lexicographical_order 1.0.2

A string generator that helps to implement a lexicographical order.

Lexicographical Order

A string generator that helps to implement a lexicographical order.

Installing

dependencies:
  lexicographical_order: 

import 'package:lexicographical_order/lexicographical_order.dart';

Usage

• Get a string between two strings in a lexicographical order.

  final mid = between(prev: 'B', next: 'D');
  final list = [mid, 'D', 'B'];
  assert(listEqauls(list..sort(), ['B', mid, 'D']);
  

  • practice

    class Todo {
      final int id;
      String title;
      bool completed
      String _orderKey;
          
      void reorderBetween(Todo? prev, Todo? next) {
    	_orderKey = between(
          prev: prev?._orderKey, 
          next: next?._orderKey,
        );
      }
          
      Todo(/* omitted */);
    }
    

• Generates strings that satisfy the minimum average string length and lexicographic order.

  const stringCount = 100;
  List<String> orderKeys = generateOrderKeys(stringCount).toList(); 
  

Constraints

• The between([String prev='', String next='']) function accepts only alphabetic characters as arguments, more precisely, the following code must return true.

  final alphabet = 'ABCDEFGHIJKLMNOPQRSTUWXYZabcdefghijklmnopqrstuwxyz'.split('');
  final String argument = /* omitted */
    
  return key.split('').every((e) => alphabet.contains(e));
  

  and the following constraint must also be satisfied:

  ​ 1. prev and next should consist only of allowed keys

  the constraints

• Don't use 'A' as first order key

  no character can precede 'A'.