Copilot commented on code in PR #438: URL: https://github.com/apache/arrow-js/pull/438#discussion_r3270720512
########## src/builder/largelist.ts: ########## @@ -0,0 +1,54 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +import { Field } from '../schema.js'; +import { DataType, LargeList } from '../type.js'; +import { OffsetsBufferBuilder } from './buffer.js'; +import { Builder, BuilderOptions, VariableWidthBuilder } from '../builder.js'; + +/** @ignore */ +export class LargeListBuilder<T extends DataType = any, TNull = any> extends VariableWidthBuilder<LargeList<T>, TNull> { + protected _offsets: OffsetsBufferBuilder<LargeList<T>>; + constructor(opts: BuilderOptions<LargeList<T>, TNull>) { + super(opts); + this._offsets = new OffsetsBufferBuilder(opts.type); + } + public addChild(child: Builder<T>, name = '0') { + if (this.numChildren > 0) { + throw new Error('LargeListBuilder can only have one child.'); + } + this.children[this.numChildren] = child; + this.type = new LargeList(new Field(name, child.type, true)); + return this.numChildren - 1; + } + protected _flushPending(pending: Map<number, T['TValue'] | undefined>) { + const offsets = this._offsets; + const [child] = this.children; + for (const [index, value] of pending) { + if (typeof value === 'undefined') { + offsets.set(index, BigInt(0)); + } else { + const v = value as T['TValue']; + const n = v.length; + const start = Number(offsets.set(index, BigInt(n)).buffer[index]); + for (let i = -1; ++i < n;) { + child.set(start + i, v[i]); + } Review Comment: LargeListBuilder narrows the BigInt offset to a JS number via `Number(...)`. If cumulative offsets exceed `Number.MAX_SAFE_INTEGER`, this will silently lose precision and lead to writing child values at incorrect indices. Use the existing `bigIntToNumber()` helper (or an explicit bounds check) when converting BigInt offsets to numbers so unsafe offsets throw instead of corrupting data. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
