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// infer_reason.h
//
// Copyright 2004 Daniel Burrows
#ifndef INFER_DEPS_H
#define INFER_DEPS_H
#include <set>
#include <apt-pkg/pkgcache.h>
/** \brief Code for inferring why a package is in its current state.
*
* \file infer_reason.h
*/
/** A structure representing a package and a dependency of that
* package. It is used below to return the reasons for a package's
* current state.
*/
struct reason
{
pkgCache::PkgIterator pkg;
pkgCache::DepIterator dep;
reason(const pkgCache::PkgIterator &_pkg, const pkgCache::DepIterator &_dep)
:pkg(_pkg), dep(_dep) {}
};
/** Compares two reasons; this is meant to support, eg, sorting
* reasons into a sensible order for output.
*/
bool operator<(const reason &a, const reason &b);
/** Return the reason for a package's current state. The
* interpretation of each output reason can vary depending on the
* state of the package:
*
* - If the package is being automatically installed, each reason
* refers to a package which depends on, recommends, or suggests
* the package being installed.
*
* - If the package is being automatically removed, each reason refers
* EITHER to a package which this package depends upon or conflicts
* with, OR to a package which conflicts with this package.
*
* - If the package was removed because it was unused, each reason
* refers to a package which depends upon (or recommends) this package,
* and is being removed (or upgraded to a version which no longer has
* the dependency).
*
* - If the package was automatically held back from upgrading, each
* reason refers to a dependency which would be broken if the package
* was upgraded.
*
* - If the package is not installed and will not be installed, each
* reason refers to a suggestion or recommendation made by a package
* which is being installed.
*
* - If the package is broken, each reason refers either to another
* package that conflicts with this package, or to a dependency of
* this package that is not satisfied.
*
* \param pkg the package to analyze
* \param reasons the reasons for the package's state will be sent to this
* set.
*/
void infer_reason(pkgCache::PkgIterator pkg, std::set<reason> &reasons);
/** Do the opposite of infer_reason: instead of finding reasons for
* why \b this package is in its present state, find reasons (if any)
* for why it breaks other packages.
*
* Possible reasons for a package A (this is meant to be an
* exhaustive enumeration):
*
* - B depends on A, but A is [being removed|not going to be installed]
*
* - B conflicts with A, but A is [installed|going to be installed]
*
* - B depends on A (version), but A is being upgraded from that version.
*
* - B conflicts with A (version), and A is being upgraded to that version.
*/
void infer_reverse_breakage(pkgCache::PkgIterator pkg,
std::set<reason> &reasons);
#endif
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