HubPlacementParseStrategyMatchProvider.cs

using Orchard.ContentManagement;
using Orchard.DisplayManagement.Descriptors;
using Patient.Framework.DisplayManagement;

namespace Patient.ContentTypes.Clinical.Providers {
    public class HubPlacementParseStrategyMatchProvider : IPlacementParseStategyMatchProvider {
        public string Key { get { return "Hub"; } }

        public bool IsMatch(ShapePlacementContext context, string expression) {
            var contentItem = context.Content.ContentItem;
            return contentItem.Has<IClincialArticlePart>() && contentItem.As<IClincialArticlePart>().IsTopicHub;
        }
    }
}

IPlacementParseStategyMatchProvider.cs

using System;
using Orchard;
using Orchard.DisplayManagement.Descriptors;

namespace Patient.Framework.DisplayManagement {
    public interface IPlacementParseStategyMatchProvider : IDependency {
        string Key { get; }
        bool IsMatch(ShapePlacementContext context, string expression);
    }
}

Placement.info

<Placement>
  <Place Parts_PageToolsShare="-" />
  <Place Parts_Common_Metadata="-" />
  
  <Match DisplayType="Detail">
    <Place Parts_PageTools="/ContentMenu:1" />
    <Place Parts_PageTools_Readspeaker="/BodyFoot:1" />
    <Place Parts_Tabs="-" />
    <Place Parts_Title="/ContentHead:0" />
    <Place Parts_ClinicalArticle_MetaData="/ContentHead:1" />
    <Place Parts_PageTools_PageOptions="-" />
    <Place Parts_ClinicalArticle_Introduction="Content:0" />
    <Place Parts_ClinicalArticle_SectionNavigation="Content:1" />
    <Place Parts_ClinicalArticle_InlineNavigation="Content:1" />
    <Place Parts_ClinicalArticle="Content:2" />
    <Place Parts_ClinicalArticle_SectionNavigation_Footer="Content:3" />
    <Place Parts_ClinicalArticle_References="Content:4" />
    <Place Parts_ClinicalArticle_RelatedContent="/ContentFoot:1" />
    <Place Parts_ClinicalArticle_Footer="/ContentFoot:2" />
    
    <Place Parts_ClinicalArticle_Related="-" />
    <Place Parts_ClinicalArticle_Discussions="-" />
    <Place Parts_ClinicalArticle_RelatedArticle_PilNudge="-" />
    <Place Parts_ClinicalArticle_RelatedArticle_ProNudge="-" />
    <Place Parts_FeedbackForm="-" />
    <Place Parts_Taboola="/AfterContentAds:1" />
    <Place Parts_ClickBait_Medianet="-" />
  
    <Match Hub="true">
      <Place Parts_Title="/ContentHead:0;Alternate=Parts_Title__Hub" />
      <Place Parts_ClinicalArticle_MetaData="-" />
      <Place Parts_ClinicalArticle_Introduction="Content:1.5" />
      <Place Parts_ClinicalArticle_InlineNavigation="-" />
      <Place Parts_ClinicalArticle="Content:2" />
      <Place Parts_ClinicalArticle_SectionNavigation_Footer="-" />
      <Place Parts_ClinicalArticle_References="-" />
      <Place Parts_ClinicalArticle_RelatedContent="-" />
      <Place Parts_ClinicalArticle_Footer="-" />
    </Match>
  </Match>
</Placement>

ShapePlacementParsingStrategy.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Orchard.DisplayManagement.Descriptors;
using Orchard.DisplayManagement.Descriptors.ShapePlacementStrategy;
using Orchard.Environment.Descriptor.Models;
using Orchard.Environment.Extensions;
using Orchard.Environment.Extensions.Models;
using Patient.Framework.DisplayManagement;

namespace Patient.Framework.DisplayManangement {
    [OrchardSuppressDependency("Orchard.DisplayManagement.Descriptors.ShapePlacementStrategy.ShapePlacementParsingStrategy")]
    public class ShapePlacementParsingStrategy : IShapeTableProvider {
        private readonly IExtensionManager _extensionManager;
        private readonly ShellDescriptor _shellDescriptor;
        private readonly IPlacementFileParser _placementFileParser;
        private readonly IEnumerable<IPlacementParseStategyMatchProvider> _parseMatchProviders;

