4 files changed, 220 insertions, 222 deletions

diff --git a/src/WixToolset.Core/Common.cs b/src/WixToolset.Core/Common.cs
index 19c77368..7a321d29 100644
--- a/src/WixToolset.Core/Common.cs
+++ b/src/WixToolset.Core/Common.cs
@@ -329,21 +329,22 @@ namespace WixToolset.Core
         /// <returns>The generated identifier.</returns>
         public static string GenerateIdentifier(string prefix, params string[] args)
         {
-            string stringData = String.Join("|", args);
-            byte[] data = Encoding.UTF8.GetBytes(stringData);
+            string base64;
 
-            // hash the data
-            byte[] hash;
-            using (SHA1 sha1 = new SHA1CryptoServiceProvider())
+            using (var sha1 = new SHA1CryptoServiceProvider())
             {
-                hash = sha1.ComputeHash(data);
+                var combined = String.Join("|", args);
+                var data = Encoding.UTF8.GetBytes(combined);
+                var hash = sha1.ComputeHash(data);
+                base64 = Convert.ToBase64String(hash);
             }
 
-            // Build up the identifier.
-            StringBuilder identifier = new StringBuilder(35, 35);
+            var identifier = new StringBuilder(32);
             identifier.Append(prefix);
-            identifier.Append(Convert.ToBase64String(hash).TrimEnd('='));
-            identifier.Replace('+', '.').Replace('/', '_');
+            identifier.Append(base64);
+            identifier.Length -= 1; // removes the trailing '=' from base64
+            identifier.Replace('+', '.');
+            identifier.Replace('/', '_');
 
             return identifier.ToString();
         }
diff --git a/src/WixToolset.Core/Compiler.cs b/src/WixToolset.Core/Compiler.cs
index 3fa06f9c..c504e96f 100644
--- a/src/WixToolset.Core/Compiler.cs
+++ b/src/WixToolset.Core/Compiler.cs
@@ -9,6 +9,7 @@ namespace WixToolset.Core
     using System.Globalization;
     using System.IO;
     using System.Linq;
+    using System.Text;
     using System.Xml.Linq;
     using WixToolset.Data;
     using WixToolset.Data.Symbols;
@@ -25,8 +26,10 @@ namespace WixToolset.Core
         private const int MinValueOfMaxCabSizeForLargeFileSplitting = 20; // 20 MB
         private const int MaxValueOfMaxCabSizeForLargeFileSplitting = 2 * 1024; // 2048 MB (i.e. 2 GB)
 
-        private const string DefaultComponentIdPlaceholderPrefix = "WixComponentIdPlaceholder";
-        private const string DefaultComponentIdPlaceholderWixVariablePrefix = "!(wix.";
+        private const char ComponentIdPlaceholderStart = (char)167;
+        private const char ComponentIdPlaceholderEnd = (char)167;
+        private Dictionary<string, string> componentIdPlaceholders;
+
         // If these are true you know you are building a module or product
         // but if they are false you cannot not be sure they will not end
         // up a product or module.  Use these flags carefully.
@@ -36,9 +39,6 @@ namespace WixToolset.Core
         private string activeName;
         private string activeLanguage;
 
-        // TODO: Implement this differently to not require the VariableResolver.
-        private VariableResolver componentIdPlaceholdersResolver;
-
         /// <summary>
         /// Type of RadioButton element in a group.
         /// </summary>
@@ -129,7 +129,7 @@ namespace WixToolset.Core
 
                 this.Core = new CompilerCore(target, this.Messaging, parseHelper, extensionsByNamespace);
                 this.Core.ShowPedanticMessages = this.ShowPedanticMessages;
-                this.componentIdPlaceholdersResolver = new VariableResolver(this.ServiceProvider);
+                this.componentIdPlaceholders = new Dictionary<string, string>();
 
