I needed to go through a large number of Xcode-generated source-code files the other day, replacing the copyright line with a license header statement. Since there were lots of files in a nested structure I decided to use a script, and I added in a glob pattern to exclude certain files/folders— because there was some public domain source in ther…

ChangeLicenses.rb

#!/usr/bin/ruby

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# A copy of the GNU General Public License can be found at
# <http://www.gnu.org/licenses/gpl-3.0.html>.

require 'optparse'
require 'fileutils'
require 'rubygems'

@@Verbose = 0
@@DryRun = false
@@Exclude = ''
@@Template = nil

OptionParser.new do |opts|
  opts.banner = "Usage: ChangeLicenses [OPTIONS] [-e exclusion_regex] [-c copyright_owner] -t template_file"
  opts.separator ""
  opts.separator "Scans recursively through the current folder (using an optional exclusion glob pattern) to"
  opts.separator "locate all C/C++ header and source files, and then modifies their Xcode-style source"
  opts.separator "headers to include the text from a named input file or stdin."
  opts.separator ""
  opts.separator "The appended text does not need to be prefixed with commenting characters; the program"
  opts.separator "will do that for you, matching Xcode's standard double-spaced indents."
  opts.separator ""
  opts.separator "Options:"
  
  opts.on_tail( "-h", "--help", "Show this message.", :NONE) do
    puts opts
    exit
  end
  opts.on("-v", "--verbose",
          "Print information about the program's operation. Specify",
          "up to three times, with each one increasing the amount",
          "of data output.", :NONE) do
    @@Verbose += 1
  end
  opts.on("-d", "--dry-run", "Don't modify any files. Best used",
          "with -vvv which will print out all new files. Optional.", :NONE) do |v|
    @@DryRun = v
  end
  opts.on("-e", "--exclude", "Specifies a glob pattern. All files",
          "whose sub-paths are matched by the pattern are ignored.",
          "Optional.", :REQUIRED) do |v|
    @@Exclude = v unless v == ''
  end
  opts.on("-t", "--template", "Specifies the path to a plain-",
          "text file containing the template for the text to",
          "insert into the document's leading header. If not",
          "specified, the template text is read from stdin.", :REQUIRED) do |v|
    fail "Error: File '#{arg}' not found." unless File.exists?(v)
    fail "Error: File '#{arg}' unreadable." unless File.readable?(v)
    @@Template = File.read(v, nil)
  end
end.parse!

if @@Template.nil?
  @@Template = STDIN.read
end

fail "Error: No template supplied." if @@Template == ''

@@CopyrightLineRegex = %r{^(//  Copyright \(c\) \d+ ).*?(\. All rights reserved.)$}

# glob ALL THE THINGS
Dir.glob("**/*.{h,c,cpp}") do |filename|
  # skip anything matched by the exclusion glob
  if File.fnmatch(@@Exclude, filename)   # File.fnmatch('something', '') always returns false
    puts "* Ignoring #{filename}" if @@Verbose > 0
    next
  end
  
  puts "#{filename}" if @@Verbose > 0
  
  tmpname = "#{filename}.tmp"
  File.open(tmpname, "w") do |tmpfile|
    # after writing the copyright/license block, we ignore all further comments lines
    #  until we see a non-comment line
    skipCommentLines = false
    
    File.foreach(filename) do |line|
      if line =~ @@CopyrightLineRegex
        # this is the copyright line, which will be replaced with the license
        # the license is expected to contain a copyright line already
        
        # For each line of the license template, prefix it and write it out
        @@Template.each_line do |template_line|
          tmpfile.puts "//  #{template_line}"
        end
        
        tmpfile.puts "//"
        
        # skip any non-empty comment lines now
        skipCommentLines = true
      elsif line !~ %r{^//} || !skipCommentLines
        skipCommentLines = false
        # all remaining lines are output verbatim
        tmpfile.puts line
      end
    end
  end
  
  if @@Verbose > 2
    File.foreach(tmpname) do |line|
      puts line
    end
  end
  
  unless @@DryRun
    # move the original file to the side, and move the new file in, then delete old file
    oldname = "#{filename}.old"
    FileUtils.mv(filename, oldname)
    FileUtils.mv(tmpname, filename)
    FileUtils.rm(oldname)
  else
    # dry-run mode: delete the temp file
    FileUtils.rm(tmpname)
  end
end