Class: Antlr4::Runtime::DefaultErrorStrategy

Inherits:
ANTLRErrorStrategy show all
Defined in:
lib/antlr4/runtime/default_error_strategy.rb

Direct Known Subclasses

BailErrorStrategy

Instance Method Summary collapse

Methods inherited from ANTLRErrorStrategy

#in_error_recovery_mode

Constructor Details

#initialize ⇒ DefaultErrorStrategy

Returns a new instance of DefaultErrorStrategy.



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 4

def initialize
  @error_recovery_mode = false
  @last_error_index = -1
  @last_error_states = nil
  @next_tokens_context = nil
  @next_tokens_state = nil
end

Instance Method Details

#begin_error_condition(_recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 16

def begin_error_condition(_recognizer)
  @error_recovery_mode = true
end

#consume_until(recognizer, set) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 302

def consume_until(recognizer, set)
  ttype = recognizer._input.la(1)
  while ttype != Token::EOF && !set.contains(ttype)
    recognizer.consume
    ttype = recognizer._input.la(1)
  end
end

#end_error_condition(_recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 24

def end_error_condition(_recognizer)
  @error_recovery_mode = false
  @last_error_states = nil
  @last_error_index = -1
end

#error_recovery_mode?(_recognizer) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 20

def error_recovery_mode?(_recognizer)
  @error_recovery_mode
end

#error_recovery_set(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 286

def error_recovery_set(recognizer)
  atn = recognizer._interp.atn
  ctx = recognizer._ctx
  recover_set = IntervalSet.new
  while !ctx.nil? && ctx.invoking_state >= 0
    # compute what follows who invoked us
    invoking_state = atn.states[ctx.invoking_state]
    rt = invoking_state.transition(0)
    follow = atn.next_tokens(rt.follow_state)
    recover_set.add_all(follow)
    ctx = ctx.parent
  end
  recover_set.remove(Token::EPSILON)
  recover_set
end

#escape_ws_and_quote(s) ⇒ Object

if ( s==nil ) return s



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 279

def escape_ws_and_quote(s) #    if ( s==nil ) return s
  s = s.sub("\n", '\\n')
  s = s.sub("\r", '\\r')
  s = s.sub("\t", '\\t')
  "'" + s + "'"
end

#expected_tokens(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 251

def expected_tokens(recognizer)
  recognizer.expected_tokens
end

#get_missing_symbol(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 229

def get_missing_symbol(recognizer)
  current_symbol = recognizer.current_token
  expecting = expected_tokens(recognizer)
  expected_token_type = Token::INVALID_TYPE
  unless expecting.is_nil
    expected_token_type = expecting.min_element # get any element
  end
  if expected_token_type == Token::EOF
    token_text = '<missing EOF>'
  else
    token_text = '<missing ' + recognizer.get_vocabulary.display_name(expected_token_type) + '>'
  end
  current = current_symbol
  look_back = recognizer._input.lt(-1)
  current = look_back if current.type == Token::EOF && !look_back.nil?

  pair = OpenStruct.new
  pair.a = current.source
  pair.b = current.source._input
  recognizer.token_factory.create(pair, expected_token_type, token_text, Token::DEFAULT_CHANNEL, -1, -1, current.line, current.char_position_in_line)
end

#recover(recognizer, _e) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 55

def recover(recognizer, _e)
  if @last_error_index == recognizer._input.index && !@last_error_states.nil? && @last_error_states.contains(recognizer._state_number)
    # uh oh, another error at same token index and previously-visited
    # state in ATN must be a case where lt(1) is in the recovery
    # token set so nothing got consumed. Consume a single token
    # at least to prevent an infinite loop this is a failsafe.
    #      System.err.println("seen error condition before index="+
    #                 lastErrorIndex+", states="+last_error_states)
    #      System.err.println("FAILSAFE consumes "+recognizer.getTokenNames()[recognizer.getInputStream().la(1)])
    recognizer.consume
  end
  @last_error_index = recognizer._input.index
  @last_error_states = IntervalSet.new if @last_error_states.nil?
  @last_error_states.add(recognizer._state_number)
  followSet = error_recovery_set(recognizer)
  consume_until(recognizer, followSet)
end

