gecko-dev/extensions/xforms/nsXFormsUtils.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla XForms support.
 *
 * The Initial Developer of the Original Code is
 * IBM Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2004
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *  Brian Ryner <bryner@brianryner.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsXFormsUtils.h"
#include "nsString.h"
#include "nsXFormsAtoms.h"
#include "nsIDOMElement.h"
#include "nsIDocument.h"
#include "nsINameSpaceManager.h"
#include "nsINodeInfo.h"
#include "nsIDOMNodeList.h"
#include "nsIDOMXPathEvaluator.h"
#include "nsIDOMXPathResult.h"
#include "nsIDOMXPathNSResolver.h"
#include "nsIDOMDocument.h"
#include "nsIXFormsModelElement.h"

/* static */ nsIDOMNode*
nsXFormsUtils::GetModelAndBind(nsIDOMElement  *aElement,
                               nsIDOMElement **aBindElement)
{
  *aBindElement = nsnull;
  NS_ENSURE_TRUE(aElement, nsnull);

  nsCOMPtr<nsIDOMDocument> domDoc;
  aElement->GetOwnerDocument(getter_AddRefs(domDoc));
  if (!domDoc)
    return nsnull;

  nsAutoString bindId;
  aElement->GetAttribute(NS_LITERAL_STRING("bind"), bindId);

  nsCOMPtr<nsIDOMNode> modelWrapper;

  if (!bindId.IsEmpty()) {
    // Get the bind element with the given id.
    domDoc->GetElementById(bindId, aBindElement);

    if (*aBindElement) {
      // Walk up the tree looking for the containing model.
      (*aBindElement)->GetParentNode(getter_AddRefs(modelWrapper));

      nsAutoString localName, namespaceURI;
      nsCOMPtr<nsIDOMNode> temp;

      while (modelWrapper) {
        modelWrapper->GetLocalName(localName);
        if (localName.EqualsLiteral("model")) {
          modelWrapper->GetNamespaceURI(namespaceURI);
          if (namespaceURI.EqualsLiteral(NS_NAMESPACE_XFORMS))
            break;
        }

        temp.swap(modelWrapper);
        temp->GetParentNode(getter_AddRefs(modelWrapper));
      }
    }
  } else {
    // If no bind was given, we use model.
    nsAutoString modelId;
    aElement->GetAttribute(NS_LITERAL_STRING("model"), modelId);

    if (modelId.IsEmpty()) {
      // No model given, so use the first one in the document.
      nsCOMPtr<nsIDOMNodeList> nodes;
      domDoc->GetElementsByTagNameNS(NS_LITERAL_STRING(NS_NAMESPACE_XFORMS),
                                     NS_LITERAL_STRING("model"),
                                     getter_AddRefs(nodes));

      if (!nodes)
        return nsnull;

      nodes->Item(0, getter_AddRefs(modelWrapper));
    } else {
      nsCOMPtr<nsIDOMElement> wrapperElement;
      domDoc->GetElementById(modelId, getter_AddRefs(wrapperElement));
      modelWrapper = wrapperElement;
    }
  }

  // We're releasing this reference, but the node is owned by the DOM.
  return modelWrapper;
}

/* static */ already_AddRefed<nsIDOMXPathResult>
nsXFormsUtils::EvaluateXPath(const nsAString &aExpression,
                             nsIDOMNode      *aContextNode,
                             nsIDOMNode      *aResolverNode,
                             PRUint16         aResultType)
{
  nsCOMPtr<nsIDOMDocument> doc;
  aContextNode->GetOwnerDocument(getter_AddRefs(doc));
  NS_ENSURE_TRUE(doc, nsnull);

  nsCOMPtr<nsIDOMXPathEvaluator> eval = do_QueryInterface(doc);
  NS_ENSURE_TRUE(eval, nsnull);

  nsCOMPtr<nsIDOMXPathNSResolver> resolver;
  eval->CreateNSResolver(aResolverNode, getter_AddRefs(resolver));
  NS_ENSURE_TRUE(resolver, nsnull);

  nsCOMPtr<nsISupports> supResult;
  eval->Evaluate(aExpression, aContextNode, resolver, aResultType, nsnull,
                 getter_AddRefs(supResult));

  nsIDOMXPathResult *result = nsnull;
  if (supResult)
    CallQueryInterface(supResult, &result);  // addrefs
  return result;
}

/* static */ already_AddRefed<nsIDOMNode>
nsXFormsUtils::FindBindContext(nsIDOMElement         *aElement,
                               nsIXFormsModelElement *aModel)
{
  // Figure out the context node for this <bind>.
  // The outermost bind has the root element of the [first] instance document
  // as its context node.  For inner binds, the first node in the nodeset
  // of the parent is used as the context node.

  nsCOMPtr<nsIDOMNode> modelNode = do_QueryInterface(aModel);

  nsCOMPtr<nsIDOMNode> parentNode;
  aElement->GetParentNode(getter_AddRefs(parentNode));
  if (!parentNode)
    return nsnull; // illegal, a bind must be contained in a model.

