(PECL ds >= 1.0.0)
Ds\Map::intersect — Creates a new map by intersecting keys with another map
Creates a new map containing the pairs of the current instance whose keys
are also present in the given map.
In other words, returns a copy of the current instance with all keys removed that
are not also in the other map.
A ∩ B = {x : x ∈ A ∧ x ∈ B}
Note:
Values from the current instance will be kept.
mapThe other map, containing the keys to intersect with.
The key intersection of the current instance and another map.
Example #1 Ds\Map::intersect() example
<?php
$a = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);
$b = new \Ds\Map(["b" => 4, "c" => 5, "d" => 6]);
var_dump($a->intersect($b));
?>
以上例程的输出类似于：
object(Ds\Map)#3 (2) {
[0]=>
object(Ds\Pair)#4 (2) {
["key"]=>
string(1) "b"
["value"]=>
int(2)
}
[1]=>
object(Ds\Pair)#5 (2) {
["key"]=>
string(1) "c"
["value"]=>
int(3)
}
}