#recover_in_line(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 171

def recover_in_line(recognizer)
  # SINGLE TOKEN DELETION
  matched_symbol = single_token_deletion(recognizer)
  unless matched_symbol.nil?
    # we have deleted the extra token.
    # now, move past ttype token as if all were ok
    recognizer.consume
    return matched_symbol
  end

  # SINGLE TOKEN INSERTION
  return get_missing_symbol(recognizer) if single_token_insertion(recognizer)

  # even that didn't work must throw the exception
  exc = InputMismatchException.new
  exc.recognizer = recognizer
  if @next_tokens_context.nil?
    raise exc
  else
    exc.offending_token = recognizer._input.lt(1)
    exc.offending_state = @next_tokens_state
    exc.context = @next_tokens_context
    raise exc
  end
end

#report_error(recognizer, e) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 34

def report_error(recognizer, e)
  # if we've already reported an error and have not matched a token
  # yet successfully, don't report any errors.
  if error_recovery_mode?(recognizer)
    #      System.err.print("[SPURIOUS] ")
    return # don't report spurious errors
  end

  begin_error_condition(recognizer)
  if e.is_a? NoViableAltException
    report_no_viable_alternative(recognizer, e)
  elsif e.is_a? InputMismatchException
    report_input_mismatch(recognizer, e)
  elsif e.is_a? FailedPredicateException
    report_failed_predicate(recognizer, e)
  else
    STDERR.puts 'unknown recognition error type: ' + e.getClass.getName
    recognizer.notify_error_listeners(e.getOffendingToken, e.getMessage, e)
  end
end

#report_failed_predicate(recognizer, e) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 141

def report_failed_predicate(recognizer, e)
  rule_name = recognizer.rule_names[recognizer._ctx.rule_index]
  msg = 'rule ' + rule_name + ' ' + e.getMessage
  recognizer.notify_error_listeners(e.getOffendingToken, msg, e)
end

#report_input_mismatch(recognizer, e) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 136

def report_input_mismatch(recognizer, e)
  msg = 'mismatched input ' + token_error_display(e.offending_token) + ' expecting ' + e.expected_tokens.to_string_from_vocabulary(recognizer.get_vocabulary)
  recognizer.notify_error_listeners(e.offending_token, msg, e)
end

#report_match(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 30

def report_match(recognizer)
  end_error_condition(recognizer)
end

#report_missing_token(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 159

def report_missing_token(recognizer)
  return if error_recovery_mode?(recognizer)

  begin_error_condition(recognizer)

  t = recognizer.current_token
  expecting = expected_tokens(recognizer)
  msg = 'missing ' + expecting.to_string_from_vocabulary(recognizer.get_vocabulary) + ' at ' + token_error_display(t)

  recognizer.notify_error_listeners(t, msg, nil)
end

#report_no_viable_alternative(recognizer, e) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 121

def report_no_viable_alternative(recognizer, e)
  tokens = recognizer._input
  input = if !tokens.nil?
            if e.start_token.type == Token::EOF
              '<EOF>'
            else
              tokens.text4(e.start_token, e.offending_token)
            end
          else
            '<unknown input>'
          end
  msg = 'no viable alternative at input ' + escape_ws_and_quote(input)
  recognizer.notify_error_listeners(e.offending_token, msg, e)
end

#report_unwanted_token(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 147

def report_unwanted_token(recognizer)
  return if error_recovery_mode?(recognizer)

  begin_error_condition(recognizer)

  t = recognizer.current_token
  token_name = token_error_display(t)
  expecting = expected_tokens(recognizer)
  msg = 'extraneous input ' + token_name + ' expecting ' + expecting.to_string_from_vocabulary(recognizer.get_vocabulary)
  recognizer.notify_error_listeners(t, msg, nil)
end

