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[platform/upstream/libsolv.git] / doc / libsolv-bindings.txt

LIBSOLV-BINDINGS(3)
===================
:man manual: LIBSOLV
:man source: libsolv


NAME
----
libsolv-bindings - access libsolv from perl/python/ruby


DESCRIPTION
-----------
Libsolv's language bindings offer an abstract, object orientated interface
to the library. The supported languages are currently perl, python, and ruby.
All example code (except in the specifics sections, of course) lists first
the ``C-ish'' interface, then the syntax for perl, python, and ruby (in that
order).


PERL SPECIFICS
--------------
Libsolv's perl bindings can be loaded with the following statement:

        use solv;

Objects are either created by calling the new() method on a class or they
are returned by calling methods on other objects.

        my $pool = solv::Pool->new();
        my $repo = $pool->add_repo("my_first_repo");

Swig encapsulates all objects as tied hashes, thus the attributes can be
accessed by treating the object as standard hash reference:

        $pool->{appdata} = 42;
        printf "appdata is %d\n", $pool->{appdata};

An special exception to this are iterator objects, they are encapsulated as
tied arrays so that it is possible to iterate with a for() statement:

        my $iter = $pool->solvables_iter();
        for my $solvable (@$iter) { ... };

As a downside of this approach, iterator objects cannot have attributes.

If an array needs to be passed to a method it is usually done by reference,
if a method returns an array it returns it on the stack:

        my @problems = $solver->solve(\@jobs);

Due to a bug in swig, stringification does not work for libsolv's object.
Instead you have to call the object's str() method.

        print $dep->str() . "\n";

Swig implements all constants as numeric variables (instead of the more
natural constant subs), so don't forget the leading ``$'' when accessing a
constant. Also do not forget to prepend the namespace of the constant:

        $pool->set_flag($solv::Pool::POOL_FLAG_OBSOLETEUSESCOLORS, 1);
        

PYTHON SPECIFICS
----------------
The python bindings can be loaded with:

        import solv

Objects are either created by calling the constructor method for a class or they
are returned by calling methods on other objects.

        pool = solv.Pool()
        repo = pool.add_repo("my_first_repo")

Attributes can be accessed as usual:

        pool.appdata = 42
        print "appdata is %d" % (pool.appdata)

Iterators also work as expected:

        for solvable in pool.solvables_iter():

Arrays are passed an returned as list objects:

        jobs = []
        problems = solver.solve(jobs)

The bindings define stringification for many classes, some also have a
__repr__ method to ease debugging.

        print dep
        print repr(repo)

Constants are attributes of the classes:

        pool.set_flag(solv.Pool.POOL_FLAG_OBSOLETEUSESCOLORS, 1);


RUBY SPECIFICS
--------------
The ruby bindings can be loaded with:

        require 'solv'

Objects are either created by calling the new method on a class or they
are returned by calling methods on other objects. Note that all classes start
with an uppercase letter in ruby, so the class is called ``Solv''.

        pool = Solv::Pool.new
        repo = pool.add_repo("my_first_repo")

Attributes can be accessed as usual:

        pool.appdata = 42
        puts "appdata is #{pool.appdata}"

Iterators also work as expected:

        for solvable in pool.solvables_iter() do ...

Arrays are passed an returned as array objects:

        jobs = []
        problems = solver.solve(jobs)

Most classes define a to_s method, so objects can be easily stringified.
Many also define an inspect() method.

        puts dep
        puts repo.inspect

Constants live in the namespace of the class they belong to:

        pool.set_flag(Solv::Pool::POOL_FLAG_OBSOLETEUSESCOLORS, 1);

Note that boolean methods have an added trailing ``?'', to be consistent with
other ruby modules:

        puts "empty repo" if repo.isempty?


THE SOLV CLASS
--------------
This is the main namespace of the library, you cannot create objects of this
type but it contains some useful constants.

=== CONSTANTS ===

Relational flag constants, the first three can be or-ed together

*REL_LT*::
  the ``less than'' bit

*REL_EQ*::
  the ``equals to'' bit

*REL_GT*::
  the ``greater then'' bit

*REL_ARCH*::
  used for relations that describe an extra architecture filter, the
  version part of the relation is interpreted as architecture.

Special Solvable Ids

*SOLVID_META*::
  Access the meta section of a repository or repodata area. This is
  like an extra Solvable that has the Id SOLVID_META.

*SOLVID_POS*::
  Use the data position stored inside of the pool instead of accessing
  some solvable by Id. The bindings have the Datapos objects as an
  abstraction mechanism, so you do not need this constant.

Constant string Ids
  
*ID_NULL*::
  Always zero

*ID_EMPTY*::
  Always one, describes the empty string

*SOLVABLE_NAME*::
  The keyname Id of the name of the solvable.

*...*::
  see the libsolv-constantids manpage for a list of fixed Ids.


THE POOL CLASS
--------------
The pool is libsolv's central resource manager. A pool consists of Solvables,
Repositories, Dependencies, each indexed by Ids.

=== CLASS METHODS ===

        Pool *Pool()
        my $pool = solv::Pool->new();
        pool = solv.Pool()
        pool = Solv::Pool.new()

Create a new pool instance. In most cases you just need
one pool.

=== ATTRIBUTES ===

        void *appdata;                  /* read/write */
        $pool->{appdata}
        pool.appdata
        pool.appdata

Application specific data that may be used in any way by the code using the
pool.

        Solvable solvables[];           /* read only */
        my $solvable = $pool->{solvables}->[$solvid];
        solvable = pool.solvables[solvid]
        solvable = pool.solvables[solvid]

Look up a Solvable by its id.

        Repo repos[];                   /* read only */
        my $repo = $pool->{repos}->[$repoid];
        repo = pool.repos[repoid]
        repo = pool.repos[repoid]

Look up a Repository by its id.

        Repo *installed;                /* read/write */
        $pool->{installed} = $repo;
        pool.installed = repo
        pool.installed = repo

Define which repository contains all the installed packages.

=== CONSTANTS ===

*POOL_FLAG_PROMOTEEPOCH*::
  Promote the epoch of the providing dependency to the requesting
  dependency if it does not contain an epoch. Used at some time
  in old rpm versions, modern systems should never need this.

*POOL_FLAG_FORBIDSELFCONFLICTS*::
  Disallow the installation of packages that conflict with themselves.
  Debian always allows self-conflicting packages, rpm used to forbid
  them but switched to also allowing them recently.

*POOL_FLAG_OBSOLETEUSESPROVIDES*::
  Make obsolete type dependency match against provides instead of
  just the name and version of packages. Very old versions of rpm
  used the name/version, then it got switched to provides and later
  switched back again to just name/version.

*POOL_FLAG_IMPLICITOBSOLETEUSESPROVIDES*::
  An implicit obsoletes is the internal mechanism to remove the
  old package on an update. The default is to remove all packages
  with the same name, rpm-5 switched to also removing packages
  providing the same name.

*POOL_FLAG_OBSOLETEUSESCOLORS*::
  Rpm's multilib implementation (used in RedHat and Fedora)
  distinguishes between 32bit and 64bit packages (the terminology
  is that they have a different color). If obsolteusescolors is
  set, packages with different colors will not obsolete each other.

*POOL_FLAG_IMPLICITOBSOLETEUSESCOLORS*::
  Same as POOL_FLAG_OBSOLETEUSESCOLORS, but used to find out if
  packages of the same name can be installed in parallel. For
  current Fedora systems, POOL_FLAG_OBSOLETEUSESCOLORS should be
  false and POOL_FLAG_IMPLICITOBSOLETEUSESCOLORS should be true
  (this is the default if FEDORA is defined when libsolv is
  compiled).

*POOL_FLAG_NOINSTALLEDOBSOLETES*::
  New versions of rpm consider the obsoletes of installed packages
  when checking for dependency, thus you may not install a package
  that is obsoleted by some other installed package, unless you
  also erase the other package.

*POOL_FLAG_HAVEDISTEPOCH*::
  Mandriva added a new field called distepoch that gets checked in
  version comparison if the epoch/version/release of two packages
  are the same.

*POOL_FLAG_NOOBSOLETESMULTIVERSION*::
  If a package is installed in multiversionmode, rpm used to ignore
  both the implicit obsoletes and the obsolete dependency of a
  package. This was changed to ignoring just the implicit obsoletes,
  thus you may install multiple versions of the same name, but
  obsoleted packages still get removed.

*POOL_FLAG_ADDFILEPROVIDESFILTERED*::
  Make the addfileprovides method only add files from the standard
  locations (i.e. the ``bin'' and ``etc'' directories). This is
  useful if you have only few packages that use non-standard file
  dependencies, but you still wand the fast speed that addfileprovides()
  generates.

=== METHODS ===

        void free()
        $pool->free();
        pool.free()
        pool.free()

Free a pool. This is currently done with a method instead of relying on
reference counting or garbage collection because it's hard to track every
reference to a pool.

        void setdebuglevel(int level)
        $pool->setdebuglevel($level);
        pool.setdebuglevel(level)
        pool.setdebuglevel(level)

Set the debug level. A value of zero means no debug output, the higher the
value, the more output is generated.

        int set_flag(int flag, int value)
        my $oldvalue = $pool->set_flag($flag, $value);
        oldvalue = pool.set_flag(flag, value)
        oldvalue = pool.set_flag(flag, value)

        int get_flag(int flag)
        my $value = $pool->get_flag($flag);
        value = pool.get_flag(flag)
        value = pool.get_flag(flag)

Set/get a pool specific flag. The flags define how the system works, e.g. how
the package manager treats obsoletes. The default flags should be sane for most
applications, but in some cases you may want to tweak a flag, for example if
you want to solv package dependencies for some other system than yours.

        void set_rootdir(const char *rootdir)
        $pool->set_rootdir(rootdir);
        pool.set_rootdir(rootdir)
        pool.set_rootdir(rootdir)

        const char *get_rootdir()
        my $rootdir = $pool->get_rootdir();
        rootdir = pool.get_rootdir()
        rootdir = pool.get_rootdir()

Set/get the rootdir to use. This is useful if you want package management
to work only in some directory, for example if you want to setup a chroot
jail. Note that the rootdir will only be prepended to file paths if the
*REPO_USE_ROOTDIR* flag is used.

        void setarch(const char *arch = 0)
        $pool->setarch();
        pool.setarch()
        pool.setarch()

Set the architecture for your system. The architecture is used to determine
which packages are installable. It defaults to the result of ``uname -m''.

        Repo add_repo(const char *name)
        $repo = $pool->add_repo($name);
        repo = pool.add_repo(name)
        repo = pool.add_repo(name)

Add a Repository with the specified name to the pool. The repository is empty
on creation, use the repository methods to populate it with packages.

        Repoiterator repos_iter()
        for my $repo (@{$pool->repos_iter()})
        for repo in pool.repos_iter():
        for repo in pool.repos_iter()

Iterate over the existing repositories.

        Solvableiterator solvables_iter()
        for my $solvable (@{$pool->solvables_iter()})
        for solvable in pool.solvables_iter():
        for solvable in pool.solvables_iter()

Iterate over the existing solvables.

        Dep Dep(const char *str, bool create = 1)
        my $dep = $pool->Dep($string);
        dep = pool.Dep(string)
        dep = pool.Dep(string)

Create an object describing a string or dependency. If the string is currently
not in the pool and _create_ is false, *undef*/*None*/*nil* is returned.

        void addfileprovides()
        $pool->addfileprovides();
        pool.addfileprovides()
        pool.addfileprovides()

        Id *addfileprovides_queue()
        my @ids = $pool->addfileprovides_queue();
        ids = pool.addfileprovides_queue()
        ids = pool.addfileprovides_queue()

Some package managers like rpm allow dependencies on files contained in other
packages. To allow libsolv to deal with those dependencies in an efficient way,
you need to call the addfileprovides method after creating and reading all
repositories. This method will scan all dependency for file names and than scan
all packages for matching files. If a filename has been matched, it will be
added to the provides list of the corresponding package. The
addfileprovides_queue variant works the same way but returns an array
containing all file dependencies. This information can be stored in the
meta section of the repositories to speed up the next time the
repository is loaded and addfileprovides is called.

        void createwhatprovides()
        $pool->createwhatprovides();
        pool.createwhatprovides()
        pool.createwhatprovides()

Create the internal ``whatprovides'' hash over all of the provides of all
packages. This method must be called before doing any lookups on provides.
It's encouraged to do it right after all repos are set up, usually right after
the call to addfileprovides().

