Complex classes like Collection often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Collection, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 16 | class Collection implements CollectionContract { |
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| 17 | |||
| 18 | /** |
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| 19 | * Collection elements. |
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| 20 | * |
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| 21 | * @var array |
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| 22 | */ |
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| 23 | protected $elements = array(); |
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| 24 | |||
| 25 | /** |
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| 26 | * Collection type to enforce. |
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| 27 | * |
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| 28 | * @var Type |
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| 29 | */ |
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| 30 | private $type; |
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| 31 | |||
| 32 | /** |
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| 33 | * Where Collection is in loop. |
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| 34 | * |
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| 35 | * @var int |
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| 36 | */ |
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| 37 | protected $position = 0; |
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| 38 | |||
| 39 | /** |
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| 40 | * Collection constructor. |
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| 41 | * |
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| 42 | * @param string $type |
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| 43 | * @param array $elements |
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| 44 | */ |
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| 45 | 186 | public function __construct( $type, array $elements = array() ) { |
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| 62 | |||
| 63 | /** |
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| 64 | * {@inheritdoc} |
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| 65 | * |
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| 66 | * @return string |
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| 67 | */ |
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| 68 | 84 | public function get_type() { |
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| 71 | |||
| 72 | /** |
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| 73 | * {@inheritdoc} |
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| 74 | * |
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| 75 | * @param mixed $element |
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| 76 | * |
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| 77 | * @return Collection |
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| 78 | * |
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| 79 | * @throws InvalidArgumentException |
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| 80 | */ |
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| 81 | 51 | public function add( $element ) { |
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| 96 | |||
| 97 | /** |
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| 98 | * {@inheritdoc} |
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| 99 | * |
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| 100 | * @return Collection |
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| 101 | */ |
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| 102 | 3 | public function clear() { |
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| 103 | 3 | return new static( $this->get_type() ); |
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| 104 | } |
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| 105 | |||
| 106 | /** |
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| 107 | * {@inheritdoc} |
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| 108 | * |
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| 109 | * @param callable $condition Condition to satisfy. |
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| 110 | * |
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| 111 | * @return bool |
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| 112 | */ |
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| 113 | 6 | public function contains( $condition ) { |
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| 114 | 6 | return (bool) $this->find( $condition ); |
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| 115 | } |
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| 116 | |||
| 117 | /** |
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| 118 | * {@inheritdoc} |
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| 119 | * |
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| 120 | * @param callable $condition Condition to satisfy. |
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| 121 | * |
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| 122 | * @return mixed |
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| 123 | */ |
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| 124 | 12 | public function find( $condition ) { |
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| 125 | 12 | $index = $this->find_index( $condition ); |
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| 126 | |||
| 127 | 12 | return -1 === $index ? null : $this->elements[ $index ]; |
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| 128 | } |
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| 129 | |||
| 130 | /** |
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| 131 | * {@inheritdoc} |
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| 132 | * |
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| 133 | * @param callable $condition Condition to satisfy. |
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| 134 | * |
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| 135 | * @return int |
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| 136 | */ |
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| 137 | 18 | public function find_index( $condition ) { |
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| 138 | 18 | $index = -1; |
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| 139 | |||
| 140 | 18 | for ( $i = 0, $count = count( $this->elements ); $i < $count; $i++ ) { |
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| 141 | 18 | if ( call_user_func( $condition, ($this->at( $i ) ) ) ) { |
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| 142 | 9 | $index = $i; |
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| 143 | 9 | break; |
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| 144 | } |
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| 145 | 12 | } |
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| 146 | |||
| 147 | 18 | return $index; |
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| 148 | } |
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| 149 | |||
| 150 | /** |
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| 151 | * Fetches the element at the provided index. |
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| 152 | * |
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| 153 | * @param int $index Index to get element from. |
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| 154 | * |
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| 155 | * @return mixed |
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| 156 | * |