                 // parse the document
                 var source = this.Context.Source;
@@ -247,7 +247,7 @@ namespace WixToolset.Core
 
         private void ResolveComponentIdPlaceholders(Intermediate target)
         {
-            if (0 < this.componentIdPlaceholdersResolver.VariableCount)
+            if (0 < this.componentIdPlaceholders.Count)
             {
                 foreach (var section in target.Sections)
                 {
@@ -255,15 +255,40 @@ namespace WixToolset.Core
                     {
                         foreach (var field in symbol.Fields)
                         {
-                            if (field?.Type == IntermediateFieldType.String)
+                            if (field != null && field.Type == IntermediateFieldType.String)
                             {
                                 var data = field.AsString();
                                 if (!String.IsNullOrEmpty(data))
                                 {
-                                    var resolved = this.componentIdPlaceholdersResolver.ResolveVariables(symbol.SourceLineNumbers, data, errorOnUnknown: false);
-                                    if (resolved.UpdatedValue)
+                                    var changed = false;
+                                    var start = data.IndexOf(ComponentIdPlaceholderStart);
+                                    while (start != -1)
+                                    {
+                                        var end = data.IndexOf(ComponentIdPlaceholderEnd, start + 1);
+                                        if (end == -1)
+                                        {
+                                            break;
+                                        }
+
+                                        var placeholderId = data.Substring(start, end - start + 1);
+                                        if (this.componentIdPlaceholders.TryGetValue(placeholderId, out var value))
+                                        {
+                                            var sb = new StringBuilder(data);
+                                            sb.Remove(start, end - start + 1);
+                                            sb.Insert(start, value);
+
+                                            data = sb.ToString();
+                                            changed = true;
+
+                                            end = start + value.Length;
+                                        }
+
+                                        start = data.IndexOf(ComponentIdPlaceholderStart, end);
+                                    }
+
+                                    if (changed)
                                     {
-                                        field.Set(resolved.Value);
+                                        field.Overwrite(data);
                                     }
                                 }
                             }
@@ -2096,9 +2121,8 @@ namespace WixToolset.Core
             var encounteredODBCDataSource = false;
             var files = 0;
             var guid = "*";
-            var componentIdPlaceholder = Compiler.DefaultComponentIdPlaceholderPrefix + this.componentIdPlaceholdersResolver.VariableCount; // placeholder id for defaulting Component/@Id to keypath id.
-            var componentIdPlaceholderWixVariable = Compiler.DefaultComponentIdPlaceholderWixVariablePrefix + componentIdPlaceholder + ")";
-            var id = new Identifier(AccessModifier.Private, componentIdPlaceholderWixVariable);
+            Identifier id = null;
+            string componentIdPlaceholder = null;
             var keyFound = false;
             string keyPath = null;
 
@@ -2253,6 +2277,13 @@ namespace WixToolset.Core
                 win64 = true;
             }
 
+            if (id == null)
+            {
+                // Placeholder id for defaulting Component/@Id to keypath id.
+                componentIdPlaceholder = String.Concat(Compiler.ComponentIdPlaceholderStart, this.componentIdPlaceholders.Count, Compiler.ComponentIdPlaceholderEnd);
+                id = new Identifier(AccessModifier.Private, componentIdPlaceholder);
+            }
+
             if (null == directoryId)
             {
                 this.Core.Write(ErrorMessages.ExpectedAttribute(sourceLineNumbers, node.Name.LocalName, "Directory"));
@@ -2466,14 +2497,14 @@ namespace WixToolset.Core
                 this.Core.Write(ErrorMessages.ImplicitComponentKeyPath(sourceLineNumbers, id.Id));
             }
 
-            // if there isn't an @Id attribute value, replace the placeholder with the id of the keypath.
+            // If there isn't an @Id attribute value, replace the placeholder with the id of the keypath.
             // either an explicit KeyPath="yes" attribute must be specified or requirements for
             // generatable guid must be met.
-            if (componentIdPlaceholderWixVariable == id.Id)
+            if (componentIdPlaceholder == id.Id)
             {
                 if (isGeneratableGuidOk || keyFound && !String.IsNullOrEmpty(keyPath))
                 {
-                    this.componentIdPlaceholdersResolver.AddVariable(sourceLineNumbers, componentIdPlaceholder, keyPath, false);
+                    this.componentIdPlaceholders.Add(componentIdPlaceholder, keyPath);
 
                     id = new Identifier(AccessModifier.Private, keyPath);
                 }
@@ -2483,12 +2514,6 @@ namespace WixToolset.Core
                 }
             }
 
