lib/rubygems/version.rb

# frozen_string_literal: true

require_relative "deprecate"

##
# The Version class processes string versions into comparable
# values. A version string should normally be a series of numbers
# separated by periods. Each part (digits separated by periods) is
# considered its own number, and these are used for sorting. So for
# instance, 3.10 sorts higher than 3.2 because ten is greater than
# two.
#
# If any part contains letters (currently only a-z are supported) then
# that version is considered prerelease. Versions with a prerelease
# part in the Nth part sort less than versions with N-1
# parts. Prerelease parts are sorted alphabetically using the normal
# Ruby string sorting rules. If a prerelease part contains both
# letters and numbers, it will be broken into multiple parts to
# provide expected sort behavior (1.0.a10 becomes 1.0.a.10, and is
# greater than 1.0.a9).
#
# Prereleases sort between real releases (newest to oldest):
#
# 1. 1.0
# 2. 1.0.b1
# 3. 1.0.a.2
# 4. 0.9
#
# If you want to specify a version restriction that includes both prereleases
# and regular releases of the 1.x series this is the best way:
#
#   s.add_dependency 'example', '>= 1.0.0.a', '< 2.0.0'
#
# == How Software Changes
#
# Users expect to be able to specify a version constraint that gives them
# some reasonable expectation that new versions of a library will work with
# their software if the version constraint is true, and not work with their
# software if the version constraint is false.  In other words, the perfect
# system will accept all compatible versions of the library and reject all
# incompatible versions.
#
# Libraries change in 3 ways (well, more than 3, but stay focused here!).
#
# 1. The change may be an implementation detail only and have no effect on
#    the client software.
# 2. The change may add new features, but do so in a way that client software
#    written to an earlier version is still compatible.
# 3. The change may change the public interface of the library in such a way
#    that old software is no longer compatible.
#
# Some examples are appropriate at this point.  Suppose I have a Stack class
# that supports a <tt>push</tt> and a <tt>pop</tt> method.
#
# === Examples of Category 1 changes:
#
# * Switch from an array based implementation to a linked-list based
#   implementation.
# * Provide an automatic (and transparent) backing store for large stacks.
#
# === Examples of Category 2 changes might be:
#
# * Add a <tt>depth</tt> method to return the current depth of the stack.
# * Add a <tt>top</tt> method that returns the current top of stack (without
#   changing the stack).
# * Change <tt>push</tt> so that it returns the item pushed (previously it
#   had no usable return value).
#
# === Examples of Category 3 changes might be:
#
# * Changes <tt>pop</tt> so that it no longer returns a value (you must use
#   <tt>top</tt> to get the top of the stack).
# * Rename the methods to <tt>push_item</tt> and <tt>pop_item</tt>.
#
# == RubyGems Rational Versioning
#
# * Versions shall be represented by three non-negative integers, separated
#   by periods (e.g. 3.1.4).  The first integers is the "major" version
#   number, the second integer is the "minor" version number, and the third
#   integer is the "build" number.
#
# * A category 1 change (implementation detail) will increment the build
#   number.
#
# * A category 2 change (backwards compatible) will increment the minor
#   version number and reset the build number.
#
# * A category 3 change (incompatible) will increment the major build number
#   and reset the minor and build numbers.
#
# * Any "public" release of a gem should have a different version.  Normally
#   that means incrementing the build number.  This means a developer can
#   generate builds all day long, but as soon as they make a public release,
#   the version must be updated.
#
# === Examples
#
# Let's work through a project lifecycle using our Stack example from above.
#
# Version 0.0.1:: The initial Stack class is release.
# Version 0.0.2:: Switched to a linked=list implementation because it is
#                 cooler.
# Version 0.1.0:: Added a <tt>depth</tt> method.
# Version 1.0.0:: Added <tt>top</tt> and made <tt>pop</tt> return nil
#                 (<tt>pop</tt> used to return the  old top item).
# Version 1.1.0:: <tt>push</tt> now returns the value pushed (it used it
#                 return nil).
# Version 1.1.1:: Fixed a bug in the linked list implementation.
# Version 1.1.2:: Fixed a bug introduced in the last fix.
#
# Client A needs a stack with basic push/pop capability.  They write to the
# original interface (no <tt>top</tt>), so their version constraint looks like:
#
#   gem 'stack', '>= 0.0'
#
# Essentially, any version is OK with Client A.  An incompatible change to
# the library will cause them grief, but they are willing to take the chance
# (we call Client A optimistic).
#
# Client B is just like Client A except for two things: (1) They use the
# <tt>depth</tt> method and (2) they are worried about future
# incompatibilities, so they write their version constraint like this:
#
#   gem 'stack', '~> 0.1'
#
# The <tt>depth</tt> method was introduced in version 0.1.0, so that version
# or anything later is fine, as long as the version stays below version 1.0
# where incompatibilities are introduced.  We call Client B pessimistic
# because they are worried about incompatible future changes (it is OK to be
# pessimistic!).
#
# == Preventing Version Catastrophe:
#
# From: https://www.zenspider.com/ruby/2008/10/rubygems-how-to-preventing-catastrophe.html
#
# Let's say you're depending on the fnord gem version 2.y.z. If you
# specify your dependency as ">= 2.0.0" then, you're good, right? What
# happens if fnord 3.0 comes out and it isn't backwards compatible
# with 2.y.z? Your stuff will break as a result of using ">=". The
# better route is to specify your dependency with an "approximate" version
# specifier ("~>"). They're a tad confusing, so here is how the dependency
# specifiers work:
#
#   Specification From  ... To (exclusive)
#   ">= 3.0"      3.0   ... &infin;
#   "~> 3.0"      3.0   ... 4.0
#   "~> 3.0.0"    3.0.0 ... 3.1
#   "~> 3.5"      3.5   ... 4.0
#   "~> 3.5.0"    3.5.0 ... 3.6
#   "~> 3"        3.0   ... 4.0
#
# For the last example, single-digit versions are automatically extended with
# a zero to give a sensible result.

