add internal command `_stanza`

to extract the compiled/interpolated values for a given stanza.

lib/cask/cli.rb

@@ -24,6 +24,7 @@ require 'cask/cli/update'
 require 'cask/cli/internal_use_base'
 require 'cask/cli/internal_dump'
 require 'cask/cli/internal_help'
+require 'cask/cli/internal_stanza'
 
 class Cask::CLI
 

lib/cask/cli/internal_stanza.rb

@@ -0,0 +1,133 @@
+class Cask::CLI::InternalStanza < Cask::CLI::InternalUseBase
+
+  # Syntax
+  #
+  #     brew cask _stanza <stanza_name> [ --table | --yaml | --inspect | --quiet ] [ <cask_names> ]
+  #
+  # If no Cask names are given, then all are returned.
+  #
+  # The pseudo-stanzas "artifacts" and "sums" are available.
+  #
+  # On failure, a blank line is returned on the standard output.
+  #
+  # Examples
+  #
+  #     brew cask _stanza appcast   --table
+  #     brew cask _stanza link      --table alfred google-chrome adium voicemac logisim vagrant
+  #     brew cask _stanza url       --table alfred google-chrome adium voicemac logisim vagrant
+  #     brew cask _stanza version   --table alfred google-chrome adium voicemac logisim vagrant
+  #     brew cask _stanza artifacts --table --inspect alfred google-chrome adium voicemac logisim vagrant
+  #     brew cask _stanza artifacts --table --yaml    alfred google-chrome adium voicemac logisim vagrant
+  #
+
+  # todo: this should be retrievable from Cask::DSL
+  ARTIFACTS = Set.new([
+                       :link,
+                       :prefpane,
+                       :qlplugin,
+                       :font,
+                       :widget,
+                       :service,
+                       :colorpicker,
+                       :binary,
+                       :input_method,
+                       :screen_saver,
+                       :install,
+                       :caskroom_only,
+                       :nested_container,
+                       :uninstall,
+                       :after_install,
+                       :after_uninstall,
+                       :before_install,
+                       :before_uninstall,
+                       ])
+
+  def self.run(*arguments)
+
+    table = arguments.include? '--table'
+    quiet = arguments.include? '--quiet'
+    format = :to_yaml if arguments.include? '--yaml'
+    format = :inspect if arguments.include? '--inspect'
+    cask_names = arguments.reject { |arg| arg.chars.first == '-' }
+    stanza = cask_names.shift.to_sym
+    cask_names = Cask.all_titles if cask_names.empty?
+
+    retval = print_stanzas(stanza, format, table, quiet, *cask_names)
+
+    # retval is ternary: true/false/nil
+    if retval.nil?
+      exit 1 if quiet
+      raise CaskError.new("nothing to print")
+    elsif ! retval
+      exit 1 if quiet
+      raise CaskError.new("print incomplete")
+    end
+  end
+
+  def self.print_stanzas(stanza, format=nil, table=nil, quiet=nil, *cask_names)
+    count = 0
+    stanza = :sums if stanza == :sha256
+    if ARTIFACTS.include?(stanza)
+      artifact_name = stanza
+      stanza = :artifacts
+    end
+
+    cask_names.each do |cask_name|
+
+      print "#{cask_name}\t" if table
+
+      begin
+        cask = Cask.load(cask_name)
+      rescue StandardError
+        opoo "Cask '#{cask_name}' was not found" unless quiet
+        puts ''
+        next
+      end
+
+      unless cask.respond_to?(stanza)
+        opoo "no such stanza '#{stanza}' on Cask '#{cask_name}'" unless quiet
+        puts ''
+        next
+      end
+
+      begin
+        value = cask.send(stanza)
+      rescue StandardError
+        opoo "failure calling '#{stanza}' on Cask '#{cask_name}'" unless quiet
+        puts ''
+        next
+      end
+
+      if artifact_name and not value.key?(artifact_name)
+        opoo "no such stanza '#{artifact_name}' on Cask '#{cask_name}'" unless quiet
+        puts ''
+        next
+      end
+
+      if artifact_name
+        value = value.fetch(artifact_name).to_a.flatten
+      end
+
+      if format
+        puts value.send(format)
+      else
+        if artifact_name or value.is_a?(Symbol)
+          puts value.inspect
+        elsif stanza == :sums
+          # hack. why does "to_s" equal "inspect" for checksum objects?
+          puts value
+        else
+          puts value.to_s
+        end
+      end
+
+      count += 1
+
+    end
+    count == 0 ? nil : count == cask_names.length
+  end
+
+  def self.help
+    "Extract and render a specific stanza for the given Casks"
+  end
+end