1 files changed, 150 insertions, 0 deletions
diff --git a/lib/rubygems/commands/dependency_command.rb b/lib/rubygems/commands/dependency_command.rb
new file mode 100644
index 0000000000..1a43505d7c
--- /dev/null
+++ b/lib/rubygems/commands/dependency_command.rb
@@ -0,0 +1,150 @@
+require 'rubygems/command'
+require 'rubygems/local_remote_options'
+require 'rubygems/version_option'
+require 'rubygems/source_info_cache'
+
+class Gem::Commands::DependencyCommand < Gem::Command
+
+  include Gem::LocalRemoteOptions
+  include Gem::VersionOption
+
+  def initialize
+    super 'dependency',
+          'Show the dependencies of an installed gem',
+          :version => Gem::Requirement.default, :domain => :local
+
+    add_version_option
+    add_platform_option
+
+    add_option('-R', '--[no-]reverse-dependencies',
+               'Include reverse dependencies in the output') do
+      |value, options|
+      options[:reverse_dependencies] = value
+    end
+
+    add_option('-p', '--pipe',
+               "Pipe Format (name --version ver)") do |value, options|
+      options[:pipe_format] = value
+    end
+
+    add_local_remote_options
+  end
+
+  def arguments # :nodoc:
+    "GEMNAME       name of gem to show dependencies for"
+  end
+
+  def defaults_str # :nodoc:
+    "--local --version '#{Gem::Requirement.default}' --no-reverse-dependencies"
+  end
+
+  def usage # :nodoc:
+    "#{program_name} GEMNAME"
+  end
+
+  def execute
+    options[:args] << '.' if options[:args].empty?
+    specs = {}
+
+    source_indexes = []
+
+    if local? then
+      source_indexes << Gem::SourceIndex.from_installed_gems
+    end
+
+    if remote? then
+      Gem::SourceInfoCache.cache_data.map do |_, sice|
+        source_indexes << sice.source_index
+      end
+    end
+
+    options[:args].each do |name|
+      new_specs = nil
+      source_indexes.each do |source_index|
+        new_specs =  find_gems(name, source_index)
+      end
+
+      say "No match found for #{name} (#{options[:version]})" if
+        new_specs.empty?
+
+      specs = specs.merge new_specs
+    end
+
+    terminate_interaction 1 if specs.empty?
+
+    reverse = Hash.new { |h, k| h[k] = [] }
+
+    if options[:reverse_dependencies] then
+      specs.values.each do |source_index, spec|
+        reverse[spec.full_name] = find_reverse_dependencies spec, source_index
+      end
+    end
+
+    if options[:pipe_format] then
+      specs.values.sort_by { |_, spec| spec }.each do |_, spec|
+        unless spec.dependencies.empty?
+          spec.dependencies.each do |dep|
+            say "#{dep.name} --version '#{dep.version_requirements}'"
+          end
+        end
+      end
+    else
+      response = ''
+
+      specs.values.sort_by { |_, spec| spec }.each do |_, spec|
+        response << print_dependencies(spec)
+        unless reverse[spec.full_name].empty? then
+          response << "  Used by\n"
+          reverse[spec.full_name].each do |sp, dep|
+            response << "    #{sp} (#{dep})\n"
+          end
+        end
+        response << "\n"
+      end
+
+      say response
+    end
+  end
+
+  def print_dependencies(spec, level = 0)
+    response = ''
+    response << '  ' * level + "Gem #{spec.full_name}\n"
+    unless spec.dependencies.empty? then
+      spec.dependencies.each do |dep|
+        response << '  ' * level + "  #{dep}\n"
+      end
+    end
+    response
+  end
+
+  # Retuns list of [specification, dep] that are satisfied by spec.
+  def find_reverse_dependencies(spec, source_index)
+    result = []
+
+    source_index.each do |name, sp|
+      sp.dependencies.each do |dep|
+        dep = Gem::Dependency.new(*dep) unless Gem::Dependency === dep
+
+        if spec.name == dep.name and
+           dep.version_requirements.satisfied_by?(spec.version) then
+          result << [sp.full_name, dep]
+        end
+      end
+    end
+
+    result
+  end
+
+  def find_gems(name, source_index)
+    specs = {}
+
+    spec_list = source_index.search name, options[:version]
+
+    spec_list.each do |spec|
+      specs[spec.full_name] = [source_index, spec]
+    end
+
+    specs
+  end
+end
+