trxcllnt commented on a change in pull request #9962:
URL: https://github.com/apache/arrow/pull/9962#discussion_r611226795
##########
File path: js/src/util/bit.ts
##########
@@ -64,16 +64,51 @@ export function packBools(values: Iterable<any>) {
}
/** @ignore */
-export function* iterateBits<T>(bytes: Uint8Array, begin: number, length:
number, context: any,
- get: (context: any, index: number, byte:
number, bit: number) => T) {
- let bit = begin % 8;
- let byteIndex = begin >> 3;
- let index = 0, remaining = length;
- for (; remaining > 0; bit = 0) {
- let byte = bytes[byteIndex++];
- do {
- yield get(context, index++, byte, bit);
- } while (--remaining > 0 && ++bit < 8);
+export class BitIterator<T> implements IterableIterator<T> {
+ bit: number;
+ byte: number;
+ byteIndex: number;
+ index: number;
+
+ constructor(
+ private bytes: Uint8Array,
+ begin: number,
+ private length: number,
+ private context: any,
+ private get: (context: any, index: number, byte: number, bit: number)
=> T
+ ) {
+ this.bit = begin % 8;
+ this.byteIndex = begin >> 3;
+ this.byte = bytes[this.byteIndex];
+ this.index = 0;
+ }
+
+ next(): IteratorResult<T> {
+ if (this.index >= this.length) {
+ return {
+ done: true,
+ value: null
+ };
+ }
+
+ if (this.bit < 8) {
+ return {
+ value: this.get(this.context, this.index++, this.byte,
this.bit++)
+ };
+ }
+
+ this.byteIndex++;
+ this.bit = 0;
+
+ if (this.byteIndex < this.bytes.length) {
+ this.byte = this.bytes[this.byteIndex];
+ }
+
+ return this.next();
+ }
Review comment:
Can we do this without recursion?
```suggestion
next(): IteratorResult<T> {
if (this.index < this.length) {
if (this.bit === 8) {
this.bit = 0;
this.byte = this.bytes[this.byteIndex++];
}
return {
done: false,
value: this.get(this.context, this.index++, this.byte,
this.bit++)
};
}
return { done: true, value: null };
}
```
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