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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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/**
 * ElementMatcherSimpleCI.java
 *
 * Created on 25. 11. 2015, 15:29:26 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 simplified implementation of the element matcher. This implementation requires
 * that the {@code Element.getAttribute()} method provided by the DOM implementation returns
 * an empty string (not {@code null}) when the attribute is not defined. 
 * 
 * @author burgetr
 */
public class ElementMatcherSimpleCI 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(final Element e, final String name)
    {
        return e.getAttribute(name);
    }
    
    public Collection elementClasses(final Element e) 
    {
        final String classNames = e.getAttribute(CLASS_ATTR);
        if (!classNames.isEmpty())
        {
            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(final Element e, final String className)
    {
        final String classNames = e.getAttribute(CLASS_ATTR).toLowerCase();
        if (!classNames.isEmpty())
        {
            final String search = className.toLowerCase();
            final 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(final Element e) 
    {
        return e.getAttribute(ID_ATTR);
    }
    
    public boolean matchesID(final Element e, final String id) 
    {
        return id.equalsIgnoreCase(e.getAttribute(ID_ATTR));
    }
    
    public String elementName(final Element e) 
    {
        return e.getNodeName();
    }
    
    public boolean matchesName(final Element e, final String name)
    {
        return name.equalsIgnoreCase(e.getNodeName());
    }
    
    public boolean matchesAttribute(final Element e, final String name, final String value, final 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;
    }

}