1 files changed, 182 insertions, 0 deletions
diff --git a/lib/rubygems/source_list.rb b/lib/rubygems/source_list.rb
new file mode 100644
index 0000000000..19bf4595c4
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+++ b/lib/rubygems/source_list.rb
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+# frozen_string_literal: true
+
+##
+# The SourceList represents the sources rubygems has been configured to use.
+# A source may be created from an array of sources:
+#
+#   Gem::SourceList.from %w[https://rubygems.example https://internal.example]
+#
+# Or by adding them:
+#
+#   sources = Gem::SourceList.new
+#   sources << 'https://rubygems.example'
+#
+# The most common way to get a SourceList is Gem.sources.
+
+class Gem::SourceList
+  include Enumerable
+
+  ##
+  # Creates a new SourceList
+
+  def initialize
+    @sources = []
+  end
+
+  ##
+  # The sources in this list
+
+  attr_reader :sources
+
+  ##
+  # Creates a new SourceList from an array of sources.
+
+  def self.from(ary)
+    list = new
+
+    list.replace ary
+
+    list
+  end
+
+  def initialize_copy(other) # :nodoc:
+    @sources = @sources.dup
+  end
+
+  ##
+  # Appends +obj+ to the source list which may be a Gem::Source, Gem::URI or URI
+  # String.
+
+  def <<(obj)
+    src = case obj
+          when Gem::Source
+            obj
+          else
+            Gem::Source.new(obj)
+    end
+
+    @sources << src unless @sources.include?(src)
+    src
+  end
+
+  ##
+  # Prepends +obj+ to the beginning of the source list which may be a Gem::Source, Gem::URI or URI
+  # Moves +obj+ to the beginning of the list if already present.
+  # String.
+
+  def prepend(obj)
+    src = case obj
+          when Gem::Source
+            obj
+          else
+            Gem::Source.new(obj)
+    end
+
+    @sources.delete(src) if @sources.include?(src)
+    @sources.unshift(src)
+    src
+  end
+
+  ##
+  # Appends +obj+ to the end of the source list, moving it if already present.
+  # +obj+ may be a Gem::Source, Gem::URI or URI String.
+  # Moves +obj+ to the end of the list if already present.
+
+  def append(obj)
+    src = case obj
+          when Gem::Source
+            obj
+          else
+            Gem::Source.new(obj)
+    end
+
+    @sources.delete(src) if @sources.include?(src)
+    @sources << src
+    src
+  end
+
+  ##
+  # Replaces this SourceList with the sources in +other+  See #<< for
+  # acceptable items in +other+.
+
+  def replace(other)
+    clear
+
+    other.each do |x|
+      self << x
+    end
+
+    self
+  end
+
+  ##
+  # Removes all sources from the SourceList.
+
+  def clear
+    @sources.clear
+  end
+
+  ##
+  # Yields each source URI in the list.
+
+  def each
+    @sources.each {|s| yield s.uri.to_s }
+  end
+
+  ##
+  # Yields each source in the list.
+
+  def each_source(&b)
+    @sources.each(&b)
+  end
+
+  ##
+  # Returns true if there are no sources in this SourceList.
+
+  def empty?
+    @sources.empty?
+  end
+
+  def ==(other) # :nodoc:
+    to_a == other
+  end
+
+  ##
+  # Returns an Array of source URI Strings.
+
+  def to_a
+    @sources.map {|x| x.uri.to_s }
+  end
+
+  alias_method :to_ary, :to_a
+
+  ##
+  # Returns the first source in the list.
+
+  def first
+    @sources.first
+  end
+
+  ##
+  # Returns true if this source list includes +other+ which may be a
+  # Gem::Source or a source URI.
+
+  def include?(other)
+    if other.is_a? Gem::Source
+      @sources.include? other
+    else
+      @sources.find {|x| x.uri.to_s == other.to_s }
+    end
+  end
+
+  ##
+  # Deletes +source+ from the source list which may be a Gem::Source or a URI.
+
+  def delete(source)
+    if source.is_a? Gem::Source
+      @sources.delete source
+    else
+      @sources.delete_if {|x| x.uri.to_s == source.to_s }
+    end
+  end
+end