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babel-plugin-add-module-to-define.js
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babel-plugin-add-module-to-define.js
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// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* This is a babel plugin to add the Moodle module names to the AMD modules
* as part of the transpiling process.
*
* In addition it will also add a return statement for the default export if the
* module is using default exports. This is a highly specific Moodle thing because
* we're transpiling to AMD and none of the existing Babel 7 plugins work correctly.
*
* This will fix the issue where an ES6 module using "export default Foo" will be
* transpiled into an AMD module that returns {default: Foo}; Instead it will now
* just simply return Foo.
*
* Note: This means all other named exports in that module are ignored and won't be
* exported.
*
* @copyright 2018 Ryan Wyllie <ryan@moodle.com>
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
"use strict";
/* eslint-env node */
module.exports = ({template, types}) => {
const fs = require('fs');
const path = require('path');
const cwd = process.cwd();
const ComponentList = require(path.resolve('GruntfileComponents.js'));
/**
* Search the list of components that match the given file name
* and return the Moodle component for that file, if found.
*
* Throw an exception if no matching component is found.
*
* @throws {Error}
* @param {string} searchFileName The file name to look for.
* @return {string} Moodle component
*/
function getModuleNameFromFileName(searchFileName) {
searchFileName = fs.realpathSync(searchFileName);
const relativeFileName = searchFileName.replace(`${cwd}${path.sep}`, '').replace(/\\/g, '/');
const [componentPath, file] = relativeFileName.split('/amd/src/');
const fileName = file.replace('.js', '');
// Check subsystems first which require an exact match.
const componentName = ComponentList.getComponentFromPath(componentPath);
if (componentName) {
return `${componentName}/${fileName}`;
}
// This matches the previous PHP behaviour that would throw an exception
// if it couldn't parse an AMD file.
throw new Error(`Unable to find module name for ${searchFileName} (${componentPath}::${file}}`);
}
/**
* This is heavily inspired by the babel-plugin-add-module-exports plugin.
* See: https://github.com/59naga/babel-plugin-add-module-exports
*
* This is used when we detect a module using "export default Foo;" to make
* sure the transpiled code just returns Foo directly rather than an object
* with the default property (i.e. {default: Foo}).
*
* Note: This means that we can't support modules that combine named exports
* with a default export.
*
* @param {String} path
* @param {String} exportObjectName
*/
function addModuleExportsDefaults(path, exportObjectName) {
const rootPath = path.findParent(path => {
return path.key === 'body' || !path.parentPath;
});
// HACK: `path.node.body.push` instead of path.pushContainer(due doesn't work in Plugin.post).
// This is hardcoded to work specifically with AMD.
rootPath.node.body.push(template(`return ${exportObjectName}.default`)());
}
return {
pre() {
this.seenDefine = false;
this.addedReturnForDefaultExport = false;
},
visitor: {
// Plugin ordering is only respected if we visit the "Program" node.
// See: https://babeljs.io/docs/en/plugins.html#plugin-preset-ordering
//
// We require this to run after the other AMD module transformation so
// let's visit the "Program" node.
Program: {
exit(path) {
path.traverse({
CallExpression(path) {
// If we find a "define" function call.
if (!this.seenDefine && path.get('callee').isIdentifier({name: 'define'})) {
// We only want to modify the first instance of define that we find.
this.seenDefine = true;
// Get the Moodle component for the file being processed.
var moduleName = getModuleNameFromFileName(this.file.opts.filename);
// Add the module name as the first argument to the define function.
path.node.arguments.unshift(types.stringLiteral(moduleName));
// Add a space after the define function in the built file so that previous versions
// of Moodle will not try to add the module name to the file when it's being served
// by PHP. This forces the regex in PHP to not match for this file.
path.node.callee.name = 'define ';
}
// Check for any Object.defineProperty('exports', 'default') calls.
if (!this.addedReturnForDefaultExport && path.get('callee').matchesPattern('Object.defineProperty')) {
const [identifier, prop] = path.get('arguments');
const objectName = identifier.get('name').node;
const propertyName = prop.get('value').node;
if ((objectName === 'exports' || objectName === '_exports') && propertyName === 'default') {
addModuleExportsDefaults(path, objectName);
this.addedReturnForDefaultExport = true;
}
}
},
AssignmentExpression(path) {
// Check for an exports.default assignments.
if (
!this.addedReturnForDefaultExport &&
(
path.get('left').matchesPattern('exports.default') ||
path.get('left').matchesPattern('_exports.default')
)
) {
const objectName = path.get('left.object.name').node;
addModuleExportsDefaults(path, objectName);
this.addedReturnForDefaultExport = true;
}
}
}, this);
}
}
}
};
};