::set<std::string> > f_attr_;
};

struct symbolizer_attributes
{
    symbolizer_attributes(std::set<std::string>& names,
                          double & filter_factor)
        : filter_factor_(filter_factor),
          f_attrs_(names),
          g_attrs_(names, true) {}

    template <typename T>
    void operator () (T const& sym)
    {
        for (auto const& prop : sym.properties)
        {
            util::apply_visitor(f_attrs_, prop.second);
        }
    }

    void operator () (raster_symbolizer const& sym)
    {
        boost::optional<double> filter_factor = get_optional<double>(sym, keys::filter_factor);
        if (filter_factor)
        {
            filter_factor_ = *filter_factor;
        }
        else
        {
            boost::optional<scaling_method_e> scaling_method = get_optional<scaling_method_e>(sym, keys::scaling);
            if (scaling_method && *scaling_method != SCALING_NEAR)
            {
                filter_factor_ = 2;
            }
        }
        for (auto const& prop : sym.properties)
        {
            util::apply_visitor(f_attrs_, prop.second);
        }
    }

    void operator () (group_symbolizer const& sym)
    {
        g_attrs_(sym);
    }

private:
    double & filter_factor_;
    extract_attribute_names<std::set<std::string> > f_attrs_;
    group_attribute_collector g_attrs_;
};


class attribute_collector : public util::noncopyable
{
private:
    std::set<std::string> & names_;
    double filter_factor_;
    expression_attributes<std::set<std::string> > f_attr;
public:

    attribute_collector(std::set<std::string>& names)
        : names_(names),
          filter_factor_(1.0),
          f_attr(names) {}
    template <typename RuleType>
    void operator() (RuleType const& r)
    {
        typename RuleType::symbolizers const& symbols = r.get_symbolizers();
        symbolizer_attributes s_attr(names_,filter_factor_);
        for (auto const& sym : symbols)
        {
            util::apply_visitor(std::ref(s_attr), sym);
        }

        expression_ptr const& expr = r.get_filter();
        util::apply_visitor(f_attr,*expr);
    }

    double get_filter_factor() const
    {
        return filter_factor_;
    }
};


inline void group_attribute_collector::operator() (group_symbolizer const& sym)
{
    // find all column names referenced in the group symbolizer
    std::set<std::string> group_columns;
    attribute_collector column_collector(group_columns);
    expression_attributes<std::set<std::string> > rk_attr(group_columns);

    // get columns from symbolizer repeat key
    expression_ptr repeat_key = get<mapnik::expression_ptr>(sym, keys::repeat_key);
    if (repeat_key)
    {
        util::apply_visitor(rk_attr, *repeat_key);
    }

    // get columns from child rules and symbolizers
    group_symbolizer_properties_ptr props = get<group_symbolizer_properties_ptr>(sym, keys::group_properties);
    if (props)
    {
        for (auto const& rule : props->get_rules())
        {
            // note that this recurses down on to the symbolizer
            // internals too, so we get all free variables.
            column_collector(*rule);
            // still need to collect repeat key columns
            if (rule->get_repeat_key())
            {
                util::apply_visitor(rk_attr, *(rule->get_repeat_key()));
            }
        }
    }

    // get indexed column names
    value_integer start = get<value_integer>(sym, keys::start_column);
    value_integer end = start + get<value_integer>(sym, keys::num_columns);
    for (auto const& col_name : group_columns)
    {
        if (expand_index_columns_ && col_name.find('%') != std::string::npos)
        {
            // Note: ignore column name if it is '%' by itself.
            // '%' is a special case to access the index value itself,
            // rather than acessing indexed columns from data source.
            if (col_name.size() > 1)
            {
                // Indexed column name. add column name for each index value.
                for (value_integer col_idx = start; col_idx < end; ++col_idx)
                {
                    std::string col_idx_str;
                    if (mapnik::util::to_string(col_idx_str,col_idx))
                    {
                        std::string col_idx_name = col_name;
                        boost::replace_all(col_idx_name, "%", col_idx_str);
                        names_.emplace(col_idx_name);
                    }
                }
            }
        }
        else
        {
            // This is not an indexed column, or we are ignoring indexes.
            // Insert the name as is.
            names_.emplace(col_name);
        }
    }
}

} // namespace mapnik

#endif // MAPNIK_ATTRIBUTE_COLLECTOR_HPP