        public ShapePlacementParsingStrategy(
                IExtensionManager extensionManager,
                ShellDescriptor shellDescriptor,
                IPlacementFileParser placementFileParser,
                IEnumerable<IPlacementParseStategyMatchProvider> parseMatchProviders) {
            _extensionManager = extensionManager;
            _shellDescriptor = shellDescriptor;
            _placementFileParser = placementFileParser;
            _parseMatchProviders = parseMatchProviders;
        }

        public void Discover(ShapeTableBuilder builder) {

            var availableFeatures = _extensionManager.AvailableFeatures();
            var activeFeatures = availableFeatures.Where(fd => FeatureIsTheme(fd) || FeatureIsEnabled(fd));
            var activeExtensions = Once(activeFeatures);

            foreach (var extensionDescriptor in activeExtensions) {
                foreach (var featureDescriptor in extensionDescriptor.Features.Where(fd => fd.Id == fd.Extension.Id)) {
                    ProcessFeatureDescriptor(builder, featureDescriptor);
                }
            }
        }

        private void ProcessFeatureDescriptor(ShapeTableBuilder builder, FeatureDescriptor featureDescriptor) {
            var virtualPath = featureDescriptor.Extension.Location + "/" + featureDescriptor.Extension.Id + "/Placement.info";
            var placementFile = _placementFileParser.Parse(virtualPath);
            if (placementFile != null) {
                ProcessPlacementFile(builder, featureDescriptor, placementFile);
            }
        }

        private void ProcessPlacementFile(ShapeTableBuilder builder, FeatureDescriptor featureDescriptor, PlacementFile placementFile) {
            var feature = new Feature { Descriptor = featureDescriptor };

            // invert the tree into a list of leaves and the stack
            var entries = DrillDownShapeLocations(placementFile.Nodes, Enumerable.Empty<PlacementMatch>());
            foreach (var entry in entries) {
                var shapeLocation = entry.Item1;
                var matches = entry.Item2;

                string shapeType;
                string differentiator;
                GetShapeType(shapeLocation, out shapeType, out differentiator);

                Func<ShapePlacementContext, bool> predicate = ctx => true;
                if (differentiator != "") {
                    predicate = ctx => (ctx.Differentiator ?? "") == differentiator;
                }

                if (matches.Any()) {
                    predicate = matches.SelectMany(match => match.Terms).Aggregate(predicate, BuildPredicate);
                }

                var placement = new PlacementInfo();

                var segments = shapeLocation.Location.Split(';').Select(s => s.Trim());
                foreach (var segment in segments) {
                    if (!segment.Contains('=')) {
                        placement.Location = segment;
                    }
                    else {
                        var index = segment.IndexOf('=');
                        var property = segment.Substring(0, index).ToLower();
                        var value = segment.Substring(index + 1);
                        switch (property) {
                            case "shape":
                                placement.ShapeType = value;
                                break;
                            case "alternate":
                                placement.Alternates = new[] { value };
                                break;
                            case "wrapper":
                                placement.Wrappers = new[] { value };
                                break;
                        }
                    }
                }

                builder.Describe(shapeType)
                    .From(feature)
                    .Placement(ctx => {
                        var hit = predicate(ctx);
                        // generate 'debugging' information to trace which file originated the actual location
                        if (hit) {
                            var virtualPath = featureDescriptor.Extension.Location + "/" + featureDescriptor.Extension.Id + "/Placement.info";
                            ctx.Source = virtualPath;
                        }
                        return hit;
                    }, placement);
            }
        }

        private void GetShapeType(PlacementShapeLocation shapeLocation, out string shapeType, out string differentiator) {
            differentiator = "";
            shapeType = shapeLocation.ShapeType;
            var separatorLengh = 2;
            var separatorIndex = shapeType.LastIndexOf("__");

            var dashIndex = shapeType.LastIndexOf('-');
            if (dashIndex > separatorIndex) {
                separatorIndex = dashIndex;
                separatorLengh = 1;
            }

