frontend/node_modules/apache-arrow/io/file.mjs

// 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 { ByteStream, AsyncByteStream } from './stream';
import { toUint8Array } from '../util/buffer';
/** @ignore */
export class RandomAccessFile extends ByteStream {
    constructor(buffer, byteLength) {
        super();
        this.position = 0;
        this.buffer = toUint8Array(buffer);
        this.size = typeof byteLength === 'undefined' ? this.buffer.byteLength : byteLength;
    }
    readInt32(position) {
        const { buffer, byteOffset } = this.readAt(position, 4);
        return new DataView(buffer, byteOffset).getInt32(0, true);
    }
    seek(position) {
        this.position = Math.min(position, this.size);
        return position < this.size;
    }
    read(nBytes) {
        const { buffer, size, position } = this;
        if (buffer && position < size) {
            if (typeof nBytes !== 'number') {
                nBytes = Infinity;
            }
            this.position = Math.min(size, position + Math.min(size - position, nBytes));
            return buffer.subarray(position, this.position);
        }
        return null;
    }
    readAt(position, nBytes) {
        const buf = this.buffer;
        const end = Math.min(this.size, position + nBytes);
        return buf ? buf.subarray(position, end) : new Uint8Array(nBytes);
    }
    close() { this.buffer && (this.buffer = null); }
    throw(value) { this.close(); return { done: true, value }; }
    return(value) { this.close(); return { done: true, value }; }
}
/** @ignore */
export class AsyncRandomAccessFile extends AsyncByteStream {
    constructor(file, byteLength) {
        super();
        this.position = 0;
        this._handle = file;
        if (typeof byteLength === 'number') {
            this.size = byteLength;
        }
        else {
            this._pending = (async () => {
                this.size = (await file.stat()).size;
                delete this._pending;
            })();
        }
    }
    async readInt32(position) {
        const { buffer, byteOffset } = await this.readAt(position, 4);
        return new DataView(buffer, byteOffset).getInt32(0, true);
    }
    async seek(position) {
        this._pending && await this._pending;
        this.position = Math.min(position, this.size);
        return position < this.size;
    }
    async read(nBytes) {
        this._pending && await this._pending;
        const { _handle: file, size, position } = this;
        if (file && position < size) {
            if (typeof nBytes !== 'number') {
                nBytes = Infinity;
            }
            let pos = position, offset = 0, bytesRead = 0;
            let end = Math.min(size, pos + Math.min(size - pos, nBytes));
            let buffer = new Uint8Array(Math.max(0, (this.position = end) - pos));
            while ((pos += bytesRead) < end && (offset += bytesRead) < buffer.byteLength) {
                ({ bytesRead } = await file.read(buffer, offset, buffer.byteLength - offset, pos));
            }
            return buffer;
        }
        return null;
    }
    async readAt(position, nBytes) {
        this._pending && await this._pending;
        const { _handle: file, size } = this;
        if (file && (position + nBytes) < size) {
            const end = Math.min(size, position + nBytes);
            const buffer = new Uint8Array(end - position);
            return (await file.read(buffer, 0, nBytes, position)).buffer;
        }
        return new Uint8Array(nBytes);
    }
    async close() { const f = this._handle; this._handle = null; f && await f.close(); }
    async throw(value) { await this.close(); return { done: true, value }; }
    async return(value) { await this.close(); return { done: true, value }; }
}

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