import context, functions

# Parser
type
  Parser* = ref object of RootObj


method parseOn*(self: Parser, context: Context): Result =
  raise newException(Exception, "should be implemented by subclass")

method parse*(self: Parser, input: string): Result =
  self.parseOn(newContext(input, 0))

method accept*(self: Parser, input: string): bool =
  self.parse(input).isSuccess

method matches*[T](self: Parser, input: string): seq[T] =
  result = @[]
  self.andd.map(result.add).seq(any).orr(any).star.parse(input)

method getChildren*(self: Parser): seq[Parser] =
  @[]

method hasEqualProperties*(self, other: Parser): bool =
  true

method replace*(self, source, target: Parser) =
  # no referring parsers
  discard

method name*(self: Parser): string =
  "Parser"
  
method `$`*(self: Parser): string =
  self.name

#  public String toString() {
#    return getClass().getSimpleName();
#  }


# DelegateParser
type
  DelegateParser* = ref object of Parser
    delegate*: Parser

proc newDelegateParser*(delegate: Parser): DelegateParser =
  DelegateParser(delegate: delegate)

method parseOn*(self: DelegateParser, context: Context): Result =
  self.delegate.parseOn(context)

method replace*(self: DelegateParser, source, target: Parser) =
  procCall(Parser(self).replace(source, target))
  if self.delegate == source:
    self.delegate = target

method getChildren(self: DelegateParser): seq[Parser] =
  @[self.delegate]

method copy(self: DelegateParser): Parser =
  newDelegateParser(self.delegate)

method name*(self: DelegateParser): string =
  "DelegateParser"

## A parser that optionally parsers its delegate, or answers nil.
type
  OptionalParser*[T] = ref object of DelegateParser
    otherwise*: T

proc newOptionalParser*[T](delegate: Parser, otherwise: T): OptionalParser =
  OptionalParser(delegate: delegate, otherwise: otherwise)

#  public OptionalParser(Parser delegate, Object otherwise) {
#    super(delegate);
#    this.otherwise = otherwise;
#  }

method parseOn*(self: OptionalParser, context: Context): Result =
  result = self.delegate.parseOn(context)
  if result.isSuccess:
    return
  return context.success(self.otherwise)


#  public Result parseOn(Context context) {
#    Result result = delegate.parseOn(context);
#    if (result.isSuccess()) {
#      return result;
#    } else {
#      return context.success(otherwise);
#    }
#  }

method hasEqualProperties*(self: OptionalParser, other: OptionalParser): bool =
  procCall(Parser(self).hasEqualProperties(Parser(other))) and self.otherwise == other.otherwise
  
#  protected boolean hasEqualProperties(Parser other) {
#    return super.hasEqualProperties(other) &&
#        Objects.equals(otherwise, ((OptionalParser) other).otherwise);
#  }

method copy*(self: OptionalParser): Parser =
  newOptionalParser(self.delegate, self.otherwise)

#  @Override
#  public Parser copy() {
#    return new OptionalParser(delegate, otherwise);
#  }

method name*(self: OptionalParser): string =
  "OptionalParser"

# An abstract parser that repeatedly parses between 'min' and 'max' instances of its delegate.
type
  RepeatingParser* = ref object of DelegateParser
    min*: int
    max*: int

const UNBOUNDED = 1

proc newRepeatingParser*(delegate: Parser, min: int, max: int): RepeatingParser =
  if min < 0:
    raise newException(Exception, "Invalid min repetitions")
  if max != UNBOUNDED and min > max:
    raise newException(Exception, "Invalid max repetitions")
  RepeatingParser(delegate: delegate, min: min, max: max)

method hasEqualProperties*(self: RepeatingParser, other: RepeatingParser): bool =
  # No super implementation in DelegateParser
  procCall(Parser(self).hasEqualProperties(Parser(other))) and self.min == other.min and self.max == other.max

method name*(self: RepeatingParser): string =
  "RepeatingParser"
  
method `$`*(self: RepeatingParser): string =
  result = procCall($Parser(self)) & "[" & $self.min & ".."
  if self.max == UNBOUNDED:
    result = result & "*]"
  else:
    result = result & $self.max & "]"
  
#  public String toString() {
#    return super.toString() + "[" + min + ".." + (max == UNBOUNDED ? "*" : max) + "]";
#  }