            if (separatorIndex > 0 && separatorIndex < shapeType.Length - separatorLengh) {
                differentiator = shapeType.Substring(separatorIndex + separatorLengh);
                shapeType = shapeType.Substring(0, separatorIndex);
            }
        }

        private Func<ShapePlacementContext, bool> BuildPredicate(Func<ShapePlacementContext, bool> predicate, KeyValuePair<string, string> term) {
            var expression = term.Value;

            switch (term.Key) {
                case "ContentPart":
                    return ctx => ctx.Content != null
                        && ctx.Content.ContentItem.Parts.Any(part => part.PartDefinition.Name == expression)
                        && predicate(ctx);
                case "ContentType":
                    if (expression.EndsWith("*")) {
                        var prefix = expression.Substring(0, expression.Length - 1);
                        return ctx => ((ctx.ContentType ?? "").StartsWith(prefix) || (ctx.Stereotype ?? "").StartsWith(prefix)) && predicate(ctx);
                    }
                    return ctx => ((ctx.ContentType == expression) || (ctx.Stereotype == expression)) && predicate(ctx);
                case "DisplayType":
                    if (expression.EndsWith("*")) {
                        var prefix = expression.Substring(0, expression.Length - 1);
                        return ctx => (ctx.DisplayType ?? "").StartsWith(prefix) && predicate(ctx);
                    }
                    return ctx => (ctx.DisplayType == expression) && predicate(ctx);
                case "Path":
                    var normalizedPath = VirtualPathUtility.IsAbsolute(expression)
                                             ? VirtualPathUtility.ToAppRelative(expression)
                                             : VirtualPathUtility.Combine("~/", expression);

                    if (normalizedPath.EndsWith("*")) {
                        var prefix = normalizedPath.Substring(0, normalizedPath.Length - 1);
                        return ctx => VirtualPathUtility.ToAppRelative(String.IsNullOrEmpty(ctx.Path) ? "/" : ctx.Path).StartsWith(prefix, StringComparison.OrdinalIgnoreCase) && predicate(ctx);
                    }

                    normalizedPath = VirtualPathUtility.AppendTrailingSlash(normalizedPath);
                    return ctx => (ctx.Path.Equals(normalizedPath, StringComparison.OrdinalIgnoreCase)) && predicate(ctx);
            }

            if (_parseMatchProviders != null) {
                var providersForTerm = _parseMatchProviders.Where(x => x.Key.Equals(term.Key));
                if (providersForTerm.Any()) {
                    return ctx => providersForTerm.Any(x => x.IsMatch(ctx, expression)) && predicate(ctx);
                }
            }

            return predicate;
        }


        private static IEnumerable<Tuple<PlacementShapeLocation, IEnumerable<PlacementMatch>>> DrillDownShapeLocations(
            IEnumerable<PlacementNode> nodes,
            IEnumerable<PlacementMatch> path) {

            // return shape locations nodes in this place
            foreach (var placementShapeLocation in nodes.OfType<PlacementShapeLocation>()) {
                yield return new Tuple<PlacementShapeLocation, IEnumerable<PlacementMatch>>(placementShapeLocation, path);
            }
            // recurse down into match nodes
            foreach (var placementMatch in nodes.OfType<PlacementMatch>()) {
                foreach (var findShapeLocation in DrillDownShapeLocations(placementMatch.Nodes, path.Concat(new[] { placementMatch }))) {
                    yield return findShapeLocation;
                }
            }
        }

        private bool FeatureIsTheme(FeatureDescriptor fd) {
            return DefaultExtensionTypes.IsTheme(fd.Extension.ExtensionType);
        }

        private bool FeatureIsEnabled(FeatureDescriptor fd) {
            return _shellDescriptor.Features.Any(sf => sf.Name == fd.Id);
        }

        private static IEnumerable<ExtensionDescriptor> Once(IEnumerable<FeatureDescriptor> featureDescriptors) {
            var once = new ConcurrentDictionary<string, object>();
            return featureDescriptors.Select(fd => fd.Extension).Where(ed => once.TryAdd(ed.Id, null)).ToList();
        }

    }
}