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NAME

       Dpkg::Deps - parse and manipulate dependencies of Debian packages

DESCRIPTION

       The Dpkg::Deps module provides objects implementing various types of dependencies.

       The most important function is deps_parse(), it turns a dependency line in a set of
       Dpkg::Deps::{Simple,AND,OR,Union} objects depending on the case.

FUNCTIONS

       All the deps_* functions are exported by default.

       deps_eval_implication($rel_p, $v_p, $rel_q, $v_q)
           ($rel_p, $v_p) and ($rel_q, $v_q) express two dependencies as (relation, version). The
           relation variable can have the following values that are exported by Dpkg::Version:
           REL_EQ, REL_LT, REL_LE, REL_GT, REL_GT.

           This functions returns 1 if the "p" dependency implies the "q" dependency. It returns
           0 if the "p" dependency implies that "q" is not satisfied. It returns undef when
           there's no implication.

           The $v_p and $v_q parameter should be Dpkg::Version objects.

       $dep = deps_concat(@dep_list)
           This function concatenates multiple dependency lines into a single line, joining them
           with ", " if appropriate, and always returning a valid string.

       $dep = deps_parse($line, %options)
           This function parses the dependency line and returns an object, either a
           Dpkg::Deps::AND or a Dpkg::Deps::Union. Various options can alter the behaviour of
           that function.

           use_arch (defaults to 1)
               Take into account the architecture restriction part of the dependencies.  Set to 0
               to completely ignore that information.

           host_arch (defaults to the current architecture)
               Define the host architecture. By default it uses Dpkg::Arch::get_host_arch() to
               identify the proper architecture.

           build_arch (defaults to the current architecture)
               Define the build architecture. By default it uses Dpkg::Arch::get_build_arch() to
               identify the proper architecture.

           reduce_arch (defaults to 0)
               If set to 1, ignore dependencies that do not concern the current host
               architecture. This implicitly strips off the architecture restriction list so that
               the resulting dependencies are directly applicable to the current architecture.

           use_profiles (defaults to 1)
               Take into account the profile restriction part of the dependencies. Set to 0 to
               completely ignore that information.

           build_profiles (defaults to no profile)
               Define the active build profiles. By default no profile is defined.

           reduce_profiles (defaults to 0)
               If set to 1, ignore dependencies that do not concern the current build profile.
               This implicitly strips off the profile restriction formula so that the resulting
               dependencies are directly applicable to the current profiles.

           reduce_restrictions (defaults to 0)
               If set to 1, ignore dependencies that do not concern the current set of
               restrictions. This implicitly strips off any architecture restriction list or
               restriction formula so that the resulting dependencies are directly applicable to
               the current restriction.  This currently implies "reduce_arch" and
               "reduce_profiles", and overrides them if set.

           union (defaults to 0)
               If set to 1, returns a Dpkg::Deps::Union instead of a Dpkg::Deps::AND. Use this
               when parsing non-dependency fields like Conflicts.

           build_dep (defaults to 0)
               If set to 1, allow build-dep only arch qualifiers, that is “:native”.  This should
               be set whenever working with build-deps.

           tests_dep (defaults to 0)
               If set to 1, allow tests-specific package names in dependencies, that is "@" and
               "@builddeps@" (since dpkg 1.18.7). This should be set whenever working with
               dependency fields from debian/tests/control.

       $bool = deps_iterate($deps, $callback_func)
           This function visits all elements of the dependency object, calling the callback
           function for each element.

           The callback function is expected to return true when everything is fine, or false if
           something went wrong, in which case the iteration will stop.

           Return the same value as the callback function.

       deps_compare($a, $b)
           Implements a comparison operator between two dependency objects.  This function is
           mainly used to implement the sort() method.

OBJECTS - Dpkg::Deps::*

       There are several kind of dependencies. A Dpkg::Deps::Simple dependency represents a
       single dependency statement (it relates to one package only).  Dpkg::Deps::Multiple
       dependencies are built on top of this object and combine several dependencies in different
       manners. Dpkg::Deps::AND represents the logical "AND" between dependencies while
       Dpkg::Deps::OR represents the logical "OR". Dpkg::Deps::Multiple objects can contain
       Dpkg::Deps::Simple object as well as other Dpkg::Deps::Multiple objects.

       In practice, the code is only meant to handle the realistic cases which, given Debian's
       dependencies structure, imply those restrictions: AND can contain Simple or OR objects, OR
       can only contain Simple objects.

       Dpkg::Deps::KnownFacts is a special object that is used while evaluating dependencies and
       while trying to simplify them. It represents a set of installed packages along with the
       virtual packages that they might provide.

CHANGES

   Version 1.06 (dpkg 1.18.7; module version bumped on dpkg 1.18.24)
       New option: Add tests_dep option to Dpkg::Deps::deps_parse().

   Version 1.05 (dpkg 1.17.14)
       New function: Dpkg::Deps::deps_iterate().

   Version 1.04 (dpkg 1.17.10)
       New options: Add use_profiles, build_profiles, reduce_profiles and reduce_restrictions to
       Dpkg::Deps::deps_parse().

   Version 1.03 (dpkg 1.17.0)
       New option: Add build_arch option to Dpkg::Deps::deps_parse().

   Version 1.02 (dpkg 1.17.0)
       New function: Dpkg::Deps::deps_concat()

   Version 1.01 (dpkg 1.16.1)
       <Used to document changes to Dpkg::Deps::* modules before they were split.>

   Version 1.00 (dpkg 1.15.6)
       Mark the module as public.