-            // If an id was not determined by now, we have to error.
-            if (null == id)
-            {
-                this.Core.Write(ErrorMessages.ExpectedAttribute(sourceLineNumbers, node.Name.LocalName, "Id"));
-            }
-
             // finally add the Component table row
             if (!this.Core.EncounteredError)
             {
@@ -4120,9 +4145,9 @@ namespace WixToolset.Core
             Identifier id = null;
             string componentGuidGenerationSeed = null;
             var fileSourceAttribSet = false;
-            var nameHasValue = false;
+            XAttribute nameAttribute = null;
             var name = "."; // default to parent directory.
-            string[] inlineSyntax = null;
+            string inlineSyntax = null;
             string shortName = null;
             string sourceName = null;
             string shortSourceName = null;
@@ -4148,15 +4173,8 @@ namespace WixToolset.Core
                         fileSourceAttribSet = true;
                         break;
                     case "Name":
-                        nameHasValue = true;
-                        if (attrib.Value == ".")
-                        {
-                            name = attrib.Value;
-                        }
-                        else
-                        {
-                            inlineSyntax = this.Core.GetAttributeInlineDirectorySyntax(sourceLineNumbers, attrib);
-                        }
+                        name = this.Core.GetAttributeValue(sourceLineNumbers, attrib);
+                        nameAttribute = attrib;
                         break;
                     case "ShortName":
                         shortName = this.Core.GetAttributeShortFilename(sourceLineNumbers, attrib, false);
@@ -4185,37 +4203,7 @@ namespace WixToolset.Core
                 }
             }
 
-            // Create the directory rows for the inline.
-            if (null != inlineSyntax)
-            {
-                // Special case the single entry in the inline syntax since it is the most common case
-                // and needs no extra processing. It's just the name of the directory.
-                if (1 == inlineSyntax.Length)
-                {
-                    name = inlineSyntax[0];
-                }
-                else
-                {
-                    var pathStartsAt = 0;
-                    if (inlineSyntax[0].EndsWith(":"))
-                    {
-                        parentId = inlineSyntax[0].TrimEnd(':');
-                        this.Core.CreateSimpleReference(sourceLineNumbers, SymbolDefinitions.Directory, parentId);
-
-                        pathStartsAt = 1;
-                    }
-
-                    for (var i = pathStartsAt; i < inlineSyntax.Length - 1; ++i)
-                    {
-                        var inlineId = this.Core.CreateDirectoryRow(sourceLineNumbers, null, parentId, inlineSyntax[i]);
-                        parentId = inlineId.Id;
-                    }
-
-                    name = inlineSyntax[inlineSyntax.Length - 1];
-                }
-            }
-
-            if (!nameHasValue)
+            if (nameAttribute == null)
             {
                 if (!String.IsNullOrEmpty(shortName))
                 {
@@ -4264,39 +4252,55 @@ namespace WixToolset.Core
                 }
             }
 
-            // Update the file source path appropriately.
-            if (fileSourceAttribSet)
+            // Create the directory rows for the inline.
+            if (nameAttribute != null)
             {
-                if (!fileSource.EndsWith(Path.DirectorySeparatorChar.ToString(), StringComparison.Ordinal))
+                var lastSlash = name.LastIndexOf('\\');
+                if (lastSlash > 0)
                 {
-                    fileSource = String.Concat(fileSource, Path.DirectorySeparatorChar);
+                    inlineSyntax = name;
+                    name = inlineSyntax.Substring(lastSlash + 1);
+
+                    parentId = this.Core.CreateDirectoryReferenceFromInlineSyntax(sourceLineNumbers, nameAttribute, parentId, inlineSyntax.Substring(0, lastSlash));
+
+                    if (!this.Core.IsValidLongFilename(name, false, false))
+                    {
+                        this.Messaging.Write(ErrorMessages.IllegalLongFilename(sourceLineNumbers, node.Name.LocalName, nameAttribute.Name.LocalName, nameAttribute.Value, name));
+                    }
                 }
             }
-            else // add the appropriate part of this directory element to the file source.
+
+            if (null == id)
             {
-                string append = String.IsNullOrEmpty(sourceName) ? name : sourceName;
+                id = this.Core.CreateIdentifier("dir", parentId, name, shortName, sourceName, shortSourceName);
 