# A greedy parser that repeatedly parses between 'min' and 'max' instances of its delegate.
type
  PossessiveRepeatingParser = ref object of RepeatingParser
  
proc newPossessiveRepeatingParser*(delegate: Parser, min, max: int): PossessiveRepeatingParser =
  PossessiveRepeatingParser(newRepeatingParser(delegate, min, max))

method name*(self: PossessiveRepeatingParser): string =
  "PossessiveRepeatingParser"


method copy*(self: PossessiveRepeatingParser): Parser =
  newPossessiveRepeatingParser(self.delegate, self.min, self.max)

method parseOn*[T](self: PossessiveRepeatingParser, context: Context): Result =
  var
    current = context
    elements = newSeq[T]()
  while elements.len < self.min:
    result = self.delegate.parseOn(current)
    if result.isFailure:
      return
    elements.add(get[T](result))
    current = result
  while self.max == UNBOUNDED or elements.len < max:
    result = self.delegate.parseOn(current)
    if result.isFailure:
      return current.success[T](elements)
    elements.add(get[T](result))
    current = result    
  current.success[T](elements)


# Abstract parser that parses a list of things in some way (to be specified by the subclasses).
type
  ListParser* = ref object of Parser
    parsers*: seq[Parser]

#proc newListParser*(parsers: seq[Parser] not nil): ListParser =
#  ListParser(parsers: parsers)

method replace*(self: ListParser, source, target: Parser) =
  procCall(Parser(self).replace(source, target))
  for i in 0..high(self.parsers):
    if self.parsers[i] == source:
      self.parsers[i] = target

#  public void replace(Parser source, Parser target) {
#    super.replace(source, target);
#    for (int i = 0; i < parsers.length; i++) {
#      if (parsers[i] == source) {
#        parsers[i] = target;
#      }
#    }
#  }

method getChildren(self: ListParser): seq[Parser] =
  self.parsers
  
#  public List<Parser> getChildren() {
#    return Arrays.asList(parsers);
#  }


method name*(self: ListParser): string =
  "ListParser"

  
# A parser that parses a sequence of parsers.
type
  SequenceParser* = ref object of ListParser

proc newSequenceParser*(parsers: seq[Parser]): SequenceParser =
  SequenceParser(parsers: parsers)

method parseOn*[T](self: SequenceParser, context: Context): Result =
  var
    current = context
    elements = newSeq[T](self.parsers.len)
  for parser in self.parsers:
    result = parser.parseOn(current)
    if result.isFailure:
      return
    elements.add(get[T](result))
    current = result
  current.success[T](elements)
  
#  public Result parseOn(Context context) {
#    Context current = context;
#    List<Object> elements = new ArrayList<>(parsers.length);
#   for (Parser parser : parsers) {
#      Result result = parser.parseOn(current);
#      if (result.isFailure()) {
#        return result;
#      }
#      elements.add(result.get());
#      current = result;
#    }
#    return current.success(elements);
#  }

method seq*(self: SequenceParser, others: varargs[Parser]): Parser =
  newSequenceParser(self.parsers & @others)
#  let all = newSeq[Parser](self.parsers.len + others.len)
  
#  public Parser seq(Parser... others) {
#    Parser[] array = Arrays.copyOf(parsers, parsers.length + others.length);
#    System.arraycopy(others, 0, array, parsers.length, others.length);
#    return new SequenceParser(array);
#  }

method copy*(self: SequenceParser): Parser =
  var parsersCopy = self.parsers
  newSequenceParser(parsersCopy)


#  public Parser copy() {
#    return new SequenceParser(Arrays.copyOf(parsers, parsers.length));
#  }

method name*(self: SequenceParser): string =
  "SequenceParser"

# An abstract parser that repeatedly parses between 'min' and 'max' instances of its delegate and
# that requires the input to be completed with a specified parser 'limit'. Subclasses provide
# repeating behavior as typically seen in regular expression implementations (non-blind).
type
  LimitedRepeatingParser* = ref object of RepeatingParser
    limit*: Parser

proc newLimitedRepeatingParser*(delegate: Parser, limit: Parser not nil, min, max: int): LimitedRepeatingParser =
  LimitedRepeatingParser(delegate: delegate, limit: limit, min: min, max: max)

method getChildren(self: LimitedRepeatingParser): seq[Parser] =
  @[self.delegate, self.limit]

method replace*(self: LimitedRepeatingParser, source, target: Parser) =
  procCall(DelegateParser(self).replace(source, target))
  if self.limit == source:
    self.limit = target

method name*(self: LimitedRepeatingParser): string =
  "LimitedRepeatingParser"


