caver-js/packages/caver-middleware/src/builtins/rpcFilter.js

caver-js is a JavaScript API library that allows developers to interact with a Kaia node

/*
    Copyright 2018 The caver-js Authors
    This file is part of the caver-js library.

    The caver-js library is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    The caver-js library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with the caver-js. If not, see <http://www.gnu.org/licenses/>.
*/

const rpcFilter = (filterColl, filterOption = 'include') => {
    if (!Array.isArray(filterColl)) {
        throw Error('rpcFilter only takes an array for first argument')
    }

    // For filterColl indexing. (Since Array traversing is slower than Object)
    filterColl = filterColl.reduce((acc, cur) => {
        acc[cur] = cur
        return acc
    }, {})

    return (data, next) => {
        if (filterOption === 'include') {
            if (!filterColl[data.method]) return
            next(data)
        } else if (filterOption === 'exclude') {
            if (!filterColl[data.method]) next(data)
        }
    }
}

module.exports = rpcFilter