product-addons / includes / common / class-safe-math-evaluator.php

class-safe-math-evaluator.php in WowAddons – Product Addons and Product Options With Custom Fields trunk, at includes/common/class-safe-math-evaluator.php

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1	<?php //phpcs:ignore
2	/**
3	* Class SafeMathEvaluator
4	*
5	* @package WowAddons
6	*/
7
8	namespace PRAD\Includes\Common;
9
10	if ( ! defined( 'ABSPATH' ) ) {
11	exit; // Exit if accessed directly.
12	}
13
14	/**
15	* SafeMathEvaluator class.
16	*/
17	class SafeMathEvaluator {
18
19	/**
20	* Evaluates a mathematical expression safely, replacing dynamic variables and handling percentages.
21	*
22	* @param string $expression The mathematical expression to evaluate.
23	* @param array $dynamic_variables Associative array of dynamic variables to replace in the expression.
24	* @return float The evaluated result or 0 on error.
25	*/
26	public static function evaluate_expression( $expression, $dynamic_variables = array() ) {
27	$expression = sanitize_text_field( $expression );
28
29	// Replace dynamic variables.
30	$processed_expression = preg_replace_callback(
31	'/\{\{([a-zA-Z0-9_-]+)\}\}/',
32	function ( $matches ) use ( $dynamic_variables ) {
33	return ! empty( $dynamic_variables[ $matches[1] ] ) ? $dynamic_variables[ $matches[1] ] : 0;
34	},
35	$expression
36	);
37
38	// Handle percentages: convert 'X%' to '(X/100)'.
39	$processed_expression = preg_replace( '/(\d+(?:\.\d+)?)%/', '($1/100)', $processed_expression );
40
41	try {
42	$result = self::safe_evaluate( $processed_expression );
43	return is_numeric( $result ) && $result >= 0 ? (float) $result : 0;
44	} catch ( \Exception $e ) {
45	echo esc_html( 'Error evaluating expression: ' . $e->getMessage() );
46	return 0;
47	}
48	}
49
50	/**
51	* Safely evaluates a sanitized mathematical expression.
52	*
53	* @param string $expression The sanitized mathematical expression to evaluate.
54	* @return float The evaluated result.
55	* @throws \Exception If the expression contains invalid characters or unbalanced parentheses.
56	*/
57	public static function safe_evaluate( $expression ) {
58	// Remove whitespace.
59	$expression = preg_replace( '/\s+/', '', $expression );
60
61	// Validate expression contains only allowed characters.
62	if ( ! preg_match( '/^[0-9+\-*\/().]+$/', $expression ) ) {
63	throw new \Exception( 'Invalid characters in expression' );
64	}
65
66	// Check for balanced parentheses.
67	if ( ! self::has_balanced_parentheses( $expression ) ) {
68	throw new \Exception( 'Unbalanced parentheses' );
69	}
70
71	// Evaluate the expression.
72	return self::parse_expression( $expression );
73	}
74
75	/**
76	* Checks if the given expression has balanced parentheses.
77	*
78	* @param string $expression The expression to check.
79	* @return bool True if parentheses are balanced, false otherwise.
80	*/
81	public static function has_balanced_parentheses( $expression ) {
82	$count = 0;
83	$exp_length = strlen( $expression );
84	for ( $i = 0; $i < $exp_length; $i++ ) {
85	if ( '(' === $expression[ $i ] ) {
86	++$count;
87	} elseif ( ')' === $expression[ $i ] ) {
88	--$count;
89	if ( $count < 0 ) {
90	return false;
91	}
92	}
93	}
94	return 0 === $count;
95	}
96
97	/**
98	* Parses and evaluates a mathematical expression, handling parentheses recursively.
99	*
100	* @param string $expression The mathematical expression to parse and evaluate.
101	* @return float The evaluated result.
102	* @throws \Exception If the expression is invalid.
103	*/
104	public static function parse_expression( $expression ) {
105	// Handle parentheses first.
106	while ( strpos( $expression, '(' ) !== false ) {
107	$expression = preg_replace_callback(
108	'/$([^()]+)$/',
109	function ( $matches ) {
110	return self::evaluate_simple_expression( $matches[1] );
111	},
112	$expression
113	);
114	}
115
116	return self::evaluate_simple_expression( $expression );
117	}
118
119	/**
120	* Evaluates a simple mathematical expression without parentheses.
121	*
122	* Handles multiplication, division, addition, and subtraction operations.
123	*
124	* @param string $expression The mathematical expression to evaluate.
125	* @return float The evaluated result.
126	* @throws \Exception If the expression is invalid or division by zero occurs.
127	*/
128	public static function evaluate_simple_expression( $expression ) {
129	// Handle multiplication and division first (left to right).
130	while ( preg_match( '/(-?\d+(?:\.\d+)?)\s([\/])\s*(-?\d+(?:\.\d+)?)/', $expression, $matches ) ) {
131	$left = (float) $matches[1];
132	$operator = $matches[2];
133	$right = (float) $matches[3];
134
135	if ( '*' === $operator ) {
136	$result = $left * $right;
137	} elseif ( '/' === $operator ) {
138	if ( 0 == $right ) {
139	throw new \Exception( 'Division by zero' );
140	}
141	$result = $left / $right;
142	}
143
144	$expression = str_replace( $matches[0], $result, $expression );
145	}
146
147	// Handle addition and subtraction (left to right).
148	while ( preg_match( '/(-?\d+(?:\.\d+)?)\s([+\-])\s(-?\d+(?:\.\d+)?)/', $expression, $matches ) ) {
149	$left = (float) $matches[1];
150	$operator = $matches[2];
151	$right = (float) $matches[3];
152
153	if ( '+' === $operator ) {
154	$result = $left + $right;
155	} elseif ( '-' === $operator ) {
156	$result = $left - $right;
157	}
158
159	$expression = str_replace( $matches[0], $result, $expression );
160	}
161
162	// Should be left with just a number.
163	if ( ! is_numeric( $expression ) ) {
164	throw new \Exception( 'Invalid expression result: ' . esc_html( $expression ) );
165	}
166
167	return (float) $expression;
168	}
169	}
170