require 'ext_arr'
require 'stringio'
require 'strscan'

class ExtArc < ExtArr
  
  def str_to_entry(str)
    str
  end
  
  def entry_to_str(entry)
    entry.to_s
  end
  
  def reindex_by_scan(pattern=/\r?\n|$/)
    index_format = index.format
    reindex do |index|
      io.scan do |scan_pos, string|
        scanner = StringScanner.new(string)
        while advanced = scanner.search_full(pattern, true, false)
          break unless advanced > 0
            
          index.unframed_write [scan_pos, advanced]
          scan_pos += advanced 
        end
          
        scanner.restsize
      end
    end
  end
  
  def reindex_by_sep(options={})
    options = {
      :sep_string => $/,
      :entry_follows_sep => false,
      :exclude_sep => false
    }.merge(options)
    
    sep_string = options[:sep_string]
    entry_follows_sep = options[:entry_follows_sep]
    exclude_sep = options[:exclude_sep]
    sep_string_length = sep_string.length 
    
    reindex do |index|
      current_pos = 0
      entry_begin = 0
      
      io_length = io.length
      io.each_line(sep_string) do |line|
        # Note positions MUST be built up using line.length
        # io.pos cannot return positions greater than ~2.1e9
        current_pos += line.length
        entry_end = current_pos - (entry_follows_sep && current_pos != io_length ? 1 : 0)
        
        unless entry_end == entry_begin
          if exclude_sep
            if entry_follows_sep
              entry_begin += sep_string_length
            else
              entry_end -= sep_string_length
            end
          end
          
          index.unframed_write [entry_begin, entry_end-entry_begin]
          entry_begin = entry_end
        end
      end
    end
  end

  def reindex_by_line(options={}) # :nodoc:
    options = {
      :sep_string => $/,
      :break_before => false,
      :exclude_break => false
    }.merge(options)
    
    sep_string = options[:sep_string]
    break_before = options[:break_before]
    exclude_break = options[:exclude_break]
    
    reindex do |index|
      last_pos = 0
      current_pos = 0
      range_begin = 0
       
      io.each_line(sep_string) do |line|
        # Note positions MUST be built up using line.length
        # io.pos cannot return positions greater than ~2.1e9
        last_pos = current_pos
        current_pos += line.length
        
        if (block_given? ? yield(line) : true)
          range_end = (break_before || exclude_break) ? last_pos : current_pos
          unless range_end == range_begin
            index.unframed_write [range_begin, range_end-range_begin]
          end
          range_begin = (break_before && !exclude_break) ? last_pos : current_pos
        end
      end
      
      range_end = current_pos
      unless range_end == range_begin
        index.unframed_write [range_begin, range_end-range_begin]
      end
    end
  end
end