        Solvable *whatprovides(DepId dep)
        my @solvables = $pool->whatprovides($dep);
        solvables = pool.whatprovides(dep)
        solvables = pool.whatprovides(dep)

Return all solvables that provide the specified dependency. You can use either
a Dep object or an simple Id as argument.

        Id *matchprovidingids(const char *match, int flags)
        my @ids = $pool->matchprovidingids($match, $flags);
        ids = pool.matchprovidingids(match, flags)
        ids = pool.matchprovidingids(match, flags)

Search the names of all provides and return the ones matching the specified
string. See the Dataiterator class for the allowed flags.

        Id towhatprovides(Id *ids)
        my $offset = $pool->towhatprovides(\@ids);
        offset = pool.towhatprovides(ids)
        offset = pool.towhatprovides(ids)

``Internalize'' an array containing Ids. The returned value can be used to
create solver jobs working on a specific set of packages. See the Solver class
for more information.

        bool isknownarch(DepId id)
        my $bool = $pool->isknownarch($id);
        bool = pool.isknownarch(id)
        bool = pool.isknownarch?(id)

Return true if the specified Id describes a known architecture.

        Solver Solver()
        my $solver = $pool->Solver();
        solver = pool.Solver()
        solver = pool.Solver()

Create a new solver object.

        Job Job(int how, Id what)
        my $job = $pool->Job($how, $what);
        job = pool.Job(how, what)
        job = pool.Job(how, what)

Create a new Job object. Kind of low level, in most cases you would use a
Selection or Dep job constructor instead.

        Selection Selection()
        my $sel = $pool->Selection();
        sel = pool.Selection()
        sel = pool.Selection()

Create an empty selection. Useful as a starting point for merging other
selections.

        Selection Selection_all()
        my $sel = $pool->Selection_all();
        sel = pool.Selection_all()
        sel = pool.Selection_all()
        
Create a selection containing all packages. Useful as starting point for
intersecting other selections or for update/distupgrade jobs.

        Selection select(const char *name, int flags)
        my $sel = $pool->select($name, $flags);
        sel = pool.select(name, flags)
        sel = pool.select(name, flags)

Create a selection by matching packages against the specified string. See the
Selection class for a list of flags and how to create solver jobs from a
selection.

        void setpooljobs(Jobs *jobs)
        $pool->setpooljobs(\@jobs);
        pool.setpooljobs(jobs)
        pool.setpooljobs(jobs)

        Job *getpooljobs()
        @jobs = $pool->getpooljobs();
        jobs = pool.getpooljobs()
        jobs = pool.getpooljobs()

Get/Set fixed jobs stored in the pool. Those jobs are automatically appended to
all solver jobs, they are meant for fixed configurations like which packages
can be multiversion installed, which packages were userinstalled or must not be
erased.

        void set_loadcallback(Callable *callback)
        $pool->setloadcallback(\&callbackfunction);
        pool.setloadcallback(callbackfunction)
        pool.setloadcallback { |repodata| ... }

Set the callback function called when repository metadata needs to be loaded on
demand. To make use of this feature, you need to create repodata stubs that
tell the library which data is available but not loaded. If later on the data
needs to be accessed, the callback function is called with a repodata argument.
You can then load the data (maybe fetching it first from an remote server).
The callback should return true if the data has been made available.

=== DATA RETRIEVAL METHODS ===

In the following functions, the _keyname_ argument describes what to retrieve.
For the standard cases you can use the available Id constants. For example,

        $solv::SOLVABLE_SUMMARY
        solv.SOLVABLE_SUMMARY
        Solv::SOLVABLE_SUMMARY

selects the ``Summary'' entry of a solvable. The _solvid_ argument selects the
desired solvable by Id.

        const char *lookup_str(Id solvid, Id keyname)
        my $string = $pool->lookup_str($solvid, $keyname);
        string = pool.lookup_str(solvid, keyname)
        string = pool.lookup_str(solvid, keyname)

        Id lookup_id(Id solvid, Id keyname)
        my $id = $pool->lookup_id($solvid, $keyname);
        id = pool.lookup_id(solvid, keyname)
        id = pool.lookup_id(solvid, keyname)

        unsigned long long lookup_num(Id solvid, Id keyname, unsigned long long notfound = 0)
        my $num = $pool->lookup_num($solvid, $keyname);
        num = pool.lookup_num(solvid, keyname)
        num = pool.lookup_num(solvid, keyname)

        bool lookup_void(Id solvid, Id keyname)
        my $bool = $pool->lookup_void($solvid, $keyname);
        bool = pool.lookup_void(solvid, keyname)
        bool = pool.lookup_void(solvid, keyname)

        Id *lookup_idarray(Id solvid, Id keyname)
        my @ids = $pool->lookup_idarray($solvid, $keyname);
        ids = pool.lookup_idarray(solvid, keyname)
        ids = pool.lookup_idarray(solvid, keyname)

        Chksum lookup_checksum(Id solvid, Id keyname)
        my $chksum = $pool->lookup_checksum($solvid, $keyname);
        chksum = pool.lookup_checksum(solvid, keyname)
        chksum = pool.lookup_checksum(solvid, keyname)

Lookup functions. Return the data element stored in the specified solvable.
You should probably use the methods of the Solvable class instead.

        Dataiterator Dataiterator(Id solvid, Id keyname, const char *match, int flags)
        my $di = $pool->Dataiterator($solvid, $keyname, $match, $flags);
        di = pool.Dataiterator(solvid, keyname, match, flags)
        di = pool.Dataiterator(solvid, keyname, match, flags)

        for my $d (@$di)
        for d in di:
        for d in di

Iterate over the matching data elements. See the Dataiterator class for more
information.

=== ID METHODS ===

The following methods deal with Ids, i.e. integers representing objects in the
pool. They are considered ``low level'', in most cases you would not use them
but instead the object orientated methods.

        Repo id2repo(Id id)
        $repo = $pool->id2repo($id);
        repo = pool.id2repo(id)
        repo = pool.id2repo(id)

Lookup an existing Repository by id. You can also do this by using the *repos*
attribute.

        Solvable id2solvable(Id id)
        $solvable = $pool->id2solvable($id);
        solvable = pool.id2solvable(id)
        solvable = pool.id2solvable(id)

Lookup an existing Repository by id. You can also do this by using the
*solvables* attribute.

        const char *solvid2str(Id id)
        my $str = $pool->solvid2str($id);
        str = pool.solvid2str(id)
        str = pool.solvid2str(id)

Return a string describing the Solvable with the specified id. The string
consists of the name, version, and architecture of the Solvable.

        Id str2id(const char *str, bool create = 1)
        my $id = pool->str2id($string);
        id = pool.str2id(string)
        id = pool.str2id(string)

        const char *id2str(Id id)
        $string = pool->id2str($id);
        string = pool.id2str(id)
        string = pool.id2str(id)

Convert a string into an Id and back. If the string is currently not in the
pool and _create_ is false, zero is returned.

        Id rel2id(Id name, Id evr, int flags, bool create = 1)
        my $id = pool->rel2id($nameid, $evrid, $flags);
        id = pool.rel2id(nameid, evrid, flags)
        id = pool.rel2id(nameid, evrid, flags)

Create a ``relational'' dependency. Such dependencies consist of a name part,
the _flags_ describing the relation, and a version part. The flags are:

        $solv::REL_EQ | $solv::REL_GT | $solv::REL_LT
        solv.REL_EQ | solv.REL_GT | solv.REL_LT
        Solv::REL_EQ | Solv::REL_GT | Solv::REL_LT

Thus, if you want a ``\<='' relation, you would use *REL_LT | REL_EQ*.

        Id id2langid(Id id, const char *lang, bool create = 1)
        my $id = $pool->id2langid($id, $language);
        id = pool.id2langid(id, language)
        id = pool.id2langid(id, language)

Create a language specific Id from some other id. This function simply converts
the id into a string, appends a dot and the specified language to the string
and converts the result back into an Id.

        const char *dep2str(Id id)
        $string = pool->dep2str($id);
        string = pool.dep2str(id)
        string = pool.dep2str(id)

Convert a dependency id into a string. If the id is just a string, this
function has the same effect as id2str(). For relational dependencies, the
result is the correct ``name relation evr'' string.


THE DEPENDENCY CLASS
--------------------
The dependency class is an object orientated way to work with strings and
dependencies. Internally, dependencies are represented as Ids, i.e. simple
numbers. Dependency objects can be constructed by using the Pool's Dep()
method.

=== ATTRIBUTES ===

        Pool *pool;             /* read only */
        $dep->{pool}
        dep.pool
        dep.pool

Back reference to the pool this dependency belongs to.

        Id id;          /* read only */
        $dep->{id}
        dep.id
        dep.id

The id of this dependency.

== Methods ==

        Dep Rel(int flags, DepId evrid, bool create = 1)
        my $reldep = $dep->Rel($flags, $evrdep);
        reldep = dep.Rel(flags, evrdep)
        reldep = dep.Rel(flags, evrdep)

Create a relational dependency from to string dependencies and a flags
argument. See the pool's rel2id method for a description of the flags.

        Selection Selection_name(int setflags = 0)
        my $sel = $dep->Selection_name();
        sel = dep.Selection_name()
        sel = dep.Selection_name()

Create a Selection from a dependency. The selection consists of all packages
that have a name equal to the dependency. If the dependency is of a relational
type, the packages version must also fulfill the dependency.

        Selection Selection_provides(int setflags = 0)
        my $sel = $dep->Selection_provides();
        sel = dep.Selection_provides()
        sel = dep.Selection_provides()

Create a Selection from a dependency. The selection consists of all packages
that have at least one provides matching the dependency.

        const char *str()
        my $str = $dep->str();
        str = $dep.str()
        str = $dep.str()

Return a string describing the dependency.

        <stringification>
        my $str = $dep->str;
        str = str(dep)
        str = dep.to_s

Same as calling the str() method.

        <equality>
        if ($dep1 == $dep2)
        if dep1 == dep2:
        if dep1 == dep2

The dependencies are equal if they are part of the same pool and have the same
ids.


THE REPOSITORY CLASS
--------------------
A Repository describes a group of packages, normally coming from the same
source. Repositories are created by the Pool's add_repo() method.

=== ATTRIBUTES ===

        Pool *pool;                     /* read only */
        $repo->{pool}
        repo.pool
        repo.pool

Back reference to the pool this dependency belongs to.

        Id id;                          /* read only */
        $repo->{id}
        repo.id
        repo.id

The id of the repository.

        const char *name;               /* read/write */
        $repo->{name}
        repo.name
        repo.name
        
The repositories name. To libsolv, the name is just a string with no specific
meaning.

        int priority;                   /* read/write */
        $repo->{priority}
        repo.priority
        repo.priority

The priority of the repository. A higher number means that packages of this
repository will be chosen over other repositories, even if they have a greater
package version.

        int subpriority;                /* read/write */
        $repo->{subpriority}
        repo.subpriority
        repo.subpriority

The sub-priority of the repository. This value is compared when the priorities
of two repositories are the same. It is useful to make the library prefer
on-disk repositories to remote ones.

        int nsolvables;                 /* read only */
        $repo->{nsolvables}
        repo.nsolvables
        repo.nsolvables

The number of solvables in this repository.

        void *appdata;                  /* read/write */
        $repo->{appdata}
        repo.appdata
        repo.appdata

Application specific data that may be used in any way by the code using the
repository.

        Datapos *meta;                  /* read only */
        $repo->{meta}
        repo.meta
        repo.meta

Return a Datapos object of the repodata's metadata. You can use the lookup
methods of the Datapos class to lookup metadata attributes, like the repository
timestamp.

=== CONSTANTS ===

*REPO_REUSE_REPODATA*::
  Reuse the last repository data area (``repodata'') instead of creating a new
  one.

