1 -----------------------------------------------------------------------------

2 -- |

3 -- Module : Data.Version

4 -- Copyright : (c) The University of Glasgow 2004

5 -- License : BSD-style (see the file libraries/base/LICENSE)

6 --

7 -- Maintainer : libraries@haskell.org

8 -- Stability : experimental

9 -- Portability : non-portable (local universal quantification in ReadP)

10 --

11 -- A general library for representation and manipulation of versions.

12 --

13 -- Versioning schemes are many and varied, so the version

14 -- representation provided by this library is intended to be a

15 -- compromise between complete generality, where almost no common

16 -- functionality could reasonably be provided, and fixing a particular

17 -- versioning scheme, which would probably be too restrictive.

18 --

19 -- So the approach taken here is to provide a representation which

20 -- subsumes many of the versioning schemes commonly in use, and we

21 -- provide implementations of 'Eq', 'Ord' and conversion to\/from 'String'

22 -- which will be appropriate for some applications, but not all.

23 --

24 -----------------------------------------------------------------------------

27 -- * The @Version@ type

28 Version(..),

29 -- * A concrete representation of @Version@

35 -- These #ifdefs are necessary because this code might be compiled as

36 -- part of ghc/lib/compat, and hence might be compiled by an older version

37 -- of GHC. In which case, we might need to pick up ReadP from

38 -- Distribution.Compat.ReadP, because the version in

39 -- Text.ParserCombinators.ReadP doesn't have all the combinators we need.

44 #endif

52 #endif

58 {- |

59 A 'Version' represents the version of a software entity.

61 An instance of 'Eq' is provided, which implements exact equality

62 modulo reordering of the tags in the 'versionTags' field.

64 An instance of 'Ord' is also provided, which gives lexicographic

65 ordering on the 'versionBranch' fields (i.e. 2.1 > 2.0, 1.2.3 > 1.2.2,

66 etc.). This is expected to be sufficient for many uses, but note that

67 you may need to use a more specific ordering for your versioning

68 scheme. For example, some versioning schemes may include pre-releases

69 which have tags @\"pre1\"@, @\"pre2\"@, and so on, and these would need to

70 be taken into account when determining ordering. In some cases, date

71 ordering may be more appropriate, so the application would have to

72 look for @date@ tags in the 'versionTags' field and compare those.

73 The bottom line is, don't always assume that 'compare' and other 'Ord'

74 operations are the right thing for every 'Version'.

76 Similarly, concrete representations of versions may differ. One

77 possible concrete representation is provided (see 'showVersion' and

78 'parseVersion'), but depending on the application a different concrete

79 representation may be more appropriate.

80 -}

83 -- ^ The numeric branch for this version. This reflects the

84 -- fact that most software versions are tree-structured; there

85 -- is a main trunk which is tagged with versions at various

86 -- points (1,2,3...), and the first branch off the trunk after

87 -- version 3 is 3.1, the second branch off the trunk after

88 -- version 3 is 3.2, and so on. The tree can be branched

89 -- arbitrarily, just by adding more digits.

90 --

91 -- We represent the branch as a list of 'Int', so

92 -- version 3.2.1 becomes [3,2,1]. Lexicographic ordering

93 -- (i.e. the default instance of 'Ord' for @[Int]@) gives

94 -- the natural ordering of branches.

97 -- ^ A version can be tagged with an arbitrary list of strings.

98 -- The interpretation of the list of tags is entirely dependent

99 -- on the entity that this version applies to.

100 }

103 ,Typeable

104 #endif

105 )

108 versionTc :: TyCon

114 versionTc :: TyCon

119 #endif

124 -- tags may be in any order

129 -- -----------------------------------------------------------------------------

130 -- A concrete representation of 'Version'

132 -- | Provides one possible concrete representation for 'Version'. For

133 -- a version with 'versionBranch' @= [1,2,3]@ and 'versionTags'

134 -- @= [\"tag1\",\"tag2\"]@, the output will be @1.2.3-tag1-tag2@.

135 --

141 -- | A parser for versions in the format produced by 'showVersion'.

142 --

144 parseVersion :: ReadP Version

145 #elif __NHC__

146 parseVersion :: ReadPN r Version

148 parseVersion :: ReadP r Version

149 #endif