Function to compare package versions added

This commit is contained in:
Christoph Haas 2016-02-26 17:32:04 +01:00
parent bd46e4c9e8
commit 26c8605256
2 changed files with 79 additions and 2 deletions

View file

@ -149,4 +149,71 @@ module DebImporter
end # Enumerator
end # def
# Determine which version string denotes the newer package
# v1: version of the first package
# v2: version of the second package
# op: the comparison operator (default: 'gt' / greater-than)
#
# The algorithm is described in the Debian Policy at
# https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version
# The reference implementation is "dpkg --compare-versions …"
def dpkg_compare_version(v1, v2, op: 'gt')
system("dpkg --compare-versions #{v1} #{op} #{v2}")
end
class Version
def initialize(version_string)
@version_string = version_string
# Split into "[epoch:]version[-revision]"
unless version_string =~ /^(?<epoch>(\d+)\:)?(?<version>.+)(?<revision>\-[\+\.~]+)?/
raise ArgumentError, "Cannot parse version string: #{version_string}"
end
@epoch = epoch if epoch
@version = version
@revision = revision if revision
end # /def
def to_s
@version
end
def >(a,b)
return true if a.epoch > b.epoch
return true if version_compare(a.version, b.version)
return true if version_compare(a.revision, b.revision)
end
private
def version_compare(x,y)
# Compare a version string (like the upstream_version or
# debian_revision string) against another version string.
# The algorithm works like this:
#
# The strings are compared from left to right.
# First the initial part of each string consisting entirely of non-digit
# characters is determined. These two parts (one of which may be empty)
# are compared lexically. If a difference is found it is returned.
# The lexical comparison is a comparison of ASCII values modified so
# that all the letters sort earlier than all the non-letters and so that
# a tilde sorts before anything, even the end of a part.
# For example, the following parts are in sorted order from
# earliest to latest: ~~, ~~a, ~, the empty part, a.[37]
#
# Then the initial part of the remainder of each string which
# consists entirely of digit characters is determined. The
# numerical values of these two parts are compared, and any
# difference found is returned as the result of the comparison.
# For these purposes an empty string (which can only occur at
# the end of one or both version strings being compared) counts as zero.
#
# These two steps (comparing and removing initial non-digit strings
# and initial digit strings) are repeated until a difference is
# found or both strings are exhausted.
(x.chars).zip(y.chars) do |xchar,ychar|
puts xchar, ychar
end
end
end # /class
end # module