bionic (3) Lintian::Relation.3.gz
NAME
Lintian::Relation - Lintian operations on dependencies and relationships
SYNOPSIS
my $depends = Lintian::Relation->new('foo | bar, baz');
print "yes\n" if $depends->implies('baz');
print "no\n" if $depends->implies('foo');
DESCRIPTION
This module provides functions for parsing and evaluating package relationship fields such as Depends and
Recommends for binary packages and Build-Depends for source packages. It parses a relationship into an
internal format and can then answer questions such as "does this dependency require that a given package
be installed" or "is this relationship a superset of another relationship."
A dependency line is viewed as a predicate formula. The comma separator means "and", and the
alternatives separator means "or". A bare package name is the predicate "a package of this name is
available". A package name with a version clause is the predicate "a package of this name that satisfies
this version clause is available." Architecture restrictions, as specified in Policy for build
dependencies, are supported and also checked in the implication logic unless the new_noarch() constructor
is used. With that constructor, architecture restrictions are ignored.
CLASS METHODS
new(RELATION)
Creates a new Lintian::Relation object corresponding to the parsed relationship RELATION. This
object can then be used to ask questions about that relationship. RELATION may be "undef" or the
empty string, in which case the returned Lintian::Relation object is empty (always satisfied).
new_norestriction(RELATION)
Creates a new Lintian::Relation object corresponding to the parsed relationship RELATION, ignoring
architecture restrictions and restriction lists. This should be used in cases where we only care if a
dependency is present in some cases and we don't want to require that the architectures match (such
as when checking for proper build dependencies, since if there are architecture constraints the
maintainer is doing something beyond Lintian's ability to analyze) or that the restrictions list
match (Lintian can't handle dependency implications with build profiles yet). RELATION may be
"undef" or the empty string, in which case the returned Lintian::Relation object is empty (always
satisfied).
new_noarch(RELATION)
An alias for new_norestriction.
and(RELATION, ...)
Creates a new Lintian::Relation object produced by AND'ing all the relations together. Semantically
it is the similar to:
Lintian::Relation->new (join (', ', @relations))
Except it can avoid some overhead and it works if some of the elements are Lintian::Relation objects
already.
INSTANCE METHODS
duplicates()
Returns a list of duplicated elements within the relation object. Each element of the returned list
will be a reference to an anonymous array holding a set of relations considered duplicates of each
other. Two relations are considered duplicates if one implies the other, meaning that if one
relationship is satisfied, the other is necessarily satisfied. This relationship does not have to be
commutative: the opposite implication may not hold.
restriction_less()
Returns a restriction-less variant of this relation (or this relation object if it has no
restrictions).
implies(RELATION)
Returns true if the relationship implies RELATION, meaning that if the Lintian::Relation object is
satisfied, RELATION will always be satisfied. RELATION may be either a string or another
Lintian::Relation object.
By default, architecture restrictions are honored in RELATION if it is a string. If architecture
restrictions should be ignored in RELATION, create a Lintian::Relation object with new_noarch() and
pass that in as RELATION instead of the string.
implies_inverse(RELATION)
Returns true if the relationship implies that RELATION is certainly false, meaning that if the
Lintian::Relation object is satisfied, RELATION cannot be satisfied. RELATION may be either a string
or another Lintian::Relation object.
As with implies(), by default, architecture restrictions are honored in RELATION if it is a string.
If architecture restrictions should be ignored in RELATION, create a Lintian::Relation object with
new_noarch() and pass that in as RELATION instead of the string.
unparse()
Returns the textual form of a relationship. This converts the internal form back into the textual
representation and returns that, not the original argument, so the spacing is standardized. Returns
undef on internal failures (such as an object in an unexpected format).
matches (REGEX[, WHAT])
Check if one of the predicates in this relation matches REGEX. WHAT determines what is tested
against REGEX and if not given, defaults to VISIT_PRED_NAME.
This method will return a truth value if REGEX matches at least one predicate or clause (as defined
by the WHAT parameter - see below).
NOTE: Often "implies" (or "implies_inverse") is a better choice than this method. This method should
generally only be used when checking for a "pattern" package (e.g. phpapi-[\d\w+]+).
WHAT can be one of:
VISIT_PRED_NAME
Match REGEX against the package name in each predicate (i.e. version and architecture constrains
are ignored). Each predicate is tested in isolation. As an example:
my $rel = Lintian::Relation->new ('somepkg | pkg-0 (>= 1)');
# Will match (version is ignored)
$rel->matches (qr/^pkg-\d$/, VISIT_PRED_NAME);
VISIT_PRED_FULL
Match REGEX against the full (normalized) predicate (i.e. including version and architecture).
Each predicate is tested in isolation. As an example:
my $vrel = Lintian::Relation->new ('somepkg | pkg-0 (>= 1)');
my $uvrel = Lintian::Relation->new ('somepkg | pkg-0');
# Will NOT match (does not match with version)
$vrel->matches (qr/^pkg-\d$/, VISIT_PRED_FULL);
# Will match (this relation does not have a version)
$uvrel->matches (qr/^pkg-\d$/, VISIT_PRED_FULL);
# Will match (but only because there is a version)
$vrel->matches (qr/^pkg-\d \(.*\)$/, VISIT_PRED_FULL);
# Will NOT match (there is no version in the relation)
$uvrel->matches (qr/^pkg-\d \(.*\)$/, VISIT_PRED_FULL);
VISIT_OR_CLAUSE_FULL
Match REGEX against the full (normalized) OR clause. Each predicate will have both version and
architecture constrains present. As an example:
my $vpred = Lintian::Relation->new ('pkg-0 (>= 1)');
my $orrel = Lintian::Relation->new ('somepkg | pkg-0 (>= 1)');
my $rorrel = Lintian::Relation->new ('pkg-0 (>= 1) | somepkg');
# Will match
$vrel->matches (qr/^pkg-\d(?: \([^\)]\))?$/, VISIT_OR_CLAUSE_FULL);
# These Will NOT match (does not match the "|" and the "somepkg" part)
$orrel->matches (qr/^pkg-\d(?: \([^\)]\))?$/, VISIT_OR_CLAUSE_FULL);
$rorrel->matches (qr/^pkg-\d(?: \([^\)]\))?$/, VISIT_OR_CLAUSE_FULL);
visit (CODE[, FLAGS])
Visit clauses or predicates of this relation. Each clause or predicate is passed to CODE as first
argument and will be available as $_.
The optional bitmask parameter, FLAGS, can be used to control what is visited and such. If FLAGS is
not given, it defaults to VISIT_PRED_NAME. The possible values of FLAGS are:
VISIT_PRED_NAME
The package name in each predicate is visited, but the version and architecture part(s) are left
out (if any).
VISIT_PRED_FULL
The full predicates are visited in turn. The predicate will be normalized (by "unparse").
VISIT_OR_CLAUSE_FULL
CODE will be passed the full OR clauses of this relation. The clauses will be normalized (by
"unparse")
Note: It will not visit the underlying predicates in the clause.
VISIT_STOP_FIRST_MATCH
Stop the visits the first time CODE returns a truth value. This is similar to first, except
visit will return the value returned by CODE.
Except where a given flag specifies otherwise, the return value of visit is last value returned by
CODE (or "undef" for the empty relation).
empty
Returns a truth value if this relation is empty (i.e. it contains no predicates).
unparsable_predicates
Returns a list of predicates that were unparsable.
They are returned in the original textual representation and are also sorted by said representation.
AUTHOR
Originally written by Russ Allbery <rra@debian.org> for Lintian.
SEE ALSO
lintian(1)