Rake example

dot_file_parser.rb

# Parses Graphviz .dot files
class DotFileParser
  EDGE_PATTERN = /"([^"]*)" -> "([^"]*)"/
  NODE_PATTERN = /\A\t"([^"]*)" \[/

  def initialize(filename)
    @filename = filename
  end

  def each_edge
    readlines.each do |line|
      matchdata = line.match(EDGE_PATTERN)
      next if matchdata.nil?

      yield(matchdata[1], matchdata[2])
    end
  end

  def each_node
    readlines.each do |line|
      matchdata = line.match(NODE_PATTERN)
      next if matchdata.nil?

      yield(matchdata[1])
    end
  end

  def all_nodes
    return @all_nodes if @all_nodes

    @all_nodes = Set.new
    each_node do |node|
      @all_nodes.add(node)
    end
    @all_nodes
  end

  def connections(node)
    nodes = Set.new
    each_edge do |from, to|
      next unless from == node || to == node

      nodes.add(from) if to == node
      nodes.add(to) if from == node
    end
    nodes
  end

  def clusters
    return @clusters if @clusters

    remaining_nodes = all_nodes

    @clusters = []
    one_node_clusters = Set.new

    until remaining_nodes.empty?
      cluster_nodes = Set.new

      current_nodes = Set[remaining_nodes.first]
      current_connections = Set.new

      until current_nodes.empty?
        cluster_nodes += current_nodes
        remaining_nodes -= current_nodes

        current_connections = Set.new
        current_nodes.each do |node|
          current_connections += connections(node) & remaining_nodes
        end
        current_nodes = current_connections
      end

      if cluster_nodes.size == 1
        one_node_clusters << cluster_nodes.first
      else
        @clusters << cluster_nodes
      end
    end

    @clusters << one_node_clusters unless one_node_clusters.empty?
    @clusters
  end

  def filtered_lines(nodes)
    readlines.each.with_index do |line, i|
      yield(line) if i < 3 || i > readlines.length - 2

      yield(line) if line =~ NODE_PATTERN && nodes.include?(line.match(NODE_PATTERN)[1])
      yield(line) if line =~ EDGE_PATTERN && nodes.include?(line.match(EDGE_PATTERN)[1]) &&
                     nodes.include?(line.match(EDGE_PATTERN)[2])
    end
  end

  private

  def readlines
    @readlines ||= File.readlines(@filename)
  end
end

railroad.rake

require 'rake/clean'
require_relative 'dot_file_parser'

namespace :railroady_demo do
  desc 'set up railroady demo prerequisites'
  task :setup do
    # Usage: bin/rake railroady_demo:setup
    system 'brew install graphviz librsvg'
  end
end

MODEL_PATTERN = %r{\Adoc/models_(brief|complete)\.dot\z}

rule MODEL_PATTERN => 'railroady_demo:setup' do |t|
  # Usage: bin/rake doc/models_{brief,complete}.dot
  require 'open3'

  command = ['railroady', '-o', t.name, '-lamM']
  command << '-b' if 'brief' == t.name.match(MODEL_PATTERN)[1]

  stdin, stdout, stderr = Open3.popen3(*command)
  stdin.close
  puts stderr.read + stdout.read
end
CLEAN << FileList['doc/*.dot']

desc 'clusters'
task clusters: 'doc/models_brief.dot' do |t|
  dot_parser = DotFileParser.new(t.source)

  source_parts = t.source.split('.')
  dot_parser.clusters.each.with_index do |cluster_nodes, i|
    output_file = [source_parts[0..-2], "cluster#{i}", source_parts[-1]].join('.')
    File.open(output_file, 'w') do |output|
      dot_parser.filtered_lines(cluster_nodes) do |line|
        output << line
      end
    end
  end
end

rule %r{\Adoc/.*\.svg\z} => '.dot' do |t|
  # Usage: bin/rake doc/<anything>.svg
  require 'shellwords'

  system "dot -Tsvg #{Shellwords.escape(t.source)} > " \
         "#{Shellwords.escape(t.name)}"
end
CLEAN << FileList['doc/*.svg']

rule %r{\Adoc/.*\.pdf\z} => '.svg' do |t|
  # Usage: bin/rake doc/<anything>.pdf
  require 'shellwords'

  system "rsvg-convert -f pdf -o #{Shellwords.escape(t.name)} " \
         "#{Shellwords.escape(t.source)}"
end
CLOBBER << FileList['doc/*.pdf']

desc 'Generate cluster PDFs'
task generate_pdfs: FileList['doc/*.cluster*.dot'].ext('.pdf')
# Usage: bin/rake clusters generate_pdfs