# module Puppet::Util::Diff

Provide a diff between two strings.

### Public Class Methods

diff(old, new) click to toggle source

    # File lib/puppet/util/diff.rb, line 8
    def diff(old, new)
      return '' unless diff_cmd = Puppet[:diff] and diff_cmd != ""

      command = [diff_cmd]
      if args = Puppet[:diff_args] and args != ""
        command << args
      end
      command << old << new
      Puppet::Util::Execution.execute(command, :failonfail => false, :combine => false)
    end

### Public Instance Methods

lcs_diff(data_old, data_new, format=:unified, context_lines=3) click to toggle source

return diff string of two input strings format defaults to unified context defaults to 3 lines

    # File lib/puppet/util/diff.rb, line 24
    def lcs_diff(data_old, data_new, format=:unified, context_lines=3)
      unless Puppet.features.diff?
        Puppet.warning "Cannot provide diff without the diff/lcs Ruby library"
        return ""
      end
      data_old = data_old.split(/\n/).map! { |e| e.chomp }
      data_new = data_new.split(/\n/).map! { |e| e.chomp }

      output = ""

      diffs = ::Diff::LCS.diff(data_old, data_new)
      return output if diffs.empty?

      oldhunk = hunk = nil
      file_length_difference = 0

      diffs.each do |piece|
        begin

          hunk = ::Diff::LCS::Hunk.new(
            data_old, data_new, piece,
              context_lines,

              file_length_difference)
          file_length_difference = hunk.file_length_difference
        next unless oldhunk
        # Hunks may overlap, which is why we need to be careful when our
        # diff includes lines of context. Otherwise, we might print
        # redundant lines.
        if (context_lines > 0) and hunk.overlaps?(oldhunk)
          hunk.unshift(oldhunk)
        else
          output << oldhunk.diff(format)
        end
        ensure
          oldhunk = hunk
          output << "\n"
        end
      end

      # Handle the last remaining hunk
      output << oldhunk.diff(format) << "\n"
    end

string_file_diff(path, string) click to toggle source

    # File lib/puppet/util/diff.rb, line 68
    def string_file_diff(path, string)
      tempfile = Tempfile.new("puppet-diffing")
      tempfile.open
      tempfile.print string
      tempfile.close
      notice "\n" + diff(path, tempfile.path)
      tempfile.delete
    end