Hostname final

final class Hostname extends Host

An ASCII hostname, validated per RFC 1123.

Rules: 1–253 characters total; each dot-separated label is 1–63 characters; labels may contain letters, digits, and hyphens but must not start or end with a hyphen.

Inheritance

Object → Ordered<A> → Host → Hostname

Constructors

Hostname() const

const Hostname(IList<HostnameLabel> labels, String repr)

Implementation

const Hostname(this.labels, this.repr);

Properties

asHost no setter inherited

Host get asHost

Returns this as a Host (identity).

Inherited from Host.

Implementation

Host get asHost => this;

hashCode no setter override

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Implementation

@override
int get hashCode => Object.hash(toString(), 'Hostname'.hashCode);

labels final

final IList<HostnameLabel> labels

The dot-separated label components of this hostname.

Implementation

final IList<HostnameLabel> labels;

repr final

final String repr

The original string representation of this hostname.

Implementation

final String repr;

runtimeType no setter inherited

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

Methods

compareTo() inherited

int compareTo(Host that)

Compares this object to another object.

Returns a value like a Comparator when comparing this to other. That is, it returns a negative integer if this is ordered before other, a positive integer if this is ordered after other, and zero if this and other are ordered together.

The other argument must be a value that is comparable to this object.

Inherited from Host.

Implementation

@override
int compareTo(Host that) {
  return switch (this) {
    final Ipv4Address x => switch (that) {
      final Ipv4Address y => IpAddress.compareBytes(x, y),
      final Ipv6Address y => IpAddress.compareBytes(x.toCompatV6(), y),
      _ => -1,
    },
    final Ipv6Address x => switch (that) {
      final Ipv4Address y => IpAddress.compareBytes(x, y.toCompatV6()),
      final Ipv6Address y => IpAddress.compareBytes(x, y),
      _ => -1,
    },
    final Hostname x => switch (that) {
      final Ipv4Address _ => 1,
      final Ipv6Address _ => 1,
      final Hostname y => x.toString().compareTo(y.toString()),
      final IDN y => x.toString().compareTo(y.hostname.toString()),
    },
    final IDN x => switch (that) {
      final Ipv4Address _ => 1,
      final Ipv6Address _ => 1,
      final Hostname y => x.hostname.toString().compareTo(y.toString()),
      final IDN y => x.hostname.toString().compareTo(y.hostname.toString()),
    },
  };
}

normalized()

Hostname normalized()

Returns a copy of this hostname with all labels lowercased.

Implementation

Hostname normalized() => Hostname(
  labels.map((l) => HostnameLabel(l.toString().toLowerCase())),
  toString().toLowerCase(),
);

noSuchMethod() inherited

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

resolve() inherited

IO<IList<IpAddress>> resolve()

Resolves this host to a list of IpAddress values.

If this is already an IpAddress, returns it immediately. For Hostname and IDN values, performs a DNS lookup via Dns.resolve.

Inherited from Host.

Implementation

IO<IList<IpAddress>> resolve() => switch (this) {
  final IpAddress ip => IO.pure(ilist([ip])),
  final Hostname hostname => Dns.resolve(hostname),
  final IDN idn => Dns.resolve(idn.hostname),
};

toString() override

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Implementation

@override
String toString() => repr;

Operators

operator <() inherited

bool operator <(Host that)

Returns true if this value is less than that.

Inherited from Ordered.

Implementation

bool operator <(A that) => compareTo(that) < 0;

operator <=() inherited

bool operator <=(Host that)

Returns true if this value is less than or equal to that.

Inherited from Ordered.

Implementation

bool operator <=(A that) => compareTo(that) <= 0;

operator ==() override

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Implementation

@override
bool operator ==(Object other) => switch (other) {
  final Hostname that => toString() == that.toString(),
  _ => false,
};

operator >() inherited

bool operator >(Host that)

Returns true if this value is greater than that.

Inherited from Ordered.

Implementation

bool operator >(A that) => compareTo(that) > 0;

operator >=() inherited

bool operator >=(Host that)

Returns true if this value is greater than or equal to that.

Inherited from Ordered.

Implementation

bool operator >=(A that) => compareTo(that) >= 0;

Static Methods

fromString() override

Option<Hostname> fromString(String value)

Parses value as an ASCII hostname, returning None if validation fails.

Implementation

static Option<Hostname> fromString(String value) {
  if (value.isEmpty || value.length > 253) {
    return none();
  } else if (_regex.hasMatch(value)) {
    final labels = value.split('.').toIList().map(HostnameLabel.new);
    return Option.when(
      () =>
          labels.nonEmpty &&
          !labels.exists(
            (lbl) =>
                lbl.toString().length > 63 ||
                lbl.toString().startsWith('-') ||
                lbl.toString().endsWith('-'),
          ),
      () => Hostname(labels, value),
    );
  } else {
    return none();
  }
}