Class: Sequence

Layout~Sequence(elementLayout, count, propertyopt)

Represent a contiguous sequence of a specific layout as an Array.

Factory: seq

Constructor

new Sequence(elementLayout, count, propertyopt)

Parameters:
Name Type Attributes Description
elementLayout module:Layout~Layout

initializer for elementLayout.
count Number | ExternalLayout

initializer for count. The parameter must be either a positive integer or an instance of ExternalLayout.
property string <optional>

initializer for property.
Source:

Extends

Members

count

The number of elements in the sequence.

This will be either a non-negative integer or an instance of ExternalLayout for which isCount() is true.

Source:

elementLayout

The layout for individual elements of the sequence.

Source:

property

The property name used when this layout is represented in an Object.

Used only for layouts that decode to Object instances. If left undefined the span of the unnamed layout will be treated as padding: it will not be mutated by encode nor represented as a property in the decoded Object.

Inherited From:
Source:

span

The span of the layout in bytes.

Positive values are generally expected.

Zero will only appear in Constants and in Sequences where the count is zero.

A negative value indicates that the span is value-specific, and must be obtained using getSpan.

Inherited From:
Source:

Methods

decode(b, offsetopt) → {Number|Array|Object}

Decode from a Buffer into an JavaScript value.

Parameters:
Name Type Attributes Description
b Buffer

the buffer from which encoded data is read.
offset Number <optional>

the offset at which the encoded data starts. If absent a zero offset is inferred.
Overrides:
Source:
Returns:
  • the value of the decoded data.
Type
Number | Array | Object

encode()

Implement encode for Sequence.

NOTE If src is shorter than count then the unused space in the buffer is left unchanged. If src is longer than count the unneeded elements are ignored.

NOTE If count is an instance of ExternalLayout then the length of src will be encoded as the count after src is encoded.

Overrides:
Source:

fromArray(values) → {Object|undefined}

Create an object from layout properties and an array of values.

NOTE This function returns undefined if invoked on a layout that does not return its value as an Object. Objects are returned for things that are a Structure, which includes variant layouts if they are structures, and excludes Unions. If you want this feature for a union you must use getVariant to select the desired layout.

Parameters:
Name Type Description
values Array

an array of values that correspond to the default order for properties. As with decode layout elements that have no property name are skipped when iterating over the array values. Only the top-level properties are assigned; arguments are not assigned to properties of contained layouts. Any unused values are ignored.
Inherited From:
Source:
Returns:
Type
Object | undefined

getSpan(b, offsetopt) → {Number}

Calculate the span of a specific instance of a layout.

Parameters:
Name Type Attributes Description
b Buffer

the buffer that contains an encoded instance.
offset Number <optional>

the offset at which the encoded instance starts. If absent a zero offset is inferred.
Overrides:
Source:
Throws:
  • if the length of the value cannot be determined.
Type
RangeError
Returns:
  • the number of bytes covered by the layout instance. If this method is not overridden in a subclass the definition-time constant span will be returned.
Type
Number

makeDestinationObject()

Function to create an Object into which decoded properties will be written.

Used only for layouts that decode to Object instances, which means:

If left undefined the JavaScript representation of these layouts will be Object instances.

See bindConstructorLayout.

Inherited From:
Source:

replicate(property) → {module:Layout~Layout}

Replicate the layout using a new property.

This function must be used to get a structurally-equivalent layout with a different name since all Layout instances are immutable.

NOTE This is a shallow copy. All fields except property are strictly equal to the origin layout.

Parameters:
Name Type Description
property String

the value for property in the replica.
Inherited From:
Source:
Returns:
  • the copy with property set to property.
Type
module:Layout~Layout