@teradataprebuilt/fastcall-linux-node-v59/lib/scope.js

fastcall - Very fast, asynchronous, dyncall based foreign function interface library for Node.js

/*
Copyright 2016 Gábor Mező (gabor.mezo@outlook.com)

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

'use strict';
const _ = require('lodash');
const verify = require('./verify');
const a = verify.a;
const ert = verify.ert;
const assert = require('assert');
const Promise = require('bluebird');

module.exports = scope;

function scope(body) {
    assert(_.isFunction(body), 'Body should be a function.');
    begin();
    try {
        const result = body(scope);
        if (result) {
            if (_.isFunction(result.then)) {
                return result
                    .then(function (asyncResult) {
                        escape(asyncResult, true);
                        return Promise.try(end).then(() => asyncResult);
                    },
                    function (asyncError) {
                        return Promise.try(end)
                        .then(() => {
                            throw asyncError;
                        });
                    });
            }
            escape(result, true);
        }
        const endSyncResult = end();
        verifyEndSyncResult(endSyncResult);
        return result;
    }
    catch (err) {
        end();
        throw err;
    }

    function verifyEndSyncResult(endSyncResult) {
        if (endSyncResult) {
            if (_.isFunction(endSyncResult.then)) {
                throw new Error('disposeFunction should be synchronous in a synchronous scope.');
            }
            throw new Error('disposeFunction should not return anything in a synchronous scope.');
        }
    }
}

scope._add = function (disposable) {
    add(disposable);
};

scope.async = function (body) {
    assert(_.isFunction(body), 'Body should be a function.');
    return scope(Promise.coroutine(body));
};

scope.escape = function (value) {
    return escape(value);
};

scope.begin = begin;
scope.end = end;

const layers = [];

function begin() {
    layers.push(new Set());
}

function end() {
    const last = layers.pop();
    let promises = null;
    if (last) {
        for (let disposable of last.values()) {
            const result = disposable.dispose();
            if (result && _.isFunction(result.then)) {
                if (!promises) {
                    promises = [];
                }
                promises.push(Promise.resolve(result));
            }
        }
    }
    if (promises) {
        return Promise.all(promises);
    }
    return null;
}

function add(disposable, layer) {
    if (verify.enabled) {
        const Disposable = scope.Disposable;
        a&&ert(disposable instanceof Disposable);
    }
    const currentLayer = layer || (layers.length ? layers[layers.length - 1] : null);
    if (currentLayer) {
        currentLayer.add(disposable);
    }
}

function escape(result, propagate) {
    let currentLayer = null;
    let prevLayer = null;
    if (layers.length > 1) {
        currentLayer = layers[layers.length - 1];
        if (propagate) {
            prevLayer = layers[layers.length - 2];
        }
    }
    else if (layers.length) {
        currentLayer = layers[layers.length - 1];
    }

    if (currentLayer) {
        for (let disposable of enumDisposable(result)) {
            currentLayer.delete(disposable);
            if (prevLayer) {
                prevLayer.add(disposable);
            }
        }
    }
}

function* enumDisposable(result) {
    const Disposable = scope.Disposable;
    if (result instanceof Disposable) {
        yield result;
    }
    else if (_.isArray(result)) {
        for (let item of result) {
            yield* enumDisposable(item);
        }
    }
    else if (result instanceof Map || result instanceof Set) {
        for (let item of result.values()) {
            yield* enumDisposable(item);
        }
    }
    else if (_.isObject(result)) {
        for (let key in result) {
            if (result.hasOwnProperty(key)) {
                yield* enumDisposable(result[key]);
            }
        }
    }
}