Add method to get BOS token.

LLama/LLamaContext.cs

@@ -1,4 +1,4 @@
-using LLama.Exceptions;
+using LLama.Exceptions;
 using LLama.Native;
 using System;
 using System.Collections.Generic;
@@ -521,6 +521,17 @@ namespace LLama
             return candidates_p;
         }
 
+        /// <summary>
+        /// Gets whether or not the Bos token should be added.
+        /// From common.cpp https://github.com/ggerganov/llama.cpp/blob/60325fa56f61c228464c9f065db3aa6a61f2156e/common/common.cpp#L2417
+        /// </summary>
+        /// <returns></returns>
+        public bool ShouldAddBosToken()
+        {
+            var addBos = NativeApi.llama_add_bos_token(NativeHandle.ModelHandle);
+            return addBos != -1 ? Convert.ToBoolean(addBos) : NativeHandle.LLamaVocabType == LLamaVocabType.SentencePiece;
+        }
+
         #region eval overloads
         /// <summary>
         /// </summary>

LLama/Native/SafeLLamaContextHandle.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -19,6 +19,8 @@ namespace LLama.Native
         /// </summary>
         public int VocabCount => ThrowIfDisposed().VocabCount;
 
+        public LLamaVocabType LLamaVocabType => ThrowIfDisposed().VocabType;
+
         /// <summary>
         /// Total number of tokens in the context
         /// </summary>