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StringOps ​

extension StringOps on String

Scala-style string operations, treating a String as a sequence of single-character strings.

Properties ​

head extension no setter ​

String get head

The first character. Throws RangeError if the string is empty.

Available on String, provided by the StringOps extension

Implementation
dart
String get head => nonEmpty ? this[0] : throw RangeError('.head on empty string');

headOption extension no setter ​

Option<String> get headOption

The first character as Some, or None if the string is empty.

Available on String, provided by the StringOps extension

Implementation
dart
Option<String> get headOption => nonEmpty ? Some(this[0]) : none();

init extension no setter ​

String get init

All characters except the last. Returns an empty string if already empty.

Available on String, provided by the StringOps extension

Implementation
dart
String get init => !isEmpty ? substring(0, length - 1) : this;

inits extension no setter ​

RIterator<String> get inits

An iterator over successive init prefixes, from longest to shortest, ending with an empty string.

Available on String, provided by the StringOps extension

Implementation
dart
RIterator<String> get inits => _iterateUntilEmpty((s) => s.init);

last extension no setter ​

String get last

The last character. Throws RangeError if the string is empty.

Available on String, provided by the StringOps extension

Implementation
dart
String get last => nonEmpty ? this[length - 1] : throw RangeError('.last on empty string');

lastOption extension no setter ​

Option<String> get lastOption

The last character as Some, or None if the string is empty.

Available on String, provided by the StringOps extension

Implementation
dart
Option<String> get lastOption => nonEmpty ? Some(this[length - 1]) : none();

nonEmpty extension no setter ​

bool get nonEmpty

Returns true if the string is not empty.

Available on String, provided by the StringOps extension

Implementation
dart
bool get nonEmpty => !isEmpty;

riterator extension no setter ​

RIterator<String> get riterator

An RIterator over the individual characters of this string.

Available on String, provided by the StringOps extension

Implementation
dart
RIterator<String> get riterator => RIterator.tabulate(length, (ix) => this[ix]);

tail extension no setter ​

String get tail

All characters except the first. Throws RangeError if the string is empty.

Available on String, provided by the StringOps extension

Implementation
dart
String get tail => nonEmpty ? substring(1, length) : throw RangeError('.tail on empty string');

tails extension no setter ​

RIterator<String> get tails

An iterator over successive tail suffixes, from longest to shortest, ending with an empty string.

Available on String, provided by the StringOps extension

Implementation
dart
RIterator<String> get tails => _iterateUntilEmpty((s) => s.tail);

Methods ​

drop() extension ​

String drop(int n)

Returns all characters after the first n, or an empty string if n >= length.

Available on String, provided by the StringOps extension

Implementation
dart
String drop(int n) => slice(min(n, length), length);

dropRight() extension ​

String dropRight(int n)

Returns all characters except the last n, or an empty string if n >= length.

Available on String, provided by the StringOps extension

Implementation
dart
String dropRight(int n) => take(length - max(n, 0));

dropWhile() extension ​

String dropWhile(bool Function(String) p)

Drops the longest prefix of characters satisfying p and returns the remainder.

Available on String, provided by the StringOps extension

Implementation
dart
String dropWhile(Function1<String, bool> p) => switch (indexWhere((c) => !p(c))) {
  -1 => '',
  final x => substring(x),
};

exists() extension ​

bool exists(bool Function(String) p)

Returns true if at least one character satisfies p.

Available on String, provided by the StringOps extension

Implementation
dart
bool exists(Function1<String, bool> p) => indexWhere(p) != -1;

filter() extension ​

String filter(bool Function(String) p)

Returns a new string containing only the characters satisfying p.

Available on String, provided by the StringOps extension

Implementation
dart
String filter(Function1<String, bool> p) {
  final buf = StringBuffer();
  var i = 0;

  while (i < length) {
    if (p(this[i])) buf.write(this[i]);
    i += 1;
  }

  return length == buf.length ? this : buf.toString();
}

filterNot() extension ​

String filterNot(bool Function(String) p)

Returns a new string containing only the characters not satisfying p.