-                if (!String.IsNullOrEmpty(append))
+                if (!String.IsNullOrEmpty(inlineSyntax))
                 {
-                    fileSource = String.Concat(fileSource, append, Path.DirectorySeparatorChar);
+                    this.Core.AddInlineDirectoryId(inlineSyntax, id.Id);
                 }
             }
 
-            if (null == id)
+            if ("TARGETDIR".Equals(id.Id, StringComparison.Ordinal) && !("SourceDir".Equals(name, StringComparison.Ordinal) && shortName == null && shortSourceName == null && sourceName == null))
             {
-                id = this.Core.CreateIdentifier("dir", parentId, name, shortName, sourceName, shortSourceName);
+                this.Core.Write(ErrorMessages.IllegalTargetDirDefaultDir(sourceLineNumbers, name));
             }
 
-            // Calculate the DefaultDir for the directory row.
-            var defaultDir = String.IsNullOrEmpty(shortName) ? name : String.Concat(shortName, "|", name);
-            if (!String.IsNullOrEmpty(sourceName))
+            // Update the file source path appropriately.
+            if (fileSourceAttribSet)
             {
-                defaultDir = String.Concat(defaultDir, ":", String.IsNullOrEmpty(shortSourceName) ? sourceName : String.Concat(shortSourceName, "|", sourceName));
+                if (!fileSource.EndsWith(Path.DirectorySeparatorChar.ToString(), StringComparison.Ordinal))
+                {
+                    fileSource = String.Concat(fileSource, Path.DirectorySeparatorChar);
+                }
             }
-
-            if ("TARGETDIR".Equals(id.Id, StringComparison.Ordinal) && !"SourceDir".Equals(defaultDir, StringComparison.Ordinal))
+            else // add the appropriate part of this directory element to the file source.
             {
-                this.Core.Write(ErrorMessages.IllegalTargetDirDefaultDir(sourceLineNumbers, defaultDir));
+                string append = String.IsNullOrEmpty(sourceName) ? name : sourceName;
+
+                if (!String.IsNullOrEmpty(append))
+                {
+                    fileSource = String.Concat(fileSource, append, Path.DirectorySeparatorChar);
+                }
             }
 
             foreach (var child in node.Elements())
diff --git a/src/WixToolset.Core/CompilerCore.cs b/src/WixToolset.Core/CompilerCore.cs
index d88858ae..e2c1a3d6 100644
--- a/src/WixToolset.Core/CompilerCore.cs
+++ b/src/WixToolset.Core/CompilerCore.cs
@@ -120,7 +120,7 @@ namespace WixToolset.Core
         private readonly IParseHelper parseHelper;
         private readonly Intermediate intermediate;
         private readonly IMessaging messaging;
-        private HashSet<string> activeSectionInlinedDirectoryIds;
+        private Dictionary<string, string> activeSectionCachedInlinedDirectoryIds;
         private HashSet<string> activeSectionSimpleReferences;
 
         /// <summary>
@@ -354,12 +354,13 @@ namespace WixToolset.Core
         /// Creates directories using the inline directory syntax.
         /// </summary>
         /// <param name="sourceLineNumbers">Source line information.</param>
-        /// <param name="attribute">The attribute to parse.</param>
+        /// <param name="attribute">Attribute containing the inline syntax.</param>
         /// <param name="parentId">Optional identifier of parent directory.</param>
+        /// <param name="inlineSyntax">Optional inline syntax to override attribute's value.</param>
         /// <returns>Identifier of the leaf directory created.</returns>
-        public string CreateDirectoryReferenceFromInlineSyntax(SourceLineNumber sourceLineNumbers, XAttribute attribute, string parentId)
+        public string CreateDirectoryReferenceFromInlineSyntax(SourceLineNumber sourceLineNumbers, XAttribute attribute, string parentId, string inlineSyntax = null)
         {
-            return this.parseHelper.CreateDirectoryReferenceFromInlineSyntax(this.ActiveSection, sourceLineNumbers, parentId, attribute, this.activeSectionInlinedDirectoryIds);
+            return this.parseHelper.CreateDirectoryReferenceFromInlineSyntax(this.ActiveSection, sourceLineNumbers, attribute, parentId, inlineSyntax, this.activeSectionCachedInlinedDirectoryIds);
         }
 
