1 files changed, 95 insertions, 0 deletions
diff --git a/lib/rubygems/available_set.rb b/lib/rubygems/available_set.rb
new file mode 100644
index 0000000000..cd6df1ddc7
--- /dev/null
+++ b/lib/rubygems/available_set.rb
@@ -0,0 +1,95 @@
+module Gem
+  class AvailableSet
+    Tuple = Struct.new(:spec, :source)
+
+    def initialize
+      @set = []
+      @sorted = nil
+    end
+
+    attr_reader :set
+
+    def add(spec, source)
+      @set << Tuple.new(spec, source)
+      @sorted = nil
+      self
+    end
+
+    def <<(o)
+      case o
+      when AvailableSet
+        s = o.set
+      when Array
+        s = o.map do |sp,so|
+          if !sp.kind_of?(Specification) or !so.kind_of?(Source)
+            raise TypeError, "Array must be in [[spec, source], ...] form"
+          end
+
+          Tuple.new(sp,so)
+        end
+      else
+        raise TypeError, "Must be an AvailableSet"
+      end
+
+      @set += s
+      @sorted = nil
+
+      self
+    end
+
+    def empty?
+      @set.empty?
+    end
+
+    def all_specs
+      @set.map { |t| t.spec }
+    end
+
+    def match_platform!
+      @set.reject! { |t| !Gem::Platform.match(t.spec.platform) }
+      @sorted = nil
+      self
+    end
+
+    def sorted
+      @sorted ||= @set.sort do |a,b|
+        i = b.spec <=> a.spec
+        i != 0 ? i : (a.source <=> b.source)
+      end
+    end
+
+    def size
+      @set.size
+    end
+
+    def source_for(spec)
+      f = @set.find { |t| t.spec == spec }
+      f.source
+    end
+
+    def pick_best!
+      return self if empty?
+
+      @set = [sorted.first]
+      @sorted = nil
+      self
+    end
+
+    def remove_installed!(dep)
+      @set.reject! do |t|
+        # already locally installed
+        Gem::Specification.any? do |installed_spec|
+          dep.name == installed_spec.name and
+            dep.requirement.satisfied_by? installed_spec.version
+        end
+      end
+
+      @sorted = nil
+      self
+    end
+
+    def inject_into_list(dep_list)
+      @set.each { |t| dep_list.add t.spec }
+    end
+  end
+end