Class: Deb822::Scanner

Inherits:
Object
  • Object
show all
Defined in:
lib/deb822/scanner.rb

Overview

Low-level parser for deb822 documents

Constant Summary collapse

WS = 
/[ \t]/

Instance Method Summary collapse

Constructor Details

#initialize(input) ⇒ Scanner

Returns a new instance of Scanner.



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# File 'lib/deb822/scanner.rb', line 7

def initialize(input)
  @input = input.is_a?(String) ? StringIO.new(input) : input

  @in_paragraph = false
end

Instance Method Details

#each_line ⇒ Object Also known as: lines 



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# File 'lib/deb822/scanner.rb', line 55

def each_line
  return to_enum(:each_line) unless block_given?

  while l = next_line
    yield l
  end
end

#next_line ⇒ Object 



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# File 'lib/deb822/scanner.rb', line 15

def next_line
  loop do
    begin
      line = @input.readline
    rescue EOFError
      break
    end

    case line
    when /\A#{WS}*\Z/o
      # > The paragraphs are separated by empty lines.
      # > Parsers may accept lines consisting solely of U+0020 SPACE and U+0009 TAB as paragraph separators
      if @in_paragraph
        @in_paragraph = false
        break [:paragraph_separator]
      else
        next
      end
    when /\A#/
      # > Lines starting with U+0023 ‘#’, without any preceding whitespace are comments lines
      break [:comment, $']
    when /\A(#{FieldName::PATTERN}):#{WS}*/o
      name = $1
      value = $'.chomp
      @in_paragraph = true
      break [:field, name, value]
    when /\A#{WS}\.?/o
      # > The lines after the first are called continuation lines and must start with a U+0020 SPACE or a U+0009 TAB.
      # > Empty lines in field values are usually escaped by representing them by a U+0020 SPACE followed
      # > by a dot (U+002E ‘.’).
      raise FormatError, "Unexpected continuation line: #{line.inspect}" unless @in_paragraph
      break [:continuation, $']
    else
      raise FormatError, "Ill-formed line: #{line.inspect}"
    end

    return nil
  end
end