Module: Emfsvg::Svg::PathData::Parser

Defined in:
lib/emfsvg/svg/path_data.rb

Overview

Stateful parser walks the string once, emitting Commands as enough args accumulate for the current letter. Implicit repeats: subsequent arg groups after M/m are treated as L/l.

Class Method Summary collapse

Class Method Details

.emit_command(commands, letter, args) ⇒ Object

Raises:



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# File 'lib/emfsvg/svg/path_data.rb', line 58

def emit_command(commands, letter, args)
  raise FormatError, "unknown path command: #{letter}" unless ARG_COUNTS.key?(letter.upcase)

  commands << Command.new(letter: letter, args: args.dup)
end

.flush_command(_commands, letter, args) ⇒ Object

Raises:



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# File 'lib/emfsvg/svg/path_data.rb', line 64

def flush_command(_commands, letter, args)
  return unless letter
  return if args.empty?

  expected = ARG_COUNTS.fetch(letter.upcase, 0)
  return if args.size == expected

  raise FormatError, "path command #{letter} expected #{expected} args, got #{args.size}"
end

.implicit_repeat_letter(letter) ⇒ Object

M/m repeats as L/l per SVG spec; all other commands repeat as themselves.



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# File 'lib/emfsvg/svg/path_data.rb', line 76

def implicit_repeat_letter(letter)
  case letter
  when "M" then "L"
  when "m" then "l"
  else letter
  end
end

.parse(string) ⇒ Object 



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# File 'lib/emfsvg/svg/path_data.rb', line 23

def parse(string)
  return [] if string.nil? || string.empty?

  commands = []
  scanner = Scanner.new(string)
  current_letter = nil
  args = []

  while (token = scanner.next_token)
    case token
    when Symbol # command letter
      flush_command(commands, current_letter, args) if current_letter && args.any?
      current_letter = token.to_s
      args = []
      # Zero-arg commands (Z/z) emit immediately.
      if ARG_COUNTS.fetch(current_letter.upcase, 1).zero?
        emit_command(commands, current_letter, [])
        current_letter = nil
      end
    when Numeric
      raise FormatError, "path data begins with a number: #{string.inspect}" if current_letter.nil?

      args << token
      if args.size == ARG_COUNTS.fetch(current_letter.upcase)
        emit_command(commands, current_letter, args)
        args = []
        current_letter = implicit_repeat_letter(current_letter)
      end
    end
  end

  flush_command(commands, current_letter, args) if current_letter && args.any?
  commands
end