es-string-algorithm

es-string-algorithm

Introduction

C++ STL provide find_first_of / find_first_not_of / find_last_of / find_last_not_of member function.

However, JavaScript String class does not provide such method. So, this package provide these functions.

(When you want find / rfind that C++ STL provide, please use indexOf / lastIndexOf)

Reference

Every function manipulate a string as if that is UTF-32 encoded.

To describe simply, we use two function like below:

• size(s: string) => number: Returns the length of s.
• at(s: string, n: number) => string: Returns nth charactor.

findFirstOf

export declare const findFirstOf: (target: string, key: string, pos?: number, n?: number | undefined) => number;

Determines the lowest position xpos, if possible, such that both of the following conditions hold:

1. pos <= xpos and xpos < size(target)
2. k.includes(at(target, xpos)) (When n is undefined (omitted), k is equal to key. Otherwise, k is equal to key.substring(0, n))

Parameters

• target: search target string
• key: string identifying characters to search for
• pos = 0: position at which to begin searching
• n(opt): length of character string identifying characters to search for

Return value

xpos if the function can determine such a value for xpos. Otherwise, returns -1.

Example

const std = require('es-string-algorithm');
const s = 'Hello, world. Welcome to C++ world.';
const str = 'world';
console.log(std.findFirstOf(s, str, 14));// => 16
console.log(std.findFirstOf(s, ',.+', 14));// => 26
console.log(std.findFirstOf('arikitari na sekai', 'a', 1));// => 6
console.log(std.findFirstOf('🍣🍺', '🍺'));// => 1

findLastof

export declare const findLastof: (target: string, key: string, pos?: number, n?: number | undefined) => number;

Determines the highest position xpos, if possible, such that both of the following conditions hold:

1. pos <= xpos and xpos < size(target)
2. k.includes(at(target, xpos)) (When n is undefined (omitted), k is equal to key. Otherwise, k is equal to key.substring(0, n))

Parameters

• target: search target string
• key: string identifying characters to search for
• pos = -1: position at which the search is to finish. -1 is equal to the length of search target string
• n(opt): length of character string identifying characters to search for

Return value

xpos if the function can determine such a value for xpos. Otherwise, returns -1.

Example

const std = require('es-string-algorithm');
const s = 'Hello, world. Welcome to C++ world.';
const str = 'world';
console.log(std.findLastof(s, str, 25));// => 23
console.log(std.findLastof(s, ',.+', 5));// => 5
console.log(std.findLastof('arikitari na sekai', 'a', 1));// => 0
console.log(std.findLastof('🍣🍺', '🍺'));// => 1

findFirstNotOf

export declare const findFirstNotOf: (target: string, key: string, pos?: number, n?: number | undefined) => number;

Determines the lowest position xpos, if possible, such that both of the following conditions hold:

1. pos <= xpos and xpos < size(target)
2. !k.includes(at(target, xpos)) (When n is undefined (omitted), k is equal to key. Otherwise, k is equal to key.substring(0, n))

Parameters

• target: search target string
• key: string identifying characters to search for
• pos = 0: position at which to begin searching
• n(opt): length of character string identifying characters to search for

Return value

xpos if the function can determine such a value for xpos. Otherwise, returns -1.

Example

const std = require('es-string-algorithm');
const s = 'Hello, world. Welcome to C++ world.';
const str = 'world';
console.log(std.findFirstNotOf(s, str, 2));// => 5
console.log(std.findFirstNotOf(s, 'worlde,. ', 1));// => 14
console.log(std.findFirstNotOf('arikitari na sekai datta', 't', 21));// => 23
console.log(std.findFirstNotOf('🍣🍺', '🍣'));// => 1

findLastNotof

export declare const findLastNotof: (target: string, key: string, pos?: number, n?: number | undefined) => number;

Determines the highest position xpos, if possible, such that both of the following conditions hold:

1. pos <= xpos and xpos < size(target)
2. k.includes(at(target, xpos)) (When n is undefined (omitted), k is equal to key. Otherwise, k is equal to key.substring(0, n))

Parameters

• target: search target string
• key: string identifying characters to search for
• pos = -1: position at which the search is to finish. -1 is equal to the length of search target string
• n(opt): length of character string identifying characters to search for

Return value

xpos if the function can determine such a value for xpos. Otherwise, returns -1.

Example

const std = require('es-string-algorithm');
const s = 'Hello, world. Welcome to C++ world.';
const str = 'world';
console.log(std.findLastNotof(s, str, 11));// => 6
console.log(std.findLastNotof(s, 'Welcome to C++ world.', 1));// => 5
console.log(std.findLastNotof('arikitari na sekai', 'a', 0));// => -1
console.log(std.findLastNotof('🍣🍺', '🍺'));// => 0