OverrideDirective.java

package cn.org.rapid_framework.freemarker.directive; 

import java.io.IOException;
import java.io.Writer;
import java.util.LinkedList;
import java.util.Map;

import freemarker.core.Environment;
import freemarker.template.TemplateDirectiveBody;
import freemarker.template.TemplateDirectiveModel;
import freemarker.template.TemplateException;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;

/**
 * @author badqiu
 */
public class OverrideDirective implements TemplateDirectiveModel {

	public final static String DIRECTIVE_NAME = "override";
	
	public void execute(Environment env,
            Map params, TemplateModel[] loopVars,
            TemplateDirectiveBody body) throws TemplateException, IOException {
		String name = DirectiveUtils.getRequiredParam(params, "name");
		String overrideVariableName = DirectiveUtils.getOverrideVariableName(name);
		
		TemplateDirectiveBodyOverrideWraper override = DirectiveUtils.getOverrideBody(env, name);
		TemplateDirectiveBodyOverrideWraper current = new TemplateDirectiveBodyOverrideWraper(body,env);
		if(override == null) {
			env.setVariable(overrideVariableName, current);
		}else {
			DirectiveUtils.setTopBodyForParentBody(env, current, override);
		}
	}
	
	static class TemplateDirectiveBodyOverrideWraper implements TemplateDirectiveBody,TemplateModel{
		private TemplateDirectiveBody body;
		public TemplateDirectiveBodyOverrideWraper parentBody;
		public Environment env;
		
		public TemplateDirectiveBodyOverrideWraper(TemplateDirectiveBody body,
				Environment env) {
			super();
			this.body = body;
			this.env = env;
		}
		
		public void render(Writer out) throws TemplateException, IOException {
			if(body == null) return;
			TemplateDirectiveBodyOverrideWraper preOverridy = (TemplateDirectiveBodyOverrideWraper)env.getVariable(DirectiveUtils.OVERRIDE_CURRENT_NODE);
			try {
				env.setVariable(DirectiveUtils.OVERRIDE_CURRENT_NODE, this);
				body.render(out);
			}finally {
				env.setVariable(DirectiveUtils.OVERRIDE_CURRENT_NODE, preOverridy);
			}
		}
	}
	
}