# A greedy repeating parser, commonly seen in regular expression implementations. It aggressively
# consumes as much input as possible and then backtracks to meet the 'limit' condition.
type
  GreedyRepeatingParser* = ref object of LimitedRepeatingParser

proc newGreedyRepeatingParser*(delegate, limit: Parser, min, max: int): GreedyRepeatingParser =
  GreedyRepeatingParser(delegate: delegate, limit: limit, min: min, max: max)

method copy*(self: GreedyRepeatingParser): Parser =
  newGreedyRepeatingParser(self.delegate, self.limit, self.min, self.max)

#method parseOn*[T](self: GreedyRepeatingParser, context: Context): Result =
#  result = self.delegate.parseOn(context)
# if result.isSuccess:
#    return context.success(get[T](result))

method parseOn*[T](self: GreedyRepeatingParser, context: Context): Result =
  var
    current = context
    elements = newSeq[T]()
  while elements.len < self.min:
    result = self.delegate.parseOn(current)
    if result.isFailure:
      return
    elements.add(get[T](result))
    current = result
  var contexts = newSeq[Context]()
  contexts.add(current)
  while self.max == UNBOUNDED or elements.len < max:
    result = self.delegate.parseOn(current)
    if result.isFailure:
      break
    elements.add(get[T](result))
    contexts.add(current = result)
  while true:
    var stop = self.limit.parseOn(contexts[contexts.high])
    if stop.isSuccess:
      return contexts[contexts.high].success(elements)
    if elements.len == 0:
      return stop
    contexts.pop()
    elements.pop()
    if contexts.len == 0:
      return stop


discard """

  public Result parseOn(Context context) {
    Context current = context;
    List<Object> elements = new ArrayList<>();
    while (elements.size() < min) {
      Result result = delegate.parseOn(current);
      if (result.isFailure()) {
        return result;
      }
      elements.add(result.get());
      current = result;
    }
    List<Context> contexts = new ArrayList<>();
    contexts.add(current);
    while (max == UNBOUNDED || elements.size() < max) {
      Result result = delegate.parseOn(current);
      if (result.isFailure()) {
        break;
      }
      elements.add(result.get());
      contexts.add(current = result);
    }
    while (true) {
      Result stop = limit.parseOn(contexts.get(contexts.size() - 1));
      if (stop.isSuccess()) {
        return contexts.get(contexts.size() - 1).success(elements);
      }
      if (elements.isEmpty()) {
        return stop;
      }
      contexts.remove(contexts.size() - 1);
      elements.remove(elements.size() - 1);
      if (contexts.isEmpty()) {
        return stop;
      }
    }
  }

}
"""

# A parser that uses the first parser that succeeds.
type
  ChoiceParser* = ref object of ListParser

proc newChoiceParser*(parsers: varargs[Parser]): ChoiceParser =
  ChoiceParser(parsers: @parsers)

method orr*(self: ChoiceParser, others: varargs[Parser]): Parser =
  ## Returns a parser that accepts the receiver or `other`. The resulting parser returns the
  ## parse result of the receiver, if the receiver fails it returns the parse result of `other`
  ## (exclusive ordered choice).
  newChoiceParser(self.parsers & @others)

method copy*(self: ChoiceParser): Parser =
  let parsersCopy = self.parsers
  newChoiceParser(parsersCopy)

method parseOn*(self: ChoiceParser, context: Context): Result =
  for parser in self.parsers:
    result = parser.parseOn(context)
    if result.isSuccess:
      return  
  
#  public Result parseOn(Context context) {
#    Result result = null;
#    for (Parser parser : parsers) {
#      result = parser.parseOn(context);
#      if (result.isSuccess()) {
#        return result;
#      }
#    }
#    return result;
#  }

# The and-predicate, a parser that succeeds whenever its delegate does, but does not consume the
# input stream [Parr 1994, 1995].
type
  AndParser* = ref object of DelegateParser

proc newAndParser*(delegate: Parser): AndParser =
  AndParser(delegate)

method parseOn*[T](self: AndParser, context: Context): Result =
  result = self.delegate.parseOn(context)
  if result.isSuccess:
    return context.success(get[T](result))

method copy*(self: AndParser): Parser =
  newAndParser(self.delegate)

