fix-client/src/lib/FIXParserBase.js

A minimalist FIX API client

const Field = require('./fields/Field')
const { Fields: FieldsCache } = require('./fields/Fields')
const { Enums: EnumsCache } = require('./enums/Enums')
const { Message } = require('./message/Message')
const { SOH, RE_FIND, RE_ESCAPE, STRING_EQUALS } = require('./util/util')

class FIXParserBase {
    // static version = {
    //     version: process.env.__PACKAGE_VERSION__,
    //     build: process.env.__BUILD_TIME__
    // };

    constructor() {
        this.message = null;
        this.messageTags = [];
        this.messageString = '';
        this.reBeginString = new RegExp(/(?=8=FIX)/g);
        this.fields = new FieldsCache();
        this.enums = new EnumsCache();
    }

    processMessage() {
        const matches = RE_FIND.exec(this.messageString);
        if (matches && matches.length === 2) {
            const stringData = this.messageString.replace(
                new RegExp(matches[1].replace(RE_ESCAPE, '\\$&'), 'g'),
                SOH
            );
            this.message.setString(stringData);
            this.messageTags = stringData.split(SOH);
        } else {
            this.message = null;
            this.messageTags = [];
        }
    }

    processFields() {
        let tag = null,
            value = null,
            i = 0,
            equalsOperator = '',
            field = null;

        for (i; i < this.messageTags.length - 1; i++) {
            equalsOperator = this.messageTags[i].indexOf(STRING_EQUALS);

            tag = this.messageTags[i].substring(0, equalsOperator);
            value = this.messageTags[i].substring(equalsOperator + 1);

            field = new Field(tag, value);

            this.fields.processField(this.message, field);
            this.enums.processEnum(field);
            if (field.tag === 9) {
                this.message.validateBodyLength(value);
            } else if (field.tag === 10) {
                this.message.validateChecksum(value);
            }

            this.message.addField(field);
        }
    }

    parse(data) {
        let i = 0;

        const messageStrings = data ? data.split(this.reBeginString) : [];
        const messages = [];

        for (i; i < messageStrings.length; i++) {
            this.message = new Message();
            this.messageString = messageStrings[i];
            if (this.messageString.indexOf(SOH) > -1) {
                // SOH separator
                this.message.setString(this.messageString);
                this.messageTags = this.messageString.split(SOH);
            } else {
                this.processMessage();
            }

            if (this.message) {
                this.processFields();
                messages.push(this.message);
            }
        }

        return messages;
    }
}

module.exports = FIXParserBase