paludis  Version 2.6.0
example_mask.cc

This example demonstrates how to use Mask. It displays all the mask keys for a particular PackageID.

/* vim: set sw=4 sts=4 et foldmethod=syntax : */
/** \file
*
* Example \ref example_mask.cc "example_mask.cc" .
*
* \ingroup g_mask
*/
/** \example example_mask.cc
*
* This example demonstrates how to use Mask. It displays all the
* mask keys for a particular PackageID.
*/
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <set>
#include <time.h>
using namespace paludis;
using namespace examples;
using std::cout;
using std::endl;
using std::left;
using std::setw;
namespace
{
/* We use this visitor to display extra information about a Mask,
* depending upon its type. */
class MaskInformationVisitor
{
public:
void visit(const UserMask &)
{
cout << left << setw(30) << " Class:" << " " << "UserMask" << endl;
}
void visit(const UnacceptedMask & mask)
{
cout << left << setw(30) << " Class:" << " " << "UnacceptedMask" << endl;
cout << left << setw(30) << " Unaccepted key:" << " " << mask.unaccepted_key_name() << endl;
}
void visit(const RepositoryMask & mask)
{
cout << left << setw(30) << " Class:" << " " << "RepositoryMask" << endl;
cout << left << setw(30) << " Mask file:" << " " << mask.mask_file() << endl;
if (! mask.comment().empty())
cout << left << setw(30) << " Comment:" << " " << mask.comment() << endl;
if (! mask.token().empty())
cout << left << setw(30) << " Token:" << " " << mask.token() << endl;
}
void visit(const UnsupportedMask & mask)
{
cout << left << setw(30) << " Class:" << " " << "UnsupportedMask" << endl;
cout << left << setw(30) << " Explanation:" << " " << mask.explanation() << endl;
}
};
}
int main(int argc, char * argv[])
{
int exit_status(0);
try
{
CommandLine::get_instance()->run(argc, argv,
"example_mask", "EXAMPLE_MASK_OPTIONS", "EXAMPLE_MASK_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 package IDs for 'sys-apps/paludis'. */
std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsSorted(
generator::Package(QualifiedPackageName("sys-apps/paludis")))]);
/* For each ID: */
for (PackageIDSequence::ConstIterator i(ids->begin()), i_end(ids->end()) ;
i != i_end ; ++i)
{
cout << **i << ":" << endl;
/* For each mask key: */
for (PackageID::MasksConstIterator m((*i)->begin_masks()), m_end((*i)->end_masks()) ;
m != m_end ; ++m)
{
/* All Mask instances have two basic bits of information: a one
* character short key, and a longer description. */
cout << left << setw(30) << " Key:" << " " << std::string(1, (*m)->key()) << endl;
cout << left << setw(30) << " Description:" << " " << (*m)->description() << endl;
/* To display more information about a Mask we create a visitor
* that visits the appropriate subtype. */
MaskInformationVisitor v;
(*m)->accept(v);
cout << endl;
}
cout << 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;
}