Return a string replacing a placeholder by a sequential number.

unique-string-id.php

<?php

/**
 * Return a string replacing placeholder by a number
 *
 * You can create 'item-1', 'item-2', 'item-3'... globally
 * just calling unique_string_id('item{id}')
 *
 * @param  string  $string
 * @param  bool    $includeOne
 * @param  string  $placeholder
 * @param  string  $separator
 *
 * @return string
 */

function unique_string_id($string, $includeOne = true, $placeholder = '{id}', $separator = '-')
{
    global $unique_string_id;

    if (! is_array($unique_string_id)) {
        $unique_string_id = [];
    }

    $identifier = str_replace($placeholder, $separator, $string);

    if (empty($unique_string_id[ $identifier ])) {
        $unique_string_id[ $identifier ] = 0;
    }

    $unique_string_id[ $identifier ]++;

    // Create a impossible placeholder, so we can trim at the end
    $impossibleSeparator = '__impossible_%_separator__';

    // Add unique ID
    $replace = $impossibleSeparator;
    if ($unique_string_id[ $identifier ] > 1 || ($unique_string_id[ $identifier ] === 1 && $includeOne)) {
        $replace .= $unique_string_id[ $identifier ] . $impossibleSeparator;
    }

    $string = str_replace($placeholder, $replace, $string);

    // Trimming
    while (strpos($string, $impossibleSeparator) === 0) {
        $string = substr($string, strlen($impossibleSeparator));
    }

    while (strrpos($string, $impossibleSeparator) === (strlen($string) - strlen($impossibleSeparator))) {
        $string = substr($string, 0, strlen($string) - strlen($impossibleSeparator));
    }

    return str_replace($impossibleSeparator, $separator, $string);
}

/*

Test

public function testUniqueStringIdFunction()
{
    // Test common
    $this->assertSame('item-1', unique_string_id('item{id}'));
    $this->assertSame('item-2', unique_string_id('item{id}'));
    $this->assertSame('item-3', unique_string_id('item{id}'));

    // Test without first
    $this->assertSame('no-first', unique_string_id('no-first{id}', false));
    $this->assertSame('no-first-2', unique_string_id('no-first{id}', false));
    $this->assertSame('no-first-3', unique_string_id('no-first{id}', false));

    // Test with another placeholder
    $this->assertSame('placeholder-{id}-1', unique_string_id('placeholder-{id}{key}', true, '{key}'));
    $this->assertSame('placeholder-{id}-2', unique_string_id('placeholder-{id}{key}', true, '{key}'));
    $this->assertSame('placeholder-{id}-3', unique_string_id('placeholder-{id}{key}', true, '{key}'));

    // Test with another separator
    $this->assertSame('item_1', unique_string_id('item{id}', true, '{id}', '_'));
    $this->assertSame('item_2', unique_string_id('item{id}', true, '{id}', '_'));
    $this->assertSame('item_3', unique_string_id('item{id}', true, '{id}', '_'));

    // Test not remove char equal to separator with ID on start
    $this->assertSame('starting-id-', unique_string_id('{id}starting-id-', false));
    $this->assertSame('2-starting-id-', unique_string_id('{id}starting-id-', false));

    // Test not remove char equal to separator with ID on end
    $this->assertSame('-ending-id', unique_string_id('-ending-id{id}', false));
    $this->assertSame('-ending-id-2', unique_string_id('-ending-id{id}', false));
}

**/