*REPO_NO_INTERNALIZE*::
  Do not internalize the added repository data. This is useful if
  you plan to add more data because internalization is a costly
  operation.

*REPO_LOCALPOOL*::
  Use the repodata's pool for Id storage instead of the global pool. Useful
  if you don't want to pollute the global pool with many unneeded ids, like
  when storing the filelist.

*REPO_USE_LOADING*::
  Use the repodata that is currently being loaded instead of creating a new one.
  This only makes sense if used in a load callback.

*REPO_EXTEND_SOLVABLES*::
  Do not create new solvables for the new data, but match existing solvables and
  add the data to them. Repository metadata is often split into multiple parts,
  with one primary file describing all packages and other parts holding
  information that is normally not needed, like the changelog.

*REPO_USE_ROOTDIR*::
  Prepend the pool's rootdir to the path when doing file operations.

*REPO_NO_LOCATION*::
  Do not add a location element to the solvables. Useful if the solvables are
  not in the final position, so you can add the correct location later in your code.

*SOLV_ADD_NO_STUBS*::
  Do not create stubs for repository parts that can be downloaded on demand.

*SUSETAGS_RECORD_SHARES*::
  This is specific to the add_susetags() method. Susetags allows to refer to already
  read packages to save disk space. If this data sharing needs to work over multiple
  calls to add_susetags, you need to specify this flag so that the share information
  is made available to subsequent calls.

=== METHODS ===

        void free(bool reuseids = 0)
        $repo->free();
        repo.free()
        repo.free()

Free the repository and all solvables it contains. If _reuseids_ is set to
true, the solvable ids and the repository id may be reused by the library when
added new solvables. Thus you should leave it false if you are not sure that
somebody holds a reference.

        void empty(bool reuseids = 0)
        $repo->empty();
        repo.empty()
        repo.empty()

Free all the solvables in a repository. The repository will be empty after this
call. See the free() method for the meaning of _reuseids_.

        bool isempty()
        $repo->isempty()
        repo.empty()
        repo.empty?

Return true if there are no solvables in this repository.

        void internalize()
        $repo->internalize();
        repo.internalize()
        repo.internalize()

Internalize added data. Data must be internalized before it is available to the
lookup and data iterator functions.

        bool write(FILE *fp)
        $repo->write($fp)
        repo.write(fp)
        repo.write(fp)

Write a repo as a ``solv'' file. These files can be read very fast and thus are
a good way to cache repository data. Returns false if there was some error
writing the file.

        Solvableiterator solvables_iter()
        for my $solvable (@{$repo->solvables_iter()})
        for solvable in repo.solvables_iter():
        for solvable in repo.solvables_iter()

Iterate over all solvables in a repository.

        Repodata add_repodata(int flags = 0)
        my $repodata = $repo->add_repodata();
        repodata = repo.add_repodata()
        repodata = repo.add_repodata()

Add a new repodata area to the repository. This is normally automatically
done by the repo_add methods, so you need this method only in very
rare circumstances.

        void create_stubs()
        $repo->create_stubs();
        repo.create_stubs()
        repo.create_stubs()

Calls the create_stubs() repodata method for the last repodata of the
repository.

        bool iscontiguous()
        $repo->iscontiguous()
        repo.iscontiguous()
        repo.iscontiguous?

Return true if the solvables of this repository are all in a single block with
no holes, i.e. they have consecutive ids.

        Repodata first_repodata()
        my $repodata = $repo->first_repodata();
        repodata = repo.first_repodata()
        repodata = repo.first_repodata()

Checks if all repodatas but the first repodata are extensions, and return the
first repodata if this is the case. Useful if you want to do a store/retrieve
sequence on the repository to reduce the memory using and enable paging, as
this does not work if the repository contains multiple non-extension repodata
areas.

        Selection Selection(int setflags = 0)
        my $sel = $repo->Selection();
        sel = repo.Selection()
        sel = repo.Selection()

Create a Selection consisting of all packages in the repository.

        Dataiterator Dataiterator(Id p, Id key, const char *match, int flags)
        my $di = $repo->Dataiterator($solvid, $keyname, $match, $flags);
        di = repo.Dataiterator(solvid, keyname, match, flags)
        di = repo.Dataiterator(solvid, keyname, match, flags)

        for my $d (@$di)
        for d in di:
        for d in di

Iterate over the matching data elements in this repository. See the
Dataiterator class for more information.

        <stringification>
        my $str = $repo->str;
        str = str(repo)
        str = repo.to_s

Return the name of the repository, or "Repo#<id>" if no name is set.

        <equality>
        if ($repo1 == $repo2)
        if repo1 == repo2:
        if repo1 == repo2

Two repositories are equal if they belong to the same pool and have the same id.

=== DATA ADD METHODS ===

        Solvable add_solvable()
        $repo->add_solvable();
        repo.add_solvable()
        repo.add_solvable()

Add a single empty solvable to the repository. Returns a Solvable object, see
the Solvable class for more information.

        bool add_solv(const char *name, int flags = 0)
        $repo->add_solv($name, $flags);
        repo.add_solv(name, flags)
        repo.add_solv(name, flags)

        bool add_solv(FILE *fp, int flags = 0)
        $repo->add_solv($fp, $flags);
        repo.add_solv(fp, flags)
        repo.add_solv(fp, flags)

Read a ``solv'' file and add its contents to the repository. These files can be
written with the write() method and are normally used as fast cache for
repository metadata.

        bool add_rpmdb(int flags = 0)
        $repo->add_rpmdb($flags);
        repo.add_rpmdb(flags)
        repo.add_rpmdb(flags)

        bool add_rpmdb_reffp(FILE *reffp, int flags = 0)
        $repo->add_rpmdb_reffp($reffp, $flags);
        repo.add_rpmdb_reffp($reffp, flags)
        repo.add_rpmdb_reffp($reffp, flags)

Add the contents of the rpm database to the repository. If a solv file
containing an old version of the database is available, it can be passed as
reffp to speed up reading.

        bool add_rpm(const char *name, int flags = 0)
        $repo->add_rpm($name, $flags);
        repo.add_rpm(name, flags)
        repo.add_rpm(name, flags)

Add the metadata of a single rpm package to the repository.

        bool add_rpmdb_pubkeys(int flags = 0)
        $repo->add_rpmdb_pubkeys();
        repo.add_rpmdb_pubkeys()
        repo.add_rpmdb_pubkeys()

Add all pubkeys contained in the rpm database to the repository. Note that
newer rpm versions also allow to store the pubkeys in some directory instead
of the rpm database.

        bool add_pubkey(const char *keyfile, int flags = 0)
        $repo->add_pubkey($keyfile);
        repo.add_pubkey($keyfile)
        repo.add_pubkey($keyfile)

Add a pubkey from a file to the repository.

        bool add_rpmmd(FILE *fp, const char *language, int flags = 0)
        $repo->add_rpmmd($fp, $language);
        repo.add_rpmmd(fp, language)
        repo.add_rpmmd(fp, language)

Add metadata stored in the "rpm-md" format (i.e. from files in the ``repodata''
directory) to a repository. Supported files are "primary", "filelists",
"other", "suseinfo". Do not forget to specify the *REPO_EXTEND_SOLVABLES* for
extension files like "filelists" and "other". Use the _language_ parameter if
you have language extension files, otherwise simply use a *undef*/*None*/*nil*
parameter.

        bool add_repomdxml(FILE *fp, int flags = 0)
        $repo->add_repomdxml($fp);
        repo.add_repomdxml(fp)
        repo.add_repomdxml(fp)

Add the repomd.xml meta description from the "rpm-md" format to the repository.
This file contains information about the repository like keywords, and also a
list of all database files with checksums. The data is added the the "meta"
section of the repository, i.e. no package gets created.

        bool add_updateinfoxml(FILE *fp, int flags = 0)
        $repo->add_updateinfoxml($fp);
        repo.add_updateinfoxml(fp)
        repo.add_updateinfoxml(fp)

Add the updateinfo.xml file containing available maintenance updates to the
repository. All updates are created as special packages that have a "patch:"
prefix in their name.

        bool add_deltainfoxml(FILE *fp, int flags = 0)
        $repo->add_deltainfoxml($fp);
        repo.add_deltainfoxml(fp)
        repo.add_deltainfoxml(fp)

Add the deltainfo.xml file (also called prestodelta.xml) containing available
delta-rpms to the repository. The data is added to the "meta" section, i.e. no
package gets created.

        bool add_debdb(int flags = 0)
        $repo->add_debdb();
        repo.add_debdb()
        repo.add_debdb()

Add the contents of the debian installed package database to the repository.

        bool add_debpackages(FILE *fp, int flags = 0)
        $repo->add_debpackages($fp);
        repo.add_debpackages($fp)
        repo.add_debpackages($fp)

Add the contents of the debian repository metadata (the "packages" file)
to the repository.

        bool add_deb(const char *filename, int flags = 0)
        $repo->add_deb($filename);
        repo.add_deb(filename)
        repo.add_deb(filename)

Add the metadata of a single deb package to the repository.

        bool add_mdk(FILE *fp, int flags = 0)
        $repo->add_mdk($fp);
        repo.add_mdk($fp)
        repo.add_mdk($fp)

Add the contents of the mageia/mandriva repository metadata (the
"synthesis.hdlist" file) to the repository.

        bool add_mdk_info(FILE *fp, int flags = 0)
        $repo->add_mdk($fp);
        repo.add_mdk($fp)
        repo.add_mdk($fp)

Extend the packages from the synthesis file with the info.xml and files.xml
data. Do not forget to specify *REPO_EXTEND_SOLVABLES*.

        bool add_arch_repo(FILE *fp, int flags = 0)
        $repo->add_arch_repo($fp);
        repo.add_arch_repo($fp)
        repo.add_arch_repo($fp)

Add the contents of the archlinux repository metadata (the ".db.tar" file) to
the repository.

        bool add_arch_local(const char *dir, int flags = 0)
        $repo->add_arch_local($dir);
        repo.add_arch_local($dir)
        repo.add_arch_local($dir)

Add the contents of the archlinux installed package database to the repository.
The _dir_ parameter is usually set to "/var/lib/pacman/local".

        bool add_content(FILE *fp, int flags = 0)
        $repo->add_content($fp);
        repo.add_content(fp)
        repo.add_content(fp)

Add the ``content'' meta description from the susetags format to the repository.
This file contains information about the repository like keywords, and also
a list of all database files with checksums. The data is added the the "meta"
section of the repository, i.e. no package gets created.

        bool add_susetags(FILE *fp, Id defvendor, const char *language, int flags = 0)
        $repo->add_susetags($fp, $defvendor, $language);
        repo.add_susetags(fp, defvendor, language)
        repo.add_susetags(fp, defvendor, language)

Add repository metadata in the susetags format to the repository. Like with
add_rpmmd, you can specify a language if you have language extension files. The
_defvendor_ parameter provides a default vendor for packages with missing
vendors, it is usually provided in the content file.

        bool add_products(const char *dir, int flags = 0)
        $repo->add_products($dir);
        repo.add_products(dir)
        repo.add_products(dir)

Add the installed SUSE products database to the repository. The _dir_ parameter
is usually "/etc/products.d".


THE SOLVABLE CLASS
------------------
A solvable describes all the information of one package. Each solvable
belongs to one repository, it can be added and filled manually but in
most cases solvables will get created by the repo_add methods.

=== ATTRIBUTES ===

        Repo *repo;                     /* read only */
        $solvable->{repo}
        solvable.repo
        solvable.repo

The repository this solvable belongs to.

        Pool *pool;                     /* read only */
        $solvable->{pool}
        solvable.pool
        solvable.pool

The pool this solvable belongs to, same as the pool of the repo.

        Id id;                          /* read only */
        $solvable->{id}
        solvable.id
        solvable.id

The specific id of the solvable.

        char *name;                     /* read/write */
        $solvable->{name}
        solvable.name
        solvable.name

        char *evr;                      /* read/write */
        $solvable->{evr}
        solvable.evr
        solvable.evr

        char *arch;                     /* read/write */
        $solvable->{arch}
        solvable.arch
        solvable.arch

        char *vendor;                   /* read/write */
        $solvable->{vendor}
        solvable.vendor
        solvable.vendor

Easy access to often used attributes of solvables. They are
internally stored as Ids.

