@sap/odata-v4/lib/deserializer/LineReader.js

OData V4.0 server library

'use strict';

const CRLF = '\r\n';
const Reader = require('./Reader');

/**
 * Events
 */
const EVENTS = {
    DATA: 'line.data'                      // body reader consumed data from cache
};


/**
 * Reads a line from the cache, the line is terminated by CRLF
 *
 * @extends Reader
 */
class LineReader extends Reader {

    constructor() {
        super();

        this._line = null;
    }

    /**
     * Returns the read line
     * @returns {string}
     */
    getLine() {
        return this._line;
    }


    /**
     * Reads a line from the cache. A line is terminated by CRLF.
     * If the cache is empty and more data is required, this is signaled and readCach is called again. The state is preserved.
     *
     * @param {ContentDeserializer} reader - Current reader
     * @param {Cache} cache - Cache containing data for processing
     * @returns {boolean}
     *      this: this reader needs more data and caller should call this method again with more data in cache
     *      false: this reader is finished caller should pop this reader from stack
     *      null:  new sub reader is on stack, call this method again after the sub reader is finished
     */
    readCache(reader, cache) {
        if (cache.getLength() < CRLF.length) {
            return true;
        }

        const pos = cache.indexOf(CRLF, cache.getSearchPosition());
        if (pos === -1) {
            return true;
        }

        // line may be empty
        this._line = cache.getBytesTo(pos);
        this.emitAndConsume(cache, pos - cache.getReadPos(), EVENTS.DATA); // emit only the line, not the CLRF
        cache.advance(CRLF.length);

        return false;
    }
}

LineReader.EVENTS = EVENTS;
module.exports = LineReader;