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| 157 | * @throws OutOfRangeException |
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| 158 | */ |
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| 159 | 57 | public function at( $index ) { |
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| 164 | |||
| 165 | /** |
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| 166 | * {@inheritdoc} |
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| 167 | * |
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| 168 | * @param int $index Index to check for existence. |
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| 169 | * |
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| 170 | * @return bool |
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| 171 | * |
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| 172 | * @throws InvalidArgumentException |
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| 173 | */ |
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| 174 | 57 | public function index_exists( $index ) { |
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| 175 | 57 | if ( ! is_int( $index ) ) { |
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| 176 | 3 | throw new InvalidArgumentException( 'Index must be an integer' ); |
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| 177 | } |
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| 178 | |||
| 179 | 54 | if ( $index < 0 ) { |
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| 180 | 3 | throw new InvalidArgumentException( 'Index must be a non-negative integer' ); |
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| 181 | } |
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| 182 | |||
| 183 | 51 | return $index < $this->count(); |
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| 184 | } |
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| 185 | |||
| 186 | /** |
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| 187 | * {@inheritdoc} |
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| 188 | * |
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| 189 | * @param callable $condition Condition to satisfy. |
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| 190 | * |
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| 191 | * @return mixed |
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| 192 | */ |
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| 193 | 3 | public function filter( $condition ) { |
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| 194 | 3 | $elements = array(); |
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| 195 | |||
| 196 | 3 | foreach ( $this->elements as $element ) { |
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| 197 | 3 | if ( call_user_func( $condition, $element ) ) { |
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| 198 | 3 | $elements[] = $element; |
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| 199 | 3 | } |
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| 200 | 3 | } |
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| 201 | |||
| 202 | 3 | return $this->new_from_trusted( $elements ); |
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| 203 | } |
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| 204 | /** |
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| 205 | * {@inheritdoc} |
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| 206 | * |
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| 207 | * @param callable $condition Condition to satisfy. |
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| 208 | * |
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| 209 | * @return mixed |
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| 210 | */ |
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| 211 | 6 | public function find_last( $condition ) { |
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| 212 | 6 | $index = $this->find_last_index( $condition ); |
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| 213 | |||
| 214 | 6 | return -1 === $index ? null : $this->elements[ $index ]; |
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| 215 | } |
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| 216 | |||
| 217 | /** |
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| 218 | * {@inheritdoc} |
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| 219 | * |
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| 220 | * @param callable $condition |
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| 221 | * @return int |
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| 222 | */ |
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| 223 | 12 | public function find_last_index( $condition ) { |
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| 224 | 12 | $index = -1; |
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| 225 | |||
| 226 | 12 | for ( $i = count( $this->elements ) - 1; $i >= 0; $i-- ) { |
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| 227 | 12 | if ( call_user_func( $condition, $this->elements[ $i ] ) ) { |
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| 228 | 6 | $index = $i; |
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| 229 | 6 | break; |
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| 230 | } |
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| 231 | 9 | } |
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| 232 | |||
| 233 | 12 | return $index; |
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| 234 | } |
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| 235 | |||
| 236 | /** |
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| 237 | * {@inheritdoc} |
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| 238 | * |
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| 239 | * @param int $start Begining index to slice from. |
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| 240 | * @param int $end End index to slice to. |
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| 241 | * |
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| 242 | * @return Collection |
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| 243 | * |
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| 244 | * @throws InvalidArgumentException |
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| 245 | */ |
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| 246 | 27 | public function slice( $start, $end ) { |
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| 247 | 27 | if ( $start < 0 || ! is_int( $start ) ) { |
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| 248 | throw new InvalidArgumentException( 'Start must be a non-negative integer' ); |
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| 249 | } |
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| 250 | |||
| 251 | 27 | if ( $end < 0 || ! is_int( $end ) ) { |
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| 252 | throw new InvalidArgumentException( 'End must be a positive integer' ); |
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| 253 | } |
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| 254 | |||
| 255 | 27 | if ( $start > $end ) { |
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| 256 | throw new InvalidArgumentException( 'End must be greater than start' ); |
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| 257 | } |
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| 258 | |||
| 259 | 27 | if ( $end > $this->count() + 1 ) { |
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| 260 | throw new InvalidArgumentException( 'End must be less than the count of the items in the Collection' ); |
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| 261 | } |
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| 262 | |||
| 263 | 27 | $length = $end - $start + 1; |
