@swim/collections
@swim/collections implements data structures for key-value maps and sequential lists, including B-trees and S-trees (implicitly indexed B-tree). @swim/collections is written in TypeScript, but can be used from either TypeScript or JavaScript. @swim/collections is part of the @swim/core framework.
Overview
B-trees
The BTree
class implements the OrderedMap
interface from @swim/util,
and compares keys using Objects.compare
, also from @swim/util. BTree
is internally immutable, enabling lightweight snapshotting via BTree.clone
,
and non-destructive mutation via BTree.updated
, and BTree.removed
.
BTree
also implements the ReducedMap
interface from @swim/util,
providing storage of sub-tree reductions in b-tree nodes to support log
time recomputation of whole tree reductions after incremental updates.
S-trees
The STree
class implements a sequential list data type that's backed by an
implicitly indexed b-tree. Like BTree
, STree
supports lightweight
snapshotting via STree.clone
.
STree
associated a unique ID with each list item, which can be used to
reconcile concurrent, conflicting updates to the same logical list.
Installation
npm
For an npm-managed project, npm install @swim/collections
to
make it a dependency. TypeScript sources will be installed into
node_modules/@swim/collections/main
. Transpiled JavaScript and TypeScript
definition files install into node_modules/@swim/collections/lib/main
.
And a pre-built UMD script can be found in
node_modules/@swim/collections/dist/main/swim-collections.js
.
Browser
Browser applications can load swim-core.js
, which comes bundled with the
@swim/collections library, directly from the SwimOS CDN.
<!-- Development -->
<script src="https://cdn.swimos.org/js/latest/swim-core.js"></script>
<!-- Production -->
<script src="https://cdn.swimos.org/js/latest/swim-core.min.js"></script>
Alternatively, the standalone swim-system.js
script may be loaded
from the SwimOS CDN, which bundles @swim/collections together with all other
@swim/system
libraries.
<!-- Development -->
<script src="https://cdn.swimos.org/js/latest/swim-system.js"></script>
<!-- Production -->
<script src="https://cdn.swimos.org/js/latest/swim-system.min.js"></script>
Usage
ES6/TypeScript
@swim/collections can be imported as an ES6 module from TypeScript and other ES6-compatible environments.
import * as collections from "@swim/collections";
CommonJS/Node.js
@swim/collections can also be used as a CommonJS module in Node.js applications.
var collections = require("@swim/collections");
Browser
When loaded by a web browser, the swim-core.js
script adds all
@swim/collections library exports to the global swim
namespace.
The swim-system.js
script also adds all @swim/collections library exports
to the global swim
namespace, making it a drop-in replacement for
swim-core.js
when additional @swim/system libraries are needed.