class Gem::Version
  include Comparable

  VERSION_PATTERN = '[0-9]+(?>\.[0-9a-zA-Z]+)*(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?' # :nodoc:
  ANCHORED_VERSION_PATTERN = /\A\s*(#{VERSION_PATTERN})?\s*\z/ # :nodoc:

  ##
  # A string representation of this Version.

  def version
    @version
  end

  alias_method :to_s, :version

  ##
  # True if the +version+ string matches RubyGems' requirements.

  def self.correct?(version)
    nil_versions_are_discouraged! if version.nil?

    ANCHORED_VERSION_PATTERN.match?(version.to_s)
  end

  ##
  # Factory method to create a Version object. Input may be a Version
  # or a String. Intended to simplify client code.
  #
  #   ver1 = Version.create('1.3.17')   # -> (Version object)
  #   ver2 = Version.create(ver1)       # -> (ver1)
  #   ver3 = Version.create(nil)        # -> nil

  def self.create(input)
    if self === input # check yourself before you wreck yourself
      input
    elsif input.nil?
      nil_versions_are_discouraged!

      nil
    else
      new input
    end
  end

  @@all = {}
  @@bump = {}
  @@release = {}

  def self.new(version) # :nodoc:
    return super unless self == Gem::Version

    @@all[version] ||= super
  end

  def self.nil_versions_are_discouraged!
    unless Gem::Deprecate.skip
      warn "nil versions are discouraged and will be deprecated in Rubygems 4"
    end
  end

  private_class_method :nil_versions_are_discouraged!

  ##
  # Constructs a Version from the +version+ string.  A version string is a
  # series of digits or ASCII letters separated by dots.

  def initialize(version)
    unless self.class.correct?(version)
      raise ArgumentError, "Malformed version number string #{version}"
    end

    # If version is an empty string convert it to 0
    version = 0 if version.is_a?(String) && /\A\s*\Z/.match?(version)

    @version = version.to_s

    # optimization to avoid allocation when given an integer, since we know
    # it's to_s won't have any spaces or dashes
    unless version.is_a?(Integer)
      @version = @version.strip
      @version.gsub!("-",".pre.")
    end
    @version = -@version
    @segments = nil
  end

  ##
  # Return a new version object where the next to the last revision
  # number is one greater (e.g., 5.3.1 => 5.4).
  #
  # Pre-release (alpha) parts, e.g, 5.3.1.b.2 => 5.4, are ignored.

  def bump
    @@bump[self] ||= begin
                       segments = self.segments
                       segments.pop while segments.any? {|s| String === s }
                       segments.pop if segments.size > 1

                       segments[-1] = segments[-1].succ
                       self.class.new segments.join(".")
                     end
  end

  ##
  # A Version is only eql? to another version if it's specified to the
  # same precision. Version "1.0" is not the same as version "1".

