Function to compare package versions added
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2 changed files with 79 additions and 2 deletions
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@ -149,4 +149,71 @@ module DebImporter
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end # Enumerator
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end # def
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# Determine which version string denotes the newer package
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# v1: version of the first package
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# v2: version of the second package
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# op: the comparison operator (default: 'gt' / greater-than)
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#
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# The algorithm is described in the Debian Policy at
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# https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version
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# The reference implementation is "dpkg --compare-versions …"
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def dpkg_compare_version(v1, v2, op: 'gt')
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system("dpkg --compare-versions #{v1} #{op} #{v2}")
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end
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class Version
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def initialize(version_string)
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@version_string = version_string
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# Split into "[epoch:]version[-revision]"
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unless version_string =~ /^(?<epoch>(\d+)\:)?(?<version>.+)(?<revision>\-[\+\.~]+)?/
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raise ArgumentError, "Cannot parse version string: #{version_string}"
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end
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@epoch = epoch if epoch
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@version = version
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@revision = revision if revision
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end # /def
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def to_s
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@version
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end
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def >(a,b)
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return true if a.epoch > b.epoch
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return true if version_compare(a.version, b.version)
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return true if version_compare(a.revision, b.revision)
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end
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private
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def version_compare(x,y)
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# Compare a version string (like the upstream_version or
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# debian_revision string) against another version string.
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# The algorithm works like this:
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#
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# The strings are compared from left to right.
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# First the initial part of each string consisting entirely of non-digit
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# characters is determined. These two parts (one of which may be empty)
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# are compared lexically. If a difference is found it is returned.
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# The lexical comparison is a comparison of ASCII values modified so
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# that all the letters sort earlier than all the non-letters and so that
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# a tilde sorts before anything, even the end of a part.
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# For example, the following parts are in sorted order from
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# earliest to latest: ~~, ~~a, ~, the empty part, a.[37]
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#
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# Then the initial part of the remainder of each string which
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# consists entirely of digit characters is determined. The
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# numerical values of these two parts are compared, and any
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# difference found is returned as the result of the comparison.
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# For these purposes an empty string (which can only occur at
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# the end of one or both version strings being compared) counts as zero.
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#
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# These two steps (comparing and removing initial non-digit strings
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# and initial digit strings) are repeated until a difference is
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# found or both strings are exhausted.
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(x.chars).zip(y.chars) do |xchar,ychar|
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puts xchar, ychar
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end
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end
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end # /class
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end # module
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