/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

interface nsIAtom;
interface nsIDOMNode;
interface nsIRDFResource;

/**
 * A single result generated from a template query. Each result is identified
 * by an id, which must be unique within the set of results produced from a
 * query. The result may optionally be identified by an RDF resource.
 *
 * Generally, the result and its id will be able to uniquely identify a node
 * in the source data, such as an RDF or XML node. In other contexts, such as
 * a database query, a result would represent a particular record.
 *
 * A result is expected to only be created by a query processor.
 *
 * Each result also contains a set of variable bindings. The value for a
 * particular variable may be retrieved using the getBindingFor and
 * getBindingObjectFor methods.
 */
[scriptable, uuid(ebea0230-36fa-41b7-8e31-760806057965)]
interface nsIXULTemplateResult : nsISupports
{
  /**
   * True if the result represents a container.
   */
  readonly attribute boolean isContainer;

  /**
   * True if the result represents an empty container.
   */
  readonly attribute boolean isEmpty;

  /**
   * True if the template builder may use this result as the reference point
   * for additional recursive processing of the template. The template builder
   * will reprocess the template using this result as the reference point and
   * generate output content that is expected to be inserted as children of the
   * output generated for this result. If false, child content is not
   * processed. This property identifies only the default handling and may be
   * overriden by syntax used in the template.
   */
  readonly attribute boolean mayProcessChildren;

  /**
   * ID of the result. The DOM element created for this result, if any, will
   * have its id attribute set to this value. The id must be unique for a
   * query.
   */
  readonly attribute AString id;

  /**
   * Resource for the result, which may be null. If set, the resource uri
   * must be the same as the ID property.
   */
  readonly attribute nsIRDFResource resource;

  /**
   * The type of the object. The predefined value 'separator' may be used
   * for separators. Other values may be used for application specific
   * purposes.
   */
  readonly attribute AString type;

  /**
   * Get the string representation of the value of a variable for this
   * result. This string will be used in the action body from a template as
   * the replacement text. For instance, if the text ?name appears in an
   * attribute within the action body, it will be replaced with the result
   * of this method. The question mark is considered part of the variable
   * name, thus aVar should be ?name and not simply name.
   *
   * @param aVar the variable to look up
   *
   * @return the value for the variable or a null string if it has no value
   */
  AString getBindingFor(in nsIAtom aVar);

  /**
   * Get an object value for a variable such as ?name for this result. 
   *
   * This method may return null for a variable, even if getBindingFor returns
   * a non-null value for the same variable. This method is provided as a
   * convenience when sorting results.
   *
   * @param aVar the variable to look up
   *
   * @return the value for the variable or null if it has no value
   */
  nsISupports getBindingObjectFor(in nsIAtom aVar);

  /**
   * Indicate that a particular rule of a query has matched and that output
   * will be generated for it. Both the query as compiled by the query
   * processor's compileQuery method and the XUL <rule> element are supplied.
   * The query must always be one that was compiled by the query processor
   * that created this result. The <rule> element must always be a child of
   * the <query> element that was used to compile the query.
   *
   * @param aQuery the query that matched
   * @param aRuleNode the rule node that matched
   */
  void ruleMatched(in nsISupports aQuery, in nsIDOMNode aRuleNode);

  /**
   * Indicate that the output for a result has beeen removed and that the
   * result is no longer being used by the builder.
   */
  void hasBeenRemoved();
};