Package org.eclipse.aether.util.version

package org.eclipse.aether.util.version
Version scheme for parsing/comparing versions and utility classes.

Contains the "generic" scheme GenericVersionScheme that serves the purpose of "factory" (and/or parser) for all corresponding elements (all those are package private).

On the other hand, the UnionVersionRange is universal implementation of "unions" of various VersionRange instances.

Below is the Generic Version Spec described:

Version string is parsed into version according to these rules:

  • The version string is parsed into segments, from left to right.
  • Segments are explicitly delimited by a single "." (dot), "-" (hyphen), or "_" (underscore) character.
  • Segments are implicitly delimited by a transition between ASCII digits and non-digits.
  • Segments are classified as numeric, string, qualifiers (special case of string), and min/max.
  • Numeric segments are composed of the ASCII digits 0-9. Non-ASCII digits are treated as letters.
  • Numeric segments are sorted numerically, ascending.
  • Non-numeric segments may be qualifiers (predefined) or strings (non-empty letter sequence). All of them are interpreted as being case-insensitive in terms of the ROOT locale.
  • Qualifier segments (strings listed below) and their sort order (ascending) are:
    • "alpha" (== "a" when immediately followed by number)
    • "beta" (== "b" when immediately followed by number)
    • "milestone" (== "m" when immediately followed by number)
    • "rc" == "cr" (use of "cr" is discouraged)
    • "snapshot"
    • "ga" == "final" == "release"
    • "sp"
  • String segments are sorted lexicographically and case-insensitively per ROOT locale, ascending.
  • There are two special segments, "min" and "max" that represent absolute minimum and absolute maximum in comparisons. They can be used only as the trailing segment.
  • As last step, trailing "zero segments" are trimmed. Similarly, "zero segments" positioned before numeric and non-numeric transitions (either explicitly or implicitly delimited) are trimmed.
  • When trimming, "zero segments" are qualifiers "ga", "final", "release" only if being last (right-most) segment, empty string and "0" always.
  • In comparison of same kind segments, the given type of segment determines comparison rules.
  • In comparison of different kind of segments, following applies: max > numeric > string > qualifier > min.
  • Any version can be considered to have an infinite number of invisible trailing "zero segments", for the purposes of comparison (in other words, "1" == "1.0.0.0.0.0.0.0.0....")
  • It is common that a version identifier starts with numeric segment (consider this "best practice").

Note: this version spec does not document (or cover) many corner cases that we believe are "atypical" or not used commonly. None of these are enforced, but in future implementations they probably will be. Some known examples are:

  • Using "min" or "max" special segments as a non-trailing segment. This yields in "undefined" behaviour and should be avoided.
  • Having a non-number as the first segment of a version. Versions are expected (but not enforced) to start with numbers.