paludis  Version 2.6.0
example_dep_spec_flattener.cc

This example demonstrates how to use DepSpecFlattener. It extracts various metadata items from a package.

/* vim: set sw=4 sts=4 et foldmethod=syntax : */
/** \file
*
* Example \ref example_dep_spec_flattener.cc "example_dep_spec_flattener.cc" .
*
* \ingroup g_dep_spec
*/
/** \example example_dep_spec_flattener.cc
*
* This example demonstrates how to use DepSpecFlattener. It extracts various
* metadata items from a package.
*/
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <cstdlib>
#include <set>
#include <map>
using namespace paludis;
using namespace examples;
using std::cout;
using std::endl;
using std::setw;
using std::left;
int main(int argc, char * argv[])
{
try
{
CommandLine::get_instance()->run(argc, argv,
"example_dep_spec_flattener", "EXAMPLE_DEP_SPEC_FLATTENER_OPTIONS", "EXAMPLE_DEP_SPEC_FLATTENER_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 all installed packages. */
std::shared_ptr<const PackageIDSequence> ids((*env)[selection::AllVersionsSorted(
/* For each ID: */
for (PackageIDSequence::ConstIterator i(ids->begin()), i_end(ids->end()) ;
i != i_end ; ++i)
{
cout << "Information about '" << **i << "':" << endl;
/* Do we have a homepage? All PackageID key methods may return a
* null pointer. */
if ((*i)->homepage_key())
{
(*i)->homepage_key()->parse_value()->top()->accept(homepages);
cout << " " << left << setw(24) << "Homepages:" << " "
<< join(indirect_iterator(homepages.begin()), indirect_iterator(homepages.end()), " ")
<< endl;
}
/* And again for restricts. There's no global restrict key, since
* it has no meaning outside of the repositories that support it.
* Instead, we use PackageID::find_metadata to see if the key we
* want exists, and then visitor_cast<> to see whether it's
* of a suitable type (the key could be something other than a
* MetadataSpecTreeKey<PlainTextSpecTree>). */
if ((*i)->end_metadata() != (*i)->find_metadata("RESTRICT") &&
visitor_cast<const MetadataSpecTreeKey<PlainTextSpecTree> >(**(*i)->find_metadata("RESTRICT")))
{
**(*i)->find_metadata("RESTRICT"))->parse_value()->top()->accept(restricts);
cout << " " << left << setw(24) << "Restricts:" << " "
<< join(indirect_iterator(restricts.begin()), indirect_iterator(restricts.end()), " ")
<< 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_SUCCESS;
}