byte_selection›Classes

ByteSelection

class ByteSelection

Represents a selection of bytes in the hex viewer.

This class describes a range of selected bytes with inclusive start and end offsets. It provides utilities for querying selection properties and extracting selected bytes.

Example:

// Single byte selection
final selection = ByteSelection.single(10);
print(selection.length); // 1

// Range selection
final range = ByteSelection.range(5, 15);
print(range.length); // 11 bytes (5-15 inclusive)
print(range.contains(10)); // true

// Get selected bytes
final bytes = range.getBytes(myData);

See also:

• HexViewer.onSelectionChanged which provides this object

Constructors

ByteSelection() const

const ByteSelection({required int startOffset, required int endOffset})

Creates a byte selection with the given offsets.

Both offsets are inclusive. For selecting bytes 5 through 10, use ByteSelection(startOffset: 5, endOffset: 10).

Consider using ByteSelection.single or ByteSelection.range factory constructors for more convenient creation.

Implementation

const ByteSelection({required this.startOffset, required this.endOffset});

ByteSelection.range() factory

factory ByteSelection.range(int start, int end)

Creates a selection from a range of bytes.

Automatically orders the offsets so startOffset ≤ endOffset, regardless of the order of start and end parameters.

Example:

// Both create the same selection (5-10):
final sel1 = ByteSelection.range(5, 10);
final sel2 = ByteSelection.range(10, 5);
print(sel1 == sel2); // true

Implementation

factory ByteSelection.range(int start, int end) {
  final actualStart = start < end ? start : end;
  final actualEnd = start < end ? end : start;
  return ByteSelection(startOffset: actualStart, endOffset: actualEnd);
}

ByteSelection.single() factory

factory ByteSelection.single(int offset)

Creates a selection of a single byte at the given offset.

This is equivalent to ByteSelection(startOffset: offset, endOffset: offset).

Example:

final sel = ByteSelection.single(42);
print(sel.length); // 1
print(sel.contains(42)); // true

Implementation

factory ByteSelection.single(int offset) {
  return ByteSelection(startOffset: offset, endOffset: offset);
}

Properties

end no setter

int get end

Convenience getter for end offset.

Alias for endOffset for more natural usage:

print('Selected from ${selection.start} to ${selection.end}');

Implementation

int get end => endOffset;

endOffset final

final int endOffset

End offset of the selection (inclusive).

This is the index of the last selected byte in the data array. For a single-byte selection, endOffset equals startOffset.

Implementation

final int endOffset;

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(startOffset, endOffset);

length no setter

int get length

Number of bytes in the selection.

Returns the count of selected bytes. For inclusive range 0, 9, returns 10. Guaranteed to be non-negative.

Example:

ByteSelection(startOffset: 5, endOffset: 9).length; // 5 bytes
ByteSelection.single(10).length; // 1 byte

Implementation

int get length =>
    (endOffset - startOffset + 1).clamp(0, double.infinity).toInt();

runtimeType no setter inherited

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

start no setter

int get start

Convenience getter for start offset.

Alias for startOffset for more natural usage:

print('Selected from ${selection.start} to ${selection.end}');

Implementation

int get start => startOffset;

startOffset final

final int startOffset

Start offset of the selection (inclusive).

This is the index of the first selected byte in the data array. For a single-byte selection, startOffset equals endOffset.

Implementation

final int startOffset;

Methods

contains()

bool contains(int offset)

Checks if the given offset is within this selection.

Returns true if offset is between startOffset and endOffset (inclusive).

Example:

final sel = ByteSelection.range(5, 10);
sel.contains(7);  // true
sel.contains(5);  // true (inclusive)
sel.contains(10); // true (inclusive)
sel.contains(11); // false

Implementation

bool contains(int offset) {
  return offset >= startOffset && offset <= endOffset;
}

getBytes()

List<int> getBytes(List<int> data)

Extracts the selected bytes from the given data.

Returns a sublist of data containing only the selected bytes. If the selection is out of bounds, returns an empty list or truncates to available data.

Example:

final data = [0x48, 0x65, 0x6C, 0x6C, 0x6F]; // "Hello"
final sel = ByteSelection.range(0, 2);
final bytes = sel.getBytes(data); // [0x48, 0x65, 0x6C]

Implementation

List<int> getBytes(List<int> data) {
  if (startOffset < 0 || startOffset >= data.length) {
    return [];
  }
  &#47;&#47; Use min to avoid integer overflow when endOffset is near int.maxValue
  final end = min(endOffset + 1, data.length);
  return data.sublist(startOffset, end);
}

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);

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() {
  if (startOffset == endOffset) {
    return 'ByteSelection(offset: 0x${startOffset.toRadixString(16)})';
  }
  return 'ByteSelection(0x${startOffset.toRadixString(16)} - 0x${endOffset.toRadixString(16)}, $length bytes)';
}

Operators

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) {
  if (identical(this, other)) return true;
  return other is ByteSelection &&
      other.startOffset == startOffset &&
      other.endOffset == endOffset;
}