# Testing a type class to match the Java interface
# This means, a ContinuationHandler is any type which
# you can call `apply` on, with the given arguments.
type
  ContinuationHandler = generic handler
    handler.callParseOn(Parser, Context) is Result
    #handler.apply(proc(c: Context): Result, Context) is Result

# Just a sample ContinuationHandler type
type
  Sammy = ref object
proc callParseOn*(self: Sammy, p: Parser, c: Context): Result =
  p.parseOn(c)

# Continuation parser that when activated captures a continuation function and passes it together
# with the current context into the handler.
type
  ContinuationParser*[T] = ref object of DelegateParser
    handler*: T

proc newContinuationParser*(delegate: Parser, handler: ContinuationHandler): ContinuationParser =
  ContinuationParser(delegate: delegate, handler: handler)

# TODO
method parseOn*(self: ContinuationParser, context: Context): Result =
  self.handler.callParseOn(self, context)
  
method copy*(self: ContinuationParser): Parser =
  newContinuationParser(self.delegate, self.handler)

method hasEqualProperties*(self: ContinuationParser, other: ContinuationParser): bool =
  procCall(Parser(self).hasEqualProperties(Parser(other))) and self.handler == other.handler



# The not-predicate, a parser that succeeds whenever its delegate does not, but consumes no input [Parr 1994, 1995].
type
  NotParser* = ref object of DelegateParser
    message*: string

proc newNotParser*(delegate: Parser, message: string): NotParser =
  NotParser(delegate: delegate, message: message)

method parseOn*[T](self: NotParser, context: Context): Result =
  if self.delegate.parseOn(context).isFailure:
    return context.success(nil)
  else:
    return context.failure(self.message)

method hasEqualProperties*(self: NotParser, other: NotParser): bool =
  procCall(Parser(self).hasEqualProperties(Parser(other))) and self.message == other.message

method copy*(self: NotParser): NotParser =
  newNotParser(self.delegate, self.message)

method `$`*(self: NotParser): string =
  procCall($Parser(self)) & "[" & self.message & "]"





# Parses a single character.
type
  CharacterParser* = ref object of Parser

proc newCharacterParser*(predicate: CharacterPredicate, message: string): Parser =
  CharacterParser(predicate, message)

proc off*(predicate: CharacterPredicate, message: string): Parser =
  newCharacterParser(predicate, message)

discard """
  /**
   * Returns a parser that accepts a specific {@link CharacterPredicate}.
   */
  public static Parser of(CharacterPredicate predicate, String message) {
    return new CharacterParser(predicate, message);
  }

  /**
   * Returns a parser that accepts a specific {@code character}.
   */
  public static Parser of(char character) {
    return of(character, "'" + character + "' expected");
  }

  public static Parser of(char character, String message) {
    return of(CharacterPredicate.of(character), message);
  }

  /**
   * Returns a parser that accepts any character.
   */
  public static Parser any() {
    return any("any character expected");
  }

  public static Parser any(String message) {
    return of(CharacterPredicate.any(), message);
  }

  /**
   * Returns a parser that accepts any of the provided characters.
   */
  public static Parser anyOf(String chars) {
    return anyOf(chars, "any of '" + chars + "' expected");
  }

  public static Parser anyOf(String chars, String message) {
    return of(CharacterPredicate.anyOf(chars), message);
  }

  /**
   * Returns a parser that accepts no character.
   */
  public static Parser none() {
    return none("no character expected");
  }

  public static Parser none(String message) {
    return of(CharacterPredicate.none(), message);
  }

  /**
   * Returns a parser that accepts none of the provided characters.
   */
  public static Parser noneOf(String chars) {
    return noneOf(chars, "none of '" + chars + "' expected");
  }

  public static Parser noneOf(String chars, String message) {
    return of(CharacterPredicate.noneOf(chars), message);
  }

  /**
   * Returns a parser that accepts a single digit.
   */
  public static Parser digit() {
    return digit("digit expected");
  }

  public static Parser digit(String message) {
    return new CharacterParser(Character::isDigit, message);
  }

  /**
   * Returns a parser that accepts a single letter.
   */
  public static Parser letter() {
    return letter("letter expected");
  }

  public static Parser letter(String message) {
    return of(Character::isLetter, message);
  }

  /**
   * Returns a parser that accepts an lower-case letter.
   */
  public static Parser lowerCase() {
    return lowerCase("lowercase letter expected");
  }

  public static Parser lowerCase(String message) {
    return of(Character::isLowerCase, message);
  }

