First pass on a VersionString class.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

1 files changed, 172 insertions, 0 deletions

diff --git a/lib/chef/version_string.rb b/lib/chef/version_string.rb
new file mode 100644
index 0000000000..2777a635d7
--- /dev/null
+++ b/lib/chef/version_string.rb
@@ -0,0 +1,172 @@
+# Copyright:: Copyright 2017, Noah Kantrowitz
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+class Chef
+  # String-like object for version strings.
+  #
+  # @since 13.1
+  # @api internal
+  class VersionString < String
+    # Parsed version object for the string.
+    # @return [Gem::Version]
+    attr_reader :parsed_version
+
+    # Create a new VersionString from an input String.
+    #
+    # @param val [String] Version string to parse.
+    def initialize(val)
+      super
+      @parsed_version = ::Gem::Version.create(self)
+    end
+
+    # @!group Compat wrappers for String
+
+    # Compat wrapper for + to behave like a normal String.
+    #
+    # @param other [String]
+    # @return [String]
+    def +(other)
+      to_s + other
+    end
+
+    # Compat wrapper for * to behave like a normal String.
+    #
+    # @param other [Integer]
+    # @return [String]
+    def *(other)
+      to_s * other
+    end
+
+    # @!group Comparison operators
+
+    # Compare a VersionString to an object. If compared to another VersionString
+    # then sort like `Gem::Version`, otherwise try to treat the other object as
+    # a version but fall back to normal string comparison.
+    #
+    # @param other [Object]
+    # @return [Integer]
+    def <=>(other)
+      other_ver = case other
+                  when VersionString
+                    other.pased_version
+                  else
+                    begin
+                      Gem::Version.create(other.to_s)
+                    rescue ArgumentError
+                      # Comparing to a string that isn't a version.
+                      return super
+                    end
+                  end
+      parsed_version <=> other_ver
+    end
+
+    # Compat wrapper for == based on <=>.
+    #
+    # @param other [Object]
+    # @return [Boolean]
+    def ==(other)
+      (self <=> other) == 0
+    end
+
+    # Compat wrapper for != based on <=>.
+    #
+    # @param other [Object]
+    # @return [Boolean]
+    def !=(other)
+      (self <=> other) != 0
+    end
+
+    # Compat wrapper for < based on <=>.
+    #
+    # @param other [Object]
+    # @return [Boolean]
+    def <(other)
+      (self <=> other) < 0
+    end
+
+    # Compat wrapper for <= based on <=>.
+    #
+    # @param other [Object]
+    # @return [Boolean]
+    def <=(other)
+      (self <=> other) < 1
+    end
+
+    # Compat wrapper for > based on <=>.
+    #
+    # @param other [Object]
+    # @return [Boolean]
+    def >(other)
+      (self <=> other) > 0
+    end
+
+    # Compat wrapper for >= based on <=>.
+    #
+    # @param other [Object]
+    # @return [Boolean]
+    def >=(other)
+      (self <=> other) > -1
+    end
+
+    # @!group Matching operators
+
+    # Matching operator to support checking against a requirement string.
+    #
+    # @param other [Regexp, String]
+    # @return [Boolean]
+    # @example Match against a Regexp
+    #   Chef::VersionString.new('1.0.0') =~ /^1/
+    # @example Match against a requirement
+    #   Chef::VersionString.new('1.0.0') =~ '~> 1.0'
+    def =~(other)
+      case other
+      when Regexp
+        super
+      else
+        Gem::Requirement.create(other) =~ parsed_version
+      end
+    end
+
+    # Grouping operator to support fancy `case` blocks. Requires the String
+    # monkeypatch below to function.
+    #
+    # @param other [Object]
+    # @return [Boolean]
+    # @example
+    #   case Chef::VersionString.new('1.0.0')
+    #   when '~> 2.0'
+    #     :two
+    #   when '~> 1.0'
+    #     :one
+    #   end
+    def ===(other)
+      self =~ other
+    rescue ArgumentError
+      super
+    end
+
+  end
+end
+
+# Monkeypatch string grouping to allow the nice case syntax shown above.
+String.prepend(Module.new do
+  def ===(other)
+    if other.is_a?(Chef::VersionString)
+      other === self
+    else
+      super
+    end
+  end
+end)