Invalid rules return array(0, 0). This is per the spec.
| public static parseAnB ( $rule ) | ||
| $rule | Some rule in the an+b format. | |
public function testParseAnB()
{
// even
$this->assertEquals(array(2, 0), Util::parseAnB('even'));
// odd
$this->assertEquals(array(2, 1), Util::parseAnB('odd'));
// 5
$this->assertEquals(array(0, 5), Util::parseAnB('5'));
// +5
$this->assertEquals(array(0, 5), Util::parseAnB('+5'));
// n
$this->assertEquals(array(1, 0), Util::parseAnB('n'));
// 2n
$this->assertEquals(array(2, 0), Util::parseAnB('2n'));
// -234n
$this->assertEquals(array(-234, 0), Util::parseAnB('-234n'));
// -2n+1
$this->assertEquals(array(-2, 1), Util::parseAnB('-2n+1'));
// -2n + 1
$this->assertEquals(array(-2, 1), Util::parseAnB(' -2n + 1 '));
// +2n-1
$this->assertEquals(array(2, -1), Util::parseAnB('2n-1'));
$this->assertEquals(array(2, -1), Util::parseAnB('2n - 1'));
// -n + 3
$this->assertEquals(array(-1, 3), Util::parseAnB('-n+3'));
// Test invalid values
$this->assertEquals(array(0, 0), Util::parseAnB('obviously + invalid'));
}
/**
* Provides functionality for all "An+B" rules.
* Provides ntoh-child and also the functionality required for:
*
*- nth-last-child
*- even
*- odd
*- first
*- last
*- eq
*- nth
*- nth-of-type
*- first-of-type
*- last-of-type
*- nth-last-of-type
*
* See also QueryPath::CSS::DOMTraverser::Util::parseAnB().
*/
protected function isNthChild($node, $value, $reverse = FALSE, $byType = FALSE)
{
list($groupSize, $elementInGroup) = Util::parseAnB($value);
$parent = $node->parentNode;
if (empty($parent) || $groupSize == 0 && $elementInGroup == 0 || $groupSize > 0 && $elementInGroup > $groupSize) {
return FALSE;
}
// First we need to find the position of $node in other elements.
if ($reverse) {
$pos = $this->nodePositionFromEnd($node, $byType);
} else {
$pos = $this->nodePositionFromStart($node, $byType);
}
// If group size is 0, we just check to see if this
// is the nth element:
if ($groupSize == 0) {
return $pos == $elementInGroup;
}
// Next, we normalize $elementInGroup
if ($elementInGroup < 0) {
$elementInGroup = $groupSize + $elementInGroup;
}
$prod = ($pos - $elementInGroup) / $groupSize;
// fprintf(STDOUT, "%d n + %d on %d is %3.5f\n", $groupSize, $elementInGroup, $pos, $prod);
return is_int($prod) && $prod >= 0;
}