         /// <summary>
@@ -1001,6 +1002,16 @@ namespace WixToolset.Core
         }
 
         /// <summary>
+        /// Adds inline directory syntax generated identifier.
+        /// </summary>
+        /// <param name="inlineSyntax">Inline directory syntax the identifier was generated.</param>
+        /// <param name="id">Generated identifier for inline syntax.</param>
+        internal void AddInlineDirectoryId(string inlineSyntax, string id)
+        {
+            this.activeSectionCachedInlinedDirectoryIds.Add(inlineSyntax, id);
+        }
+
+        /// <summary>
         /// Creates a new section and makes it the active section in the core.
         /// </summary>
         /// <param name="id">Unique identifier for the section.</param>
@@ -1011,7 +1022,7 @@ namespace WixToolset.Core
         {
             this.ActiveSection = this.CreateSection(id, type, codepage, compilationId);
 
-            this.activeSectionInlinedDirectoryIds = new HashSet<string>();
+            this.activeSectionCachedInlinedDirectoryIds = new Dictionary<string, string>();
             this.activeSectionSimpleReferences = new HashSet<string>();
 
             return this.ActiveSection;
@@ -1060,9 +1071,9 @@ namespace WixToolset.Core
         /// <param name="sourceName">Optional source name for the directory.</param>
         /// <param name="shortSourceName">Optional short source name for the directory.</param>
         /// <returns>Identifier for the newly created row.</returns>
-        internal Identifier CreateDirectoryRow(SourceLineNumber sourceLineNumbers, Identifier id, string parentId, string name, string shortName = null, string sourceName = null, string shortSourceName = null)
+        internal Identifier CreateDirectorySymbol(SourceLineNumber sourceLineNumbers, Identifier id, string parentId, string name, string shortName = null, string sourceName = null, string shortSourceName = null)
         {
-            return this.parseHelper.CreateDirectorySymbol(this.ActiveSection, sourceLineNumbers, id, parentId, name, this.activeSectionInlinedDirectoryIds, shortName, sourceName, shortSourceName);
+            return this.parseHelper.CreateDirectorySymbol(this.ActiveSection, sourceLineNumbers, id, parentId, name, shortName, sourceName, shortSourceName);
         }
 
         public void CreateWixSearchSymbol(SourceLineNumber sourceLineNumbers, string elementName, Identifier id, string variable, string condition, string after)
@@ -1070,18 +1081,6 @@ namespace WixToolset.Core
             this.parseHelper.CreateWixSearchSymbol(this.ActiveSection, sourceLineNumbers, elementName, id, variable, condition, after, null);
         }
 
-        /// <summary>
-        /// Gets the attribute value as inline directory syntax.
-        /// </summary>
-        /// <param name="sourceLineNumbers">Source line information.</param>
-        /// <param name="attribute">Attribute containing the value to get.</param>
-        /// <param name="resultUsedToCreateReference">Flag indicates whether the inline directory syntax should be processed to create a directory row or to create a directory reference.</param>
-        /// <returns>Inline directory syntax split into array of strings or null if the syntax did not parse.</returns>
-        internal string[] GetAttributeInlineDirectorySyntax(SourceLineNumber sourceLineNumbers, XAttribute attribute, bool resultUsedToCreateReference = false)
-        {
-            return this.parseHelper.GetAttributeInlineDirectorySyntax(sourceLineNumbers, attribute, resultUsedToCreateReference);
-        }
-
         internal WixActionSymbol ScheduleActionSymbol(SourceLineNumber sourceLineNumbers, AccessModifier access, SequenceTable sequence, string actionName, string condition = null, string beforeAction = null, string afterAction = null, bool overridable = false)
         {
             return this.parseHelper.ScheduleActionSymbol(this.ActiveSection, sourceLineNumbers, access, sequence, actionName, condition, beforeAction, afterAction, overridable);
diff --git a/src/WixToolset.Core/ExtensibilityServices/ParseHelper.cs b/src/WixToolset.Core/ExtensibilityServices/ParseHelper.cs
index d9087ce3..e75f5fe5 100644
--- a/src/WixToolset.Core/ExtensibilityServices/ParseHelper.cs
+++ b/src/WixToolset.Core/ExtensibilityServices/ParseHelper.cs
@@ -19,6 +19,8 @@ namespace WixToolset.Core.ExtensibilityServices
 