  /**
   * Returns a parser that accepts a specific character pattern.
   * <p>
   * Characters match themselves. A dash {@code -} between two characters matches the range of those
   * characters. A caret {@code ^} at the beginning negates the pattern.
   */
  public static Parser pattern(String pattern) {
    return pattern(pattern, "[" + pattern + "] expected");
  }

  public static Parser pattern(String pattern, String message) {
    return of(CharacterPredicate.pattern(pattern), message);
  }

  /**
   * Returns a parser that accepts a specific character range.
   */
  public static Parser range(char start, char stop) {
    return range(start, stop, start + ".." + stop + " expected");
  }

  public static Parser range(char start, char stop, String message) {
    return of(CharacterPredicate.range(start, stop), message);
  }

  /**
   * Returns a parser that accepts an upper-case letter.
   */
  public static Parser upperCase() {
    return upperCase("uppercase letter expected");
  }

  public static Parser upperCase(String message) {
    return of(Character::isUpperCase, message);
  }

  /**
   * Returns a parser that accepts a single whitespace.
   */
  public static Parser whitespace() {
    return whitespace("whitespace expected");
  }

  public static Parser whitespace(String message) {
    return of(Character::isWhitespace, message);
  }

  /**
   * Returns a parser that accepts a single letter or digit.
   */
  public static Parser word() {
    return word("letter or digit expected");
  }

  public static Parser word(String message) {
    return of(Character::isLetterOrDigit, message);
  }

  private final CharacterPredicate matcher;
  private final String message;

  private CharacterParser(CharacterPredicate matcher, String message) {
    this.matcher = Objects.requireNonNull(matcher, "Undefined matcher");
    this.message = Objects.requireNonNull(message, "Undefined message");
  }

  @Override
  public Result parseOn(Context context) {
    String buffer = context.getBuffer();
    int position = context.getPosition();
    if (position < buffer.length()) {
      char result = buffer.charAt(position);
      if (matcher.test(result)) {
        return context.success(result, position + 1);
      }
    }
    return context.failure(message);
  }

  @Override
  public Parser neg(String message) {
    return of(matcher.not(), message);
  }

  @Override
  protected boolean hasEqualProperties(Parser other) {
    return super.hasEqualProperties(other) &&
        Objects.equals(matcher, ((CharacterParser) other).matcher) &&
        Objects.equals(message, ((CharacterParser) other).message);
  }

  @Override
  public Parser copy() {
    return of(matcher, message);
  }

  @Override
  public String toString() {
    return super.toString() + "[" + message + "]";
  }
"""



#  /**
#   * Returns a list of all successful overlapping parses of the {@code input}.
#   */
#  @SuppressWarnings("unchecked")
#  public <T> List<T> matches(String input) {
#    List<Object> list = new ArrayList<>();
#    this.and().map(list::add).seq(any()).or(any()).star().parse(input);
#    return (List<T>) list;
#  }

method matchesSkipping*[T](self: Parser, input: string): seq[T] =
  result = @[]
  self.map(result.add).`or`(any).star.parse(input)

#  /**
#   * Returns a list of all successful non-overlapping parses of the {@code input}.
#   */
#  @SuppressWarnings("unchecked")
#  public <T> List<T> matchesSkipping(String input) {
#    List<Object> list = new ArrayList<>();
#    this.map(list::add).or(any()).star().parse(input);
#    return (List<T>) list;
#  }


method repeat*(self: Parser, min, max: int): Parser =
  ## Returns a parser that accepts the receiver between `min` and `max` times. The
  ## resulting parser returns a list of the parse results of the receiver.
  ##
  ## This is a greedy and blind implementation that tries to consume as much input as possible and
  ## that does not consider what comes afterwards.
  newPossessiveRepeatingParser(self, min, max)

#  public Parser repeat(int min, int max) {
#    return new PossessiveRepeatingParser(this, min, max);
#  }


method optional*[T](self: Parser, otherwise: T): Parser =
  ## Returns new parser that accepts the receiver, if possible.
  ## The returned value can be provided as `otherwise`.
  newOptionalParser(self, otherwise)

#  public Parser optional(Object otherwise) {
#    return new OptionalParser(this, otherwise);
#  }

method optional*[T](self: Parser): Parser =
  ## Returns new parser that accepts the receiver, if possible. The resulting parser returns the
  ## result of the receiver, or `nil` if not applicable.
  optional[T](self, nil)