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| 264 | |||
| 265 | 27 | return $this->new_from_trusted( array_slice( $this->elements, $start, $length ) ); |
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| 266 | } |
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| 267 | |||
| 268 | /** |
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| 269 | * {@inheritdoc} |
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| 270 | * |
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| 271 | * @param int $index Index to start at. |
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| 272 | * @param mixed $element Element to insert. |
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| 273 | * |
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| 274 | * @return Collection |
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| 275 | * |
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| 276 | * @throws InvalidArgumentException |
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| 277 | * @throws OutOfRangeException |
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| 278 | */ |
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| 279 | public function insert( $index, $element ) { |
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| 290 | |||
| 291 | /** |
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| 292 | * {@inheritdoc} |
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| 293 | * |
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| 294 | * @param int $index Index to start insertion at. |
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| 295 | * @param array $elements Elements in insert. |
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| 296 | * |
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| 297 | * @return Collection |
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| 298 | * |
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| 299 | * @throws OutOfRangeException |
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| 300 | */ |
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| 301 | public function insert_range( $index, array $elements ) { |
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| 317 | |||
| 318 | /** |
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| 319 | * {@inheritdoc} |
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| 320 | * |
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| 321 | * @param callable $condition Condition to satisfy. |
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| 322 | * |
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| 323 | * @return Collection |
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| 324 | */ |
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| 325 | public function without( $condition ) { |
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| 332 | |||
| 333 | /** |
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| 334 | * {@inheritdoc} |
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| 335 | * |
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| 336 | * @param int $index Index to remove. |
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| 337 | * |
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| 338 | * @return Collection |
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| 339 | * |
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| 340 | * @throws OutOfRangeException |
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| 341 | */ |
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| 342 | public function remove_at( $index ) { |
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| 354 | /** |
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| 355 | * {@inheritdoc} |
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| 356 | * |
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| 357 | * @return Collection |
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| 358 | */ |
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| 359 | public function reverse() { |
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| 364 | |||
| 365 | /** |
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| 366 | * {@inheritdoc} |
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| 367 | * |
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| 368 | * @param callable $callback Sort callback. |
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| 369 | * |
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| 370 | * @return Collection |
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| 371 | */ |
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| 372 | public function sort( $callback ) { |
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| 377 | |||
| 378 | /** |
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| 379 | * {@inheritdoc} |
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| 380 | * |
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| 381 | * @return array |
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| 382 | */ |
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| 383 | 9 | public function to_array() { |
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| 386 | |||
| 387 | /** |
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| 388 | * {@inheritdoc} |
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| 389 | * |
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| 390 | * @param callable $callable Reducer function. |
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| 391 | * |
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| 392 | * @param null $initial Initial reducer value. |
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| 393 | * |
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| 394 | * @return mixed |
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| 395 | */ |
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| 396 | public function reduce( $callable, $initial = null ) { |
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| 399 | |||
| 400 | /** |
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| 401 | * {@inheritdoc} |
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| 402 | * |
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| 403 | * @param callable $condition Condition callback. |
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| 404 | * |
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| 405 | * @return bool |
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| 406 | */ |
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| 407 | 6 | public function every( $condition ) { |
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| 421 | |||
| 422 | /** |
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| 423 | * {@inheritdoc} |
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| 424 | * |
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| 425 | * @param int $num Number of elements to drop. |
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| 426 | * |
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| 427 | * @return Collection |
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| 428 | * |
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| 429 | * @throws InvalidArgumentException |
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| 430 | */ |
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| 431 | 18 | public function drop( $num ) { |
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| 438 | |||
| 439 | /** |
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| 440 | * {@inheritdoc} |
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| 441 | * |
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| 442 | * @param int $num Number of elements to drop. |
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| 443 | * |
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| 444 | * @return Collection |
