S3LineLogParser

S3LineLogParser.rb

class S3LineLogParser
  attr_reader :data, :cursor
  def initialize(data)
    @data = data
    @cursor = 0
  end
  def read_all
    tokens = []
    while @cursor < @data.length
      tokens << read_something
    end
    
    tokens
  end
  def read_something
    la = @data[@cursor]
    case la
    when '['; read_bracketed
    when '"'; read_quoted
    when ' '; raise "Error: found a space at #{@cursor}"
    else; read_plain
    end
  end
  def read_bracketed
    s = []
    @cursor += 1
    loop do
      c = @data[@cursor]
      @cursor += 1
      if c == ']' || c == nil
        @cursor += 1
        break
      end
      s << c
    end
    s.join
  end
  def read_quoted
    s = []
    esc = nil
    @cursor += 1
    loop do
      c = @data[@cursor]
      @cursor += 1
      if esc
        if c == '"'
          s << c
        else
          raise "Unknown escape char: 0x#{c.ord.to_s(16)}."
        end
        esc = nil
      elsif c == '"' || c == nil
        @cursor += 1
        break
      end
      s << c
    end
    s.join
  end
  def read_plain
    s = []
    loop do
      c = @data[@cursor]
      @cursor += 1
      break if c == " " || c == "\t" || c == nil
      s << c
    end
    s.join
  end
end