#  public Parser optional() {
#    return optional(null);
#  }

method start*(self: Parser): Parser =
  ## Returns a parser that accepts the receiver zero or more times. The resulting parser returns a
  ## list of the parse results of the receiver.
  ##
  ## This is a greedy and blind implementation that tries to consume as much input as possible and
  ## that does not consider what comes afterwards.
  self.repeat(0, UNBOUNDED)

#  public Parser star() {
#    return repeat(0, RepeatingParser.UNBOUNDED);
#  }

# Forward dec
method repeatGreedy*(self, limit: Parser, min, max: int): Parser

method starGreedy*(self, limit: Parser): Parser =
  ## Returns a parser that parses the receiver zero or more times until it reaches a `limit`.
  ## This is a greedy non-blind implementation of the `star <#star>`_ operator. 
  ## The `limit` is not consumed.
  self.repeatGreedy(limit, 0, UNBOUNDED)

#  public Parser starGreedy(Parser limit) {
#    return repeatGreedy(limit, 0, RepeatingParser.UNBOUNDED);
#  }
method repeatLazy*(self, limit: Parser, min, max: int): Parser
method starLazy*(self, limit: Parser): Parser =
  ## Returns a parser that parses the receiver zero or more times until it reaches a `limit`.
  ## This is a lazy non-blind implementation of the `star <#star>`_ operator.
  ## The `limit` is not consumed.
  self.repeatLazy(limit, 0, UNBOUNDED)


#  public Parser starLazy(Parser limit) {
#    return repeatLazy(limit, 0, RepeatingParser.UNBOUNDED);
#  }

method plus*(self: Parser): Parser =
  ## Returns a parser that accepts the receiver one or more times. The resulting parser returns a
  ## list of the parse results of the receiver.
  ##
  ## This is a greedy and blind implementation that tries to consume as much input as possible and
  ## that does not consider what comes afterwards.
  self.repeat(1, UNBOUNDED)

#  public Parser plus() {
#    return repeat(1, RepeatingParser.UNBOUNDED);
#  }


method plusGreedy*(self, limit: Parser): Parser =
  ## Returns a parser that parses the receiver one or more times until it reaches `limit`.
  ## This is a reedy non-blind implementation of the `plus <#plus>`_ operator.
  ## The `limit` is not consumed.
  self.repeatGreedy(limit, 1, UNBOUNDED)

#  public Parser plusGreedy(Parser limit) {
#    return repeatGreedy(limit, 1, RepeatingParser.UNBOUNDED);
#  }


method plusLazy*(self, limit: Parser): Parser =
  ## Returns a parser that parses the receiver one or more times until it reaches a `limit`.
  ## This is a lazy non-blind implementation of the `plus <#plus>`_ operator.
  ## The `limit` is not consumed.
  self.repeatLazy(limit, 1, UNBOUNDED)


#  public Parser plusLazy(Parser limit) {
#    return repeatLazy(limit, 1, RepeatingParser.UNBOUNDED);
#  }


method repeatGreedy*(self, limit: Parser, min, max: int): Parser =
  ## Returns a parser that parses the receiver at least `min` and at most `max` times
  ## until it reaches a {@code limit}. This is a greedy non-blind implementation of the
  ## `repeat <#repeat>`_ operator. The `limit` is not consumed.
  newGreedyRepeatingParser(self, limit, min, max)

#  public Parser repeatGreedy(Parser limit, int min, int max) {
#    return new GreedyRepeatingParser(this, limit, min, max);
#  }


method repeatLazy*(self, limit: Parser, min, max: int): Parser =
  ## Returns a parser that parses the receiver at least `min` and at most `max` times
  ## until it reaches a `limit`. This is a lazy non-blind implementation of the
  ## `repeat <#repeat>`_ operator. The `limit` is not consumed.
  newGreedyRepeatingParser(self, limit, min, max)

#  public Parser repeatLazy(Parser limit, int min, int max) {
#    return new LazyRepeatingParser(this, limit, min, max);
#  }

method times*(self: Parser, count: int): Parser =
  ## Returns a parser that accepts the receiver exactly `count` times.
  ## The resulting parser returns a list of the parse results of the receiver.
  self.repeat(count, count)

#  public Parser times(int count) {
#    return repeat(count, count);
#  }


method seq*(self: Parser, others: varargs[Parser]): Parser =
  ## Returns a parser that accepts the receiver followed by `others`. The resulting parser
  ## returns a list of the parse result of the receiver followed by the parse result of `others`.
  ## Calling this method on an existing sequence code not nest this sequence into a new one,
  ## but instead augments the existing sequence with `others`.
  
