مشاهدة ملف: ReadStreamTokenizer.js

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ReadStreamTokenizer = void 0;
const AbstractTokenizer_1 = require("./AbstractTokenizer");
const peek_readable_1 = require("peek-readable");
const maxBufferSize = 256000;
class ReadStreamTokenizer extends AbstractTokenizer_1.AbstractTokenizer {
    constructor(stream, fileInfo) {
        super(fileInfo);
        this.streamReader = new peek_readable_1.StreamReader(stream);
    }
    /**
     * Get file information, an HTTP-client may implement this doing a HEAD request
     * @return Promise with file information
     */
    async getFileInfo() {
        return this.fileInfo;
    }
    /**
     * Read buffer from tokenizer
     * @param uint8Array - Target Uint8Array to fill with data read from the tokenizer-stream
     * @param options - Read behaviour options
     * @returns Promise with number of bytes read
     */
    async readBuffer(uint8Array, options) {
        const normOptions = this.normalizeOptions(uint8Array, options);
        const skipBytes = normOptions.position - this.position;
        if (skipBytes > 0) {
            await this.ignore(skipBytes);
            return this.readBuffer(uint8Array, options);
        }
        else if (skipBytes < 0) {
            throw new Error('`options.position` must be equal or greater than `tokenizer.position`');
        }
        if (normOptions.length === 0) {
            return 0;
        }
        const bytesRead = await this.streamReader.read(uint8Array, normOptions.offset, normOptions.length);
        this.position += bytesRead;
        if ((!options || !options.mayBeLess) && bytesRead < normOptions.length) {
            throw new peek_readable_1.EndOfStreamError();
        }
        return bytesRead;
    }
    /**
     * Peek (read ahead) buffer from tokenizer
     * @param uint8Array - Uint8Array (or Buffer) to write data to
     * @param options - Read behaviour options
     * @returns Promise with number of bytes peeked
     */
    async peekBuffer(uint8Array, options) {
        const normOptions = this.normalizeOptions(uint8Array, options);
        let bytesRead = 0;
        if (normOptions.position) {
            const skipBytes = normOptions.position - this.position;
            if (skipBytes > 0) {
                const skipBuffer = new Uint8Array(normOptions.length + skipBytes);
                bytesRead = await this.peekBuffer(skipBuffer, { mayBeLess: normOptions.mayBeLess });
                uint8Array.set(skipBuffer.subarray(skipBytes), normOptions.offset);
                return bytesRead - skipBytes;
            }
            else if (skipBytes < 0) {
                throw new Error('Cannot peek from a negative offset in a stream');
            }
        }
        if (normOptions.length > 0) {
            try {
                bytesRead = await this.streamReader.peek(uint8Array, normOptions.offset, normOptions.length);
            }
            catch (err) {
                if (options && options.mayBeLess && err instanceof peek_readable_1.EndOfStreamError) {
                    return 0;
                }
                throw err;
            }
            if ((!normOptions.mayBeLess) && bytesRead < normOptions.length) {
                throw new peek_readable_1.EndOfStreamError();
            }
        }
        return bytesRead;
    }
    async ignore(length) {
        // debug(`ignore ${this.position}...${this.position + length - 1}`);
        const bufSize = Math.min(maxBufferSize, length);
        const buf = new Uint8Array(bufSize);
        let totBytesRead = 0;
        while (totBytesRead < length) {
            const remaining = length - totBytesRead;
            const bytesRead = await this.readBuffer(buf, { length: Math.min(bufSize, remaining) });
            if (bytesRead < 0) {
                return bytesRead;
            }
            totBytesRead += bytesRead;
        }
        return totBytesRead;
    }
}
exports.ReadStreamTokenizer = ReadStreamTokenizer;