# lib/tb/ltsv.rb - LTSV related fetures for table library
#
# Copyright (C) 2013-2014 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
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# GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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require 'stringio'

module Tb
  def Tb.ltsv_escape_key(str)
    if /[\0-\x1f":\\\x7f]/ =~ str
      '"' +
      str.gsub(/[\0-\x1f":\\\x7f]/) {
        ch = $&
        case ch
        when "\0"; '\0'
        when "\a"; '\a'
        when "\b"; '\b'
        when "\f"; '\f'
        when "\n"; '\n'
        when "\r"; '\r'
        when "\t"; '\t'
        when "\v"; '\v'
        when "\e"; '\e'
        else
          "\\x%02X" % ch.ord
        end
      } +
      '"'
    else
      str
    end
  end

  def Tb.ltsv_escape_value(str)
    if /[\0-\x1f"\\\x7f]/ =~ str
      '"' +
      str.gsub(/[\0-\x1f"\\\x7f]/) {
        ch = $&
        case ch
        when "\0"; '\0'
        when "\a"; '\a'
        when "\b"; '\b'
        when "\f"; '\f'
        when "\n"; '\n'
        when "\r"; '\r'
        when "\t"; '\t'
        when "\v"; '\v'
        when "\e"; '\e'
        else
          "\\x%02X" % ch.ord
        end
      } +
      '"'
    else
      str
    end
  end

  def Tb.ltsv_unescape_string(str)
    if /\A\s*"(.*)"\s*\z/ =~ str
      $1.gsub(/\\([0abfnrtve]|x([0-9A-Fa-f][0-9A-Fa-f]))/) {
        if $2
          [$2].pack("H2")
        else
          case $1
          when "0"; "\0"
          when "a"; "\a"
          when "b"; "\b"
          when "f"; "\f"
          when "n"; "\n"
          when "r"; "\r"
          when "t"; "\t"
          when "v"; "\v"
          when "e"; "\e"
          else
            raise "[bug] unexpected escape"
          end
        end
      }
    else
      str
    end
  end

  def Tb.ltsv_split_line(line)
    line = line.chomp("\n")
    line = line.chomp("\r")
    ary = line.split(/\t/, -1)
    assoc = ary.map {|str|
      /:/ =~ str
      key = $`
      val = $'
      key = Tb.ltsv_unescape_string(key)
      val = Tb.ltsv_unescape_string(val)
      [key, val]
    }
    assoc
  end

  def Tb.ltsv_assoc_join(assoc)
    assoc.map {|key, val|
      Tb.ltsv_escape_key(key) + ':' + Tb.ltsv_escape_value(val)
    }.join("\t")
  end

  class LTSVReader < Tb::HashReader
    def initialize(io)
      super lambda {
        line = io.gets
        if line
          Hash[Tb.ltsv_split_line(line)]
        else
          nil
        end
      }
    end
  end

  class LTSVWriter < Tb::HashWriter
    def initialize(io)
      super lambda {|hash|
        io << (Tb.ltsv_assoc_join(hash) + "\n")
      }
    end
  end
end