     internal class ParseHelper : IParseHelper
     {
+        private static readonly char[] InlineDirectorySeparators = new char[] { ':', '\\', '/' };
+
         public ParseHelper(IWixToolsetServiceProvider serviceProvider)
         {
             this.ServiceProvider = serviceProvider;
@@ -53,13 +55,7 @@ namespace WixToolset.Core.ExtensibilityServices
             this.CreateWixGroupSymbol(section, sourceLineNumbers, parentType, parentId, childType, childId);
         }
 
-        [Obsolete]
-        public Identifier CreateDirectoryRow(IntermediateSection section, SourceLineNumber sourceLineNumbers, Identifier id, string parentId, string name, ISet<string> sectionInlinedDirectoryIds, string shortName = null, string sourceName = null, string shortSourceName = null)
-        {
-            return this.CreateDirectorySymbol(section, sourceLineNumbers, id, parentId, name, sectionInlinedDirectoryIds, shortName, sourceName, shortSourceName);
-        }
-
-        public Identifier CreateDirectorySymbol(IntermediateSection section, SourceLineNumber sourceLineNumbers, Identifier id, string parentId, string name, ISet<string> sectionInlinedDirectoryIds, string shortName = null, string sourceName = null, string shortSourceName = null)
+        public Identifier CreateDirectorySymbol(IntermediateSection section, SourceLineNumber sourceLineNumbers, Identifier id, string parentId, string name, string shortName = null, string sourceName = null, string shortSourceName = null)
         {
             // For anonymous directories, create the identifier. If this identifier already exists in the
             // active section, bail so we don't add duplicate anonymous directory symbols (which are legal
@@ -67,11 +63,6 @@ namespace WixToolset.Core.ExtensibilityServices
             if (null == id)
             {
                 id = this.CreateIdentifier("dir", parentId, name, shortName, sourceName, shortSourceName);
-
-                if (!sectionInlinedDirectoryIds.Add(id.Id))
-                {
-                    return id;
-                }
             }
 
             var symbol = section.AddSymbol(new DirectorySymbol(sourceLineNumbers, id)
@@ -86,48 +77,30 @@ namespace WixToolset.Core.ExtensibilityServices
             return symbol.Id;
         }
 
-        public string CreateDirectoryReferenceFromInlineSyntax(IntermediateSection section, SourceLineNumber sourceLineNumbers, string parentId, XAttribute attribute, ISet<string> sectionInlinedDirectoryIds)
+        public string CreateDirectoryReferenceFromInlineSyntax(IntermediateSection section, SourceLineNumber sourceLineNumbers, XAttribute attribute, string parentId, string inlineSyntax, IDictionary<string, string> sectionCachedInlinedDirectoryIds)
         {
-            string id = null;
-            var inlineSyntax = this.GetAttributeInlineDirectorySyntax(sourceLineNumbers, attribute, true);
-
-            if (null != inlineSyntax)
+            if (String.IsNullOrEmpty(inlineSyntax))
             {
-                // Special case the single entry in the inline syntax since it is the most common case
-                // and needs no extra processing. It's just a reference to an existing directory.
-                if (1 == inlineSyntax.Length)
-                {
-                    id = inlineSyntax[0];
-                    this.CreateSimpleReference(section, sourceLineNumbers, SymbolDefinitions.Directory, id);
-                }
-                else // start creating symbols for the entries in the inline syntax
-                {
-                    id = parentId;
-
-                    var pathStartsAt = 0;
-                    if (inlineSyntax[0].EndsWith(":", StringComparison.Ordinal))
-                    {
-                        // TODO: should overriding the parent identifier with a specific id be an error or a warning or just let it slide?
-                        //if (null != parentId)
-                        //{
-                        //    this.core.Write(WixErrors.Xxx(sourceLineNumbers));
-                        //}
-
-                        id = inlineSyntax[0].TrimEnd(':');
-                        this.CreateSimpleReference(section, sourceLineNumbers, SymbolDefinitions.Directory, id);
+                inlineSyntax = attribute.Value;
+            }
 