#reset(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 12

def reset(recognizer)
  end_error_condition(recognizer)
end

#single_token_deletion(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 214

def single_token_deletion(recognizer)
  next_token_type = recognizer._input.la(2)
  expecting = expected_tokens(recognizer)
  if expecting.contains(next_token_type)
    report_unwanted_token(recognizer)

    recognizer.consume # simply delete extra token
    # we want to return the token we're actually matching
    matched_symbol = recognizer.current_token
    report_match(recognizer) # we know current token is correct
    return matched_symbol
  end
  nil
end

#single_token_insertion(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 197

def single_token_insertion(recognizer)
  current_symbol_type = recognizer._input.la(1)
  # if current token is consistent with what could come after current
  # ATN state, then we know we're missing a token error recovery
  # is free to conjure up and insert the missing token
  current_state = recognizer._interp.atn.states[recognizer._state_number]
  next_t = current_state.transition(0).target
  atn = recognizer._interp.atn
  expecting_at_ll2 = atn.next_tokens_ctx(next_t, recognizer._ctx)
  #    System.out.println("lt(2) set="+expecting_at_ll2.to_s(recognizer.getTokenNames()))
  if expecting_at_ll2.contains(current_symbol_type)
    report_missing_token(recognizer)
    return true
  end
  false
end

#symbol_text(symbol) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 270

def symbol_text(symbol)
  return symbol.text if symbol.respond_to? :text
  symbol.to_s
end

#symbol_type(symbol) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 275

def symbol_type(symbol)
  symbol.type
end

#sync(recognizer) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 73

def sync(recognizer)
  s = recognizer._interp.atn.states[recognizer._state_number]
  #    System.err.println("sync @ "+s.stateNumber+"="+s.getClass().getSimpleName())
  # If already recovering, don't try to sync
  return if error_recovery_mode?(recognizer)

  tokens = recognizer._input
  la = tokens.la(1)

  # try cheaper subset first might get lucky. seems to shave a wee bit off
  next_tokens = recognizer.atn.next_tokens(s)
  if next_tokens.contains(la)
    # We are sure the token matches
    @next_tokens_context = nil
    @next_tokens_state = ATNState.invalid_state_number
    return
  end

  if next_tokens.contains(Token::EPSILON)
    if @next_tokens_context.nil?
      # It's possible the next token won't match information tracked
      # by sync is restricted for performance.
      @next_tokens_context = recognizer._ctx
      @next_tokens_state = recognizer._state_number
    end
    return
  end

  case s.state_type
  when ATNState::BLOCK_START, ATNState::STAR_BLOCK_START, ATNState::PLUS_BLOCK_START, ATNState::STAR_LOOP_ENTRY
    # report error and recover if possible
    return unless single_token_deletion(recognizer).nil?

    exc = InputMismatchException.create(recognizer)
    raise exc

  when ATNState::PLUS_LOOP_BACK, ATNState::STAR_LOOP_BACK

    #      System.err.println("at loop back: "+s.getClass().getSimpleName())
    report_unwanted_token(recognizer)
    expecting = recognizer.expected_tokens
    what_follows_loop_iteration_or_rule = expecting.or(error_recovery_set(recognizer))
    consume_until(recognizer, what_follows_loop_iteration_or_rule)

  else # do nothing if we can't identify the exact kind of ATN state end
  end
end

#token_error_display(t) ⇒ Object 



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# File 'lib/antlr4/runtime/default_error_strategy.rb', line 255

def token_error_display(t)
  return '<no token>' if t.nil?

  s = symbol_text(t)
  if s.nil?
    s = if symbol_type(t) == Token::EOF
          '<EOF>'
        else
          '<' << symbol_type(t).to_s << '>'
        end
  end

  escape_ws_and_quote(s)
end