四好公路
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3 years ago
"use strict";
/**
* Returns the given plugins as an array, rather than an object map.
* All other methods in this module expect an array of plugins rather than an object map.
*
* @param {object} plugins - A map of plugin objects
* @return {object[]}
*/
exports.all = function (plugins) {
return Object.keys(plugins)
.filter((key) => {
return typeof plugins[key] === "object";
})
.map((key) => {
plugins[key].name = key;
return plugins[key];
});
};
/**
* Filters the given plugins, returning only the ones return `true` for the given method.
*
* @param {object[]} plugins - An array of plugin objects
* @param {string} method - The name of the filter method to invoke for each plugin
* @param {object} file - A file info object, which will be passed to each method
* @return {object[]}
*/
exports.filter = function (plugins, method, file) {
return plugins
.filter((plugin) => {
return !!getResult(plugin, method, file);
});
};
/**
* Sorts the given plugins, in place, by their `order` property.
*
* @param {object[]} plugins - An array of plugin objects
* @returns {object[]}
*/
exports.sort = function (plugins) {
for (let plugin of plugins) {
plugin.order = plugin.order || Number.MAX_SAFE_INTEGER;
}
return plugins.sort((a, b) => { return a.order - b.order; });
};
/**
* Runs the specified method of the given plugins, in order, until one of them returns a successful result.
* Each method can return a synchronous value, a Promise, or call an error-first callback.
* If the promise resolves successfully, or the callback is called without an error, then the result
* is immediately returned and no further plugins are called.
* If the promise rejects, or the callback is called with an error, then the next plugin is called.
* If ALL plugins fail, then the last error is thrown.
*
* @param {object[]} plugins - An array of plugin objects
* @param {string} method - The name of the method to invoke for each plugin
* @param {object} file - A file info object, which will be passed to each method
* @returns {Promise}
*/
exports.run = function (plugins, method, file, $refs) {
let plugin, lastError, index = 0;
return new Promise(((resolve, reject) => {
runNextPlugin();
function runNextPlugin () {
plugin = plugins[index++];
if (!plugin) {
// There are no more functions, so re-throw the last error
return reject(lastError);
}
try {
// console.log(' %s', plugin.name);
let result = getResult(plugin, method, file, callback, $refs);
if (result && typeof result.then === "function") {
// A promise was returned
result.then(onSuccess, onError);
}
else if (result !== undefined) {
// A synchronous result was returned
onSuccess(result);
}
else if (index === plugins.length) {
throw new Error("No promise has been returned or callback has been called.");
}
}
catch (e) {
onError(e);
}
}
function callback (err, result) {
if (err) {
onError(err);
}
else {
onSuccess(result);
}
}
function onSuccess (result) {
// console.log(' success');
resolve({
plugin,
result
});
}
function onError (error) {
// console.log(' %s', err.message || err);
lastError = {
plugin,
error,
};
runNextPlugin();
}
}));
};
/**
* Returns the value of the given property.
* If the property is a function, then the result of the function is returned.
* If the value is a RegExp, then it will be tested against the file URL.
* If the value is an aray, then it will be compared against the file extension.
*
* @param {object} obj - The object whose property/method is called
* @param {string} prop - The name of the property/method to invoke
* @param {object} file - A file info object, which will be passed to the method
* @param {function} [callback] - A callback function, which will be passed to the method
* @returns {*}
*/
function getResult (obj, prop, file, callback, $refs) {
let value = obj[prop];
if (typeof value === "function") {
return value.apply(obj, [file, callback, $refs]);
}
if (!callback) {
// The synchronous plugin functions (canParse and canRead)
// allow a "shorthand" syntax, where the user can match
// files by RegExp or by file extension.
if (value instanceof RegExp) {
return value.test(file.url);
}
else if (typeof value === "string") {
return value === file.extension;
}
else if (Array.isArray(value)) {
return value.indexOf(file.extension) !== -1;
}
}
return value;
}