cz.vutbr.web.csskit.ElementMatcherSafeCI Maven / Gradle / Ivy

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jStyleParser is a CSS parser written in Java. It has its own application interface that is designed to allow an efficient CSS processing in Java and mapping the values to the Java data types. It parses CSS 2.1 style sheets into structures that can be efficiently assigned to DOM elements. It is intended be the primary CSS parser for the CSSBox library. While handling errors, it is user agent conforming according to the CSS specification.

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/**
 * ElementMatcherSafeCI.java
 *
 * Created on 25. 11. 2015, 13:47:26 by burgetr
 */
package cz.vutbr.web.csskit;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;

import org.w3c.dom.Element;
import org.w3c.dom.Node;

import cz.vutbr.web.css.ElementMatcher;
import cz.vutbr.web.css.Selector;

/**
 * A case-insensitive matcher that corresponds to the HTML quirks mode matching. 
 * 
 * This is a safe implementation of the element matcher. It should be compatible with any
 * DOM implementation. On the other hand, its performance is slightly worse because of some
 * additional tests required due to the differences among the DOM implementations. 
 * 
 * @author burgetr
 */
public class ElementMatcherSafeCI implements ElementMatcher
{
    public static final String CLASS_DELIM = " ";
    public static final String CLASS_ATTR = "class";
    public static final String ID_ATTR = "id";
    
    public String getAttribute(Element e, String name)
    {
        final String ret = e.getAttribute(name);
        return (ret == null) ? "" : ret;
    }
    
    public Collection elementClasses(Element e) 
    {
        if (e.hasAttribute(CLASS_ATTR))
        {
            String classNames = getAttribute(e, CLASS_ATTR);
            
            Collection list = new ArrayList();
            for (String cname : classNames.toLowerCase().split(CLASS_DELIM)) 
            {
                cname = cname.trim();
                if(cname.length() > 0)
                    list.add(cname);
            }
            return list;
        }
        else
            return Collections.emptyList();
    }
    
    public boolean matchesClass(Element e, String className)
    {
        if (e.hasAttribute(CLASS_ATTR))
        {
            String classNames = getAttribute(e, CLASS_ATTR).toLowerCase();
            String search = className.toLowerCase();
            int len = className.length();
            int lastIndex = 0;
            
            while ((lastIndex = classNames.indexOf(search, lastIndex)) != -1) {
                if ((lastIndex == 0 || Character.isWhitespace(classNames.charAt(lastIndex - 1))) &&
                        (lastIndex + len == classNames.length() || Character.isWhitespace(classNames.charAt(lastIndex + len)))) {
                    return true;
                }
                lastIndex += len;
            }
            return false;
        }
        else
            return false;
    }

    
    public String elementID(Element e) 
    {
        return getAttribute(e, ID_ATTR);
    }
    
    public boolean matchesID(Element e, String id) 
    {
        return id.equalsIgnoreCase(elementID(e));
    }
    
    public String elementName(Element e) 
    {
        return e.getNodeName();
    }
    
    public boolean matchesName(Element e, String name)
    {
        return name.equalsIgnoreCase(elementName(e));
    }
    
    public boolean matchesAttribute(Element e, String name, String value, Selector.Operator o) 
    {
        final Node attributeNode = e.getAttributeNode(name);
        if (attributeNode != null && o != null)
        {
            String attributeValue = attributeNode.getNodeValue();
            
            switch(o) {
                case EQUALS:
                    return attributeValue.equals(value);
                case INCLUDES:
                    if (value.isEmpty() || containsWhitespace(value))
                        return false;
                    else
                    {
                        attributeValue = " " + attributeValue + " ";
                        return attributeValue.matches(".* " + value + " .*");
                    }
                case DASHMATCH:
                    return attributeValue.matches("^" + value + "(-.*|$)");
                case CONTAINS:
                    return !value.isEmpty() && attributeValue.matches(".*" + value + ".*");
                case STARTSWITH:
                    return !value.isEmpty() && attributeValue.matches("^" + value + ".*");
                case ENDSWITH:
                    return !value.isEmpty() && attributeValue.matches(".*" + value + "$");
                default:
                    return true;
            }
        }
        else
            return false;
    }
    
    private static boolean containsWhitespace(String s)
    {
        for (int i = 0; i < s.length(); i++)
        {
            if (Character.isWhitespace(s.charAt(i)))
                    return true;
        }
        return false;
    }

}