lib/buildr/core/help.rb

# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with this
# work for additional information regarding copyright ownership.  The ASF
# licenses this file to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
# License for the specific language governing permissions and limitations under
# the License.

module Buildr #:nodoc:

  module Help #:nodoc:
    class << self

      def <<(arg)
        if arg.respond_to?(:call)
          texters << arg
        else
          texters << lambda { arg }
        end
      end

      def to_s
        texters.map(&:call).join("\n")
      end

    protected
      def texters
        @texters ||= []
      end

    end
  end

  class << self
    def help(&block)
      Help << block if block_given?
      Help
    end
  end

end


task 'help' do
  # Greeter
  puts 'Usage:'
  puts '  buildr [-f rakefile] {options} targets...'
  puts

  # Show only the top-level projects.
  projects.reject(&:parent).tap do |top_level|
    unless top_level.empty?
      puts 'Top-level projects (buildr help:projects for full list):'
      width = [top_level.map(&:name).map(&:size), 20].flatten.max
      top_level.each do |project|
        puts project.comment.to_s.empty? ? project.name : ("  %-#{width}s  # %s" % [project.name, project.comment])
      end
      puts
    end
  end

  # Show all the top-level tasks, excluding projects.
  puts 'Common tasks:'
  task('help:tasks').invoke
  puts
  puts 'For help on command line options:'
  puts '  buildr --help'
  puts Buildr.help.to_s
end


module Buildr

  # :call-seq:
  #   help() { ... }
  #
  # Use this to enhance the help task, e.g. to print some important information about your build,
  # configuration options, build instructions, etc.
  def help(&block)
    Buildr.help << block
  end

end


namespace 'help' do

  desc 'List all projects defined by this buildfile'
  task 'projects' do
    width = projects.map(&:name).map(&:size).max
    projects.each do |project|
      puts project.comment.to_s.empty? ? "  #{project.name}" : ("  %-#{width}s  # %s" % [project.name, project.comment])
    end
  end

  desc 'List all tasks available from this buildfile'
  task 'tasks' do
    Buildr.application.tasks.select(&:comment).reject { |task| Project === task }.tap do |tasks|
      width = [tasks.map(&:name).map(&:size), 20].flatten.max
      tasks.each do |task|
        printf "  %-#{width}s  # %s\n", task.name, task.comment
      end
      puts
    end
  end

end