@swim/util
v4.0.0
Published
Interfaces for ordering, equality, hashing, type conversions, functional maps, interpolators, scales, iterators, builders, key-value maps, caches, and assertions
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Swim Util Library
The Swim Util library provides interfaces for ordering, equality, hashing, type conversions, functional maps, interpolators, scales, iterators, builders, key-value maps, caches, and assertions.
Overview
Ordering, equality, and hashing
Swim Util exports Comparable
, Equals
, and HashCode
interfaces that can
be implemented by ordered, equatable, and hash-able classes, respectively.
export interface Comparable<T> {
compareTo(that: T): number;
}
export interface Equals {
equals(that: unknown): boolean;
}
export interface HashCode extends Equals {
hashCode(): number;
}
The exported Objects
object supports generic comparison, equality testing,
and hashing of arbitrary JavaScript values, including primitives, arrays, and
objects.
Objects.compare(x: unknown, y: unknown): 0 | 1 | -1
returns the relative
sort order of two comparable values. If x
implements Comparable
, then
Objects.compare
delegates to x
's compareTo
method. If x
and y
are
both numbers, or both strings, they are compared lexicographically. If x
and y
are both arrays, then each corresponding element is compared, in turn,
using Objects.compare
. If x
and y
are both objects, then each entry is
compared first by key, then by value, using Objects.compare
. Values of
incompatible types sort in a deterministic order based on type.
Objects.equal(x: unknown, y: unknown): boolean
returns true
if two values
are equivalent. If x
implements Equals
, then Objects.equal
delegates to
x
's equals
method. If x
and y
are both primitives, then they are
compared by value. If x
and y
are both arrays, then each corresponding
element is tested for equality, in turn, using Objects.equal
. If x
and y
are both objects, then each entry is tested for equality furst by key, then by
value, using Objects.equal
.
Objects.hash(x: unknown): number
returns a consistent hash code for x
.
If x
implements HashCode
, then Objects.hash
delegate's to x
's
hashCode
method. If x
is a primitive, it is hashed using the Murmur3
hashing algorithm. If x
is an array, each element is hashed individually
using Objects.hash
, and the hash codes of all elements get mixed together.
If x
is an object, each entry has its key and value hashed using
Objects.hash
, and the hash codes of all entries get mixed together.
The exported Murmur3
object implements the 32-bit
MurmurHash algorithm, version 3.
Builder interfaces
The exported Builder
interface abstracts over construction of collections.
And the PairBuilder
interface abstracts over construction of key-value maps,
and other pair-containing collections.
export interface Builder<I, O> {
push(...inputs: I[]): void;
build(): O;
}
export interface PairBuilder<K, V, O> {
add(key: K, value: V): void;
build(): O;
}
Map interfaces
Swim Util defines three key-value map interfaces: an ES6-compatible Map
interface, as well as an OrderedMap
interface, and a ReducedMap
interface.
An OrderedMap
has its entries sorted by key order. A ReducedMap
is an
OrderedMap
that memoizes partial combinations of sub-elements to support
efficient, incremental reduction of continuously mutating datasets.
Assertions
The exported Assert
interface provides a common API for constraint testing
and contract enforcement. The exported assert
singleton provides a default
Assert
implementation that throws AssertException
on assert failure.