Create DictionaryBase to hold helpers

SabreTools.Models/Internal/DictionaryBase.cs

@@ -0,0 +1,47 @@
+using System.Collections.Generic;
+
+namespace SabreTools.Models.Internal
+{
+    /// <summary>
+    /// Specialized dictionary base for item types
+    /// </summary>
+    public abstract class DictionaryBase : Dictionary<string, object?>
+    {
+        /// <summary>
+        /// Read a key as the specified type, returning null on error
+        /// </summary>
+        public T? Read<T>(string key)
+        {
+            if (string.IsNullOrWhiteSpace(key))
+                return default;
+            if (!ContainsKey(key))
+                return default;
+            return (T?)this[key];
+        }
+
+        /// <summary>
+        /// Read a key as a bool, returning null on error
+        /// </summary>
+        public bool? ReadBool(string key) => Read<bool>(key);
+
+        /// <summary>
+        /// Read a key as a double, returning null on error
+        /// </summary>
+        public double? ReadDouble(string key) => Read<double>(key);
+
+        /// <summary>
+        /// Read a key as a long, returning null on error
+        /// </summary>
+        public long? ReadLong(string key) => Read<long>(key);
+
+        /// <summary>
+        /// Read a key as a string, returning null on error
+        /// </summary>
+        public string? ReadString(string key) => Read<string>(key);
+
+        /// <summary>
+        /// Read a key as a string[], returning null on error
+        /// </summary>
+        public string[]? ReadStringArray(string key) => Read<string[]>(key);
+    }
+}