BytesBuilder abstract interface

abstract interface class BytesBuilder

Builds a list of bytes, allowing bytes and lists of bytes to be added at the end.

Used to efficiently collect bytes and lists of bytes.

Constructors

BytesBuilder() factory

factory BytesBuilder({bool copy = true})

Construct a new empty BytesBuilder.

If copy is true (the default), the created builder is a copying builder. A copying builder maintains its own internal buffer and copies the bytes added to it eagerly.

If copy set to false, the created builder assumes that lists added to it will not change. Any Uint8List added using add is kept until toBytes or takeBytes is called, and only then are their contents copied. A non-Uint8List may be copied eagerly. If only a single Uint8List is added to the builder, that list is returned by toBytes or takeBytes directly, without any copying. A list added to a non-copying builder should not change its content after being added, and it must not change its length after being added. (Normal Uint8Lists are fixed length lists, but growing lists implementing Uint8List exist.)

Implementation

factory BytesBuilder({bool copy = true}) =>
    copy ? _CopyingBytesBuilder() : _BytesBuilder();

Properties

hashCode no setter inherited

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.

Inherited from Object.

Implementation

external int get hashCode;

isEmpty no setter

bool get isEmpty

Whether the buffer is empty.

Implementation

bool get isEmpty;

isNotEmpty no setter

bool get isNotEmpty

Whether the buffer is non-empty.

Implementation

bool get isNotEmpty;

length no setter

int get length

The number of bytes in this builder.

Implementation

int get length;

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

add()

void add(List<int> bytes)

Appends bytes to the current contents of this builder.

Each value of bytes will be truncated to an 8-bit value in the range 0 .. 255.

Implementation

void add(List<int> bytes);

addByte()

void addByte(int byte)

Appends byte to the current contents of this builder.

The byte will be truncated to an 8-bit value in the range 0 .. 255.

Implementation

void addByte(int byte);

clear()

void clear()

Clears the contents of this builder.

The current contents are discarded and this builder becomes empty.

Implementation

void clear();

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);

takeBytes()

Uint8List takeBytes()

Returns the bytes currently contained in this builder and clears it.

The returned list may be a view of a larger buffer.

Implementation

Uint8List takeBytes();

toBytes()

Uint8List toBytes()

Returns a copy of the current byte contents of this builder.

Leaves the contents of this builder intact.

Implementation

Uint8List toBytes();

toString() inherited

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.

Inherited from Object.

Implementation

external String toString();

Operators

operator ==() inherited

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.

Inherited from Object.

Implementation

external bool operator ==(Object other);