        Id nameid;                      /* read/write */
        $solvable->{nameid}
        solvable.nameid
        solvable.nameid

        Id evrid;                       /* read/write */
        $solvable->{evrid}
        solvable.evrid
        solvable.evrid

        Id archid;                      /* read/write */
        $solvable->{archid}
        solvable.archid
        solvable.archid

        Id vendorid;                    /* read/write */
        $solvable->{vendorid}
        solvable.vendorid
        solvable.vendorid

Raw interface to the ids. Useful if you want to search for
a specific id and want to avoid the string compare overhead.

=== METHODS ===

        const char *lookup_str(Id keyname)
        my $string = $solvable->lookup_str($keyname);
        string = solvable.lookup_str(keyname)
        string = solvable.lookup_str(keyname)

        Id lookup_id(Id keyname)
        my $id = $solvable->lookup_id($keyname);
        id = solvable.lookup_id(solvid)
        id = solvable.lookup_id(solvid)

        unsigned long long lookup_num(Id solvid, Id keyname, unsigned long long notfound = 0)
        my $num = $solvable->lookup_num($keyname);
        num = solvable.lookup_num(keyname)
        num = solvable.lookup_num(keyname)

        bool lookup_void(Id keyname)
        my $bool = $solvable->lookup_void($keyname);
        bool = solvable.lookup_void(keyname)
        bool = solvable.lookup_void(keyname)

        Chksum lookup_checksum(Id keyname)
        my $chksum = $solvable->lookup_checksum($keyname);
        chksum = solvable.lookup_checksum(keyname)
        chksum = solvable.lookup_checksum(keyname)

        Id *lookup_idarray(Id keyname, Id marker = -1)
        my @ids = $solvable->lookup_idarray($keyname);
        ids = solvable.lookup_idarray(keyname)
        ids = solvable.lookup_idarray(keyname)

        Dep *lookup_deparray(Id keyname, Id marker = -1)
        my @deps = $solvable->lookup_deparray($keyname);
        deps = solvable.lookup_deparray(keyname)
        deps = solvable.lookup_deparray(keyname)
        
Generic lookup methods. Retrieve data stored for the specific keyname.
The lookup_idarray() method will return an array of Ids, use
lookup_deparray if you want an array of Dependency objects instead.
Some Id arrays contain two parts of data divided by a specific marker,
for example the provides array uses the SOLVABLE_FILEMARKER id to
store both the ids provided by the package and the ids added by
the addfileprovides method. The default, -1, translates to the
correct marker for the keyname and returns the first part of the
array, use 1 to select the second part or 0 to retrieve all ids
including the marker.

        const char *lookup_location(unsigned int *OUTPUT);
        my ($location, $medianr) = $solvable->lookup_location();
        location, medianr = solvable.lookup_location()
        location, medianr = solvable.lookup_location()

Return a tuple containing the on-media location and an optional
media number for multi-part repositories (e.g. repositories
spawning multiple DVDs).

        void add_deparray(Id keyname, DepId dep, Id marker = -1);
        $solvable->add_deparray($keyname, $dep);
        solvable.add_deparray(keyname, dep)
        solvable.add_deparray(keyname, dep)

Add a new dependency to the attributes stored in keyname.

        bool installable();
        $solvable->installable()
        solvable.installable()
        solvable.installable?

Return true if the solvable is installable on the system. Solvables
are not installable if the system does not support their architecture.

        bool isinstalled();
        $solvable->isinstalled()
        solvable.isinstalled()
        solvable.isinstalled?

Return true if the solvable is installed on the system.

        Selection Selection(int setflags = 0)
        my $sel = $solvable->Selection();
        sel = solvable.Selection()
        sel = solvable.Selection()

Create a Selection containing just the single solvable.

        const char *str()
        my $str = $solvable->str();
        str = $solvable.str()
        str = $solvable.str()

Return a string describing the solvable. The string consists of the name,
version, and architecture of the Solvable.

        <stringification>
        my $str = $solvable->str;
        str = str(solvable)
        str = solvable.to_s

Same as calling the str() method.

        <equality>
        if ($solvable1 == $solvable2)
        if solvable1 == solvable2:
        if solvable1 == solvable2

Two solvables are equal if they are part of the same pool and have the same
ids.


THE DATAITERATOR CLASS
----------------------
Dataiterators can be used to do complex string searches or
to iterate over arrays. They can be created via the
constructors in the Pool, Repo, and Solvable classes. The
Repo and Solvable constructors will limit the search to
the repository or the specific package.

=== CONSTANTS ===

*SEARCH_STRING*::
  Return a match if the search string matches the value.

*SEARCH_STRINGSTART*::
  Return a match if the value starts with the search string.

*SEARCH_STRINGEND*::
  Return a match if the value ends with the search string.

*SEARCH_SUBSTRING*::
  Return a match if the search string can be matched somewhere
  in the value.

*SEARCH_GLOB*::
  Do a glob match of the search string against the value.

*SEARCH_REGEX*::
  Do a regular expression match of the search string against
  the value.

*SEARCH_NOCASE*::
  Ignore case when matching strings. Works for all the above
  match types.

*SEARCH_FILES*::
  Match the complete filenames of the file list, not just the
  base name.

*SEARCH_COMPLETE_FILELIST*::
  When matching the file list, check every file of the package
  not just the subset from the primary metadata.

*SEARCH_CHECKSUMS*::
  Allow the matching of checksum entries.

=== METHODS ===

        void prepend_keyname(Id keyname);
        $di->prepend_keyname($keyname);
        di.prepend_keyname(keyname)
        di.prepend_keyname(keyname)

Do a sub-search in the array stored in keyname.

        void skip_solvable();
        $di->kip_solvable();
        di.skip_solvable()
        di.skip_solvable()

Stop matching the current solvable and advance to the next
one.

        <iteration>
        for my $d (@$di)
        for d in di:
        for d in di

Iterate through the matches. If there is a match, the object
in d will be of type Datamatch.

THE DATAMATCH CLASS
-------------------
Objects of this type will be created for every value matched
by a dataiterator.

=== ATTRIBUTES ===

        Pool *pool;                             /* read only */
        $d->{pool}
        d.pool
        d.pool

Back pointer to pool.

        Repo *repo;                             /* read only */
        $d->{repo}
        d.repo
        d.repo

The repository containing the matched object.

        Solvable *solvable;                     /* read only */
        $d->{solvable}
        d.solvable
        d.solvable

The solvable containing the value that was matched.

        Id solvid;                              /* read only */
        $d->{solvid}
        d.solvid
        d.solvid

The id of the solvable that matched.

=== METHODS ===

        Id key_id();
        $d->key_id()
        d.key_id()
        d.key_id()

        const char *key_idstr();
        $d->key_idstr()
        d.key_idstr()
        d.key_idstr()

The keyname that matched, either as id or string.

        Id type_id();
        $d->type_id()
        d.type_id()
        d.type_id()

        const char *type_idstr();
        $d->type_idstr();
        d.type_idstr()
        d.type_idstr()

The key type of the value that was matched, either as id or string.

        Id id();
        $d->id()
        d.id()
        d.id()

        Id idstr();
        $d->idstr()
        d.idstr()
        d.idstr()

The Id of the value that was matched (only valid for id types),
either as id or string.

        const char *str();
        $d->str()
        d.str()
        d.str()

The string value that was matched (only valid for string types).

        unsigned long long num();
        $d->num()
        d.num()
        d.num()

The numeric value that was matched (only valid for numeric types).

        unsigned int num2();
        $d->num2()
        d.num2()
        d.num2()

The secondary numeric value that was matched (only valid for types
containing two values).

        Datapos pos();
        my $pos = $d->pos();
        pos = d.pos()
        pos = d.pos()

The position object of the current match. It can be used to do
sub-searches starting at the match (if it is of an array type).
See the Datapos class for more information.

        Datapos parentpos();
        my $pos = $d->parentpos();
        pos = d.parentpos()
        pos = d.parentpos()

The position object of the array containing the current match.
It can be used to do sub-searches, see the Datapos class for more
information.

        <stringification>
        my $str = $d->str;
        str = str(d)
        str = d.to_s

Return the stringification of the matched value. Stringification
depends on the search flags, for file list entries it will return
just the base name unless SEARCH_FILES is used, for checksums
it will return an empty string unless SEARCH_CHECKSUMS is used.
Numeric values are currently stringified to an empty string.


THE SELECTION CLASS
-------------------
Selections are a way to easily deal with sets of packages.
There are multiple constructors to create them, the most useful
is probably the select() method in the Pool class.

=== CONSTANTS ===

*SELECTION_NAME*::
  Create the selection by matching package names

*SELECTION_PROVIDES*::
  Create the selection by matching package provides

*SELECTION_FILELIST*::
  Create the selection by matching package files

*SELECTION_CANON*::
  Create the selection by matching the canonical representation
  of the package. This is normally a combination of the name,
  the version, and the architecture of a package.

*SELECTION_DOTARCH*::
  Allow an ``.<architecture>'' suffix when matching names or
  provides.
 
*SELECTION_REL*::
  Allow the specification of a relation when matching names
  or provides, e.g. "name >= 1.2".

*SELECTION_INSTALLED_ONLY*::
  Limit the package search to installed packages.

*SELECTION_SOURCE_ONLY*::
  Limit the package search to source packages only.

*SELECTION_WITH_SOURCE*::
  Extend the package search to also match source packages. The
  default is only to match binary packages.

*SELECTION_GLOB*::
  Allow glob matching for package names, package provides, and
  file names.

*SELECTION_NOCASE*::
  Ignore case when matching package names, package provides,
  and file names.

*SELECTION_FLAT*::
  Return only one selection element describing the selected packages.
  The default is to create multiple elements for all globbed packages.
  Multiple elements are useful if you want to turn the selection into
  an install job, in that case you want an install job for every
  globbed package.

=== ATTRIBUTES ===

        Pool *pool;                             /* read only */
        $d->{pool}
        d.pool
        d.pool

Back pointer to pool.

=== METHODS ===

        int flags();
        my $flags = $sel->flags();
        flags = sel.flags()
        flags = sel.flags()

Return the result flags of the selection. The flags are a subset
of the ones used when creating the selection, they describe which
method was used to get the result. For example, if you create the
selection with ``SELECTION_NAME | SELECTION_PROVIDES'', the resulting
flags will either be SELECTION_NAME or SELECTION_PROVIDES depending
if there was a package that matched the name or not. If there was
no match at all, the flags will be zero.

        bool isempty();
        $sel->isempty()
        sel.isempty()
        sel.isempty?

Return true if the selection is empty, i.e. no package could be matched.

        void filter(Selection *other)
        $sel->filter($other);
        sel.filter(other)
        sel.filter(other)

Intersect two selections. Packages will only stay in the selection if there
are also included in the other selecting. Does an in-place modification.

        void add(Selection *other)
        $sel->add($other);
        sel.add(other)
        sel.add(other)

Build the union of two selections. All packages of the other selection will
be added to the set of packages of the selection object. Does an in-place
modification. Note that the selection flags are no longer meaningful after the
add operation.

        void add_raw(Id how, Id what)
        $sel->add_raw($how, $what);
        sel.add_raw(how, what)
        sel.add_raw(how, what)

Add a raw element to the selection. Check the Job class for information about
the how and what parameters.

        Job *jobs(int action)
        my @jobs = $sel->jobs($action);
        jobs = sel.jobs(action)
        jobs = sel.jobs(action)

Convert a selection into an array of Job objects. The action parameter is or-ed
to the ``how'' part of the job, it describes the type of job (e.g. install,
erase). See the Job class for the action and action modifier constants.

        Solvable *solvables()
        my @solvables = $sel->solvables();
        solvables = sel.solvables()
        solvables = sel.solvables()

Convert a selection into an array of Solvable objects.

        <stringification>
        my $str = $sel->str;
        str = str(sel)
        str = sel.to_s

Return a string describing the selection.

