# escape.rb - escape/unescape library for several formats
#
# Copyright (C) 2006,2007 Tanaka Akira  <akr@fsij.org>
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
#  1. Redistributions of source code must retain the above copyright notice, this
#     list of conditions and the following disclaimer.
#  2. Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions and the following disclaimer in the documentation
#     and/or other materials provided with the distribution.
#  3. The name of the author may not be used to endorse or promote products
#     derived from this software without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
# WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
# EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
# IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
# OF SUCH DAMAGE.

# Escape module provides several escape functions.
# * shell command
# modified to work only with shell
module ShellEscape
  module_function

  # Escape.shell_command composes
  # a sequence of words to
  # a single shell command line.
  # All shell meta characters are quoted and
  # the words are concatenated with interleaving space.
  def command(*args)
    args.map{ |arg| word(arg) } * ' '
  end

  # Escape.shell_single_word quotes shell meta characters.
  #
  # The result string is always single shell word, even if
  # the argument is "".
  def word(word)
    word = word.to_s
    if word.empty?
      "''"
    elsif %r{\A[0-9A-Za-z+,./:=@_-]+\z} =~ word
      word
    else
      result = ''
      word.scan(/('+)|[^']+/) {
        if $1
          result << %q{\'} * $1.length
        else
          result << "'#{$&}'"
        end
      }
      result
    end
  end
end