package freemarker.template;
import java.io.IOException;
import java.util.Map;
import freemarker.core.Environment;
import freemarker.template.utility.DeepUnwrap;
/**
* Objects that implement this interface can be used as user-defined directives
* (much like macros). They can do arbitrary actions, write arbitrary
* text to the template output, and trigger rendering of their nested content
* any number of times.
*
* @since 2.3.11
* @author Attila Szegedi
* @version $Id: $
*/
public interface TemplateDirectiveModel extends TemplateModel
{
/**
* Executes this user-defined directive; called by FreeMarker when the user-defined
* directive is called in the template.
*
* @param env the current processing environment. Note that you can access
* the output {@link java.io.Writer Writer} by {@link Environment#getOut()}.
* @param params the parameters (if any) passed to the directive as a
* map of key/value pairs where the keys are {@link String}-s and the
* values are {@link TemplateModel} instances. This is never
* <code>null</code>. If you need to convert the template models to POJOs,
* you can use the utility methods in the {@link DeepUnwrap} class.
* @param loopVars an array that corresponds to the "loop variables", in
* the order as they appear in the directive call. ("Loop variables" are out-parameters
* that are available to the nested body of the directive; see in the Manual.)
* You set the loop variables by writing this array. The length of the array gives the
* number of loop-variables that the caller has specified.
* Never <code>null</code>, but can be a zero-length array.
* @param body an object that can be used to render the nested content (body) of
* the directive call. If the directive call has no nested content (i.e., it is like
* [@myDirective /] or [@myDirective][/@myDirective]), then this will be
* <code>null</code>.
*
* @throws TemplateException
* @throws IOException
*/
public void execute(Environment env, Map params, TemplateModel[] loopVars,
TemplateDirectiveBody body) throws TemplateException, IOException;
}
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