THE JOB CLASS
-------------
Jobs are the way to specify to the dependency solver what to do.
Most of the times jobs will get created by calling the jobs() method
on a Selection object, but there is also a Job() constructor in the
Pool class.

=== CONSTANTS ===

Selection constants:

*SOLVER_SOLVABLE*::
  The ``what'' part is the id of a solvable.

*SOLVER_SOLVABLE_NAME*::
  The ``what'' part is the id of a package name.

*SOLVER_SOLVABLE_PROVIDES*::
  The ``what'' part is the id of a package provides.

*SOLVER_SOLVABLE_ONE_OF*::
  The ``what'' part is an offset into the ``whatprovides'' data, created
  by calling the towhatprovides() pool method.

*SOLVER_SOLVABLE_REPO*::
  The ``what'' part is the id of a repository.

*SOLVER_SOLVABLE_ALL*::
  The ``what'' part is ignored, all packages are selected.

*SOLVER_SOLVABLE_SELECTMASK*::
  A mask containing all the above selection bits.

Action constants:

*SOLVER_NOOP*::
  Do nothing.

*SOLVER_INSTALL*::
  Install a package of the specified set of packages. It tries to install
  the best matching package (i.e. the highest version of the packages from
  the repositories with the highest priority).

*SOLVER_ERASE*::
  Erase all of the packages from the specified set. If a package is not
  installed, erasing it will keep it from getting installed.

*SOLVER_UPDATE*::
  Update the matching installed packages to their best version. If none
  of the specified packages are installed, try to update the installed
  packages to the specified versions. See the section about targeted
  updates about more information.
  
*SOLVER_WEAKENDEPS*::
  Allow to break the dependencies of the matching packages. Handle with care.

*SOLVER_MULTIVERSION*::
  Mark the matched packages for multiversion install. If they get to be installed
  because of some other job, the installation will keep the old version of the
  package installed (for rpm by using ``-i'' instead of ``-U'').

*SOLVER_LOCK*::
  Do not change the state of the matched packages, i.e. when they are installed
  they stay installed, if not they are not selected for installation.

*SOLVER_DISTUPGRADE*::
  Update the matching installed packages to the best version included in one
  of the repositories. After this operation, all come from one of the available
  repositories except orphaned packages. Orphaned packages are packages that
  have no relation to the packages in the repositories, i.e. no package in the
  repositories have the same name or obsolete the orphaned package.
  This action brings the installed packages in sync with the ones in the
  repository. It also turns of arch/vendor/version locking for the affected
  packages to simulate a fresh installation. This means that distupgrade can
  actually downgrade packages if only lower versions of a package are available
  in the repositories.

*SOLVER_DROP_ORPHANED*::
  Erase all the matching installed packages if they are orphaned. This only makes
  sense if there is a ``distupgrade all packages'' job. The default is to erase
  orphaned packages only if they block the installation of other packages.

*SOLVER_VERIFY*::
  Fix dependency problems of matching installed packages. The default is to ignore
  dependency problems for installed packages.

*SOLVER_USERINSTALLED*::
  The matching installed packages are considered to be installed by a user, thus
  not installed to fulfill some dependency. This is needed input for the calculation
  of unneeded packages for jobs that have the SOLVER_CLEANDEPS flag set.

*SOLVER_JOBMASK*::
  A mask containing all the above action bits.

Action modifier constants:

*SOLVER_WEAK*::
  Makes the job a weak job. The solver tries to fulfill weak jobs, but does not
  report a problem if it is not possible to do so.

*SOLVER_ESSENTIAL*::
  Makes the job an essential job. If there is a problem with the job, the solver
  will not propose to remove the job as one solution (unless all other solutions
  are also to remove essential jobs).

*SOLVER_CLEANDEPS*::
  The solver will try to also erase all packages dragged in through dependencies
  when erasing the package. This needs SOLVER_USERINSTALLED jobs to maximize user
  satisfaction.

*SOLVER_FORCEBEST*::
  Insist on the best package for install, update, and distupgrade jobs. If this
  flag is not used, the solver will use the second-best package if the best
  package cannot be installed for some reason. When this flag is used, the solver
  will generate a problem instead.

*SOLVER_TARGETED*::
  Forces targeted operation update and distupgrade jobs. See the section about
  targeted updates about more information.

Set constants.

*SOLVER_SETEV*::
  The job specified the exact epoch and version of the package set.

*SOLVER_SETEVR*::
  The job specified the exact epoch, version, and release of the package set.

*SOLVER_SETARCH*::
  The job specified the exact architecture of the packages from the set.

*SOLVER_SETVENDOR*::
  The job specified the exact vendor of the packages from the set.

*SOLVER_SETREPO*::
  The job specified the exact repository of the packages from the set.

*SOLVER_SETNAME*::
  The job specified the exact name of the packages from the set.

*SOLVER_NOAUTOSET*::
  Turn of automatic set flag generation for SOLVER_SOLVABLE jobs.

*SOLVER_SETMASK*::
  A mask containing all the above set bits.

See the section about set bits for more information.

=== ATTRIBUTES ===

        Pool *pool;                             /* read only */
        $job->{pool}
        d.pool
        d.pool

Back pointer to pool.

        Id how;                                 /* read/write */
        $job->{how}
        d.how
        d.how

Union of the selection, action, action modifier, and set flags.
The selection part describes the semantics of the ``what'' Id.

        Id what;                                /* read/write */
        $job->{what}
        d.what
        d.what

Id describing the set of packages, the meaning depends on the
selection part of the ``how'' attribute.

=== METHODS ===

        Solvable *solvables()
        my @solvables = $job->solvables();
        solvables = job.solvables()
        solvables = job.solvables()

Return the set of solvables of the job as an array of Solvable
objects.

        bool isemptyupdate();
        $job->isemptyupdate()
        job.isemptyupdate()
        job.isemptyupdate?

Convenience function to find out if the job describes an update
job with no matching packages, i.e. a job that does nothing.
Some package managers like ``zypper'' like to turn those jobs
into install jobs, i.e. an update of a not-installed package
will result into the installation of the package.

        <stringification>
        my $str = $job->str;
        str = str(job)
        str = job.to_s

Return a string describing the job.

        <equality>
        if ($job1 == $job2)
        if job1 == job2:
        if job1 == job2

Two jobs are equal if they belong to the same pool and both the
``how'' and the ``what'' attributes are the same.

=== TARGETED UPDATES ===
Libsolv has two modes for upgrades and distupgrade: targeted and
untargeted. Untargeted mode means that the installed packages from
the specified set will be updated to the best version. Targeted means
that packages that can be updated to a package in the specified set
will be updated to the best package of the set.

Here's an example to explain the subtle difference. Suppose that
you have package A installed in version "1.1", "A-1.2" is available
in one of the repositories and there is also package "B" that
obsoletes package A.

An untargeted update of "A" will update the installed "A-1.1" to
package "B", because that is the newest version (B obsoletes A and
is thus newer).

A targeted update of "A" will update "A-1.1" to "A-1.2", as the
set of packages contains both "A-1.1" and "A-1.2", and "A-1.2" is
the newer one.

An untargeted update of "B" will do nothing, as "B" is not installed.

An targeted update of "B" will update "A-1.1" to "B".

Note that the default is to do "auto-targeting", thus if the specified
set of packages does not include an installed package, the solver
will assume targeted operation even if SOLVER_TARGETED is not used.

This mostly matches the intent of the user, with one exception: In
the example above, an update of "A-1.2" will update "A-1.1" to
"A-1.2" (targeted mode), but a second update of "A-1.2" will suddenly
update to "B", as untargeted mode is chosen because "A-1.2" is now
installed.

If you want to have full control over when targeting mode is chosen,
turn off auto-targeting with the SOLVER_FLAG_NO_AUTOTARGET solver option.
In that case, all updates are considered to be untargeted unless they
include the SOLVER_TARGETED flag.

=== SET BITS ===
Set bits specify which parts of the specified packages where specified
by the user. It is used by the solver when checking if an operation is
allowed or not. For example, the solver will normally not allow the
downgrade of an installed package. But it will not report a problem if
the SOLVER_SETEVR flag is used, as it then assumes that the user specified
the exact version and thus knows what he is doing.

So if a package "screen-1-1" is installed for the x86_64 architecture and
version "2-1" is only available for the i586 architecture, installing
package "screen-2.1" will ask the user for confirmation because of the
different architecture. When using the Selection class to create jobs
the set bits are automatically added, e.g. selecting ``screen.i586'' will
automatically add SOLVER_SETARCH, and thus no problem will be reported.

THE SOLVER CLASS
----------------
Dependency solving is what this library is about. A solver object is needed
for solving to store the result of the solver run. The solver object can be
used multiple times for different jobs, reusing it allows the solver to
re-use the dependency rules it already computed.

=== CONSTANTS ===

Flags to modify some of the solver's behavior:

*SOLVER_FLAG_ALLOW_DOWNGRADE*::
  Allow the solver to downgrade packages without asking for confirmation
  (i.e. reporting a problem).

*SOLVER_FLAG_ALLOW_ARCHCHANGE*::
  Allow the solver to change the architecture of an installed package
  without asking for confirmation. Note that changes to/from noarch
  are always considered to be allowed.
  
*SOLVER_FLAG_ALLOW_VENDORCHANGE*::
  Allow the solver to change the vendor of an installed package
  without asking for confirmation. Each vendor is part of one or more
  vendor equivalence classes, normally installed packages may only
  change their vendor if the new vendor shares at least one equivalence
  class.

*SOLVER_FLAG_ALLOW_NAMECHANGE*::
  Allow the solver to change the name of an installed package, i.e.
  install a package with a different name that obsoletes the installed
  package. This option is on by default.

*SOLVER_FLAG_ALLOW_UNINSTALL*::
  Allow the solver to erase installed packages to fulfill the jobs.
  This flag also includes the above flags. You may want to set this
  flag if you only have SOLVER_ERASE jobs, as in that case it's
  better for the user to check the transaction overview instead of
  approving every single package that needs to be erased.

*SOLVER_FLAG_NO_UPDATEPROVIDE*::
  If multiple packages obsolete an installed package, the solver checks
  the provides of every such package and ignores all packages that
  do not provide the installed package name. Thus, you can have an
  official update candidate that provides the old name, and other
  packages that also obsolete the package but are not considered for
  updating. If you cannot use this feature, you can turn it off
  by setting this flag.

*SOLVER_FLAG_SPLITPROVIDES*::
  Make the solver aware of special provides of the form
  ``<packagename>:<path>'' used in SUSE systems to support package
  splits.

*SOLVER_FLAG_IGNORE_RECOMMENDED*::
  Do not process optional (aka weak) dependencies.

*SOLVER_FLAG_ADD_ALREADY_RECOMMENDED*::
  Install recommended or supplemented packages even if they have no
  connection to the current transaction. You can use this feature
  to implement a simple way for the user to install new recommended
  packages that were not available in the past.
  
*SOLVER_FLAG_NO_INFARCHCHECK*::
  Turn off the inferior architecture checking that is normally done
  by the solver. Normally, the solver allows only the installation
  of packages from the "best" architecture if a package is available
  for multiple architectures.

*SOLVER_FLAG_BEST_OBEY_POLICY*::
  Make the SOLVER_FORCEBEST job option consider only packages that
  meet the policies for installed packages, i.e. no downgrades,
  no architecture change, no vendor change (see the first flags
  of this section). If the flag is not specified, the solver will
  enforce the installation of the best package ignoring the
  installed packages, which may conflict with the set policy.

*SOLVER_FLAG_NO_AUTOTARGET*::
  Do not enable auto-targeting up update and distupgrade jobs. See
  the section on targeted updates for more information.

Basic rule types:

*SOLVER_RULE_UNKNOWN*::
  A rule of an unknown class. You should never encounter those.

*SOLVER_RULE_RPM*::
  A package dependency rule, called rpm rule for historical reasons.

*SOLVER_RULE_UPDATE*::
  A rule to implement the update policy of installed packages. Every
  installed package has an update rule that consists of the packages
  that may replace the installed package.

