Class: Flexr::Runtime::Interpreter

Inherits:
Object
  • Object
show all
Defined in:
lib/flexr/runtime/interpreter.rb

Instance Method Summary collapse

Constructor Details

#initialize(lexer) ⇒ Interpreter

Returns a new instance of Interpreter.



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# File 'lib/flexr/runtime/interpreter.rb', line 14

def initialize(lexer)
  @lexer = lexer
  klass = lexer.class
  @compiled = klass.__flexr_compiled
  @rules = klass.__flexr_rules
  @config = klass.__flexr_config
end

Instance Method Details

#scan ⇒ Object 



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# File 'lib/flexr/runtime/interpreter.rb', line 22

def scan
  machine = @compiled.machines.fetch(@lexer.state)
  position = @lexer.byte_pos
  return nil unless @lexer.valid_utf8_at?(position)
  return scan_firstmatch(position) if @config.backend == :firstmatch
  return scan_fast(machine, position) if fast_path?(machine)

  buffer = @lexer.buffer
  state = machine.dfa.start
  best = reference_match(position, buffer)
  cursor = position
  best = consider_acceptances(machine, state, cursor, position, buffer, best) if @config.options[:allow_empty_match]
  acceleration_regions = acceleration_enabled? ? acceleration_regions_for(machine) : nil

  while buffer.ensure_available?(cursor + 1)
    if acceleration_regions && (region = acceleration_regions[state]) &&
        !@disabled_auto_acceleration&.key?(region)
      acceptance = machine.dfa.accepts[state].first
      token_rule = acceptance&.rule_index
      accelerated_end = accelerate(
        region, buffer, cursor, token_rule: token_rule, token_start: position
      )
      if accelerated_end && accelerated_end > cursor
        cursor = accelerated_end
        best = consider_acceptances(machine, state, cursor, position, buffer, best)
        next
      end
    end

    byte = buffer.getbyte(cursor)
    @lexer.consume_step!
    state = transition(machine.dfa, state, byte)
    break unless state

    cursor += 1
    acceptance = machine.dfa.accepts[state].first
    ensure_token_size!(cursor, position, rule: acceptance&.rule_index)
    best = consider_acceptances(machine, state, cursor, position, buffer, best)
  end
  best
end

#scan_fast(machine, position) ⇒ Object 



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# File 'lib/flexr/runtime/interpreter.rb', line 64

def scan_fast(machine, position)
  buffer = @lexer.buffer
  dfa = machine.dfa
  accepts = dfa.accepts
  rules = @rules
  transitions = dfa.transitions
  ec = dfa.ec
  direct = dfa.direct
  direct_nxt = direct&.fetch(:nxt)
  direct_classes = direct&.fetch(:classes)
  source = buffer.stable_source
  guarded_steps = @lexer.scan_steps_guarded?
  text_start = @lexer.more_text_start || position
  max_token_size = @lexer.max_token_size
  token_limit_required = @lexer.token_limit_required?
  state = dfa.start
  cursor = position
  best = nil

  if source && !guarded_steps && !token_limit_required
    while cursor < source.bytesize || buffer.ensure_available?(cursor + 1)
      byte = source.getbyte(cursor)
      state = if direct_nxt
        class_id = ec[byte]
        value = direct_nxt[(state * direct_classes) + class_id]
        value >= 0 ? value : nil
      else
        transitions[state][ec[byte]]
      end
      break unless state

      cursor += 1
      acceptance = accepts[state].first
      next unless acceptance

      rule = rules.fetch(acceptance.rule_index)
      next if best && cursor == best.total_end_pos && rule.index > best.rule.index

      best ||= (@match ||= Match.new)
      best.rule = rule
      best.start_pos = position
      best.end_pos = cursor
      best.total_end_pos = cursor
    end
    return best
  end

  while cursor < buffer.bytesize || buffer.ensure_available?(cursor + 1)
    byte = buffer.getbyte(cursor)
    @lexer.consume_step! if guarded_steps
    state = if direct_nxt
      class_id = ec[byte]
      value = direct_nxt[(state * direct_classes) + class_id]
      value >= 0 ? value : nil
    else
      transitions[state][ec[byte]]
    end
    break unless state

    cursor += 1
    acceptance = accepts[state].first
    if token_limit_required
      size = cursor - text_start
      @lexer.defer_token_size_check!(size, rule: acceptance&.rule_index) if size > max_token_size
    end
    next unless acceptance

    rule = rules.fetch(acceptance.rule_index)
    next if best && cursor == best.total_end_pos && rule.index > best.rule.index

    best ||= (@match ||= Match.new)
    best.rule = rule
    best.start_pos = position
    best.end_pos = cursor
    best.total_end_pos = cursor
  end
  best
end