king-addons / includes / widgets / Form_Builder / helpers / Formula.php

Formula.php in King Addons for Elementor – 80+ Elementor Widgets, 4 000+ Elementor Templates, WooCommerce, Mega Menu, Popup Builder 51.1.83, at includes/widgets/Form_Builder/helpers/Formula.php

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1	<?php
2	/**
3	* Arithmetic evaluator shared by the calculation field and payments.
4	*
5	* @package King_Addons
6	*/
7
8	namespace King_Addons;
9
10	if (!defined('ABSPATH')) {
11	exit;
12	}
13
14	/**
15	* Evaluates "1 + 2 * (3 - 4)" without eval().
16	*
17	* The browser has the same rules in script.js; this copy exists so a price can
18	* be worked out again on the server rather than taken from the request.
19	*/
20	class Form_Formula
21	{
22	/**
23	* Work out a formula, substituting [field_id] with submitted values.
24	*
25	* @param string $formula Formula as the author wrote it.
26	* @param array<string,string> $values Field id => submitted value.
27	*
28	* @return float\|null Result, or null when the formula is not valid.
29	*/
30	public static function evaluate(string $formula, array $values): ?float
31	{
32	$resolved = preg_replace_callback(
33	'/\[([^\]]+)\]/',
34	static function ($matches) use ($values) {
35	$key = trim($matches[1]);
36	// Submitted names use resolve_field_key(); older payloads
37	// prefixed the same id with form_field-.
38	$raw = $values[$key] ?? $values['form_field-' . $key] ?? '0';
39	$number = (float) str_replace(',', '.', (string) $raw);
40
41	return '(' . $number . ')';
42	},
43	$formula
44	);
45
46	return self::compute((string) $resolved);
47	}
48
49	/**
50	* Evaluate an expression of numbers, + - * / and parentheses.
51	*
52	* @param string $expression Expression.
53	*
54	* @return float\|null
55	*/
56	public static function compute(string $expression): ?float
57	{
58	preg_match_all('/\d+\.?\d\|[-+\/()]/', $expression, $matches);
59	$tokens = $matches[0];
60
61	if (empty($tokens)) {
62	return null;
63	}
64
65	// Anything the tokenizer skipped means the expression held something
66	// else - a letter, a symbol - and the whole thing is rejected.
67	if (implode('', $tokens) !== preg_replace('/\s+/', '', $expression)) {
68	return null;
69	}
70
71	$precedence = ['+' => 1, '-' => 1, '*' => 2, '/' => 2];
72	$output = [];
73	$operators = [];
74	$previous = null;
75
76	foreach ($tokens as $token) {
77	if (is_numeric($token)) {
78	$output[] = (float) $token;
79	} elseif ('(' === $token) {
80	$operators[] = $token;
81	} elseif (')' === $token) {
82	while (!empty($operators) && '(' !== end($operators)) {
83	$output[] = array_pop($operators);
84	}
85
86	if (empty($operators)) {
87	return null;
88	}
89
90	array_pop($operators);
91	} else {
92	// A leading minus is a sign, not an operator.
93	if ('-' === $token && (null === $previous \|\| '(' === $previous \|\| isset($precedence[$previous]))) {
94	$output[] = 0.0;
95	}
96
97	while (
98	!empty($operators)
99	&& '(' !== end($operators)
100	&& $precedence[end($operators)] >= $precedence[$token]
101	) {
102	$output[] = array_pop($operators);
103	}
104
105	$operators[] = $token;
106	}
107
108	$previous = $token;
109	}
110
111	while (!empty($operators)) {
112	$last = array_pop($operators);
113	if ('(' === $last) {
114	return null;
115	}
116	$output[] = $last;
117	}
118
119	$stack = [];
120
121	foreach ($output as $item) {
122	if (is_float($item)) {
123	$stack[] = $item;
124	continue;
125	}
126
127	if (count($stack) < 2) {
128	return null;
129	}
130
131	$right = array_pop($stack);
132	$left = array_pop($stack);
133
134	switch ($item) {
135	case '+':
136	$stack[] = $left + $right;
137	break;
138	case '-':
139	$stack[] = $left - $right;
140	break;
141	case '*':
142	$stack[] = $left * $right;
143	break;
144	case '/':
145	if (0.0 === $right) {
146	return null;
147	}
148	$stack[] = $left / $right;
149	break;
150	default:
151	return null;
152	}
153	}
154
155	if (1 !== count($stack) \|\| !is_finite($stack[0])) {
156	return null;
157	}
158
159	return (float) $stack[0];
160	}
161	}
162