*SOLVER_RULE_FEATURE*::
  Feature rules are fallback rules used when a update rule is disabled.
  They include all packages that may replace the installed package
  ignoring the update policy, i.e. they contain downgrades, arch
  changes and so on. Without them, the solver would simply erase
  installed packages if their update rule gets disabled.

*SOLVER_RULE_JOB*::
  Job rules implement the job given to the solver.

*SOLVER_RULE_DISTUPGRADE*::
  This are simple negative assertions that make sure that only packages
  are kept that are also available in one of the repositories.

*SOLVER_RULE_INFARCH*::
  Infarch rules are also negative assertions, they disallow the installation
  of packages when there are packages of the same name but with a better
  architecture.

*SOLVER_RULE_CHOICE*::
  Choice rules are used to make sure that the solver prefers updating to
  installing different packages when some dependency is provided by
  multiple packages with different names. The solver may always break
  choice rules, so you will not see them when a problem is found.

*SOLVER_RULE_LEARNT*::
  These rules are generated by the solver to keep it from running into
  the same problem multiple times when it has to backtrack. They are
  the main reason why a sat solver is faster then other dependency solver
  implementations.

Special dependency rule types:

*SOLVER_RULE_RPM_NOT_INSTALLABLE*::
  This rule was added to prevent the installation of a package of an
  architecture that does not work on the system.

*SOLVER_RULE_RPM_NOTHING_PROVIDES_DEP*::
  The package contains a required dependency which was not provided by
  any package.

*SOLVER_RULE_RPM_PACKAGE_REQUIRES*::
  Similar to SOLVER_RULE_RPM_NOTHING_PROVIDES_DEP, but in this case
  some packages provided the dependency but none of them could be
  installed due to other dependency issues.

*SOLVER_RULE_RPM_SELF_CONFLICT*::
  The package conflicts with itself. This is not allowed by older rpm
  versions.

*SOLVER_RULE_RPM_PACKAGE_CONFLICT*::
  To fulfill the dependencies two packages need to be installed, but
  one of the packages contains a conflict with the other one.

*SOLVER_RULE_RPM_SAME_NAME*::
  The dependencies can only be fulfilled by multiple versions of
  a package, but installing multiple versions of the same package
  is not allowed.

*SOLVER_RULE_RPM_PACKAGE_OBSOLETES*::
  To fulfill the dependencies two packages need to be installed, but
  one of the packages obsoletes the other one.

*SOLVER_RULE_RPM_IMPLICIT_OBSOLETES*::
  To fulfill the dependencies two packages need to be installed, but
  one of the packages has provides a dependency that is obsoleted
  by the other one. See the POOL_FLAG_IMPLICITOBSOLETEUSESPROVIDES
  flag.

*SOLVER_RULE_RPM_INSTALLEDPKG_OBSOLETES*::
  To fulfill the dependencies a package needs to be installed that is
  obsoleted by an installed package. See the POOL_FLAG_NOINSTALLEDOBSOLETES
  flag.

*SOLVER_RULE_JOB_NOTHING_PROVIDES_DEP*::
  The user asked for installation of a package providing a specific
  dependency, but no available package provides it.

*SOLVER_RULE_JOB_UNKNOWN_PACKAGE*::
  The user asked for installation of a package with a specific name,
  but no available package has that name.

*SOLVER_RULE_JOB_PROVIDED_BY_SYSTEM*::
  The user asked for the erasure of a dependency that is provided by the
  system (i.e. for special hardware or language dependencies), this
  cannot be done with a job.

*SOLVER_RULE_JOB_UNSUPPORTED*::
  The user asked for something that is not yet implemented, e.g. the
  installation of all packages at once.

Policy error constants

*POLICY_ILLEGAL_DOWNGRADE*::
  The solver ask for permission before downgrading packages.

*POLICY_ILLEGAL_ARCHCHANGE*::
  The solver ask for permission before changing the architecture of installed
  packages.

*POLICY_ILLEGAL_VENDORCHANGE*::
  The solver ask for permission before changing the vendor of installed
  packages.

*POLICY_ILLEGAL_NAMECHANGE*::
  The solver ask for permission before replacing an installed packages with
  a package that has a different name.

Solution element type constants

*SOLVER_SOLUTION_JOB*::
  The problem can be solved by removing the specified job.

*SOLVER_SOLUTION_POOLJOB*::
  The problem can be solved by removing the specified job that is defined in the pool.

*SOLVER_SOLUTION_INFARCH*::
  The problem can be solved by allowing the installation of the specified package
  with an inferior architecture.

*SOLVER_SOLUTION_DISTUPGRADE*::
  The problem can be solved by allowing to keep the specified package installed.

*SOLVER_SOLUTION_BEST*::
  The problem can be solved by allowing to install the specified package that is
  not the best available package.

*SOLVER_SOLUTION_ERASE*::
  The problem can be solved by allowing to erase the specified package.

*SOLVER_SOLUTION_REPLACE*::
  The problem can be solved by allowing to replace the package with some other
  package.

*SOLVER_SOLUTION_REPLACE_DOWNGRADE*::
  The problem can be solved by allowing to replace the package with some other
  package that has a lower version.

*SOLVER_SOLUTION_REPLACE_ARCHCHANGE*::
  The problem can be solved by allowing to replace the package with some other
  package that has a different architecture.

*SOLVER_SOLUTION_REPLACE_VENDORCHANGE*::
  The problem can be solved by allowing to replace the package with some other
  package that has a different vendor.

*SOLVER_SOLUTION_REPLACE_NAMECHANGE*::
  The problem can be solved by allowing to replace the package with some other
  package that has a different name.


=== ATTRIBUTES ===

        Pool *pool;                             /* read only */
        $job->{pool}
        d.pool
        d.pool

Back pointer to pool.

=== METHODS ===

        int set_flag(int flag, int value)
        my $oldvalue = $pool->set_flag($flag, $value);
        oldvalue = pool.set_flag(flag, value)
        oldvalue = pool.set_flag(flag, value)

        int get_flag(int flag)
        my $value = $pool->get_flag($flag);
        value = pool.get_flag(flag)
        value = pool.get_flag(flag)

Set/get a solver specific flag. The flags define the policies the solver has
to obey. The flags are explained in the CONSTANTS section of this class.

        Problem *solve(Job *jobs)
        my @problems = $solver->solve(\@jobs);
        problems = solver.solve(jobs)
        problems = solver.solve(jobs)

Solve a problem specified in the job list (plus the jobs defined in the pool).
Returns an array of problems that need user interaction, or an empty array
if no problems were encountered. See the Problem class on how to deal with
problems.

        Transaction transaction()
        my $trans = $solver->transaction();
        trans = solver.transaction()
        trans = solver.transaction()

Return the transaction to implement the calculated package changes. A transaction
is available even if problems were found, this is useful for interactive user
interfaces that show both the job result and the problems.

THE PROBLEM CLASS
-----------------
Problems are the way of the solver to interact with the user. You can simply list
all problems and terminate your program, but a better way is to present solutions to
the user and let him pick the ones he likes.

=== ATTRIBUTES ===

        Solver *solv;                           /* read only */
        $problem->{solv}
        problem.solv
        problem.solv

Back pointer to solver object.

        Id id;                                  /* read only */
        $problem->{id}
        problem.id
        problem.id

Id of the problem. The first problem has Id 1, they are numbered consecutively.

=== METHODS ===

        Rule findproblemrule()
        my $probrule = $problem->findproblemrule();
        probrule = problem.findproblemrule()
        probrule = problem.findproblemrule()

Return the rule that caused the problem. Of course in most situations there is no
single responsible rule, but many rules that interconnect with each created the
problem. Nevertheless, the solver uses some heuristic approach to find a rule
that somewhat describes the problem best to the user.

        Rule *findallproblemrules(bool unfiltered = 0)
        my @probrules = $problem->findallproblemrules();
        probrules = problem.findallproblemrule()
        probrules = problem.findallproblemrule()

Return all rules responsible for the problem. The returned set of rules contains
all the needed information why there was a problem, but it's hard to present
them to the user in a sensible way. The default is to filter out all update and
job rules (unless the returned rules only consist of those types).

        Solution *solutions()
        my @solutions = $problem->solutions();
        solutions = problem.solutions()
        solutions = problem.solutions()

Return an array containing multiple possible solutions to fix the problem. See
the solution class for more information.

        int solution_count()
        my $cnt = $problem->solution_count();
        cnt = problem.solution_count()
        cnt = problem.solution_count()

Return the number of solutions without creating solution objects.

THE RULE CLASS
--------------
Rules are the basic block of sat solving. Each package dependency gets translated
into one or multiple rules.

=== ATTRIBUTES ===

        Solver *solv;                           /* read only */
        $rule->{solv}
        rule.solv
        rule.solv

Back pointer to solver object.

        Id id;                                  /* read only */
        $rule->{id}
        rule.id
        rule.id

The id of the rule.

        int type;                               /* read only */
        $rule->{type}
        rule.type
        rule.type

The basic type of the rule. See the constant section of the solver class for the type list.

=== METHODS ===

        Ruleinfo info()
        my $ruleinfo = $rule->info();
        ruleinfo = rule.info()
        ruleinfo = rule.info()

Return a Ruleinfo object that contains information about why the rule was created. But
see the allinfos() method below.

        Ruleinfo *allinfos()
        my @ruleinfos = $rule->allinfos();
        ruleinfos = rule.allinfos()
        ruleinfos = rule.allinfos()

As the same dependency rule can get created because of multiple dependencies, one
Ruleinfo is not enough to describe the reason. Thus the allinfos() method returns
an array of all infos about a rule.

        <equality>
        if ($rule1 == $rule2)
        if rule1 == rule2:
        if rule1 == rule2

Two rules are equal if they belong to the same solver and have the same id.

THE RULEINFO CLASS
------------------
A Ruleinfo describes one reason why a rule was created.

=== ATTRIBUTES ===

        Solver *solv;                           /* read only */
        $ruleinfo->{solv}
        ruleinfo.solv
        ruleinfo.solv

Back pointer to solver object.

        int type;                               /* read only */
        $ruleinfo->{type}
        ruleinfo.type
        ruleinfo.type

The type of the ruleinfo. See the constant section of the solver class for the
rule type list and the special type list.

        Dep *dep;                               /* read only */
        $ruleinfo->{dep}
        ruleinfo.dep
        ruleinfo.dep

The dependency leading to the creation of the rule.

        Dep *dep_id;                            /* read only */
        $ruleinfo->{'dep_id'}
        ruleinfo.dep_id
        ruleinfo.dep_id

The Id of the dependency leading to the creation of the rule, or zero.

        Solvable *solvable;                     /* read only */
        $ruleinfo->{solvable}
        ruleinfo.solvable
        ruleinfo.solvable

The involved Solvable, e.g. the one containing the dependency.

        Solvable *othersolvable;                /* read only */
        $ruleinfo->{othersolvable}
        ruleinfo.othersolvable
        ruleinfo.othersolvable

The other involved Solvable (if any), e.g. the one containing providing
the dependency for conflicts.

        const char *problemstr();
        my $str = $ruleinfo->problemstr();
        str = ruleinfo.problemstr()
        str = ruleinfo.problemstr()

A string describing the ruleinfo from a problem perspective. This probably
only makes sense if the rule is part of a problem.

THE SOLUTION CLASS
------------------
A solution solves one specific problem. It consists of multiple solution elements
that all need to be executed.

=== ATTRIBUTES ===

        Solver *solv;                           /* read only */
        $solution->{solv}
        solution.solv
        solution.solv

Back pointer to solver object.

        Id problemid;                           /* read only */
        $solution->{problemid}
        solution.problemid
        solution.problemid

Id of the problem the solution solves.

        Id id;                                  /* read only */
        $solution->{id}
        solution.id
        solution.id

Id of the solution. The first solution has Id 1, they are numbered consecutively.

=== METHODS ===

        Solutionelement *elements(bool expandreplaces = 0)
        my @solutionelements = $solution->elements();
        solutionelements = solution.elements()
        solutionelements = solution.elements()

Return an array containing the elements describing what needs to be done to
implement the specific solution. If expandreplaces is true, elements of type
SOLVER_SOLUTION_REPLACE will be replaced by one or more elements replace
elements describing the policy mismatches.

        int element_count()
        my $cnt = $solution->solution_count();
        cnt = solution.element_count()
        cnt = solution.element_count()

Return the number of solution elements without creating objects. Note that the
count does not match the number of objects returned by the elements() method
of expandreplaces is set to true.