Available on String, provided by the StringOps extension

Implementation
dart
String filterNot(Function1<String, bool> p) => filter((c) => !p(c));

find() extension ​

Option<String> find(bool Function(String) p)

Returns the first character satisfying p as Some, or None if no character satisfies p.

Available on String, provided by the StringOps extension

Implementation
dart
Option<String> find(Function1<String, bool> p) => switch (indexWhere(p)) {
  -1 => none(),
  final x => Some(this[x]),
};

fold() extension ​

String fold(String z, String Function(String, String) op)

Folds characters left-to-right using op, starting from z.

Available on String, provided by the StringOps extension

Implementation
dart
String fold(String z, Function2<String, String, String> op) => foldLeft(z, op);

foldLeft() extension ​

B foldLeft<B>(B z, B Function(B, String) op)

Left-associative fold over characters, starting from z.

Available on String, provided by the StringOps extension

Implementation
dart
B foldLeft<B>(B z, Function2<B, String, B> op) {
  var v = z;
  var i = 0;

  while (i < length) {
    v = op(v, this[i]);
    i += 1;
  }

  return v;
}

foldRight() extension ​

B foldRight<B>(B z, B Function(String, B) op)

Right-associative fold over characters, starting from z.

Available on String, provided by the StringOps extension

Implementation
dart
B foldRight<B>(B z, Function2<String, B, B> op) {
  var v = z;
  var i = length - 1;

  while (i >= 0) {
    v = op(this[i], v);
    i -= 1;
  }

  return v;
}

forall() extension ​

bool forall(bool Function(String) f)

Returns true if all characters satisfy f.

Available on String, provided by the StringOps extension

Implementation
dart
bool forall(Function1<String, bool> f) {
  var i = 0;

  while (i < length) {
    if (!f(this[i])) return false;
    i += 1;
  }

  return true;
}

foreach() extension ​

void foreach(void Function(String) f)

Applies f to each character.

Available on String, provided by the StringOps extension

Implementation
dart
void foreach(Function1<String, void> f) {
  var i = 0;

  while (i < length) {
    f(this[i]);
    i += 1;
  }
}

grouped() extension ​

RIterator<String> grouped(int size)

Returns an iterator that yields non-overlapping substrings of length size. The last group may be shorter than size if the string length is not a multiple of size.

Available on String, provided by the StringOps extension

Implementation
dart
RIterator<String> grouped(int size) => _StringGroupedIterator(this, size);

indexWhere() extension ​

int indexWhere(bool Function(String) p, [int end = 2147483647])

Returns the index of the first character satisfying p, or -1 if none does.

Available on String, provided by the StringOps extension

Implementation
dart
int indexWhere(Function1<String, bool> p, [int end = 2147483647]) {
  var i = 0;

  while (i < length) {
    if (p(this[i])) return i;
    i += 1;
  }

  return -1;
}

lastIndexWhere() extension ​

int lastIndexWhere(bool Function(String) p, [int end = 2147483647])

Returns the index of the last character satisfying p, or -1 if none does.

Available on String, provided by the StringOps extension

Implementation
dart
int lastIndexWhere(Function1<String, bool> p, [int end = 2147483647]) {
  var i = min(end, length - 1);

  while (i >= 0) {
    if (p(this[i])) return i;
    i -= 1;
  }

  return -1;
}

partition() extension ​

Record partition(bool Function(String) p)

Splits characters into two strings: those satisfying p (first) and those not satisfying p (second).

