feat: add BatchToTrxIterator

Author: Jblew

src/accounthistory/BatchToTrxIterator.ts

@@ -0,0 +1,32 @@
+import * as _ from "lodash";
+
+import { UnifiedSteemTransaction } from "../blockchain/UnifiedSteemTransaction";
+import { AsyncIterator } from "../iterator/AsyncIterator";
+
+export class BatchToTrxIterator implements AsyncIterator<UnifiedSteemTransaction> {
+    private batchIterator: AsyncIterator<UnifiedSteemTransaction[]>;
+    private currentBatch: UnifiedSteemTransaction[] = [];
+    private done: boolean = false;
+
+    public constructor(batchIterator: AsyncIterator<UnifiedSteemTransaction[]>) {
+        this.batchIterator = batchIterator;
+    }
+
+    public async next(): Promise<IteratorResult<UnifiedSteemTransaction>> {
+        if (this.done) throw AsyncIterator.AsyncIteratorError.iteratorAlreadyDoneError();
+        await this.loadNextBatchIfRequired();
+
+        const shifted = this.currentBatch.shift();
+        if (!shifted) throw new Error("BatchToTrxIterator: current batch could not be shifted");
+
+        return { done: this.done, value: shifted };
+    }
+
+    private async loadNextBatchIfRequired() {
+        if (this.currentBatch.length === 0) {
+            const { done, value } = await this.batchIterator.next();
+            this.currentBatch = value;
+            this.done = done;
+        }
+    }
+}