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| 445 | * |
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| 446 | * @throws InvalidArgumentException |
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| 447 | */ |
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| 448 | 9 | public function drop_right( $num ) { |
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| 453 | |||
| 454 | /** |
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| 455 | * {@inheritdoc} |
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| 456 | * |
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| 457 | * @param callable $condition Condition callback. |
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| 458 | * |
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| 459 | * @return Collection |
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| 460 | */ |
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| 461 | 9 | public function drop_while( $condition ) { |
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| 465 | /** |
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| 466 | * {@inheritdoc} |
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| 467 | * |
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| 468 | * @return Collection |
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| 469 | * |
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| 470 | * @throws InvalidArgumentException |
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| 471 | */ |
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| 472 | public function tail() { |
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| 475 | |||
| 476 | /** |
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| 477 | * {@inheritdoc} |
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| 478 | * |
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| 479 | * @param int $num Number of elements to take. |
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| 480 | * |
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| 481 | * @return Collection |
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| 482 | * |
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| 483 | * @throws InvalidArgumentException |
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| 484 | */ |
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| 485 | public function take( $num ) { |
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| 488 | |||
| 489 | /** |
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| 490 | * {@inheritdoc} |
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| 491 | * |
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| 492 | * @param int $num Number of elements to take. |
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| 493 | * |
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| 494 | * @return Collection |
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| 495 | * |
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| 496 | * @throws InvalidArgumentException |
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| 497 | */ |
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| 498 | public function take_right( $num ) { |
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| 501 | |||
| 502 | /** |
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| 503 | * {@inheritdoc} |
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| 504 | * |
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| 505 | * @param callable $condition Callback function. |
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| 506 | * |
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| 507 | * @return Collection |
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| 508 | */ |
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| 509 | public function take_while( $condition ) { |
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| 514 | |||
| 515 | /** |
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| 516 | * {@inheritdoc} |
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| 517 | * |
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| 518 | * @param callable $callable Callback function. |
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| 519 | */ |
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| 520 | 3 | public function each( $callable ) { |
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| 525 | |||
| 526 | /** |
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| 527 | * {@inheritdoc} |
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| 528 | * |
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| 529 | * @param callable $callable Callback function. |
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| 530 | * |
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| 531 | * @return Collection |
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| 532 | */ |
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| 533 | 9 | public function map( $callable ) { |
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| 552 | |||
| 553 | /** |
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| 554 | * {@inheritdoc} |
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| 555 | * |
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| 556 | * @param callable $callable Reducer function. |
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| 557 | * @param null $initial Initial value. |
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| 558 | * |
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| 559 | * @return mixed |
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| 560 | */ |
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| 561 | public function reduce_right( $callable, $initial = null ) { |
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| 562 | return array_reduce( |
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| 563 | array_reverse( $this->elements ), |
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| 564 | $callable, |
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| 565 | $initial |
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| 566 | ); |
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| 567 | } |
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| 568 | |||
| 569 | /** |
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| 570 | * {@inheritdoc} |
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| 571 | * |
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| 572 | * @return Collection |
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| 573 | */ |
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| 574 | public function shuffle() { |
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| 580 | |||
| 581 | /** |
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| 582 | * {@inheritdoc} |
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| 583 | * |
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| 584 | * @param array|Collection $elements Array of elements to merge. |
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| 585 | * |
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| 586 | * @return Collection |
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| 587 | * |
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| 588 | * @throws InvalidArgumentException |
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| 589 | */ |
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| 590 | public function merge( $elements ) { |
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| 605 | |||
| 606 | /** |
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| 607 | * {@inheritdoc} |
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| 608 | * |
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| 609 | * @return mixed |
