gcl/src/coooders/collection/arraystream.js

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import S from 'stream';
import { isArray, isBoolean } from 'util';
import V from '../common/tool';
/**
 * 内存流提供Stream写入与读取的一切方法，但是仅仅限于写入居多的toArray方法
 */
export const ArrayStream = class extends S.Duplex {
    constructor(size = 0,buffer = 1024 * 16) {
        super({ allowHalfOpen: true, readableObjectMode: true, writableObjectMode: true,highWaterMark:buffer });
        const _ = this;
        _.max = size;
        _.buf = [];
        _.buffersize = buffer;
    }
    _read(length) {
        const _ = this;
        if (_.buf.length) {
            // console.log('_read',length)
            _.push(Buffer.from(_.buf.splice(0, length ? length : _.buffersize)));
        } else _.push(null);
    }
    _write(chunk, encoding, callback) {
        const _ = this;
        let _buf = _.buf;
        _.buf = _buf.concat(chunk.toJSON ? chunk.toJSON().data : chunk);
        _buf = null;
        callback((_.max > 0 && _.buf.length > _.max) ? new Error('limit out of size:' + _.max) : null);
    }
    _writev(chunks, callback) {
        const _ = this;
        V.each(chunks, v => {
            let _buf = _.buf;
            _.buf = _buf.concat(v.chunk.toJSON ? v.chunk.toJSON().data : v.chunk);
            _buf.splice(0, _buf.length);
            _buf = null;
            return false;
        }, true).then(() => callback((_.max > 0 && _.buf.length > _.max) ? new Error('limit out of size:' + _.max) : null));
    };
    toArray() {
        let _ = this;
        return _.buf.splice(0, _.buf.length);
    };
}
export default { ArrayStream }