Module org.jhotdraw8.css

Package org.jhotdraw8.css.ast

Class Selector

java.lang.Object

org.jhotdraw8.css.ast.AbstractSyntaxTree

org.jhotdraw8.css.ast.Selector

Direct Known Subclasses:

Combinator, SelectorGroup, SimpleSelector

public abstract class Selector
extends AbstractSyntaxTree

A "selector" is a tree of "combinator"s.

Author:

Werner Randelshofer

Constructor Summary

Constructors

Constructor	Description
Selector(@Nullable SourceLocator sourceLocator)

Method Summary

Modifier and Type	Method	Description
abstract int	getSpecificity()	Returns the specificity of this selector.
protected abstract <T> @Nullable T	match(SelectorModel<T> model, T element)	Returns the matching element.
<T> boolean	matches(SelectorModel<T> model, T element)	Returns true if the selector matches the element.
@Nullable TypeSelector	matchesOnlyOnASpecificType()	Returns a qualified name, if this selector only matches on elements with a specific type name.

Methods inherited from class org.jhotdraw8.css.ast.AbstractSyntaxTree

getSourceLocator, produceTokens

Methods inherited from class java.lang.Object

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

Constructor Details

Selector

public Selector(@Nullable SourceLocator sourceLocator)

Method Details

getSpecificity

public abstract int getSpecificity()

Returns the specificity of this selector.

A selector's specificity is calculated as follows:

• count the number of ID selectors in the selector (= a)
• count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= b)
• count the number of type selectors and pseudo-elements in the selector (= c)
• ignore the universal selector

Selectors inside the negation pseudo-class are counted like any other, but the negation itself does not count as a pseudo-class.

Concatenating the three numbers a-b-c (in a number system with a large base) gives the specificity.

In this implementation we compute specificity with specificity=100*a+10*b+c.

References:

CSS Syntax Selectors Level 3, Chapter 9. Calculating a selector's specificity

w3.org

Returns:

the specificity

matches

public <T> boolean matches(SelectorModel<T> model,
 T element)

Returns true if the selector matches the element.

Type Parameters:

T - the element type

Parameters:

model - The helper is used to access properties of the element and parent or sibling elements in the document.

element - the element

Returns:

true on match

match

protected abstract <T> @Nullable T match(SelectorModel<T> model,
 T element)

Returns the matching element.

Type Parameters:

T - element type

Parameters:

model - The helper is used to access properties of the element and parent or sibling elements in the document.

element - the element

Returns:

the matching element or null

matchesOnlyOnASpecificType

public @Nullable TypeSelector matchesOnlyOnASpecificType()

Returns a qualified name, if this selector only matches on elements with a specific type name.

This implementation returns null.

Returns:

a type name or null