THE SOLUTIONELEMENT CLASS
-------------------------
A solution element describes a single action of a solution. The action is always
either to remove one specific job or to add a new job that installs or erases
a single specific package.

=== ATTRIBUTES ===

        Solver *solv;                           /* read only */
        $solutionelement->{solv}
        solutionelement.solv
        solutionelement.solv

Back pointer to solver object.

        Id problemid;                           /* read only */
        $solutionelement->{problemid}
        solutionelement.problemid
        solutionelement.problemid

Id of the problem the element (partly) solves.

        Id solutionid;                          /* read only */
        $solutionelement->{solutionid}
        solutionelement.solutionid
        solutionelement.solutionid

Id of the solution the element is a part of.

        Id id;                                  /* read only */
        $solutionelement->{id}
        solutionelement.id
        solutionelement.id

Id of the solution element. The first element has Id 1, they are numbered consecutively.

        Id type;                                /* read only */
        $solutionelement->{type}
        solutionelement.type
        solutionelement.type

Type of the solution element. See the constant section of the solver class for the
existing types.

        Solvable *solvable;                     /* read only */
        $solutionelement->{solvable}
        solutionelement.solvable
        solutionelement.solvable

The installed solvable that needs to be replaced for replacement elements.

        Solvable *replacement;                  /* read only */
        $solutionelement->{replacement}
        solutionelement.replacement
        solutionelement.replacement

The solvable that needs to be installed to fix the problem.

        int jobidx;                             /* read only */
        $solutionelement->{jobidx}
        solutionelement.jobidx
        solutionelement.jobidx

The index of the job that needs to be removed to fix the problem, or -1 if the
element is of another type. Note that it's better to change the job to SOLVER_NOOP
type so that the numbering of other elements does not get disturbed. This
method works both for types SOLVER_SOLUTION_JOB and SOLVER_SOLUTION_POOLJOB.

=== METHODS ===

        Solutionelement *replaceelements()
        my @solutionelements = $solutionelement->replaceelements();
        solutionelements = solutionelement.replaceelements()
        solutionelements = solutionelement.replaceelements()

If the solution element is of type SOLVER_SOLUTION_REPLACE, return an array of
elements describing the policy mismatches, otherwise return a copy of the
element. See also the ``expandreplaces'' option in the solution's elements()
method.

        int illegalreplace()
        my $illegal = $solutionelement->illegalreplace();
        illegal = solutionelement.illegalreplace()
        illegal = solutionelement.illegalreplace()

Return an integer that contains the policy mismatch bits or-ed together, or
zero if there was no policy mismatch. See the policy error constants in
the solver class.

        Job Job()
        my $job = $solutionelement->Job();
        illegal = solutionelement.Job()
        illegal = solutionelement.Job()

Create a job that implements the solution element. Add this job to the array
of jobs for all elements of type different to SOLVER_SOLUTION_JOB and
SOLVER_SOLUTION_POOLJOB. For the later two, a SOLVER_NOOB Job is created,
you should replace the old job with the new one.

        const char *str()
        my $str = $solutionelement->str();
        str = solutionelement.str()
        str = solutionelement.str()

A string describing the change the solution element consists of.

THE TRANSACTION CLASS
---------------------
Transactions describe the output of a solver run. A transaction contains
a number of transaction elements, each either the installation of a new
package or the removal of an already installed package. The Transaction
class supports a classify() method that puts the elements into different
groups so that a transaction can be presented to the user in a meaningful
way.

=== CONSTANTS ===

Transaction element types, both active and passive

*SOLVER_TRANSACTION_IGNORE*::
  This element does nothing. Used to map element types that do not
  match the view mode.

*SOLVER_TRANSACTION_INSTALL*::
  This element installs a package.

*SOLVER_TRANSACTION_ERASE*::
  This element erases a package.

*SOLVER_TRANSACTION_MULTIINSTALL*::
  This element installs a package with a different version keeping the
  other versions installed.

*SOLVER_TRANSACTION_MULTIREINSTALL*::
  This element reinstalls a installed package keeping the other versions
  installed.

Transaction element types, active view

*SOLVER_TRANSACTION_REINSTALL*::
  This element re-installs a package, i.e. installs the same package again.

*SOLVER_TRANSACTION_CHANGE*::
  This element installs a package with same name, version, architecture but
  different content.

*SOLVER_TRANSACTION_UPGRADE*::
  This element installs a newer version of an installed package.

*SOLVER_TRANSACTION_DOWNGRADE*::
  This element installs a older version of an installed package.

*SOLVER_TRANSACTION_OBSOLETES*::
  This element installs a package that obsoletes an installed package.

Transaction element types, passive view

*SOLVER_TRANSACTION_REINSTALLED*::
  This element re-installs a package, i.e. installs the same package again.

*SOLVER_TRANSACTION_CHANGED*::
  This element replaces an installed package with one of the same name,
  version, architecture but different content.

*SOLVER_TRANSACTION_UPGRADED*::
  This element replaces an installed package with a new version.

*SOLVER_TRANSACTION_DOWNGRADED*::
  This element replaces an installed package with an old version.

*SOLVER_TRANSACTION_OBSOLETED*::
  This element replaces an installed package with a package that obsoletes
  it.

Pseudo element types for showing extra information used by classify()

*SOLVER_TRANSACTION_ARCHCHANGE*::
  This element replaces an installed package with a package of a different
  architecture.

*SOLVER_TRANSACTION_VENDORCHANGE*::
  This element replaces an installed package with a package of a different
  vendor.

Transaction mode flags

*SOLVER_TRANSACTION_SHOW_ACTIVE*::
  Filter for active view types. The default is to return passive view type,
  i.e. to show how the installed packages get changed.

*SOLVER_TRANSACTION_SHOW_OBSOLETES*::
  Do not map the obsolete view type into INSTALL/ERASE elements.

*SOLVER_TRANSACTION_SHOW_ALL*::
  If multiple packages replace an installed package, only the best of them
  is kept as OBSOLETE element, the other ones are mapped to INSTALL/ERASE
  elements. This is because most applications want to show just one package
  replacing the installed one. The SOLVER_TRANSACTION_SHOW_ALL makes the
  library keep all OBSOLETE elements.

*SOLVER_TRANSACTION_SHOW_MULTIINSTALL*::
  The library maps MULTIINSTALL elements to simple INSTALL elements. This
  flag can be used to disable the mapping.

*SOLVER_TRANSACTION_CHANGE_IS_REINSTALL*::
  Use this flag if you want to map CHANGE elements to the REINSTALL type.

*SOLVER_TRANSACTION_OBSOLETE_IS_UPGRADE*::
  Use this flag if you want to map OBSOLETE elements to the UPGRADE type.

*SOLVER_TRANSACTION_MERGE_ARCHCHANGES*::
  Do not add extra categories for every architecture change, instead cumulate
  them in one category.
  
*SOLVER_TRANSACTION_MERGE_VENDORCHANGES*::
  Do not add extra categories for every vendor change, instead cumulate
  them in one category.

*SOLVER_TRANSACTION_RPM_ONLY*::
  Special view mode that just returns IGNORE, ERASE, INSTALL, MULTIINSTALL
  elements. Useful if you want to find out what to feed to the underlying
  package manager.

Transaction order flags

*SOLVER_TRANSACTION_KEEP_ORDERDATA*::
  Do not throw away the dependency graph used for ordering the transaction.
  This flag is needed if you want to do manual ordering.

=== ATTRIBUTES ===

        Pool *pool;                             /* read only */
        $trans->{pool}
        trans.pool
        trans.pool

Back pointer to pool.

=== METHODS ===

        bool isempty();
        $trans->isempty()
        trans.isempty()
        trans.isempty?

Returns true if the transaction does not do anything, i.e. has no elements.

        Solvable *newsolvables();
        my @newsolvables = $trans->newsolvables();
        newsolvables = trans.newsolvables()
        newsolvables = trans.newsolvables()

Return all packages that are to be installed by the transaction. This are
the packages that need to be downloaded from the repositories.

        Solvable *keptsolvables();
        my @keptsolvables = $trans->keptsolvables();
        keptsolvables = trans.keptsolvables()
        keptsolvables = trans.keptsolvables()

Return all installed packages that the transaction will keep installed.

        Solvable *steps();
        my @steps = $trans->steps();
        steps = trans.steps()
        steps = trans.steps()

Return all solvables that need to be installed (if the returned solvable
is not already installed) or erased (if the returned solvable is installed).
A step is also called a transaction element.

        int steptype(Solvable *solvable, int mode)
        my $type = $trans->steptype($solvable, $mode);
        type = trans.steptype(solvable, mode)
        type = trans.steptype(solvable, mode)

Return the transaction type of the specified solvable. See the CONSTANTS
sections for the mode argument flags and the list of returned types.

        TransactionClass *classify(int mode = 0)
        my @classes = $trans->classify();
        classes = trans.classify()
        classes = trans.classify()

Group the transaction elements into classes so that they can be displayed
in a structured way. You can use various mapping mode flags to tweak
the result to match your preferences, see the mode argument flag in
the CONSTANTS section. See the TransactionClass class for how to deal
with the returned objects.

        Solvable othersolvable(Solvable *solvable);
        my $other = $trans->othersolvable($solvable);
        other = trans.othersolvable(solvable)
        other = trans.othersolvable(solvable)

Return the ``other'' solvable for a given solvable. For installed packages
the other solvable is the best package with the same name that replaces
the installed package, or the best package of the obsoleting packages if
the package does not get replaced by one with the same name.

For to be installed packages, the ``other'' solvable is the best installed
package with the same name that will be replaced, or the best packages
of all the packages that are obsoleted if the new package does not replace
a package with the same name.

Thus, the ``other'' solvable is normally the package that is also shown
for a given package.

        Solvable *allothersolvables(Solvable *solvable);
        my @others = $trans->allothersolvables($solvable);
        others = trans.allothersolvables(solvable)
        others = trans.allothersolvables(solvable)

For installed packages, returns all of the packages that replace us. For to
be installed packages, returns all of the packages that the new package
replaces. The special ``other'' solvable is always the first entry of the
returned array.

        int calc_installsizechange();
        my $change = $trans->calc_installsizechange();
        change = trans.calc_installsizechange()
        change = trans.calc_installsizechange()

Return the size change of the installed system in kilobytes (kibibytes).

        void order(int flags = 0);
        $trans->order();
        trans.order()
        trans.order()

Order the steps in the transactions so that dependant packages are updated
before packages that depend on them. For rpm, you can also use rpmlib's
ordering functionality, debian's dpkg does not provide a way to order a
transaction.

=== ACTIVE/PASSIVE VIEW ===

Active view list what new packages get installed, while passive view shows
what happens to the installed packages. Most often there's not much
difference between the two modes, but things get interesting of multiple
package get replaced by one new package. Say you have installed package
A-1-1 and B-1-1, and now install A-2-1 with has a new dependency that
obsoletes B. The transaction elements will be

  updated   A-1-1 (other: A-2-1)
  obsoleted B-1-1 (other: A-2-1)

in passive mode, but

  update A-2-1 (other: A-1-1)
  erase  B

in active mode. If the mode contains SOLVER_TRANSACTION_SHOW_ALL, the 
passive mode list will be unchanged but the active mode list will just
contain A-2-1.

THE TRANSACTIONCLASS CLASS
--------------------------
Objects of this type are returned by the classify() Transaction method.

=== ATTRIBUTES ===

        Transaction *transaction;               /* read only */
        $class->{transaction}
        class.transaction
        class.transaction

Back pointer to transaction object.

        int type;                               /* read only */
        $class->{type}
        class.type
        class.type

The type of the transaction elements in the class.

        int count;                              /* read only */
        $class->{count}
        class.count
        class.count

The number of elements in the class.

        const char *fromstr;
        $class->{fromstr}
        class.fromstr
        class.fromstr

The old vendor or architecture.

        const char *tostr;
        $class->{tostr}
        class.tostr
        class.tostr

The new vendor or architecture.

