JSON見やすく表示

print_json.rb

#!/usr/bin/env ruby

require 'optparse'
require 'json'

$options = {
  :print_type => false,
  :print_each => true
}

opt = OptionParser.new
opt.on('-t') {|v| $options[:print_type] = true}
opt.on('-f') {|v| $options[:print_each] = false}

argv = opt.parse(ARGV);

def pretty_json(data, n = 0)
  indent = '  '
  dir = indent * n
  result = []

  case data
  when Hash
    if data.empty?
      result << "{}"
    else
      result << "{"
      data.each{|key, value| result << "#{dir + indent}#{key}: #{pretty_json(value, n + 1)}" }
      result << "#{dir}}"
    end
  when Array
    if data.empty?
      result << "[]"
    else
      result << "["
      data.each do |value|
        result << "#{dir + indent}#{pretty_json(value, n + 1)}"
        break if $options[:print_type] || !$options[:print_each]
      end
      result << "#{dir}]"
    end
  when String
    result << ($options[:print_type] ? '(String)' : data.to_json)
  when Numeric
    result << ($options[:print_type] ? '(Number)' : data.to_json)
  else
    result << ($options[:print_type] ? '(Null)' : data.to_json)
  end.join("\n")
end

def print_json(input)
  STDOUT.puts pretty_json(JSON.parse(input, :max_nesting => false))
  true
rescue
  begin
    STDOUT.puts JSON.parse("[#{input}]").first.to_json
    true
  rescue
    STDERR.puts 'invalid json'
    false
  end
end

class LineReader
  def initialize(stdin)
    @buffer = ''
    @stdin = stdin
  end

  def next
    @buffer += @stdin.sysread(1) until @buffer[/\n/]
    out, *others = @buffer.split("\n")
    @buffer = others.join("\n")
    out
  rescue EOFError => ex
    if @buffer == ''
      nil
    else
      out = @buffer
      @buffer = ''
      out
    end
  end

  def self.each
    STDIN.sync = true
    STDOUT.sync = true

    instance = self.new(STDIN)

    while line = instance.next
      yield line
    end
  end
end

if not argv[0].nil? then
  print_json argv[0]
elsif File.pipe?(STDIN) then
  [:INT, :TERM].each do |signal|
    trap(signal) do
      STDERR.puts "got sig#{signal.to_s.downcase}"
      exit
    end
  end

  LineReader.each do |line|
    print_json line
  end
else
  STDERR.puts "Usage: #{File.basename(__FILE__)} <json>"
  exit 1
end