adisesha

import 'dart:math' as math;

//See https://firebase.googleblog.com/2015/02/the-2120-ways-to-ensure-unique_68.html
//https://gist.github.com/amirh/0e7b480691f7e6506317a7600398124b
//Modified to remove hyphen and underscore to make ids url freindly
const String _kPushChars =
    '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
const _pushCharsLength = _kPushChars.length;

class _PushIdGenerator {

adisesha

let regex;

/* matching a specific string */
regex = /hello/; // looks for the string between the forward slashes (case-sensitive)... matches "hello", "hello123", "123hello123", "123hello"; doesn't match for "hell0", "Hello" 
regex = /hello/i; // looks for the string between the forward slashes (case-insensitive)... matches "hello", "HelLo", "123HelLO"
regex = /hello/g; // looks for multiple occurrences of string between the forward slashes...

/* wildcards */
regex = /h.llo/; // the "." matches any one character other than a new line character... matches "hello", "hallo" but not "h\nllo"
regex = /h.*llo/; // the "*" matches any character(s) zero or more times... matches "hello", "heeeeeello", "hllo", "hwarwareallo"