  # Alternative low level version of addFirst
  #var s = newSeq[Parser](others.len + 1)
  #s[0] = self
  #var j = 1
  #for p in others:
  #  s[j] = p
  #  inc(j)
  #newSequenceParser(s)
  
  # Quick version of addFirst
  newSequenceParser(@[self] & @others)

#  public Parser seq(Parser... others) {
#    Parser[] parsers = new Parser[1 + others.length];
#    parsers[0] = this;
#    System.arraycopy(others, 0, parsers, 1, others.length);
#    return new SequenceParser(parsers);
#  }

method orr*(self: Parser, others: varargs[Parser]): Parser =
  ## Returns a parser that accepts the receiver or `other`. The resulting parser returns the
  ## parse result of the receiver, if the receiver fails it returns the parse result of `other`
  ## (exclusive ordered choice).
  newChoiceParser(@[self] & @others)

#  public Parser or(Parser... others) {
#    Parser[] parsers = new Parser[1 + others.length];
#    parsers[0] = this;
#    System.arraycopy(others, 0, parsers, 1, others.length);
#    return new ChoiceParser(parsers);
#  }

method andd*(self: Parser): Parser =
  ## Returns a parser (logical and-predicate) that succeeds whenever the receiver does, but never
  ## consumes input.
  newAndParser(self) 
 
#  public Parser and() {
#    return new AndParser(this);
#  }

method callCC*(self: Parser, handler: ContinuationHandler): Parser =
  ## Returns a parser that is called with its current continuation.
  newContinuationParser(self, handler)

#  public Parser callCC(ContinuationParser.ContinuationHandler handler) {
#    return new ContinuationParser(this, handler);
#  }

method nott*(self: Parser): Parser =
  ## Returns a parser (logical not-predicate) that succeeds whenever the receiver fails, but never
  ## consumes input.
  raise newException(Exception, "unexpected call to nott")

#  public Parser not() {
#    return not("unexpected");
#  }

method nott*(self: Parser, message: string): Parser =
  ## Returns a parser (logical not-predicate) that succeeds whenever the receiver fails, but never
  ## consumes input.
  newNotParser(self, message)
  
#  public Parser not(String message) {
#   return new NotParser(this, message);
#  }

method neg*(self: Parser, message: string): Parser =
  ## Returns a parser that consumes any input token (character), but the receiver.
  self.nott(message).seq(CharacterParser.any()).pick(1)
  
#  public Parser neg(String message) {
#    return not(message).seq(CharacterParser.any()).pick(1);
#  }

method neg*(self: Parser): Parser =
  ## Returns a parser that consumes any input token (character), but the receiver.
  self.neg($self & " not expected")

#  public Parser neg() {
#    return neg(this + " not expected");
#  }

method flatten*(self: Parser): Parser =
  ## Returns a parser that discards the result of the receiver, and returns a sub-string of the
  ## consumed range in the string/list being parsed.
  newFlattenParser(self)
  
#  public Parser flatten() {
#    return new FlattenParser(this);
#  }

method token*(self: Parser): Parser =
  ## Returns a parser that returns a {@link Token}. The token carries the parsed value of the
  ## receiver {@link Token#getValue()}, as well as the consumed input {@link Token#getInput()} from
  ## {@link Token#getStart()} to {@link Token#getStop()} of the input being parsed.
  newTokenParser(self)
  
#  public Parser token() {
#    return new TokenParser(this);
#  }

method trim*(self: Parser): Parser =
  ## Returns a parser that consumes whitespace before and after the receiver.
  self.trim(CharacterParser.whitespace())
  
#  public Parser trim() {
#    return trim(CharacterParser.whitespace());
#  }

method trim*(self: Parser, both: Parser): Parser =
  ## Returns a parser that consumes input on `both` sides of the receiver.
  self.trim(both, both)

#  public Parser trim(Parser both) {
#    return trim(both, both);
#  }

method trim*(self, before, after: Parser): Parser =
  ## Returns a parser that consumes input {@code before} and {@code after} the receiver.
  newTrimmingParser(self, before, after)

#  public Parser trim(Parser before, Parser after) {
#    return new TrimmingParser(this, before, after);
#  }

method endd*(self: Parser): Parser =
  ## Returns a parser that succeeds only if the receiver consumes the complete input.
  self.endd("end of input expected")

