mapnik/plugins/input/shape/dbfile.cpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2021 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
 *
 *****************************************************************************/
// mapnik
#include <mapnik/value/types.hpp>
#include <mapnik/global.hpp>
#include <mapnik/util/utf_conv_win.hpp>
#include <mapnik/unicode.hpp>
#include <mapnik/util/trim.hpp>

#include "dbfile.hpp"

#include <mapnik/warning.hpp>
MAPNIK_DISABLE_WARNING_PUSH
#include <mapnik/warning_ignore.hpp>
#include <boost/spirit/home/x3.hpp>
#if defined(MAPNIK_MEMORY_MAPPED_FILE)
#include <boost/interprocess/mapped_region.hpp>
#include <mapnik/mapped_memory_cache.hpp>
#endif
MAPNIK_DISABLE_WARNING_POP

// stl
#include <cstdint>
#include <string>
#include <cstring>
#include <stdexcept>

dbf_file::dbf_file()
    : num_records_(0)
    , num_fields_(0)
    , record_length_(0)
    , record_(0)
{}

dbf_file::dbf_file(std::string const& file_name)
    : mapped_memory_file{file_name}
    , num_records_(0)
    , num_fields_(0)
    , record_length_(0)
    , record_(0)
{
    if (file_)
    {
        read_header();
    }
}

dbf_file::~dbf_file()
{
    ::operator delete(record_);
}

int dbf_file::num_records() const
{
    return num_records_;
}

int dbf_file::num_fields() const
{
    return num_fields_;
}

void dbf_file::move_to(int index)
{
    if (index > 0 && index <= num_records_)
    {
        std::streampos pos = (num_fields_ << 5) + 34 + (index - 1) * (record_length_ + 1);
        file_.seekg(pos, std::ios::beg);
        file_.read(record_, record_length_);
    }
}

std::string dbf_file::string_value(int col) const
{
    if (col >= 0 && col < num_fields_)
    {
        return std::string(record_ + fields_[col].offset_, fields_[col].length_);
    }
    return "";
}

const field_descriptor& dbf_file::descriptor(int col) const
{
    assert(col >= 0 && col < num_fields_);
    return fields_[col];
}

void dbf_file::add_attribute(int col, mapnik::transcoder const& tr, mapnik::feature_impl& f) const
{
    using namespace boost::spirit;

    if (col >= 0 && col < num_fields_)
    {
        std::string const& name = fields_[col].name_;

        // NOTE: ensure types handled here are matched in shape_datasource.cpp
        switch (fields_[col].type_)
        {
            case 'C':
            case 'D': {
                // FIXME - avoid constructing std::string on stack
                std::string str(record_ + fields_[col].offset_, fields_[col].length_);
                mapnik::util::trim(str);
                f.put(name, tr.transcode(str.c_str()));
                break;
            }
            case 'L': {
                char ch = record_[fields_[col].offset_];
                if (ch == '1' || ch == 't' || ch == 'T' || ch == 'y' || ch == 'Y')
                {
                    f.put(name, true);
                }
                else
                {
                    // NOTE: null logical fields use '?'
                    f.put(name, false);
                }
                break;
            }
            case 'N': // numeric
            case 'O': // double
            case 'F': // float
            {
                if (record_[fields_[col].offset_] == '*')
                {
                    // NOTE: we intentionally do not store null here
                    // since it is equivalent to the attribute not existing
                    break;
                }
                if (fields_[col].dec_ > 0)
                {
                    double val = 0.0;
                    const char* itr = record_ + fields_[col].offset_;
                    const char* end = itr + fields_[col].length_;
                    x3::ascii::space_type space;
                    static x3::double_type double_;
                    if (x3::phrase_parse(itr, end, double_, space, val))
                    {
                        f.put(name, val);
                    }
                }
                else
                {
                    mapnik::value_integer val = 0;
                    const char* itr = record_ + fields_[col].offset_;
                    const char* end = itr + fields_[col].length_;
                    x3::ascii::space_type space;
                    static x3::int_parser<mapnik::value_integer, 10, 1, -1> numeric_parser;
                    if (x3::phrase_parse(itr, end, numeric_parser, space, val))
                    {
                        f.put(name, val);
                    }
                }
                break;
            }
        }
    }
}

void dbf_file::read_header()
{
    char c = file_.get();
    if (c == '\3' || c == '\131')
    {
        skip(3);
        num_records_ = read_int();
        assert(num_records_ >= 0);
        num_fields_ = read_short();
        assert(num_fields_ > 0);
        num_fields_ = (num_fields_ - 33) / 32;
        skip(22);
        std::streampos offset = 0;
        char name[11];
        std::memset(&name, 0, 11);
        fields_.reserve(num_fields_);
        for (int i = 0; i < num_fields_; ++i)
        {
            field_descriptor desc;
            desc.index_ = i;
            file_.read(name, 10);
            desc.name_ = name;
            // TODO - when is this trim needed?
            mapnik::util::trim(desc.name_);
            skip(1);
            desc.type_ = file_.get();
            skip(4);
            desc.length_ = file_.get();
            desc.dec_ = file_.get();
            skip(14);
            desc.offset_ = offset;
            offset += desc.length_;
            fields_.push_back(desc);
        }
        record_length_ = offset;
        if (record_length_ > 0)
        {
            record_ = static_cast<char*>(::operator new(sizeof(char) * record_length_));
        }
    }
}

int dbf_file::read_short()
{
    char b[2];
    file_.read(b, 2);
    std::int16_t val;
    mapnik::read_int16_ndr(b, val);
    return val;
}

int dbf_file::read_int()
{
    char b[4];
    file_.read(b, 4);
    std::int32_t val;
    mapnik::read_int32_ndr(b, val);
    return val;
}