encode/decode minor performance optimization

#172

Author: buu700

src/decode.ts

@@ -36,6 +36,7 @@ export type DecodeOptions<ContextType = undefined> = Readonly<
   ContextOf<ContextType>;
 
 export const defaultDecodeOptions: DecodeOptions = {};
+const defaultDecoder = new Decoder(defaultDecodeOptions as any);
 
 /**
  * It decodes a single MessagePack object in a buffer.
@@ -47,7 +48,7 @@ export function decode<ContextType = undefined>(
   buffer: ArrayLike<number> | BufferSource,
   options: DecodeOptions<SplitUndefined<ContextType>> = defaultDecodeOptions as any,
 ): unknown {
-  const decoder = new Decoder(
+  const decoder = options === defaultDecodeOptions ? defaultDecoder : new Decoder(
     options.extensionCodec,
     (options as typeof options & { context: any }).context,
     options.maxStrLength,

src/encode.ts

@@ -36,6 +36,7 @@ export type EncodeOptions<ContextType = undefined> = Partial<
   ContextOf<ContextType>;
 
 const defaultEncodeOptions: EncodeOptions = {};
+const defaultEncoder = new Encoder(defaultEncodeOptions as any);
 
 /**
  * It encodes `value` in the MessagePack format and
@@ -47,7 +48,7 @@ export function encode<ContextType = undefined>(
   value: unknown,
   options: EncodeOptions<SplitUndefined<ContextType>> = defaultEncodeOptions as any,
 ): Uint8Array {
-  const encoder = new Encoder(
+  const encoder = options === defaultEncodeOptions ? defaultEncoder : new Encoder(
     options.extensionCodec,
     (options as typeof options & { context: any }).context,
     options.maxDepth,