Available on String, provided by the StringOps extension

Implementation
dart
(String, String) partition(Function1<String, bool> p) {
  final (res1, res2) = (StringBuffer(), StringBuffer());
  var i = 0;

  while (i < length) {
    p(this[i]) ? res1.write(this[i]) : res2.write(this[i]);
    i += 1;
  }

  return (res1.toString(), res2.toString());
}

regionMatches() extension ​

bool regionMatches(int toffset, String other, int ooffset, int len)

Returns true if the specified subregion of this string matches the specified subregion of other. Returns false if any index is out of bounds.

Available on String, provided by the StringOps extension

Implementation
dart
bool regionMatches(int toffset, String other, int ooffset, int len) {
  if (toffset < 0 || ooffset < 0 || toffset + len > length || ooffset + len > other.length) {
    return false;
  } else {
    return substring(toffset, toffset + len) == other.substring(ooffset, ooffset + len);
  }
}

regionMatchesIgnoreCase() extension ​

bool regionMatchesIgnoreCase(int toffset, String other, int ooffset, int len)

Case-insensitive variant of regionMatches. Returns false if any index is out of bounds.

Available on String, provided by the StringOps extension

Implementation
dart
bool regionMatchesIgnoreCase(int toffset, String other, int ooffset, int len) {
  if (toffset < 0 || ooffset < 0 || toffset + len > length || ooffset + len > other.length) {
    return false;
  } else {
    return substring(toffset, toffset + len).toLowerCase() ==
        other.substring(ooffset, ooffset + len).toLowerCase();
  }
}

slice() extension ​

String slice(int from, int until)

Returns the substring from index from (inclusive) to until (exclusive), clamped to valid bounds.

Available on String, provided by the StringOps extension

Implementation
dart
String slice(int from, int until) {
  final start = max(from, 0);
  final end = min(until, length);

  return start >= end ? '' : substring(start, end);
}

sliding() extension ​

RIterator<String> sliding(int size, [int step = 1])

Returns an iterator of overlapping substrings of length size, advancing by step characters each time.

Available on String, provided by the StringOps extension

Implementation
dart
RIterator<String> sliding(int size, [int step = 1]) =>
    riterator.sliding(size, step).map((s) => s.mkString());

span() extension ​

Record span(bool Function(String) p)

Returns the longest prefix of characters satisfying p paired with the remainder.

Available on String, provided by the StringOps extension

Implementation
dart
(String, String) span(Function1<String, bool> p) => switch (indexWhere((c) => !p(c))) {
  -1 => (this, ''),
  final x => (substring(0, x), substring(x)),
};

splitAt() extension ​

Record splitAt(int n)

Splits the string at index n, returning (take(n), drop(n)).

Available on String, provided by the StringOps extension

Implementation
dart
(String, String) splitAt(int n) => (take(n), drop(n));

stripPrefix() extension ​

String stripPrefix(String prefix)

Removes prefix from the start of this string if present; otherwise returns this string unchanged.

Available on String, provided by the StringOps extension

Implementation
dart
String stripPrefix(String prefix) => startsWith(prefix) ? substring(prefix.length) : this;

stripSuffix() extension ​

String stripSuffix(String suffix)

Removes suffix from the end of this string if present; otherwise returns this string unchanged.

Available on String, provided by the StringOps extension

Implementation
dart
String stripSuffix(String suffix) =>
    endsWith(suffix) ? substring(0, length - suffix.length) : this;

take() extension ​

String take(int n)

Returns the first n characters, or the whole string if n >= length.

Available on String, provided by the StringOps extension

Implementation
dart
String take(int n) => slice(0, min(n, length));

takeRight() extension ​

String takeRight(int n)

Returns the last n characters, or the whole string if n >= length.

Available on String, provided by the StringOps extension

Implementation
dart
String takeRight(int n) => drop(length - max(n, 0));

takeWhile() extension ​

String takeWhile(bool Function(String) p)

Returns the longest prefix of characters satisfying p.

Available on String, provided by the StringOps extension

Implementation
dart
String takeWhile(Function1<String, bool> p) => switch (indexWhere((c) => !p(c))) {
  -1 => this,
  final x => substring(0, x),
};