  def eql?(other)
    self.class === other && @version == other.version
  end

  def hash # :nodoc:
    canonical_segments.hash
  end

  def init_with(coder) # :nodoc:
    yaml_initialize coder.tag, coder.map
  end

  def inspect # :nodoc:
    "#<#{self.class} #{version.inspect}>"
  end

  ##
  # Dump only the raw version string, not the complete object. It's a
  # string for backwards (RubyGems 1.3.5 and earlier) compatibility.

  def marshal_dump
    [@version]
  end

  ##
  # Load custom marshal format. It's a string for backwards (RubyGems
  # 1.3.5 and earlier) compatibility.

  def marshal_load(array)
    string = array[0]
    raise TypeError, "wrong version string" unless string.is_a?(String)

    initialize string
  end

  def yaml_initialize(tag, map) # :nodoc:
    @version = -map["version"]
    @segments = nil
    @hash = nil
  end

  def encode_with(coder) # :nodoc:
    coder.add "version", @version
  end

  ##
  # A version is considered a prerelease if it contains a letter.

  def prerelease?
    unless instance_variable_defined? :@prerelease
      @prerelease = /[a-zA-Z]/.match?(version)
    end
    @prerelease
  end

  def pretty_print(q) # :nodoc:
    q.text "Gem::Version.new(#{version.inspect})"
  end

  ##
  # The release for this version (e.g. 1.2.0.a -> 1.2.0).
  # Non-prerelease versions return themselves.

  def release
    @@release[self] ||= if prerelease?
      segments = self.segments
      segments.pop while segments.any? {|s| String === s }
      self.class.new segments.join(".")
    else
      self
    end
  end

  def segments # :nodoc:
    _segments.dup
  end

  ##
  # A recommended version for use with a ~> Requirement.

  def approximate_recommendation
    segments = self.segments

    segments.pop    while segments.any? {|s| String === s }
    segments.pop    while segments.size > 2
    segments.push 0 while segments.size < 2

    recommendation = "~> #{segments.join(".")}"
    recommendation += ".a" if prerelease?
    recommendation
  end

  ##
  # Compares this version with +other+ returning -1, 0, or 1 if the
  # other version is larger, the same, or smaller than this
  # one. Attempts to compare to something that's not a
  # <tt>Gem::Version</tt> or a valid version String return +nil+.

  def <=>(other)
    return self <=> self.class.new(other) if (String === other) && self.class.correct?(other)

    return unless Gem::Version === other
    return 0 if @version == other.version || canonical_segments == other.canonical_segments

    lhsegments = canonical_segments
    rhsegments = other.canonical_segments

    lhsize = lhsegments.size
    rhsize = rhsegments.size
    limit  = (lhsize > rhsize ? rhsize : lhsize)

    i = 0

    while i < limit
      lhs = lhsegments[i]
      rhs = rhsegments[i]
      i += 1

      next      if lhs == rhs
      return -1 if String  === lhs && Numeric === rhs
      return  1 if Numeric === lhs && String  === rhs

      return lhs <=> rhs
    end

    lhs = lhsegments[i]

    if lhs.nil?
      rhs = rhsegments[i]

      while i < rhsize
        return 1 if String === rhs
        return -1 unless rhs.zero?
        rhs = rhsegments[i += 1]
      end
    else
      while i < lhsize
        return -1 if String === lhs
        return 1 unless lhs.zero?
        lhs = lhsegments[i += 1]
      end
    end

    0
  end

  # remove trailing zeros segments before first letter or at the end of the version
  def canonical_segments
    @canonical_segments ||= begin
      # remove trailing 0 segments, using dot or letter as anchor
      # may leave a trailing dot which will be ignored by partition_segments
      canonical_version = @version.sub(/(?<=[a-zA-Z.])[.0]+\z/, "")
      # remove 0 segments before the first letter in a prerelease version
      canonical_version.sub!(/(?<=\.|\A)[0.]+(?=[a-zA-Z])/, "") if prerelease?
      partition_segments(canonical_version)
    end
  end

  def freeze
    prerelease?
    _segments
    canonical_segments
    super
  end

  protected

  def _segments
    # segments is lazy so it can pick up version values that come from
    # old marshaled versions, which don't go through marshal_load.
    # since this version object is cached in @@all, its @segments should be frozen
    @segments ||= partition_segments(@version)
  end

  def partition_segments(ver)
    ver.scan(/\d+|[a-z]+/i).map! do |s|
      /\A\d/.match?(s) ? s.to_i : -s
    end.freeze
  end
end