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| 1 | <?php |
| 2 | |
| 3 | namespace Wikimedia\Assert; |
| 4 | |
| 5 | /** |
| 6 | * Assert provides functions for assorting preconditions (such as parameter types) and |
| 7 | * postconditions. It is intended as a safer alternative to PHP's assert() function. |
| 8 | * |
| 9 | * Note that assertions evaluate expressions and add function calls, so using assertions |
| 10 | * may have a negative impact on performance when used in performance hotspots. The idea |
| 11 | * if this class is to have a neat tool for assertions if and when they are needed. |
| 12 | * It is not recommended to place assertions all over the code indiscriminately. |
| 13 | * |
| 14 | * For more information, see the README file. |
| 15 | * |
| 16 | * @since 0.1.0 |
| 17 | * |
| 18 | * @license MIT |
| 19 | * @author Daniel Kinzler |
| 20 | * @author Thiemo Kreuz |
| 21 | * @copyright Wikimedia Deutschland e.V. |
| 22 | */ |
| 23 | class Assert { |
| 24 | |
| 25 | /** |
| 26 | * Checks a precondition, that is, throws a PreconditionException if $condition is false. |
| 27 | * For checking call parameters, use Assert::parameter() instead. |
| 28 | * |
| 29 | * This is provided for completeness, most preconditions should be covered by |
| 30 | * Assert::parameter() and related assertions. |
| 31 | * |
| 32 | * @see parameter() |
| 33 | * |
| 34 | * @note This is intended mostly for checking preconditions in constructors and setters, |
| 35 | * or before using parameters in complex computations. |
| 36 | * Checking preconditions in every function call is not recommended, since it may have a |
| 37 | * negative impact on performance. |
| 38 | * |
| 39 | * @since 0.1.0 |
| 40 | * |
| 41 | * @param bool $condition |
| 42 | * @param string $description The message to include in the exception if the condition fails. |
| 43 | * |
| 44 | * @throws PreconditionException if $condition is not true. |
| 45 | * @phan-assert-true-condition $condition |
| 46 | */ |
| 47 | public static function precondition( $condition, $description ): void { |
| 48 | if ( !$condition ) { |
| 49 | throw new PreconditionException( "Precondition failed: $description" ); |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | * Checks a parameter, that is, throws a ParameterAssertionException if $condition is false. |
| 55 | * This is similar to Assert::precondition(). |
| 56 | * |
| 57 | * @note This is intended for checking parameters in constructors and setters. |
| 58 | * Checking parameters in every function call is not recommended, since it may have a |
| 59 | * negative impact on performance. |
| 60 | * |
| 61 | * @since 0.1.0 |
| 62 | * |
| 63 | * @param bool $condition |
| 64 | * @param string $name The name of the parameter that was checked. |
| 65 | * @param string $description The message to include in the exception if the condition fails. |
| 66 | * |
| 67 | * @throws ParameterAssertionException if $condition is not true. |
| 68 | * @phan-assert-true-condition $condition |
| 69 | */ |
| 70 | public static function parameter( $condition, $name, $description ): void { |
| 71 | if ( !$condition ) { |
| 72 | throw new ParameterAssertionException( $name, $description ); |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * Checks an parameter's type, that is, throws a InvalidArgumentException if $value is |
| 78 | * not of $type. This is really a special case of Assert::precondition(). |
| 79 | * |
| 80 | * @note This is intended for checking parameters in constructors and setters. |
| 81 | * Checking parameters in every function call is not recommended, since it may have a |
| 82 | * negative impact on performance. |
| 83 | * |
| 84 | * @note If possible, type hints should be used instead of calling this function. |
| 85 | * It is intended for cases where type hints to not work, e.g. for checking union types. |
| 86 | * |
| 87 | * @since 0.1.0 |
| 88 | * |
| 89 | * @param string|string[] $types The parameter's expected type. Can be the name of a native type |
