Module: Grep

Defined in:
lib/code_zauker/grep.rb

Instance Method Summary collapse

Instance Method Details

#grep(file, pattern, pre_context = 0, post_context = 0, print_filename = true) ⇒ Object

Grep works like a shell grep. ‘file’ can be either a string, containing the name of a file to load and handle, or an IO object (such as $stdin) to deal with. ‘pattern’ can be either a string or Regexp object which contains a pattern. Patterns as strings treat no part of the string as ‘special’, such as ‘.’ or ‘?’ in a regex. ‘pre_context’ and ‘post_context’ determine the amount of lines to return that came before or after the content that was matched, respectively. If there are overlaps in the context, no duplicates will be printed.



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# File 'lib/code_zauker/grep.rb', line 58

def grep(file, pattern, pre_context=0, post_context=0, print_filename=true)
  currentline=0
  if file.kind_of? String
    fileName=file
    file = File.new(file, "r")
  else
    fileName=""
  end

  if ! file.kind_of? IO
    throw IOError.new("File must be the name of an existing file or IO object")
  end

  if pattern.kind_of? String
    pattern = /#{Regexp.escape(pattern)}/
  end

  if ! pattern.kind_of? Regexp
    throw StandardError.new("Pattern must be string or regexp")
  end

  cache = []
  lines = []

  util=CodeZauker::Util.new()

  loop do
    begin
      line = util.ensureUTF8(file.readline)
      
      currentline +=1
      cache.shift unless cache.length < pre_context

      cache.push("#{currentline}:#{line}")
      
      if line =~ pattern
        lines += cache
        cache = []
        if post_context > 0
          post_context.times do
            begin                
              utf8line=util.ensureUTF8(file.readline)
              lines.push("#{currentline}:#{utf8line}")                
              currentline +=1
            rescue IOError => e
              break
            end
          end
        end
      end
    rescue IOError => e
      break
    rescue ArgumentError =>e2
      # Rethrow a probably UTF-8 fatal error
      puts "Pattern Matching failed on \n\t#{fileName}\n\tLine:#{line}"
      puts "Encoding of line:#{line.encoding.name} Valid? #{line.valid_encoding?}"
      #raise e2
    end
  end
  

  file.each_line do |untrustedLine|
    cache.shift unless cache.length < pre_context
    line=util.ensureUTF8(untrustedLine)
    cache.push(line)

    if line =~ pattern
      lines += cache
      if post_context > 0
        post_context.times do
          begin
            utf8line=util.ensureUTF8(file.readline)
            lines.push("#{currentline}:#{utf8line}")  
            currentline +=1
          rescue Exception => e
            break
          end
        end
      end
    end
  end

  return lines
end