morton-page

Morton order index for multidimensional pages

npm install morton-page
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morton-page

A data structure for maintaining a list of pages keyed by Morton order (also known as z-order or interleaving).

Example

//Create a 2D page store having a capacity of (1<<4) == 16
var pageStore = require("morton-page")(2, 4)

//Add a page
pageStore.add({key: [10, 10], value: "foo"})

//Retrieve a page
var x = pageStore.get(10, 10)
console.log(x)

//Remove the page
pageStore.remove(10, 10)

//Try pulling the page out (returns null now)
console.log(pageStore.get(10, 10))

Install

npm install morton-page

API

var createPageStore = require("morton-page")

Constructor

var store = createPageStore(dimension, log_size[, shift, key])

Creates a z-order page store.

  • dimension is the dimension of the pages
  • log_size is the log base 2 of the number of buckets in the store
  • shift is the number of bits to shift each page by before indexing (default: 0)
  • key is the property of each page to use for the index (default: "key")

Returns An instance of a MortonPageStore class specialized for the given input parameters.

Methods

store.add(page)

Adds a page to the store

  • page is an object with a field called key which is an array of coordinates representing the identifier of the page in the store.

store.get(i0, i1, ...)

Retrieves the page with the given key from the page store

  • i0, i1, ... is the name of the page

Returns The page with the key i0, i1, ... if it is in the store, or null otherwise.

store.remove(i0, i1, ...)

Removes the page with the given key from the store.

  • i0, i1, ... is the key of the page

FAQ

Why use this instead of an object?

Basically it is faster and does not require creating any string objects. All of the methods in this class require 0 allocations and thus will not trigger garbage collection events.

Credits

(c) 2013 Mikola Lysenko. MIT License

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