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- /**
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- * @format
- */
- 'use strict';
- /**
- * This transform inlines top-level require(...) aliases with to enable lazy
- * loading of dependencies. It is able to inline both single references and
- * child property references.
- *
- * For instance:
- * var Foo = require('foo');
- * f(Foo);
- *
- * Will be transformed into:
- * f(require('foo'));
- *
- * When the assigment expression has a property access, it will be inlined too,
- * keeping the property. For instance:
- * var Bar = require('foo').bar;
- * g(Bar);
- *
- * Will be transformed into:
- * g(require('foo').bar);
- *
- * Destructuring also works the same way. For instance:
- * const {Baz} = require('foo');
- * h(Baz);
- *
- * Is also successfully inlined into:
- * g(require('foo').Baz);
- */
- module.exports = babel => ({
- name: 'inline-requires',
- visitor: {
- Program: {
- exit(path, state) {
- const t = babel.types;
- const ignoredRequires = new Set();
- const inlineableCalls = new Set(['require']);
- if (state.opts != null) {
- if (state.opts.ignoredRequires != null) {
- for (const name of state.opts.ignoredRequires) {
- ignoredRequires.add(name);
- }
- }
- if (state.opts.inlineableCalls != null) {
- for (const name of state.opts.inlineableCalls) {
- inlineableCalls.add(name);
- }
- }
- }
- path.scope.crawl();
- path.traverse(
- {
- CallExpression(path, state) {
- const parseResult =
- parseInlineableAlias(path, state) ||
- parseInlineableMemberAlias(path, state);
- if (parseResult == null) {
- return;
- }
- const {
- declarationPath,
- moduleName,
- requireFnName,
- } = parseResult;
- const init = declarationPath.node.init;
- const name = declarationPath.node.id
- ? declarationPath.node.id.name
- : null;
- const binding = declarationPath.scope.getBinding(name);
- if (binding.constantViolations.length > 0) {
- return;
- }
- deleteLocation(init);
- babel.traverse(init, {
- noScope: true,
- enter: path => deleteLocation(path.node),
- });
- let thrown = false;
- for (const referencePath of binding.referencePaths) {
- excludeMemberAssignment(moduleName, referencePath, state);
- try {
- referencePath.scope.rename(requireFnName);
- referencePath.replaceWith(t.cloneDeep(init));
- } catch (error) {
- thrown = true;
- }
- }
- // If a replacement failed (e.g. replacing a type annotation),
- // avoid removing the initial require just to be safe.
- if (!thrown) {
- declarationPath.remove();
- }
- },
- },
- {
- ignoredRequires,
- inlineableCalls,
- membersAssigned: new Map(),
- },
- );
- },
- },
- },
- });
- function excludeMemberAssignment(moduleName, referencePath, state) {
- const assignment = referencePath.parentPath.parent;
- const isValid =
- assignment.type === 'AssignmentExpression' &&
- assignment.left.type === 'MemberExpression' &&
- assignment.left.object === referencePath.node;
- if (!isValid) {
- return;
- }
- const memberPropertyName = getMemberPropertyName(assignment.left);
- if (memberPropertyName == null) {
- return;
- }
- let membersAssigned = state.membersAssigned.get(moduleName);
- if (membersAssigned == null) {
- membersAssigned = new Set();
- state.membersAssigned.set(moduleName, membersAssigned);
- }
- membersAssigned.add(memberPropertyName);
- }
- function isExcludedMemberAssignment(moduleName, memberPropertyName, state) {
- const excludedAliases = state.membersAssigned.get(moduleName);
- return excludedAliases != null && excludedAliases.has(memberPropertyName);
- }
- function getMemberPropertyName(node) {
- if (node.type !== 'MemberExpression') {
- return null;
- }
- if (node.property.type === 'Identifier') {
- return node.property.name;
- }
- if (node.property.type === 'StringLiteral') {
- return node.property.value;
- }
- return null;
- }
- function deleteLocation(node) {
- delete node.start;
- delete node.end;
- delete node.loc;
- }
- function parseInlineableAlias(path, state) {
- const module = getInlineableModule(path, state);
- if (module == null) {
- return null;
- }
- const { moduleName, requireFnName } = module;
- const isValid =
- path.parent.type === 'VariableDeclarator' &&
- path.parent.id.type === 'Identifier' &&
- path.parentPath.parent.type === 'VariableDeclaration' &&
- path.parentPath.parentPath.parent.type === 'Program';
- return !isValid || path.parentPath.node == null
- ? null
- : {
- declarationPath: path.parentPath,
- moduleName,
- requireFnName,
- };
- }
- function parseInlineableMemberAlias(path, state) {
- const module = getInlineableModule(path, state);
- if (module == null) {
- return null;
- }
- const { moduleName, requireFnName } = module;
- const isValid =
- path.parent.type === 'MemberExpression' &&
- path.parentPath.parent.type === 'VariableDeclarator' &&
- path.parentPath.parent.id.type === 'Identifier' &&
- path.parentPath.parentPath.parent.type === 'VariableDeclaration' &&
- path.parentPath.parentPath.parentPath.parent.type === 'Program';
- const memberPropertyName = getMemberPropertyName(path.parent);
- return !isValid ||
- path.parentPath.parentPath.node == null ||
- isExcludedMemberAssignment(moduleName, memberPropertyName, state)
- ? null
- : {
- declarationPath: path.parentPath.parentPath,
- moduleName,
- requireFnName,
- };
- }
- function getInlineableModule(path, state) {
- const node = path.node;
- const isInlineable =
- node.type === 'CallExpression' &&
- node.callee.type === 'Identifier' &&
- state.inlineableCalls.has(node.callee.name) &&
- node['arguments'].length >= 1;
- if (!isInlineable) {
- return null;
- }
- // require('foo');
- let moduleName =
- node['arguments'][0].type === 'StringLiteral'
- ? node['arguments'][0].value
- : null;
- // require(require.resolve('foo'));
- if (moduleName == null) {
- moduleName =
- node['arguments'][0].type === 'CallExpression' &&
- node['arguments'][0].callee.type === 'MemberExpression' &&
- node['arguments'][0].callee.object.type === 'Identifier' &&
- state.inlineableCalls.has(node['arguments'][0].callee.object.name) &&
- node['arguments'][0].callee.property.type === 'Identifier' &&
- node['arguments'][0].callee.property.name === 'resolve' &&
- node['arguments'][0]['arguments'].length >= 1 &&
- node['arguments'][0]['arguments'][0].type === 'StringLiteral'
- ? node['arguments'][0]['arguments'][0].value
- : null;
- }
- // Check if require is in any parent scope
- const fnName = node.callee.name;
- const isRequireInScope = path.scope.getBinding(fnName) != null;
- return moduleName == null ||
- state.ignoredRequires.has(moduleName) ||
- isRequireInScope
- ? null
- : { moduleName, requireFnName: fnName };
- }
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