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| 610 | * |
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| 611 | * @throws OutOfBoundsException |
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| 612 | */ |
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| 613 | 6 | public function first() { |
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| 614 | 6 | if ( empty( $this->elements ) ) { |
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| 615 | 3 | throw new OutOfBoundsException( 'Cannot get first element of empty Collection' ); |
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| 616 | } |
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| 617 | |||
| 618 | 3 | return reset( $this->elements ); |
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| 619 | } |
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| 620 | |||
| 621 | /** |
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| 622 | * {@inheritdoc} |
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| 623 | * |
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| 624 | * @return mixed |
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| 625 | * |
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| 626 | * @throws OutOfBoundsException |
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| 627 | */ |
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| 628 | 6 | public function last() { |
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| 629 | 6 | if ( empty( $this->elements ) ) { |
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| 630 | 3 | throw new OutOfBoundsException( 'Cannot get last element of empty Collection' ); |
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| 631 | } |
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| 632 | |||
| 633 | 3 | return end( $this->elements ); |
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| 634 | } |
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| 635 | |||
| 636 | /** |
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| 637 | * {@inheritdoc} |
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| 638 | * |
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| 639 | * @return int |
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| 640 | */ |
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| 641 | 105 | public function count() { |
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| 644 | |||
| 645 | /** |
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| 646 | * {@inheritDoc} |
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| 647 | * |
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| 648 | * @return array |
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| 649 | */ |
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| 650 | public function serialize() { |
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| 659 | |||
| 660 | /** |
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| 661 | * Return the current element. |
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| 662 | * |
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| 663 | * @return mixed |
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| 664 | */ |
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| 665 | 3 | public function current() { |
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| 668 | |||
| 669 | /** |
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| 670 | * Move forward to next element. |
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| 671 | */ |
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| 672 | 3 | public function next() { |
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| 675 | |||
| 676 | /** |
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| 677 | * Return the key of the current element. |
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| 678 | * |
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| 679 | * @return mixed |
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| 680 | */ |
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| 681 | 3 | public function key() { |
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| 684 | |||
| 685 | /** |
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| 686 | * Checks if current position is valid. |
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| 687 | * |
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| 688 | * @return bool |
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| 689 | */ |
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| 690 | 3 | public function valid() { |
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| 693 | |||
| 694 | /** |
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| 695 | * Rewind the Iterator to the first element. |
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| 696 | */ |
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| 697 | 3 | public function rewind() { |
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| 700 | |||
| 701 | /** |
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| 702 | * Creates a new instance of the Collection |
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| 703 | * from a trusted set of elements. |
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| 704 | * |
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| 705 | * @param array $elements Array of elements to pass into new collection. |
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| 706 | * @param null|mixed $type |
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| 707 | * |
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| 708 | * @return static |
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| 709 | */ |
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| 710 | 39 | protected function new_from_trusted( array $elements, $type = null ) { |
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| 716 | |||
| 717 | /** |
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| 718 | * Sets the elements without validating them. |
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| 719 | * |
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| 720 | * @param array $elements Pre-validated elements to set. |
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| 721 | */ |
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| 722 | 84 | protected function set_from_trusted( array $elements ) { |
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| 725 | |||
| 726 | /** |
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| 727 | * Number of elements true for the condition. |
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| 728 | * |
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| 729 | * @param callable $condition Condition to check. |
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| 730 | * @return int |
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| 731 | */ |
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| 732 | 9 | protected function count_while_true( $condition ) { |
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| 744 | |||
| 745 | /** |
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| 746 | * Validates a number to be used as an index. |
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| 747 | * |
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| 748 | * @param integer $index The number to be validated as an index. |
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| 749 | * |
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| 750 | * @throws OutOfRangeException |
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| 751 | */ |
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| 752 | 57 | protected function validate_index( $index ) { |
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| 759 | } |
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| 760 |