ts: Event decode api updates (#292)

CHANGELOG.md

@@ -18,6 +18,8 @@ incremented for features.
 
 ## Breaking Changes
 
+* ts: Event coder `decode` API changed to decode strings directly instead of buffers ([#292](https://github.com/project-serum/anchor/pull/292)).
+* ts: Event coder `encode` API removed ([#292](https://github.com/project-serum/anchor/pull/292)).
 * ts: Replace deprecated `web3.Account` with `web3.Signer` in public APIs ([#296](https://github.com/project-serum/anchor/pull/296)).
 
 ## [0.5.0] - 2021-05-07

ts/src/coder.ts

@@ -1,4 +1,5 @@
 import camelCase from "camelcase";
+import * as base64 from "base64-js";
 import { snakeCase } from "snake-case";
 import { Layout } from "buffer-layout";
 import * as sha256 from "js-sha256";
@@ -213,6 +214,11 @@ class EventCoder {
    */
   private layouts: Map<string, Layout>;
 
+  /**
+   * Maps base64 encoded event discriminator to event name.
+   */
+  private discriminators: Map<string, string>;
+
   public constructor(idl: Idl) {
     if (idl.events === undefined) {
       this.layouts = new Map();
@@ -232,18 +238,29 @@ class EventCoder {
     });
     // @ts-ignore
     this.layouts = new Map(layouts);
+
+    this.discriminators = new Map<string, string>(
+      idl.events === undefined
+        ? []
+        : idl.events.map((e) => [
+            base64.fromByteArray(eventDiscriminator(e.name)),
+            e.name,
+          ])
+    );
   }
 
-  public encode<T = any>(eventName: string, account: T): Buffer {
-    const buffer = Buffer.alloc(1000); // TODO: use a tighter buffer.
-    const layout = this.layouts.get(eventName);
-    const len = layout.encode(account, buffer);
-    return buffer.slice(0, len);
-  }
+  public decode<T = any>(log: string): T | null {
+    const logArr = Buffer.from(base64.toByteArray(log));
+    const disc = base64.fromByteArray(logArr.slice(0, 8));
+
+    // Only deserialize if the discriminator implies a proper event.
+    const eventName = this.discriminators.get(disc);
+    if (eventName === undefined) {
+      return undefined;
+    }
 
-  public decode<T = any>(eventName: string, ix: Buffer): T {
     const layout = this.layouts.get(eventName);
-    return layout.decode(ix);
+    return layout.decode(logArr.slice(8));
   }
 }
 

ts/src/program/event.ts

@@ -1,8 +1,7 @@
 import { PublicKey } from "@solana/web3.js";
 import * as base64 from "base64-js";
 import * as assert from "assert";
-import Coder, { eventDiscriminator } from "../coder";
-import { Idl } from "../idl";
+import Coder from "../coder";
 
 const LOG_START_INDEX = "Program log: ".length;
 
@@ -15,20 +14,10 @@ export type Event = {
 export class EventParser {
   private coder: Coder;
   private programId: PublicKey;
-  // Maps base64 encoded event discriminator to event name.
-  private discriminators: Map<string, string>;
 
-  constructor(coder: Coder, programId: PublicKey, idl: Idl) {
+  constructor(coder: Coder, programId: PublicKey) {
     this.coder = coder;
     this.programId = programId;
-    this.discriminators = new Map<string, string>(
-      idl.events === undefined
-        ? []
-        : idl.events.map((e) => [
-            base64.fromByteArray(eventDiscriminator(e.name)),
-            e.name,
-          ])
-    );
   }
 
   // Each log given, represents an array of messages emitted by
@@ -88,17 +77,7 @@ export class EventParser {
     // This is a `msg!` log.
     if (log.startsWith("Program log:")) {
       const logStr = log.slice(LOG_START_INDEX);
-      const logArr = Buffer.from(base64.toByteArray(logStr));
-      const disc = base64.fromByteArray(logArr.slice(0, 8));
-      // Only deserialize if the discriminator implies a proper event.
-      let event = null;
-      let eventName = this.discriminators.get(disc);
-      if (eventName !== undefined) {
-        event = {
-          name: eventName,
-          data: this.coder.events.decode(eventName, logArr.slice(8)),
-        };
-      }
+      const event = this.coder.events.decode(logStr);
       return [event, null, false];
     }
     // System log.

ts/src/program/index.ts

@@ -301,11 +301,7 @@ export class Program {
     eventName: string,
     callback: (event: any, slot: number) => void
   ): number {
-    const eventParser = new EventParser(
-      this._coder,
-      this._programId,
-      this._idl
-    );
+    const eventParser = new EventParser(this._coder, this._programId);
     return this._provider.connection.onLogs(this._programId, (logs, ctx) => {
       if (logs.err) {
         console.error(logs);

ts/src/program/namespace/simulate.ts

@@ -63,7 +63,7 @@ export default class SimulateFactory {
 
       const events = [];
       if (idl.events) {
-        let parser = new EventParser(coder, programId, idl);
+        let parser = new EventParser(coder, programId);
         parser.parseLogs(logs, (event) => {
           events.push(event);
         });