import auto from './auto.js'
import wrapAsync from './internal/wrapAsync.js'
import { isAsync } from './internal/wrapAsync.js'
var FN_ARGS = /^(?:async\s)?(?:function)?\s*(?:\w+\s*)?\(([^)]+)\)(?:\s*{)/;
var ARROW_FN_ARGS = /^(?:async\s)?\s*(?:\(\s*)?((?:[^)=\s]\s*)*)(?:\)\s*)?=>/;
var FN_ARG_SPLIT = /,/;
var FN_ARG = /(=.+)?(\s*)$/;
function stripComments(string) {
let stripped = '';
let index = 0;
let endBlockComment = string.indexOf('*/');
while (index < string.length) {
if (string[index] === '/' && string[index+1] === '/') {
// inline comment
let endIndex = string.indexOf('\n', index);
index = (endIndex === -1) ? string.length : endIndex;
} else if ((endBlockComment !== -1) && (string[index] === '/') && (string[index+1] === '*')) {
// block comment
let endIndex = string.indexOf('*/', index);
if (endIndex !== -1) {
index = endIndex + 2;
endBlockComment = string.indexOf('*/', index);
} else {
stripped += string[index];
index++;
}
} else {
stripped += string[index];
index++;
}
}
return stripped;
}
function parseParams(func) {
const src = stripComments(func.toString());
let match = src.match(FN_ARGS);
if (!match) {
match = src.match(ARROW_FN_ARGS);
}
if (!match) throw new Error('could not parse args in autoInject\nSource:\n' + src)
let [, args] = match
return args
.replace(/\s/g, '')
.split(FN_ARG_SPLIT)
.map((arg) => arg.replace(FN_ARG, '').trim());
}
/**
* A dependency-injected version of the [async.auto]{@link module:ControlFlow.auto} function. Dependent
* tasks are specified as parameters to the function, after the usual callback
* parameter, with the parameter names matching the names of the tasks it
* depends on. This can provide even more readable task graphs which can be
* easier to maintain.
*
* If a final callback is specified, the task results are similarly injected,
* specified as named parameters after the initial error parameter.
*
* The autoInject function is purely syntactic sugar and its semantics are
* otherwise equivalent to [async.auto]{@link module:ControlFlow.auto}.
*
* @name autoInject
* @static
* @memberOf module:ControlFlow
* @method
* @see [async.auto]{@link module:ControlFlow.auto}
* @category Control Flow
* @param {Object} tasks - An object, each of whose properties is an {@link AsyncFunction} of
* the form 'func([dependencies...], callback). The object's key of a property
* serves as the name of the task defined by that property, i.e. can be used
* when specifying requirements for other tasks.
* * The `callback` parameter is a `callback(err, result)` which must be called
* when finished, passing an `error` (which can be `null`) and the result of
* the function's execution. The remaining parameters name other tasks on
* which the task is dependent, and the results from those tasks are the
* arguments of those parameters.
* @param {Function} [callback] - An optional callback which is called when all
* the tasks have been completed. It receives the `err` argument if any `tasks`
* pass an error to their callback, and a `results` object with any completed
* task results, similar to `auto`.
* @returns {Promise} a promise, if no callback is passed
* @example
*
* // The example from `auto` can be rewritten as follows:
* async.autoInject({
* get_data: function(callback) {
* // async code to get some data
* callback(null, 'data', 'converted to array');
* },
* make_folder: function(callback) {
* // async code to create a directory to store a file in
* // this is run at the same time as getting the data
* callback(null, 'folder');
* },
* write_file: function(get_data, make_folder, callback) {
* // once there is some data and the directory exists,
* // write the data to a file in the directory
* callback(null, 'filename');
* },
* email_link: function(write_file, callback) {
* // once the file is written let's email a link to it...
* // write_file contains the filename returned by write_file.
* callback(null, {'file':write_file, 'email':'user@example.com'});
* }
* }, function(err, results) {
* console.log('err = ', err);
* console.log('email_link = ', results.email_link);
* });
*
* // If you are using a JS minifier that mangles parameter names, `autoInject`
* // will not work with plain functions, since the parameter names will be
* // collapsed to a single letter identifier. To work around this, you can
* // explicitly specify the names of the parameters your task function needs
* // in an array, similar to Angular.js dependency injection.
*
* // This still has an advantage over plain `auto`, since the results a task
* // depends on are still spread into arguments.
* async.autoInject({
* //...
* write_file: ['get_data', 'make_folder', function(get_data, make_folder, callback) {
* callback(null, 'filename');
* }],
* email_link: ['write_file', function(write_file, callback) {
* callback(null, {'file':write_file, 'email':'user@example.com'});
* }]
* //...
* }, function(err, results) {
* console.log('err = ', err);
* console.log('email_link = ', results.email_link);
* });
*/
export default function autoInject(tasks, callback) {
var newTasks = {};
Object.keys(tasks).forEach(key => {
var taskFn = tasks[key]
var params;
var fnIsAsync = isAsync(taskFn);
var hasNoDeps =
(!fnIsAsync && taskFn.length === 1) ||
(fnIsAsync && taskFn.length === 0);
if (Array.isArray(taskFn)) {
params = [...taskFn];
taskFn = params.pop();
newTasks[key] = params.concat(params.length > 0 ? newTask : taskFn);
} else if (hasNoDeps) {
// no dependencies, use the function as-is
newTasks[key] = taskFn;
} else {
params = parseParams(taskFn);
if ((taskFn.length === 0 && !fnIsAsync) && params.length === 0) {
throw new Error("autoInject task functions require explicit parameters.");
}
// remove callback param
if (!fnIsAsync) params.pop();
newTasks[key] = params.concat(newTask);
}
function newTask(results, taskCb) {
var newArgs = params.map(name => results[name])
newArgs.push(taskCb);
wrapAsync(taskFn)(...newArgs);
}
});
return auto(newTasks, callback);
}
