ej.mwt.stylesheet.selector

Class NthChildSelector

java.lang.Object

ej.mwt.stylesheet.selector.NthChildSelector

All Implemented Interfaces:

Selector

public class NthChildSelector
extends Object
implements Selector

A nth child selector selects by checking if a widget is the nth child of its parent.

Equivalent to :nth-child selector in CSS. Its specificity is (0,0,1,0).

The index is stored as a byte for heap optimization and therefore cannot exceed 255.

See Also:

Widget.getParent(), SelectorHelper

Constructor Summary

Constructors

Constructor and Description
NthChildSelector(int index) Creates a nth child selector.

Method Summary

Modifier and Type	Method and Description
boolean	appliesToWidget(Widget widget) Checks whether or not this selector applies to the given widget.
int	getSpecificity() Returns the specificity of this selector.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NthChildSelector

public NthChildSelector(int index)

Creates a nth child selector.

The given index is clamped between 0 and 255.

Parameters:

index - the index of the child.

Method Detail

appliesToWidget

public boolean appliesToWidget(Widget widget)

Description copied from interface: Selector

Checks whether or not this selector applies to the given widget.

Specified by:

appliesToWidget in interface Selector

Parameters:

widget - the widget to test.

Returns:

true if this selectors applies to the given widget, false otherwise.

getSpecificity

public int getSpecificity()

Description copied from interface: Selector

Returns the specificity of this selector.

The specificity allows to determine in which order the rules of a stylesheet should be applied.

A specificity is composed of four numbers (defined by CSS2 specification):

• count 1 if the declaration is from is a 'style' attribute rather than a rule with a selector, 0 otherwise (= a)
• count the number of ID attributes in the selector (= b)
• count the number of other attributes and pseudo-classes in the selector (= c)
• count the number of widget names and pseudo-widgets in the selector (= d)

Concatenating the four numbers a-b-c-d (in a number system with a large base) gives the specificity. In this implementation, each number is stored on a byte in an integer. SelectorHelper provides a method to compute the specificity of a selector.

Specified by:

getSpecificity in interface Selector

Returns:

the specificity of this selector.