Expose overridable variable APIs in balutil and Mba.Core.

Fixes #4777

1 files changed, 51 insertions, 0 deletions

diff --git a/src/api/burn/WixToolset.Mba.Core/OverridableVariables.cs b/src/api/burn/WixToolset.Mba.Core/OverridableVariables.cs
new file mode 100644
index 00000000..855ce9a9
--- /dev/null
+++ b/src/api/burn/WixToolset.Mba.Core/OverridableVariables.cs
@@ -0,0 +1,51 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Mba.Core
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Xml;
+    using System.Xml.XPath;
+
+    /// <summary>
+    /// Default implementation of <see cref="IOverridableVariables"/>.
+    /// </summary>
+    public class OverridableVariablesInfo : IOverridableVariables
+    {
+        /// <inheritdoc />
+        public IDictionary<string, IOverridableVariableInfo> Variables { get; internal set; }
+
+        internal OverridableVariablesInfo() { }
+
+        /// <summary>
+        /// Parses the overridable variable info from the BA manifest.
+        /// </summary>
+        /// <param name="root">XML root</param>
+        /// <returns>The parsed information.</returns>
+        public static IOverridableVariables ParseFromXml(XPathNavigator root)
+        {
+            XmlNamespaceManager namespaceManager = new XmlNamespaceManager(root.NameTable);
+            namespaceManager.AddNamespace("p", BootstrapperApplicationData.XMLNamespace);
+            XPathNodeIterator nodes = root.Select("/p:BootstrapperApplicationData/p:WixStdbaOverridableVariable", namespaceManager);
+
+            var overridableVariables = new OverridableVariablesInfo();
+            overridableVariables.Variables = new Dictionary<string, IOverridableVariableInfo>();
+
+            foreach (XPathNavigator node in nodes)
+            {
+                var variable = new OverridableVariableInfo();
+
+                string name = BootstrapperApplicationData.GetAttribute(node, "Name");
+                if (name == null)
+                {
+                    throw new Exception("Failed to get name for overridable variable.");
+                }
+                variable.Name = name;
+
+                overridableVariables.Variables.Add(variable.Name, variable);
+            }
+
+            return overridableVariables;
+        }
+    }
+}