brew/Library/Homebrew/cmd/desc.rb

require "descriptions"
require "cmd/search"

module Homebrew
  def desc
    search_type = []
    search_type << :either if ARGV.flag? "--search"
    search_type << :name   if ARGV.flag? "--name"
    search_type << :desc   if ARGV.flag? "--description"

    if search_type.empty?
      raise FormulaUnspecifiedError if ARGV.named.empty?
      Descriptions.named(ARGV.formulae.map(&:full_name)).print
    elsif search_type.size > 1
      odie "Pick one, and only one, of -s/--search, -n/--name, or -d/--description."
    else
      if arg = ARGV.named.first
        regex = Homebrew::query_regexp(arg)
        results = Descriptions.search(regex, search_type.first)
        results.print
      else
        odie "You must provide a search term."
      end
    end
  end
end