Method: Antlr4::Runtime::ParserATNSimulator#adaptive_predict

Defined in:
lib/antlr4/runtime/parser_atn_simulator.rb

#adaptive_predict(input, decision, outer_ctx) ⇒ Object 



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# File 'lib/antlr4/runtime/parser_atn_simulator.rb', line 41

def adaptive_predict(input, decision, outer_ctx)
  if @debug || @debug_list_atn_decisions
    puts('adaptivePredict decision ' << decision.to_s << ' exec la(1)==' << lookahead_name(input) << ' line ' << input.lt(1).line.to_s << ':' << input.lt(1).char_position_in_line.to_s)
  end

  @_input = input
  @_start_index = input.index
  @_outer_context = outer_ctx
  dfa = @decision_to_dfa[decision]
  @_dfa = dfa

  m = input.mark
  index = @_start_index

  # Now we are certain to have a specific decision's DFA
  # But, do we still need an initial state?
  begin
    dfa.precedence_dfa? ? s0 = dfa.precedence_start_state(parser.precedence) : s0 = dfa.s0

    if s0.nil?
      outer_ctx = ParserRuleContext::EMPTY if outer_ctx.nil?
      if @debug || @debug_list_atn_decisions
        puts('predictATN decision ' << dfa.decision.to_s << ' exec la(1)==' << lookahead_name(input) << ', outer_ctx=' << outer_ctx.to_s_recog(@parser))
      end

      full_ctx = false
      s0_closure = compute_start_state(dfa.atn_start_state, ParserRuleContext::EMPTY, full_ctx)

      if dfa.precedence_dfa?
        dfa.s0.configs = s0_closure # not used for prediction but useful to know start configs anyway
        s0_closure = apply_precedence_filter(s0_closure)
        s0 = add_dfa_state(dfa, DFAState.new(s0_closure))
        dfa.precedence_start_state(@parser.precedence, s0)
      else
        s0 = add_dfa_state(dfa, DFAState.new(s0_closure))
        dfa.s0 = s0
      end
    end

    alt = exec_atn(dfa, s0, input, index, outer_ctx)
    if @debug
      puts('DFA after predictATN: ' << dfa.to_s2(@parser.get_vocabulary))
    end
    return alt
  ensure
    @merge_cache = nil # wack cache after each prediction
    @_dfa = nil
    input.seek(index)
    input.release(m)
  end
end