Rough layout of local variable tables

Create the XAML and some skeletal classes.

SourceGen/LocalVariableTable.cs

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+/*
+ * Copyright 2019 faddenSoft
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+using System;
+using System.Collections.Generic;
+
+namespace SourceGen {
+    /// <summary>
+    /// Table of redefinable variables.  A project may have several of these, at different
+    /// offsets.  The contents of later tables overwrite the contents of earlier tables.
+    /// </summary>
+    public class LocalVariableTable {
+        /// <summary>
+        /// List of variables.  The symbol's label must be unique within a table, so we sort
+        /// on that.
+        /// </summary>
+        private SortedList<string, DefSymbol> mVariables;
+
+        /// <summary>
+        /// If set, all values from previous VariableTables should be discarded when this
+        /// table is encountered.
+        /// </summary>
+        /// <remarks>
+        /// Might be useful to allow addresses (DP ops) and constants (StackRel ops) to be
+        /// cleared independently, but I suspect the typical compiled-language scenario will
+        /// involve StackRel for args and a sliding DP for locals, so generally it makes
+        /// sense to just clear both.
+        /// </remarks>
+        public bool ClearPrevious { get; set; }
+
+        /// <summary>
+        /// Indexer.
+        /// </summary>
+        /// <param name="key">Symbol's label.</param>
+        /// <returns>Matching symbol.  Throws an exception if not found.</returns>
+        public DefSymbol this[string key] {
+            get {
+                return mVariables[key];
+            }
+            set {
+                mVariables[key] = value;
+            }
+        }
+
+        /// <summary>
+        /// Constructs an empty table.
+        /// </summary>
+        public LocalVariableTable() {
+            mVariables = new SortedList<string, DefSymbol>();
+        }
+    }
+}