/// <summary>
/// Generate a list of artifact summary information from a resource input stream,
/// using the default <see cref="ConformanceHarvesters"/>.
/// <para>
/// If the target resource represents a <see cref="Bundle"/> instance, then the generator
/// returns a list of summaries for all resource entries contained in the bundle.
/// </para>
/// </summary>
/// <param name="navStream">An <see cref="INavigatorStream"/> instance.</param>
/// <param name="initProperties">
/// An optional summary properties initialization method, or <c>null</c>.
/// If specified, the generator will call this method for each generated summary,
/// allowing the caller to modify or enrich the set of generated summary properties.
/// </param>
/// <param name="harvesters">
/// A list of <see cref="ArtifactSummaryHarvester"/> delegates that the
/// generator calls to harvest summary information from each artifact.
/// If the harvester list equals <c>null</c> or empty, then the generator will
/// harvest only the common default summary properties.
/// </param>
/// <returns>A list of new <see cref="ArtifactSummary"/> instances.</returns>
/// <remarks>
/// The generator catches all runtime exceptions that occur during harvesting and returns
/// them as <see cref="ArtifactSummary"/> instances with <see cref="ArtifactSummary.IsFaulted"/>
/// equal to <c>true</c> and <see cref="ArtifactSummary.Error"/> returning the exception.
/// </remarks>
public static List <ArtifactSummary> Generate(
INavigatorStream navStream,
Action <ArtifactSummaryPropertyBag> initProperties,
params ArtifactSummaryHarvester[] harvesters)
{
var result = new List <ArtifactSummary>();
// Factory returns null for unknown file formats
if (navStream == null)
{
return(result);
}
try
{
// Run default or specified (custom) harvesters
if (harvesters == null || harvesters.Length == 0)
{
harvesters = ConformanceHarvesters;
}
while (navStream.MoveNext())
{
var current = navStream.Current;
if (current != null)
{
var properties = new ArtifactSummaryPropertyBag();
// Initialize default summary information
// Note: not exposed by IElementNavigator, cannot use harvester
properties.SetPosition(navStream.Position);
properties.SetTypeName(current.Type);
properties.SetResourceUri(navStream.Position);
// Allow caller to modify/enrich harvested properties
initProperties?.Invoke(properties);
// Generate the final (immutable) ArtifactSummary instance
var summary = generate(properties, current, harvesters);
result.Add(summary);
}
}
}
// TODO Catch specific exceptions
// catch (System.IO.FileNotFoundException)
// catch (UnauthorizedAccessException)
// catch (System.Security.SecurityException)
// catch (FormatException)
catch (Exception ex)
{
result.Add(ArtifactSummary.FromException(ex));
}
finally
{
navStream?.Dispose();
}
return(result);
}
// Generate summary for a single artifact
static ArtifactSummary generate(
ArtifactSummaryPropertyBag props,
ISourceNode nav,
ArtifactSummaryHarvester[] harvesters)
{
Exception error = null;
// [WMR 20180419] Support empty harvester list (harvest only default props, no custom props)
if (harvesters != null && harvesters.Length > 0)
{
try
{
// Harvest summary information via specified harvesters
// Top-level harvesters receive navigator positioned on the first child element level
// Catch individual exceptions inside loop, return as AggregateException
var errors = new List <Exception>();
if (nav.Children().Any())
{
foreach (var harvester in harvesters)
{
try
{
if (harvester != null && harvester.Invoke(nav, props))
{
break;
}
}
// TODO Catch specific exceptions
// catch (FormatException)
catch (Exception ex)
{
errors.Add(ex);
}
}
}
// Combine all errors into single AggregateException
error = errors.Count > 0 ? new AggregateException(errors) : null;
}
// TODO Catch specific exceptions
// catch (FormatException)
// catch (NotSupportedException)
catch (Exception ex)
{
// Error in summary factory?
// Make sure we always return a valid summary
error = ex;
}
}
// Create final summary from harvested properties and optional error
return(new ArtifactSummary(props, error));
}