-                        pathStartsAt = 1;
-                    }
+            // If no separator is found, the string is a simple reference.
+            var separatorFound = inlineSyntax.IndexOfAny(InlineDirectorySeparators);
+            if (separatorFound == -1)
+            {
+                this.CreateSimpleReference(section, sourceLineNumbers, SymbolDefinitions.Directory, inlineSyntax);
+                return inlineSyntax;
+            }
 
-                    for (var i = pathStartsAt; i < inlineSyntax.Length; ++i)
-                    {
-                        var inlineId = this.CreateDirectorySymbol(section, sourceLineNumbers, null, id, inlineSyntax[i], sectionInlinedDirectoryIds);
-                        id = inlineId.Id;
-                    }
-                }
+            // If a parent id was provided and the inline syntax does not start with a directory reference, prepend the parent id.
+            if (!String.IsNullOrEmpty(parentId) && inlineSyntax[separatorFound] != ':')
+            {
+                inlineSyntax = String.Concat(parentId, ":", inlineSyntax);
             }
 
-            return id;
+            inlineSyntax = inlineSyntax.TrimEnd('\\', '/');
+
+            return this.ParseInlineSyntax(section, sourceLineNumbers, attribute, inlineSyntax, sectionCachedInlinedDirectoryIds);
         }
 
         public string CreateGuid(Guid namespaceGuid, string value)
@@ -544,69 +517,6 @@ namespace WixToolset.Core.ExtensibilityServices
             return Common.GetAttributeIdentifierValue(this.Messaging, sourceLineNumbers, attribute);
         }
 
-        public string[] GetAttributeInlineDirectorySyntax(SourceLineNumber sourceLineNumbers, XAttribute attribute, bool resultUsedToCreateReference = false)
-        {
-            string[] result = null;
-            var value = this.GetAttributeValue(sourceLineNumbers, attribute);
-
-            if (!String.IsNullOrEmpty(value))
-            {
-                var pathStartsAt = 0;
-                result = value.Split(new char[] { '\\' }, StringSplitOptions.RemoveEmptyEntries);
-                if (result[0].EndsWith(":", StringComparison.Ordinal))
-                {
-                    var id = result[0].TrimEnd(':');
-                    if (1 == result.Length)
-                    {
-                        this.Messaging.Write(ErrorMessages.InlineDirectorySyntaxRequiresPath(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, value, id));
-                        return null;
-                    }
-                    else if (!this.IsValidIdentifier(id))
-                    {
-                        this.Messaging.Write(ErrorMessages.IllegalIdentifier(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, value, id));
-                        return null;
-                    }
-
-                    pathStartsAt = 1;
-                }
-                else if (resultUsedToCreateReference && 1 == result.Length)
-                {
-                    if (value.EndsWith("\\", StringComparison.Ordinal))
-                    {
-                        if (!this.IsValidLongFilename(result[0], false, false))
-                        {
-                            this.Messaging.Write(ErrorMessages.IllegalLongFilename(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, value, result[0]));
-                            return null;
-                        }
-                    }
-                    else if (!this.IsValidIdentifier(result[0]))
-                    {
-                        this.Messaging.Write(ErrorMessages.IllegalIdentifier(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, value, result[0]));
-                        return null;
-                    }
-
-                    return result; // return early to avoid additional checks below.
-                }
-
-                // Check each part of the relative path to ensure that it is a valid directory name.
-                for (var i = pathStartsAt; i < result.Length; ++i)
-                {
-                    if (!this.IsValidLongFilename(result[i], false, false))
-                    {
-                        this.Messaging.Write(ErrorMessages.IllegalLongFilename(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, value, result[i]));
-                        return null;
-                    }
-                }
-
-                if (1 < result.Length && !value.EndsWith("\\", StringComparison.Ordinal))
-                {
-                    this.Messaging.Write(WarningMessages.BackslashTerminateInlineDirectorySyntax(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, value));
-                }
-            }
-
-            return result;
-        }
-
         public int GetAttributeIntegerValue(SourceLineNumber sourceLineNumbers, XAttribute attribute, int minimum, int maximum)
         {
             return Common.GetAttributeIntegerValue(this.Messaging, sourceLineNumbers, attribute, minimum, maximum);
@@ -1032,6 +942,90 @@ namespace WixToolset.Core.ExtensibilityServices
             this.Creator = this.ServiceProvider.GetService<ISymbolDefinitionCreator>();
         }
 
