token-js: add COption<Pubkey> support to InitializeTransferFeeConfig instruction (#6164)

Author: Joe C

token/js/src/extensions/transferFee/instructions.ts

@@ -1,7 +1,7 @@
 import { struct, u16, u8 } from '@solana/buffer-layout';
-import { publicKey, u64 } from '@solana/buffer-layout-utils';
-import type { AccountMeta, Signer } from '@solana/web3.js';
-import { PublicKey, TransactionInstruction } from '@solana/web3.js';
+import { u64 } from '@solana/buffer-layout-utils';
+import type { AccountMeta, Signer, PublicKey } from '@solana/web3.js';
+import { TransactionInstruction } from '@solana/web3.js';
 import { programSupportsExtensions, TOKEN_2022_PROGRAM_ID } from '../../constants.js';
 import {
     TokenInvalidInstructionDataError,
@@ -12,6 +12,7 @@ import {
 } from '../../errors.js';
 import { addSigners } from '../../instructions/internal.js';
 import { TokenInstruction } from '../../instructions/types.js';
+import { COptionPublicKeyLayout } from '../../serialization.js';
 
 export enum TransferFeeInstruction {
     InitializeTransferFeeConfig = 0,
@@ -28,10 +29,8 @@ export enum TransferFeeInstruction {
 export interface InitializeTransferFeeConfigInstructionData {
     instruction: TokenInstruction.TransferFeeExtension;
     transferFeeInstruction: TransferFeeInstruction.InitializeTransferFeeConfig;
-    transferFeeConfigAuthorityOption: 1 | 0;
-    transferFeeConfigAuthority: PublicKey;
-    withdrawWithheldAuthorityOption: 1 | 0;
-    withdrawWithheldAuthority: PublicKey;
+    transferFeeConfigAuthority: PublicKey | null;
+    withdrawWithheldAuthority: PublicKey | null;
     transferFeeBasisPoints: number;
     maximumFee: bigint;
 }
@@ -40,10 +39,8 @@ export interface InitializeTransferFeeConfigInstructionData {
 export const initializeTransferFeeConfigInstructionData = struct<InitializeTransferFeeConfigInstructionData>([
     u8('instruction'),
     u8('transferFeeInstruction'),
-    u8('transferFeeConfigAuthorityOption'),
-    publicKey('transferFeeConfigAuthority'),
-    u8('withdrawWithheldAuthorityOption'),
-    publicKey('withdrawWithheldAuthority'),
+    new COptionPublicKeyLayout('transferFeeConfigAuthority'),
+    new COptionPublicKeyLayout('withdrawWithheldAuthority'),
     u16('transferFeeBasisPoints'),
     u64('maximumFee'),
 ]);
@@ -78,10 +75,8 @@ export function createInitializeTransferFeeConfigInstruction(
         {
             instruction: TokenInstruction.TransferFeeExtension,
             transferFeeInstruction: TransferFeeInstruction.InitializeTransferFeeConfig,
-            transferFeeConfigAuthorityOption: transferFeeConfigAuthority ? 1 : 0,
-            transferFeeConfigAuthority: transferFeeConfigAuthority || new PublicKey(0),
-            withdrawWithheldAuthorityOption: withdrawWithheldAuthority ? 1 : 0,
-            withdrawWithheldAuthority: withdrawWithheldAuthority || new PublicKey(0),
+            transferFeeConfigAuthority: transferFeeConfigAuthority,
+            withdrawWithheldAuthority: withdrawWithheldAuthority,
             transferFeeBasisPoints: transferFeeBasisPoints,
             maximumFee: maximumFee,
         },
@@ -174,9 +169,7 @@ export function decodeInitializeTransferFeeConfigInstructionUnchecked({
     const {
         instruction,
         transferFeeInstruction,
-        transferFeeConfigAuthorityOption,
         transferFeeConfigAuthority,
-        withdrawWithheldAuthorityOption,
         withdrawWithheldAuthority,
         transferFeeBasisPoints,
         maximumFee,
@@ -190,8 +183,8 @@ export function decodeInitializeTransferFeeConfigInstructionUnchecked({
         data: {
             instruction,
             transferFeeInstruction,
-            transferFeeConfigAuthority: transferFeeConfigAuthorityOption ? transferFeeConfigAuthority : null,
-            withdrawWithheldAuthority: withdrawWithheldAuthorityOption ? withdrawWithheldAuthority : null,
+            transferFeeConfigAuthority,
+            withdrawWithheldAuthority,
             transferFeeBasisPoints,
             maximumFee,
         },

token/js/src/serialization.ts

@@ -0,0 +1,39 @@
+import { Layout } from '@solana/buffer-layout';
+import { publicKey } from '@solana/buffer-layout-utils';
+import type { PublicKey } from '@solana/web3.js';
+
+export class COptionPublicKeyLayout extends Layout<PublicKey | null> {
+    private publicKeyLayout: Layout<PublicKey>;
+
+    constructor(property?: string | undefined) {
+        super(-1, property);
+        this.publicKeyLayout = publicKey();
+    }
+
+    decode(buffer: Uint8Array, offset: number = 0): PublicKey | null {
+        const option = buffer[offset];
+        if (option === 0) {
+            return null;
+        }
+        return this.publicKeyLayout.decode(buffer, offset + 1);
+    }
+
+    encode(src: PublicKey | null, buffer: Uint8Array, offset: number = 0): number {
+        if (src === null) {
+            buffer[offset] = 0;
+            return 1;
+        } else {
+            buffer[offset] = 1;
+            this.publicKeyLayout.encode(src, buffer, offset + 1);
+            return 33;
+        }
+    }
+
+    getSpan(buffer?: Uint8Array, offset: number = 0): number {
+        if (buffer) {
+            const option = buffer[offset];
+            return option === 0 ? 1 : 1 + this.publicKeyLayout.span;
+        }
+        return 1 + this.publicKeyLayout.span;
+    }
+}