        Id fromid;
        $class->{fromid}
        class.fromid
        class.fromid

The id of the old vendor or architecture.

        Id toid;
        $class->{toid}
        class.toid
        class.toid

The id of the new vendor or architecture.

=== METHODS ===

        void solvables();
        my @solvables = $class->solvables();
        solvables = class.solvables()
        solvables = class.solvables()

Return the solvables for all transaction elements in the class.

CHECKSUMS
---------
Checksums (also called hashes) are used to make sure that downloaded data is
not corrupt and also as a fingerprint mechanism to check if data has changed.

=== CLASS METHODS ===

        Chksum Chksum(Id type)
        my $chksum = solv::Chksum->new($type);
        chksum = solv.Chksum(type)
        chksum = Solv::Chksum.new(type)

Create a checksum object. Currently the following types are supported:

        REPOKEY_TYPE_MD5
        REPOKEY_TYPE_SHA1
        REPOKEY_TYPE_SHA256

These keys are constants in the *solv* class.

        Chksum Chksum(Id type, const char *hex)
        my $chksum = solv::Chksum->new($type, $hex);
        chksum = solv.Chksum(type, hex)
        chksum = Solv::Chksum.new(type, hex)

Create an already finalized checksum object.

=== ATTRIBUTES ===

        Id type;                        /* read only */
        $chksum->{type}
        chksum.type
        chksum.type

Return the type of the checksum object.

=== METHODS ===

        void add(const char *str)
        $chksum->add($str);
        chksum.add(str)
        chksum.add(str)

Add a string to the checksum.

        void add_fp(FILE *fp)
        $chksum->add_fp($file);
        chksum.add_fp(file)
        chksum.add_fp(file)

Add the contents of a file to the checksum.
        
        void add_stat(const char *filename)
        $chksum->add_stat($filename);
        chksum.add_stat(filename)
        chksum.add_stat(filename)

Stat the file and add the dev/ino/size/mtime member to the checksum. If the
stat fails, the members are zeroed.

        void add_fstat(int fd)
        $chksum->add_fstat($fd);
        chksum.add_fstat(fd)
        chksum.add_fstat(fd)

Same as add_stat, but instead of the filename a file descriptor is used.

        unsigned char *raw()
        my $raw = $chksum->raw();
        raw = chksum.raw()
        raw = chksum.raw()

Finalize the checksum and return the result as raw bytes. This means that the
result can contain NUL bytes or unprintable characters.

        const char *hex()
        my $raw = $chksum->hex();
        raw = chksum.hex()
        raw = chksum.hex()

Finalize the checksum and return the result as hex string.

        <equality>
        if ($chksum1 == $chksum2)
        if chksum1 == chksum2:
        if chksum1 == chksum2

Checksums are equal if they are of the same type and the finalized results are
the same.

        <stringification>
        my $str = $chksum->str;
        str = str(chksum)
        str = chksum.to_s

If the checksum is finished, the checksum is returned as "<type>:<hex>" string.
Otherwise "<type>:unfinished" is returned.


FILE MANAGEMENT
---------------
This functions were added because libsolv uses standard *FILE* pointers to
read/write files, but languages like perl have their own implementation of
files. The libsolv functions also support decompression and compression, the
algorithm is selected by looking at the file name extension.

        FILE *xfopen(char *fn, char *mode = "r")
        my $file = solv::xfopen($path);
        file = solv.xfopen(path)
        file = Solv::xfopen(path)

Open a file at the specified path. The `mode` argument is passed on to the
stdio library.

        FILE *xfopen_fd(char *fn, int fileno)
        my $file = solv::xfopen_fd($path, $fileno);
        file = solv.xfopen_fd(path, fileno)
        file = Solv::xfopen_fd(path, fileno)

Create a file handle from the specified file descriptor. The path argument is
only used to select the correct (de-)compression algorithm, use an empty path
if you want to make sure to read/write raw data.

=== METHODS ===

        int fileno()
        my $fileno = $file->fileno();
        fileno = file.fileno()
        fileno = file.fileno()

Return file file descriptor of the file. If the file is not open, `-1` is
returned.

        int dup()
        my $fileno = $file->dup();
        fileno = file.dup()
        fileno = file.dup()

Return a copy of the descriptor of the file. If the file is not open, `-1` is
returned.

        bool flush()
        $file->flush();
        file.flush()
        file.flush()

Flush the file. Returns false if there was an error. Flushing a closed file
always returns true.

        bool close()
        $file->close();
        file.close()
        file.close()

Close the file. This is needed for languages like Ruby, that do not destruct
objects right after they are no longer referenced. In that case, it is good
style to close open files so that the file descriptors are freed right away.
Returns false if there was an error.


THE REPODATA CLASS
------------------
The Repodata stores attributes for packages and the repository itself, each
repository can have multiple repodata areas. You normally only need to
directly access them if you implement lazy downloading of repository data.
Repodata areas are created by calling the repository's add_repodata() method 
or by using repo_add methods without the REPO_REUSE_REPODATA or REPO_USE_LOADING
flag.

=== ATTRIBUTES ===

        Repo *repo;                     /* read only */
        $data->{repo}
        data.repo
        data.repo

Back pointer to repository object.

        Id id;                                  /* read only */
        $data->{id}
        data.id
        data.id

The id of the repodata area. Repodata ids of different repositories overlap.

=== METHODS ====

        internalize();
        $data->internalize();
        data.internalize()
        data.internalize()

Internalize newly added data. The lookup functions will only see the new data
after it has been internalized.

        bool write(FILE *fp);
        $data->write($fp);
        data.write(fp)
        data.write(fp)

Write the contents of the repodata area as solv file.

        bool add_solv(FILE *fp, int flags = 0);
        $data->add_solv($fp);
        data.add_solv(fp)
        data.add_solv(fp)

Replace a stub repodata object with the data from a solv file. This method
automatically adds the REPO_USE_LOADING flag. It should only be used from
a load callback.

        void create_stubs();
        $data->create_stubs()
        data.create_stubs()
        data.create_stubs()

Create stub repodatas from the information stored in the repodata meta
area.

        void extend_to_repo();
        $data->extend_to_repo();
        data.extend_to_repo()
        data.extend_to_repo()

Extend the repodata so that it has the same size as the repo it belongs to.
This method is only needed when switching to a just written repodata extension
to make the repodata match the written extension (which is always of the
size of the repo).

        <equality>
        if ($data1 == $data2)
        if data1 == data2:
        if data1 == data2

Two repodata objects are equal if they belong to the same repository and have
the same id.

=== DATA RETRIEVAL METHODS ===

        const char *lookup_str(Id solvid, Id keyname)
        my $string = $data->lookup_str($solvid, $keyname);
        string = data.lookup_str(solvid, keyname)
        string = data.lookup_str(solvid, keyname)

        Id *lookup_idarray(Id solvid, Id keyname)
        my @ids = $data->lookup_idarray($solvid, $keyname);
        ids = data.lookup_idarray(solvid, keyname)
        ids = data.lookup_idarray(solvid, keyname)

        Chksum lookup_checksum(Id solvid, Id keyname)
        my $chksum = $data->lookup_checksum($solvid, $keyname);
        chksum = data.lookup_checksum(solvid, keyname)
        chksum = data.lookup_checksum(solvid, keyname)

Lookup functions. Return the data element stored in the specified solvable.
The methods probably only make sense to retrieve data from the special
SOLVID_META solvid that stores repodata meta information.

=== DATA STORAGE METHODS ===

        void set_id(Id solvid, Id keyname, DepId id);
        $data->set_id($solvid, $keyname, $id);
        data.set_id(solvid, keyname, id)
        data.set_id(solvid, keyname, id)

        void set_str(Id solvid, Id keyname, const char *str);
        $data->set_str($solvid, $keyname, $str);
        data.set_str(solvid, keyname, str)
        data.set_str(solvid, keyname, str)

        void set_poolstr(Id solvid, Id keyname, const char *str);
        $data->set_poolstr($solvid, $keyname, $str);
        data.set_poolstr(solvid, keyname, str)
        data.set_poolstr(solvid, keyname, str)

        void set_checksum(Id solvid, Id keyname, Chksum *chksum);
        $data->set_checksum($solvid, $keyname, $chksum);
        data.set_checksum(solvid, keyname, chksum)
        data.set_checksum(solvid, keyname, chksum)

        void add_idarray(Id solvid, Id keyname, DepId id);
        $data->add_idarray($solvid, $keyname, $id);
        data.add_idarray(solvid, keyname, id)
        data.add_idarray(solvid, keyname, id)

        Id new_handle();
        my $handle = $data->new_handle();
        handle = data.new_handle()
        handle = data.new_handle()

        void add_flexarray(Id solvid, Id keyname, Id handle);
        $data->add_flexarray($solvid, $keyname, $handle);
        data.add_flexarray(solvid, keyname, handle)
        data.add_flexarray(solvid, keyname, handle)

Data storage methods. Probably only useful to store data in the special
SOLVID_META solvid that stores repodata meta information. Note that
repodata areas can have their own Id pool (see the REPO_LOCALPOOL flag),
so be careful if you need to store ids. Arrays are created by calling
the add function for every element. A flexarray is an array of
sub-structures, call new_handle to create a new structure, use the
handle as solvid to fill the structure with data and call add_flexarray
to put the structure in an array.


THE DATAPOS CLASS
-----------------
Datapos objects describe a specific position in the repository data area.
Thus they are only valid until the repository is modified in some way.
Datapos objects can be created by the pos() and parentpos() methods of
a Datamatch object or by accessing the ``meta'' attribute of a repository.

=== ATTRIBUTES ===

        Repo *repo;                     /* read only */
        $data->{repo}
        data.repo
        data.repo

Back pointer to repository object.

=== METHODS ===

        Dataiterator(Id keyname, const char *match, int flags)
        my $di = $datapos->Dataiterator($keyname, $match, $flags);
        di = datapos.Dataiterator(keyname, match, flags)
        di = datapos.Dataiterator(keyname, match, flags)

Create a Dataiterator at the position of the datapos object.

        const char *lookup_deltalocation(unsigned int *OUTPUT);
        my ($location, $medianr) = $datapos->lookup_deltalocation();
        location, medianr = datapos.lookup_deltalocation()
        location, medianr = datapos.lookup_deltalocation()

Return a tuple containing the on-media location and an optional media number
for a delta rpm. This obviously only works if the data position points to
structure describing a delta rpm.

        const char *lookup_deltaseq();
        my $seq = $datapos->lookup_deltaseq();
        seq = datapos.lookup_deltaseq();
        seq = datapos.lookup_deltaseq();

Return the delta rpm sequence from the structure describing a delta rpm.

=== DATA RETRIEVAL METHODS ===

        const char *lookup_str(Id keyname)
        my $string = $datapos->lookup_str($keyname);
        string = datapos.lookup_str(keyname)
        string = datapos.lookup_str(keyname)

        Id lookup_id(Id solvid, Id keyname)
        my $id = $datapos->lookup_id($keyname);
        id = datapos.lookup_id(keyname)
        id = datapos.lookup_id(keyname)

        unsigned long long lookup_num(Id keyname, unsigned long long notfound = 0)
        my $num = $datapos->lookup_num($keyname);
        num = datapos.lookup_num(keyname)
        num = datapos.lookup_num(keyname)

        bool lookup_void(Id keyname)
        my $bool = $datapos->lookup_void($keyname);
        bool = datapos.lookup_void(keyname)
        bool = datapos.lookup_void(keyname)

        Id *lookup_idarray(Id keyname)
        my @ids = $datapos->lookup_idarray($keyname);
        ids = datapos.lookup_idarray(keyname)
        ids = datapos.lookup_idarray(keyname)

        Chksum lookup_checksum(Id keyname)
        my $chksum = $datapos->lookup_checksum($keyname);
        chksum = datapos.lookup_checksum(keyname)
        chksum = datapos.lookup_checksum(keyname)

Lookup functions. Note that the returned Ids are always translated into
the Ids of the global pool even if the repodata area contains its own pool.

Author
------
Michael Schroeder <mls@suse.de>