JptAttributeNode.java

package org.caudexorigo.jpt;

import java.io.IOException;
import java.io.Serializable;
import java.io.Writer;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import nu.xom.Attribute;

import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.commons.lang3.StringUtils;
import org.caudexorigo.ErrorAnalyser;
import org.mvel2.MVEL;
import org.mvel2.ParserContext;

public class JptAttributeNode extends JptNode
{
	private String _attr_exp;

	private char[] _attribute_name;

	private static final char[] EQUAL_SIGN = "=".toCharArray();

	private static final char[] QUOTE = "\"".toCharArray();

	private static final char[] SPACE = " ".toCharArray();

	private boolean _isInSlot;

	private Serializable _compiled_exp;

	JptAttributeNode(Attribute attribute, boolean isInSlot)
	{
		_isInSlot = isInSlot;

		_attribute_name = attribute.getQualifiedName().toCharArray();
		_attr_exp = attribute.getValue().replace("\'", "\"").trim();
	}

	public int getChildCount()
	{
		return 0;
	}

	public JptNode getChild(int i)
	{
		throw new IndexOutOfBoundsException("Attributes do not have children");
	}

	public void render(Map<String, Object> context, Writer out) throws IOException
	{
		try
		{
			if (_compiled_exp == null)
			{
				ParserContext parser_context = ParserContext.create();

				Set<Entry<String, Object>> ctx_entries = context.entrySet();

				for (Entry<String, Object> entry : ctx_entries)
				{
					parser_context.addInput(entry.getKey(), entry.getValue().getClass());
				}
				// Compile the expression.
				_compiled_exp = MVEL.compileExpression(_attr_exp, parser_context);
			}
			
			//System.err.println(String.format("attribute expression: '%s';%n\tcontext: %s", _attr_exp, context));

			String v = String.valueOf(MVEL.executeExpression(_compiled_exp, context));

			if (StringUtils.isNotBlank(v))
			{
				String sout = StringEscapeUtils.escapeXml(v);
				out.write(SPACE, 0, 1);
				out.write(_attribute_name, 0, _attribute_name.length);
				out.write(EQUAL_SIGN, 0, 1);
				out.write(QUOTE, 0, 1);
				out.write(sout);
				out.write(QUOTE, 0, 1);
			}
		}
		catch (Throwable t)
		{
			Throwable r = ErrorAnalyser.findRootCause(t);
			throw new RuntimeException(String.format("Error processing JptAttributeNode:%nexpression: '%s';%ncontext: %s;%nmessage: '%s'", _attr_exp, context, r.getMessage()));
		}
	}

	public boolean isInSlot()
	{
		return _isInSlot;
	}
}