formidable / classes / helpers / FrmStringReaderHelper.php

FrmStringReaderHelper.php in Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More 6.6, at classes/helpers/FrmStringReaderHelper.php

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1	<?php
2
3	if ( ! defined( 'ABSPATH' ) ) {
4	die( 'You are not allowed to call this page directly.' );
5	}
6
7	/**
8	* Given a string, this class will read through the string using
9	* one of a number of terminating rules:
10	* - One character.
11	* - A specified number of characters.
12	* - Until a matching character is found.
13	*
14	* @since 6.2
15	*/
16	class FrmStringReaderHelper {
17
18	/**
19	* @var int
20	*/
21	private $pos = 0;
22
23	/**
24	* @var int
25	*/
26	private $max = 0;
27
28	/**
29	* @var string
30	*/
31	private $string;
32
33	/**
34	* @param string $string
35	*/
36	public function __construct( $string ) {
37	// Split the string up into an array of UTF-8 characters.
38	// As an array we can read through it one character at a time.
39
40	$this->string = $string;
41	$this->max = strlen( $this->string ) - 1;
42	}
43
44	/**
45	* Read characters until we reach the given character $char.
46	* By default, discard that final matching character and return the rest.
47	*
48	* @param string $char
49	* @param bool $discard_char
50	* @return string
51	*/
52	public function read_until( $char, $discard_char = true ) {
53	$value = '';
54
55	while ( null !== ( $one = $this->read_one() ) ) {
56	if ( $one !== $char \|\| ! $discard_char ) {
57	$value .= $one;
58	}
59
60	if ( $one === $char ) {
61	break;
62	}
63	}
64
65	return $value;
66	}
67
68	/**
69	* Read $count characters, or until we have reached the end,
70	* whichever comes first.
71	* By default, remove enclosing double-quotes from the result.
72	*
73	* @param int $count
74	* @return string
75	*/
76	public function read( $count ) {
77	$value = '';
78
79	while ( $count > 0 && ! is_null( $one = $this->read_one() ) ) {
80	$value .= $one;
81	--$count;
82	}
83
84	return $this->strip_quotes( $value );
85	}
86
87	/**
88	* Read the next character from the supplied string.
89	* Return null when we have run out of characters.
90	*
91	* @return string\|null
92	*/
93	private function read_one() {
94	if ( $this->pos <= $this->max ) {
95	$value = $this->string[ $this->pos ];
96	$this->pos += 1;
97	} else {
98	$value = null;
99	}
100	return $value;
101	}
102
103	/**
104	* Remove a single set of double-quotes from around a string.
105	* abc => abc
106	* "abc" => abc
107	* ""abc"" => "abc"
108	*
109	* @param string string
110	* @return string
111	*/
112	private function strip_quotes( $string ) {
113	// Only remove exactly one quote from the start and the end and then only if there is one at each end.
114
115	if ( strlen( $string ) < 2 \|\| substr( $string, 0, 1 ) !== '"' \|\| substr( $string, -1, 1 ) !== '"' ) {
116	// Too short, or does not start or end with a quote.
117	return $string;
118	}
119
120	// Return the middle of the string, from the second character to the second-but-last.
121	return substr( $string, 1, -1 );
122	}
123	}
124