Category talk:Wren-trait: Difference between revisions

// It it isn't, returns an empty range. Useful when bounds are variable.

// It it isn't, returns an empty range. Useful when bounds are variable.

}

/* SeqEntry represents an (index, value) pair for use with the Indexed class. */

class SeqEntry {

// Constructs a new SeqEntry object.

construct new(index, value) {

_index = index

_value = value

}

// Properties.

index { _index }

value { _value }

// Returns the current instance's string representation.

toString { "%(_index):%(_value)" }

}

/*

Indexed wraps a Sequence (other than a range) so its elements can be iterated over

together with their zero-based indices.

*/

class Indexed is Sequence {

// Constructs a new indexed sequence with a step of 'step' and optionally reversed.

construct new(seq, step, reversed) {

if (seq is Range) Fiber.abort("First argument cannot be a range.")

if (!(reversed is Bool)) Fiber.abort("Third argument must be true or false.")

_seq = !reversed ? Stepped.new(seq, step) : Reversed.new(seq, step)

}

// Constructs a new indexed sequence with a step of 'step' and 'reversed' set to false.

static new(seq, step) { new(seq, step, false) }

// Constructs a new indexed sequence with a step of 1.

construct new(seq) {

if (!(seq is Sequence) || seq is Range) {

Fiber.abort("Argument must be a sequence other than a range.")

}

_seq = seq

}

// Iterator protocol methods.

iterate(iterator) { _seq.iterate(iterator) }

iteratorValue(iterator) {

return SeqEntry.new(iterator, _seq.iteratorValue(iterator))

}

var Trait_SeqEntry = SeqEntry

var Trait_Indexed = Indexed

var Trait_ByRef = ByRef

var Trait_ByKey = ByKey</lang>