Add TryGet method to runtime compression service

Confuser.Core/Services/CompressionService.cs

@@ -22,6 +22,17 @@ public CompressionService(ConfuserContext context) {
 			this.context = context;
 		}
 
+		/// <inheritdoc />
+		public MethodDef TryGetRuntimeDecompressor(ModuleDef module, Action<IDnlibDef> init) {
+			var decompressor = context.Annotations.Get<Tuple<MethodDef, List<IDnlibDef>>>(module, Decompressor);
+			if (decompressor == null)
+				return null;
+
+			foreach (IDnlibDef member in decompressor.Item2)
+				init(member);
+			return decompressor.Item1;
+		}
+
 		/// <inheritdoc />
 		public MethodDef GetRuntimeDecompressor(ModuleDef module, Action<IDnlibDef> init) {
 			Tuple<MethodDef, List<IDnlibDef>> decompressor = context.Annotations.GetOrCreate(module, Decompressor, m => {
@@ -123,6 +134,17 @@ public void SetProgress(long inSize, long outSize) {
 	/// </summary>
 	public interface ICompressionService {
 
+		/// <summary>
+		///     Gets the runtime decompression method in the module, or null if it's not yet injected.
+		/// </summary>
+		/// <param name="module">The module which the decompression method resides in.</param>
+		/// <param name="init">The initializing method for compression helper definitions.</param>
+		/// <returns>
+		/// The requested decompression method with signature 'static Byte[] (Byte[])', 
+		/// or null if it hasn't been injected yet.
+		/// </returns>
+		MethodDef TryGetRuntimeDecompressor(ModuleDef module, Action<IDnlibDef> init);
+
 		/// <summary>
 		///     Gets the runtime decompression method in the module and inject if it does not exists.
 		/// </summary>