example_match_package.cc

This example demonstrates how to use paludis::match_package and paludis::match_package_in_set.

/* vim: set sw=4 sts=4 et foldmethod=syntax : */
 
/** \file
 *
 * Example \ref example_match_package.cc "example_match_package.cc" .
 *
 * \ingroup g_query
 */
 
/** \example example_match_package.cc
 *
 * This example demonstrates how to use paludis::match_package and
 * paludis::match_package_in_set.
 */
 
#include <paludis/paludis.hh>
#include "example_command_line.hh"
#include <iostream>
#include <iomanip>
#include <cstdlib>
 
using namespace paludis;
using namespace examples;
 
using std::cout;
using std::endl;
using std::left;
using std::setw;
 
int main(int argc, char * argv[])
{
    int exit_status(0);
 
    try
    {
        CommandLine::get_instance()->run(argc, argv,
                "example_match_package", "EXAMPLE_MATCH_PACKAGE_OPTIONS", "EXAMPLE_MATCH_PACKAGE_CMDLINE");
 
        /* We start with an Environment, respecting the user's '--environment' choice. */
        std::shared_ptr<Environment> env(EnvironmentFactory::get_instance()->create(
                    CommandLine::get_instance()->a_environment.argument()));
 
        /* Fetch all installed packages. */
        std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsSorted(
                    generator::All() |
                    filter::InstalledAtSlash())]);
 
        /* Fetch the 'system' and 'world' sets. Ordinarily we should check for
         * zero pointers here, but these two sets will always exist. */
        std::shared_ptr<const SetSpecTree> system(env->set(SetName("system")));
        std::shared_ptr<const SetSpecTree> world(env->set(SetName("world")));
 
        /* For each ID: */
        for (const auto & id : *ids)
        {
            /* Is it paludis? */
            if (match_package(*env, make_package_dep_spec({ }).package(
                            QualifiedPackageName("sys-apps/paludis")), id, nullptr, { }))
                cout << left << setw(50) << (stringify(*id) + ":") << " " << "paludis" << endl;
 
            /* No. Is it in system or world? */
            else if (match_package_in_set(*env, *system, id, { }))
                cout << left << setw(50) << (stringify(*id) + ":") << " " << "system" << endl;
            else if (match_package_in_set(*env, *world, id, { }))
                cout << left << setw(50) << (stringify(*id) + ":") << " " << "world" << endl;
            else
                cout << left << setw(50) << (stringify(*id) + ":") << " " << "nothing" << endl;
        }
 
    }
    catch (const Exception & e)
    {
        /* Paludis exceptions can provide a handy human-readable backtrace and
         * an explanation message. Where possible, these should be displayed. */
        cout << endl;
        cout << "Unhandled exception:" << endl
            << "  * " << e.backtrace("\n  * ")
            << e.message() << " (" << e.what() << ")" << endl;
        return EXIT_FAILURE;
    }
    catch (const std::exception & e)
    {
        cout << endl;
        cout << "Unhandled exception:" << endl
            << "  * " << e.what() << endl;
        return EXIT_FAILURE;
    }
    catch (...)
    {
        cout << endl;
        cout << "Unhandled exception:" << endl
            << "  * Unknown exception type. Ouch..." << endl;
        return EXIT_FAILURE;
    }
 
    return exit_status;
}