| 90 | * or a class or interface, or a list of such names. |
| 91 | * For compatibility with versions before 0.4.0, multiple types can also be given separated |
| 92 | * by pipe characters ("|"). |
| 93 | * @param mixed $value The parameter's actual value. |
| 94 | * @param string $name The name of the parameter that was checked. |
| 95 | * |
| 96 | * @throws ParameterTypeException if $value is not of type (or, for objects, is not an |
| 97 | * instance of) $type. |
| 98 | * |
| 99 | */ |
| 100 | public static function parameterType( $types, $value, $name ): void { |
| 101 | if ( is_string( $types ) ) { |
| 102 | $types = explode( '|', $types ); |
| 103 | } |
| 104 | if ( !self::hasType( $value, $types ) ) { |
| 105 | throw new ParameterTypeException( $name, implode( '|', $types ) ); |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | /** |
| 110 | * @since 0.3.0 |
| 111 | * |
| 112 | * @param string $type Either "integer" or "string". Mixing "integer|string" is not supported |
| 113 | * because this is PHP's default anyway. It is of no value to check this. |
| 114 | * @param array $value The parameter's actual value. If this is not an array, a |
| 115 | * ParameterTypeException is raised. |
| 116 | * @param string $name The name of the parameter that was checked. |
| 117 | * |
| 118 | * @throws ParameterTypeException if one of the keys in the array $value is not of type $type. |
| 119 | */ |
| 120 | public static function parameterKeyType( $type, $value, $name ): void { |
| 121 | self::parameterType( 'array', $value, $name ); |
| 122 | |
| 123 | if ( $type !== 'integer' && $type !== 'string' ) { |
| 124 | throw new ParameterAssertionException( 'type', 'must be "integer" or "string"' ); |
| 125 | } |
| 126 | |
| 127 | foreach ( $value as $key => $element ) { |
| 128 | if ( gettype( $key ) !== $type ) { |
| 129 | throw new ParameterKeyTypeException( $name, $type ); |
| 130 | } |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * Checks the type of all elements of an parameter, assuming the parameter is an array, |
| 136 | * that is, throws a ParameterElementTypeException if any elements in $value are not of $type. |
| 137 | * |
| 138 | * @note This is intended for checking parameters in constructors and setters. |
| 139 | * Checking parameters in every function call is not recommended, since it may have a |
| 140 | * negative impact on performance. |
| 141 | * |
| 142 | * @since 0.1.0 |
| 143 | * |
| 144 | * @param string|string[] $types The elements' expected type. Can be the name of a native type |
| 145 | * or a class or interface. Multiple types can be given in an array (or a string separated |
| 146 | * by a pipe character ("|"), for compatibility with versions before 0.5.0). |
| 147 | * @param array $value The parameter's actual value. If this is not an array, |
| 148 | * a ParameterTypeException is raised. |
| 149 | * @param string $name The name of the parameter that was checked. |
| 150 | * |
| 151 | * @throws ParameterTypeException If $value is not an array. |
| 152 | * @throws ParameterElementTypeException If an element of $value is not of type |
| 153 | * (or, for objects, is not an instance of) $type. |
| 154 | * |
| 155 | */ |
| 156 | public static function parameterElementType( $types, $value, $name ): void { |
| 157 | self::parameterType( 'array', $value, $name ); |
| 158 | if ( is_string( $types ) ) { |
| 159 | $types = explode( '|', $types ); |
| 160 | } |
| 161 | |
| 162 | foreach ( $value as $element ) { |
| 163 | if ( !self::hasType( $element, $types ) ) { |
| 164 | throw new ParameterElementTypeException( $name, implode( '|', $types ) ); |
| 165 | } |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * @since 0.3.0 |
| 171 | * |
| 172 | * @param string $value |
| 173 | * @param string $name |
| 174 | * |
| 175 | * @throws ParameterTypeException if $value is not a non-empty string. |
| 176 | * @phan-assert non-empty-string $value |
| 177 | */ |
| 178 | public static function nonEmptyString( $value, $name ): void { |
| 179 | if ( !is_string( $value ) || $value === '' ) { |
