Needlessly Promiscuous, Modularize!
    Wondering what’s next for npm?Check out our public roadmap! »

    unicode-trie
    DefinitelyTyped icon, indicating that this package has TypeScript declarations provided by the separate @types/unicode-trie package

    0.3.1 • Public • Published

    unicode-trie

    A data structure for fast Unicode character metadata lookup, ported from ICU

    Background

    When implementing many Unicode algorithms such as text segmentation, normalization, bidi processing, etc., fast access to character metadata is crucial to good performance. There over a million code points in the Unicode standard, many of which produce the same result when looked up, so an array or hash table is not appropriate - those data structures are fast but would require a lot of memory. The data is generally grouped in ranges, so you could do a binary search, but that is not fast enough for some applications.

    The International Components for Unicode (ICU) project came up with a data structure based on a Trie that provides fast access to Unicode metadata. The range data is precompiled to a serialized and flattened trie, which is then used at runtime to lookup the necessary data. According to my own tests, this is generally at least 50% faster than binary search, with not too much additional memory required.

    Installation

    npm install unicode-trie
    

    Building a Trie

    Unicode Tries are generally precompiled from data in the Unicode database for faster runtime performance. To build a Unicode Trie, use the UnicodeTrieBuilder class.

    UnicodeTrieBuilder = require 'unicode-trie/builder'
     
    # create a trie 
    = new UnicodeTrieBuilder
     
    # optional parameters for default value, and error value 
    # if not provided, both are set to 0 
    = new UnicodeTrieBuilder 10999
     
    # set individual values and ranges 
    t.set 0x456799
    t.setRange 0x400xe70x1234
     
    # you can lookup a value if you like 
    t.get 0x4567 # => 99 
     
    # get a compiled trie (returns a UnicodeTrie object) 
    trie = t.freeze()
     
    # write compressed trie to a binary file 
    fs.writeFile 'data.trie't.toBuffer()

    Using a precompiled Trie

    Once you've built a precompiled trie, you can load it into the UnicodeTrie class, which is a readonly representation of the trie. From there, you can lookup values.

    UnicodeTrie = require 'unicode-trie'
    fs = require 'fs'
     
    # load serialized trie from binary file 
    data = fs.readFileSync 'data.trie'
    trie = new UnicodeTrie data
     
    # lookup a value 
    trie.get 0x4567 # => 99 

    License

    MIT

    Keywords

    none

    Install

    npm i [email protected]

    Version

    0.3.1

    License

    MIT

    Last publish

    Collaborators

    • avatar