Method: EBNF::Writer#initialize

Defined in:
lib/ebnf/writer.rb

#initialize(rules, out: $stdout, html: false, **options) ⇒ Writer

Returns a new instance of Writer.

Parameters:

  • rules (Array<Rule>)
  • options (Hash{Symbol => Object})
  • :out (#write) —

    ($stdout)

Options Hash (**options):

  • :format (Symbol) 


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# File 'lib/ebnf/writer.rb', line 59

def initialize(rules, out: $stdout, html: false, **options)
  @options = options.dup

  # Determine max LHS length
  max_id = rules.max_by {|r| r.id.to_s.length}.id.to_s.length
  max_sym = rules.max_by {|r| r.sym.to_s.length}.sym.to_s.length
  lhs_length = max_sym + 3
  lhs_fmt = "%<sym>-#{max_sym}s ::= "
  if max_id > 0
    lhs_fmt = "%<id>-#{max_id+2}s " + lhs_fmt
    lhs_length += max_id + 3
  end
  rhs_length = LINE_LENGTH - lhs_length

  if html
    # Output as formatted HTML
    begin
      require 'haml'
      hout = Haml::Engine.new(HAML_DESC).render(self, rules: rules) do |rule|
        formatted_expr = format(rule.expr)
        formatted_expr.length > rhs_length ? format(rule.expr, "\n") : formatted_expr
      end
      out.write hout
      return
    rescue LoadError
      $stderr.puts "Generating HTML requires haml gem to be loaded"
    end
  end

  # Format each rule, considering the available rhs size
  rules.each do |rule|
    buffer = if rule.pass?
      "%-#{lhs_length-2}s" % "@pass"
    else
      lhs_fmt % {id: "[#{rule.id}]", sym: rule.sym}
    end
    formatted_expr = format(rule.expr)
    if formatted_expr.length > rhs_length
      buffer << format(rule.expr, ("\n" + " " * lhs_length))
    else
      buffer << formatted_expr
    end
    out.puts(buffer)
  end
end