| 180 | throw new ParameterTypeException( $name, 'non-empty string' ); |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | /** |
| 185 | * Checks a postcondition, that is, throws a PostconditionException if $condition is false. |
| 186 | * This is very similar Assert::invariant() but is intended for use only after a computation |
| 187 | * is complete. |
| 188 | * |
| 189 | * @note This is intended for double checking in the implementation of complex algorithms. |
| 190 | * Note however that it should not be used in performance hotspots, since evaluating |
| 191 | * $condition and calling postcondition() costs time. |
| 192 | * |
| 193 | * @since 0.1.0 |
| 194 | * |
| 195 | * @param bool $condition |
| 196 | * @param string $description The message to include in the exception if the condition fails. |
| 197 | * |
| 198 | * @throws PostconditionException |
| 199 | * @phan-assert-true-condition $condition |
| 200 | */ |
| 201 | public static function postcondition( $condition, $description ): void { |
| 202 | if ( !$condition ) { |
| 203 | throw new PostconditionException( "Postcondition failed: $description" ); |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Checks an invariant, that is, throws a InvariantException if $condition is false. |
| 209 | * This is very similar Assert::postcondition() but is intended for use throughout the code. |
| 210 | * |
| 211 | * @note The $condition is expected to be falsifiable. If you are trying |
| 212 | * to indicate that a code path is unreachable, use |
| 213 | * `throw new UnreachableException( 'why this code is unreachable' )` |
| 214 | * instead of `Assert::invariant( false, '…' )`. Code checking tools |
| 215 | * will complain about the latter. |
| 216 | * |
| 217 | * @note This is intended for double checking in the implementation of complex algorithms. |
| 218 | * Note however that it should not be used in performance hotspots, since evaluating |
| 219 | * $condition and calling invariant() costs time. |
| 220 | * |
| 221 | * @since 0.1.0 |
| 222 | * |
| 223 | * @param bool $condition |
| 224 | * @param string $description The message to include in the exception if the condition fails. |
| 225 | * |
| 226 | * @throws InvariantException |
| 227 | * @phan-assert-true-condition $condition |
| 228 | */ |
| 229 | public static function invariant( $condition, $description ): void { |
| 230 | if ( !$condition ) { |
| 231 | throw new InvariantException( "Invariant failed: $description" ); |
| 232 | } |
| 233 | } |
| 234 | |
| 235 | /** |
| 236 | * @param mixed $value |
| 237 | * @param string[] $allowedTypes |
| 238 | * |
| 239 | * @return bool |
| 240 | */ |
| 241 | private static function hasType( $value, array $allowedTypes ): bool { |
| 242 | // Apply strtolower because gettype returns "NULL" for null values. |
| 243 | $type = strtolower( gettype( $value ) ); |
| 244 | |
| 245 | if ( in_array( $type, $allowedTypes ) ) { |
| 246 | return true; |
| 247 | } |
| 248 | |
| 249 | if ( in_array( 'callable', $allowedTypes ) && is_callable( $value ) ) { |
| 250 | return true; |
| 251 | } |
| 252 | |
| 253 | if ( is_object( $value ) && self::isInstanceOf( $value, $allowedTypes ) ) { |
| 254 | return true; |
| 255 | } |
| 256 | |
| 257 | if ( is_array( $value ) && in_array( 'Traversable', $allowedTypes ) ) { |
| 258 | return true; |
| 259 | } |
| 260 | |
| 261 | if ( $value === false && in_array( 'false', $allowedTypes ) ) { |
| 262 | return true; |
| 263 | } |
| 264 | if ( $value === true && in_array( 'true', $allowedTypes ) ) { |
| 265 | return true; |
| 266 | } |
| 267 | |
| 268 | return false; |
| 269 | } |
| 270 | |
| 271 | /** |
| 272 | * @param object $value |
| 273 | * @param string[] $allowedTypes |
| 274 | * |
| 275 | * @return bool |
| 276 | */ |
| 277 | private static function isInstanceOf( $value, array $allowedTypes ): bool { |
| 278 | foreach ( $allowedTypes as $type ) { |
| 279 | if ( $value instanceof $type ) { |
| 280 | return true; |
| 281 | } |
| 282 | } |
| 283 | |
| 284 | return false; |
| 285 | } |
| 286 | |
| 287 | } |