/// <summary>
/// Creates a local resource provider chain for this resource path, if it is a local path
/// (see <see cref="CheckValidLocalPath"/>), and returns its result in a <see cref="IResourceAccessor"/> instance.
/// </summary>
/// <param name="result">Returns the resource accessor to access the resource represented by this path, if the
/// return value is <c>true</c>. Else, this parameter doesn't return a meaningful value.</param>
/// <returns><c>true</c>, if a resource accessor could successfully be built for this path.</returns>
/// <exception cref="IllegalCallException">If one of the referenced resource providers is not available in the system or
/// has the wrong type.</exception>
/// <exception cref="UnexpectedStateException">If this path is empty.</exception>
public bool TryCreateLocalResourceAccessor(out IResourceAccessor result)
{
IResourceAccessor resourceAccessor = null;
if (USE_RA_CACHE)
{
if (TryGetCloneFromCache(this, out resourceAccessor))
{
result = resourceAccessor;
return(true);
}
}
IMediaAccessor mediaAccessor = ServiceRegistration.Get <IMediaAccessor>();
IEnumerator <ProviderPathSegment> enumer = _pathSegments.GetEnumerator();
if (!enumer.MoveNext())
{
throw new UnexpectedStateException("Cannot build resource accessor for an empty resource path");
}
try
{
do
{
ProviderPathSegment pathSegment = enumer.Current;
IResourceProvider resourceProvider;
if (!mediaAccessor.LocalResourceProviders.TryGetValue(pathSegment.ProviderId, out resourceProvider))
{
throw new IllegalCallException("The resource provider with id '{0}' is not accessible in the current system", pathSegment.ProviderId);
}
if (resourceAccessor == null)
{
IBaseResourceProvider baseProvider = resourceProvider as IBaseResourceProvider;
if (baseProvider == null)
{
throw new IllegalCallException("The resource provider with id '{0}' does not implement the {1} interface", pathSegment.ProviderId, typeof(IBaseResourceProvider).Name);
}
if (!baseProvider.TryCreateResourceAccessor(pathSegment.Path, out resourceAccessor))
{
result = null;
return(false);
}
}
else
{
IChainedResourceProvider chainedProvider = resourceProvider as IChainedResourceProvider;
if (chainedProvider == null)
{
throw new IllegalCallException("The resource provider with id '{0}' does not implement the {1} interface", pathSegment.ProviderId, typeof(IChainedResourceProvider).Name);
}
IFileSystemResourceAccessor fsra = resourceAccessor as IFileSystemResourceAccessor;
if (fsra == null)
{
throw new IllegalCallException("Cannot chain up a resource provider to resource of type {0} (Path: '{1}')", resourceAccessor.GetType(), ToString());
}
IFileSystemResourceAccessor chainedRa;
if (!chainedProvider.TryChainUp(fsra, pathSegment.Path, out chainedRa))
{
resourceAccessor.Dispose();
result = null;
return(false);
}
resourceAccessor = chainedRa;
}
} while (enumer.MoveNext());
}
catch (Exception)
{
if (resourceAccessor != null)
{
resourceAccessor.Dispose();
}
throw;
}
if (USE_RA_CACHE)
{
AddToCache(this, resourceAccessor);
}
result = resourceAccessor;
return(true);
}