+        private string ParseInlineSyntax(IntermediateSection section, SourceLineNumber sourceLineNumbers, XAttribute attribute, string inlineSyntax, IDictionary<string, string> sectionCachedInlinedDirectoryIds)
+        {
+            if (!sectionCachedInlinedDirectoryIds.TryGetValue(inlineSyntax, out var id))
+            {
+                string parentId;
+                int nameIndex;
+
+                var separatorIndex = inlineSyntax.LastIndexOfAny(InlineDirectorySeparators);
+                if (separatorIndex == -1)
+                {
+                    nameIndex = 0;
+                    parentId = "TARGETDIR";
+                }
+                else if (inlineSyntax[separatorIndex] == '\\' || inlineSyntax[separatorIndex] == '/')
+                {
+                    nameIndex = separatorIndex + 1;
+
+                    if (separatorIndex == 0)
+                    {
+                        parentId = "TARGETDIR";
+                    }
+                    else if (inlineSyntax[separatorIndex - 1] == ':')
+                    {
+                        parentId = this.ParseParentReference(section, sourceLineNumbers, attribute, inlineSyntax, separatorIndex - 1);
+                    }
+                    else
+                    {
+                        var parentInlineDirectory = inlineSyntax.Substring(0, separatorIndex);
+                        parentId = this.ParseInlineSyntax(section, sourceLineNumbers, attribute, parentInlineDirectory.TrimEnd('\\', '/'), sectionCachedInlinedDirectoryIds);
+                    }
+                }
+                else
+                {
+                    nameIndex = separatorIndex + 1;
+                    parentId = this.ParseParentReference(section, sourceLineNumbers, attribute, inlineSyntax, separatorIndex);
+                }
+
+                if (nameIndex == inlineSyntax.Length)
+                {
+                    id = parentId;
+                }
+                else
+                {
+                    var name = nameIndex != -1 ? inlineSyntax.Substring(nameIndex) : null;
+
+                    if (!this.IsValidLongFilename(name, false, false))
+                    {
+                        this.Messaging.Write(ErrorMessages.IllegalLongFilename(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, attribute.Value, name));
+                        return null;
+                    }
+
+                    var identifier = this.CreateDirectorySymbol(section, sourceLineNumbers, null, parentId, name);
+
+                    id = identifier.Id;
+                }
+
+                sectionCachedInlinedDirectoryIds.Add(inlineSyntax, id);
+            }
+
+            return id;
+        }
+
+        private string ParseParentReference(IntermediateSection section, SourceLineNumber sourceLineNumbers, XAttribute attribute, string reference, int colonIndex)
+        {
+            if (colonIndex == 0)
+            {
+                this.Messaging.Write(ErrorMessages.IllegalIdentifier(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, attribute.Value, String.Empty));
+                return null;
+            }
+            else
+            {
+                var parentId = reference.Substring(0, colonIndex);
+
+                if (!Common.IsIdentifier(parentId))
+                {
+                    this.Messaging.Write(ErrorMessages.IllegalIdentifier(sourceLineNumbers, attribute.Parent.Name.LocalName, attribute.Name.LocalName, attribute.Value, parentId));
+                    return null;
+                }
+
+                this.CreateSimpleReference(section, sourceLineNumbers, SymbolDefinitions.Directory, parentId);
+                return parentId;
+            }
+        }
+
         private static bool TryFindExtension(IEnumerable<ICompilerExtension> extensions, XNamespace ns, out ICompilerExtension extension)
         {
             extension = null;