  if (parentNode == modelNode) {
    // This is the outermost bind.
    nsCOMPtr<nsIDOMDocument> instanceDoc;
    aModel->GetInstanceDocument(NS_LITERAL_STRING(""),
                                getter_AddRefs(instanceDoc));
    if (!instanceDoc)
      return nsnull;

    nsIDOMElement *docElement = nsnull;
    instanceDoc->GetDocumentElement(&docElement);  // addrefs
    return docElement;
  }

  // The context node is the first node in the nodeset of the parent bind.
  nsCOMPtr<nsIDOMXPathResult> parentNodeSet =
    EvaluateNodeset(nsCOMPtr<nsIDOMElement>(do_QueryInterface(parentNode)),
                    nsIDOMXPathResult::FIRST_ORDERED_NODE_TYPE);

  nsIDOMNode *nodeResult = nsnull;
  if (parentNodeSet)
    parentNodeSet->GetSingleNodeValue(&nodeResult);  // addrefs

  return nodeResult;
}

/* static */ already_AddRefed<nsIDOMXPathResult>
nsXFormsUtils::EvaluateNodeset(nsIDOMElement *aElement, PRUint16 aResultType)
{
  // The first thing we need to do is ensure that we have a nodeset attribute.
  // If we don't, we walk up and check for it on outer bind elements.
  // While we're walking up, we also locate the model element.

  nsCOMPtr<nsIXFormsModelElement> model;
  nsCOMPtr<nsIDOMElement> bindElement, element = aElement;
  nsCOMPtr<nsIDOMNode> temp;
  nsAutoString nodeset;

  while (element) {
    model = do_QueryInterface(element);
    if (model)
      break;

    if (!bindElement) {
      element->GetAttribute(NS_LITERAL_STRING("nodeset"), nodeset);
      if (!nodeset.IsEmpty()) {
        // Verify that this is a <bind> element;
        nsAutoString value;
        element->GetNamespaceURI(value);
        if (value.EqualsLiteral(NS_NAMESPACE_XFORMS)) {
          element->GetLocalName(value);
          if (value.EqualsLiteral("bind")) {
            bindElement = element;
          }
        }
      }
    }

    element->GetParentNode(getter_AddRefs(temp));
    element = do_QueryInterface(temp);
  }

  if (!bindElement || !model)
    return nsnull;

  nsCOMPtr<nsIDOMNode> contextNode = FindBindContext(bindElement, model);
  if (!contextNode)
    return nsnull;

  return EvaluateXPath(nodeset, contextNode, bindElement, aResultType);
}

/* static */ already_AddRefed<nsIDOMXPathResult>
nsXFormsUtils::EvaluateNodeBinding(nsIDOMElement  *aElement,
                                   PRUint16        aResultType,
                                   nsIDOMNode    **aModel,
                                   nsIDOMElement **aBind)
{
  // A control may be attached to a model by either using the 'bind'
  // attribute to give the id of a bind element, or using the 'model'
  // attribute to give the id of a model.  If neither of these are given,
  // the control belongs to the first model in the document.

  *aBind = nsnull;

  NS_IF_ADDREF(*aModel = GetModelAndBind(aElement, aBind));
  if (!*aModel)
    return nsnull;

  // If there is a bind element, we just evaluate its nodeset.
  if (*aBind)
    return EvaluateNodeset(*aBind, aResultType);

  // If not, we expect there to be a ref attribute.
  nsAutoString expr;
  aElement->GetAttribute(NS_LITERAL_STRING("ref"), expr);

  if (expr.IsEmpty())
    return nsnull;

  // Get the instance data and evaluate the xpath expression.
  // XXXfixme when xpath extensions are implemented (instance())
  nsCOMPtr<nsIDOMDocument> instanceDoc;
  nsCOMPtr<nsIXFormsModelElement> model = do_QueryInterface(*aModel);
  if (!model) {
    // The referenced model is not actually a model element, or does not exist.
    return nsnull;
  }

  model->GetInstanceDocument(NS_LITERAL_STRING(""),
                             getter_AddRefs(instanceDoc));

  if (!instanceDoc)
    return nsnull;

  nsCOMPtr<nsIDOMElement> docElement;
  instanceDoc->GetDocumentElement(getter_AddRefs(docElement));
  if (!docElement)
    return nsnull;   // this will happen if the doc is still loading

  return EvaluateXPath(expr, docElement, aElement, aResultType);
}

/* static */ nsresult
nsXFormsUtils::CloneScriptingInterfaces(const nsIID *aIIDList,
                                        unsigned int aIIDCount,
                                        PRUint32 *aOutCount,
                                        nsIID ***aOutArray)
{
  nsIID **iids = NS_STATIC_CAST(nsIID**,
                                nsMemory::Alloc(aIIDCount * sizeof(nsIID*)));
  if (!iids) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
 
  for (PRUint32 i = 0; i < aIIDCount; ++i) {
    iids[i] = NS_STATIC_CAST(nsIID*,
                             nsMemory::Clone(&aIIDList[i], sizeof(nsIID)));
 
    if (!iids[i]) {
      for (PRUint32 j = 0; j < i; ++j)
        nsMemory::Free(iids[j]);
      nsMemory::Free(iids);
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }
 
  *aOutArray = iids;
  *aOutCount = aIIDCount;
  return NS_OK;
}