getByIdOrHref() public method

First tries to find a resource with as id the given idOrHref, if that fails it tries to find one with the idOrHref as href.
public getByIdOrHref ( string idOrHref ) : Resource
idOrHref string
return Resource
        /// <summary>
        /// Reads the document's spine, containing all sections in reading order.
        /// </summary>
        /// <param>book</param>
        /// <param>resourcesById</param>
        /// <param name="packageDocument"></param>
        /// <param name="epubReader"></param>
        /// <param name="resources"></param>
        /// <param name="idMapping"></param>
        private static Spine readSpine(XElement packageDocument, EpubReader epubReader, Resources resources, Dictionary<String, String> idMapping)
        {
            XElement spineElement = DOMUtil.getFirstElementByTagNameNS(packageDocument, NAMESPACE_OPF, OPFTags.spine);
            if (spineElement == null)
            {
                //log.error("Element " + OPFTags.spine + " not found in package document, generating one automatically");
                return generateSpineFromResources(resources);
            }
            Spine result = new Spine();
            result.setTocResource(findTableOfContentsResource(spineElement, resources));
            var spineNodes = packageDocument.Elements(NAMESPACE_OPF + OPFTags.itemref).Elements<XElement>();
            IEnumerator spineNode = spineNodes.GetEnumerator();
            List<SpineReference> spineReferences = new List<SpineReference>();
            while (spineNode.MoveNext())
            {
                XElement spineItem = (XElement)spineNode.Current;
                String itemref = DOMUtil.getAttribute(spineItem, OPFAttributes.idref);
                if (StringUtil.isBlank(itemref))
                {
                    //log.error("itemref with missing or empty idref"); // XXX
                    continue;
                }
                String id = idMapping[itemref];
                if (id == null)
                {
                    id = itemref;
                }
                Resource resource = resources.getByIdOrHref(id);
                if (resource == null)
                {
                    //log.error("resource with id \'" + id + "\' not found");
                    continue;
                }

                SpineReference spineReference = new SpineReference(resource);
                if (OPFValues.no.Equals(DOMUtil.getAttribute(spineItem, OPFAttributes.linear)))
                {
                    spineReference.setLinear(false);
                }
                spineReferences.Add(spineReference);
            }
            result.setSpineReferences(spineReferences);
            return result;
        }
        /// <summary>
        /// The spine tag should contain a 'toc' attribute with as value the resource id of
        /// the table of contents resource.  Here we try several ways of finding this table
        /// of contents resource. We try the given attribute value, some often-used ones
        /// and finally look through all resources for the first resource with the table of
        /// contents mimetype.
        /// </summary>
        /// <param>resourcesById</param>
        /// <param name="spineElement"></param>
        /// <param name="resources"></param>
        private static Resource findTableOfContentsResource(XElement spineElement, Resources resources)
        {
            String tocResourceId = DOMUtil.getAttribute(spineElement, OPFAttributes.toc);
            Resource tocResource = null;
            if (StringUtil.isNotBlank(tocResourceId))
            {
                tocResource = resources.getByIdOrHref(tocResourceId);
            }

            if (tocResource != null)
            {
                return tocResource;
            }

            for (int i = 0; i < POSSIBLE_NCX_ITEM_IDS.Length; i++)
            {
                tocResource = resources.getByIdOrHref(POSSIBLE_NCX_ITEM_IDS[i]);
                if (tocResource != null)
                {
                    return tocResource;
                }
                tocResource = resources.getByIdOrHref(POSSIBLE_NCX_ITEM_IDS[i].ToUpper());
                if (tocResource != null)
                {
                    return tocResource;
                }
            }

            // get the first resource with the NCX mediatype
            tocResource = resources.findFirstResourceByMediaType(MediatypeService.NCX);

            if (tocResource == null)
            {
               // log.error("Could not find table of contents resource. Tried resource with id '" + tocResourceId + "', " + Constants.DEFAULT_TOC_ID + ", " + Constants.DEFAULT_TOC_ID.toUpperCase() + " and any NCX resource.");
            }
            return tocResource;
        }