swallez commented on code in PR #44247:
URL: https://github.com/apache/arrow/pull/44247#discussion_r1779657198
##########
js/src/table.ts:
##########
@@ -238,17 +238,30 @@ export class Table<T extends TypeMap = any> {
*
* @returns An Array of Table rows.
*/
- public toArray() {
+ public toArray(): Array<Struct<T>['TValue']> {
return [...this];
}
+ /**
+ * Return a JavaScript Array view of the Table rows.
+ *
+ * It is a lightweight read-only proxy that delegates to the table.
Accessing elements has some
+ * overhead compared to the regular array returned by `toArray()` because
of this indirection,
+ * but it avoids potentially large memory allocation.
+ *
+ * @returns An Array proxy to the Table rows.
+ */
+ public toArrayView(): Array<Struct<T>['TValue']> {
+ return new Proxy([] as Array<Struct<T>['TValue']>, new
TableArrayProxyHandler(this));
+ }
+
/**
* Returns a string representation of the Table rows.
*
* @returns A string representation of the Table rows.
*/
public toString() {
- return `[\n ${this.toArray().join(',\n ')}\n]`;
+ return `[\n ${this.toArrayView().join(',\n ')}\n]`;
Review Comment:
We need an array (or array-like) to use `join()`. This _was_ creating an
array, and with `toArrayView()` this now just creates a proxy. Or did I
misunderstand your comment?
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