#  public Parser end() {
#    return end("end of input expected");
#  }

method endd*(self: Parser, message: string): Parser =
  ## Returns a parser that succeeds only if the receiver consumes the complete input, otherwise
  ## return a failure with the {@code message}.
  newEndOfInputParser(self, message)
  
#  public Parser end(String message) {
#    return new EndOfInputParser(this, message);
#  }

method settable*(self: Parser): SettableParser =
  ## Returns a parser that points to the receiver, but can be changed to point to something else at
  ## a later point in time.
  newSettableParserWith(self)

#  public SettableParser settable() {
#    return SettableParser.with(this);
#  }

method map*[A, B](self: Parser, function: proc (x: A): B {.closure.}): Parser =
  ## Returns a parser that evaluates a {@code function} as the production action on success of the
  ## receiver.
  newActionParser(self, function)

#  public <A, B> Parser map(Function<A, B> function) {
#    return new ActionParser<>(this, function);
#  }

method pick*(self: Parser, index: int): Parser =
  ## Returns a parser that transform a successful parse result by returning the element at {@code
  ## index} of a list. A negative index can be used to access the elements from the back of the
  ## list.
  self.map(nthOfList(index))
  
#  public Parser pick(int index) {
#    return map(Functions.nthOfList(index));
#  }

method permute*(self: Parser, indexes: varargs[int]): Parser =
  ## Returns a parser that transforms a successful parse result by returning the permuted elements
  ## at {@code indexes} of a list. Negative indexes can be used to access the elements from the back
  ## of the list.
  self.map(permutationOfList(indexes))


#  public Parser permute(int... indexes) {
#    return this.map(Functions.permutationOfList(indexes));
#  }

  ## Returns a new parser that parses the receiver one or more times, separated
  ## by a {@code separator}.
  newSequenceParser(self, newSequenceParser(separator, self).star())
    .map( 

#  public Parser separatedBy(Parser separator) {
#    return new SequenceParser(this, new SequenceParser(separator, this).star())
#       .map(new Function<List<List<List<Object>>>, List<Object>>() {
#          @Override
#          public List<Object> apply(List<List<List<Object>>> input) {
#            List<Object> result = new ArrayList<>();
#            result.add(input.get(0));
#            input.get(1).forEach(result::addAll);
#            return result;
#          }
#        });
#  }

discard """
  /**
   * Returns a new parser that parses the receiver one or more times, separated
   * and possibly ended by a {@code separator}."
   */
  public Parser delimitedBy(Parser separator) {
    return separatedBy(separator)
        .seq(separator.optional())
        .map(new Function<List<List<Object>>, List<Object>>() {
          @Override
          public List<Object> apply(List<List<Object>> input) {
            List<Object> result = new ArrayList<>(input.get(0));
            if (input.get(1) != null) {
              result.add(input.get(1));
            }
            return result;
          }
        });
  }

  /**
   * Returns a shallow copy of the receiver.
   */
  public abstract Parser copy();

  /**
   * Recursively tests for structural similarity of two parsers.
   *
   * The code can automatically deals with recursive parsers and parsers that refer to other
   * parsers. This code is supposed to be overridden by parsers that add other state.
   */
  public boolean isEqualTo(Parser other) {
    return isEqualTo(other, new HashSet<>());
  }

  /**
   * Recursively tests for structural similarity of two parsers.
   */
  protected boolean isEqualTo(Parser other, Set<Parser> seen) {
    if (this.equals(other) || seen.contains(this)) {
      return true;
    }
    seen.add(this);
    return getClass().equals(other.getClass())
        && hasEqualProperties(other)
        && hasEqualChildren(other, seen);
  }

  /**
   * Compares the properties of two parsers.
   *
   * Override this method in all subclasses that add new state.
   */
  protected boolean hasEqualProperties(Parser other) {
    return true;
  }

  /**
   * Compares the children of two parsers.
   *
   * Normally subclasses should not override this method, but instead {@link #getChildren()}.
   */
  protected boolean hasEqualChildren(Parser other, Set<Parser> seen) {
    List<Parser> thisChildren = this.getChildren();
    List<Parser> otherChildren = other.getChildren();
    if (thisChildren.size() != otherChildren.size()) {
      return false;
    }
    for (int i = 0; i < thisChildren.size(); i++) {
      if (!thisChildren.get(i).isEqualTo(otherChildren.get(i), seen)) {
        return false;
      }
    }
    return true;
  }
"""