inline-plugin.js

/**
 * 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.
 *
 * @flow
 * @format
 */

'use strict';

const createInlinePlatformChecks = require('./utils/createInlinePlatformChecks');

import type {Ast} from '@babel/core';
import type {Path} from '@babel/traverse';
import type {Types} from '@babel/types';

export type Options = {
  dev: boolean,
  inlinePlatform: boolean,
  isWrapped: boolean,
  requireName?: string,
  platform: string,
  ...
};

type State = {opts: Options, ...};

export type Visitors = {|
  visitor: {|
    CallExpression: (path: Path, state: State) => void,
    Identifier: (path: Path, state: State) => void,
    MemberExpression: (path: Path, state: State) => void,
  |},
|};

const env = {name: 'env'};
const nodeEnv = {name: 'NODE_ENV'};
const processId = {name: 'process'};

const dev = {name: '__DEV__'};

function inlinePlugin(
  {types: t}: {types: Types, ...},
  options: Options,
): Visitors {
  const {isPlatformNode, isPlatformSelectNode} = createInlinePlatformChecks(
    t,
    options.requireName || 'require',
  );

  const isGlobal = binding => !binding;

  const isFlowDeclared = binding => t.isDeclareVariable(binding.path);

  const isGlobalOrFlowDeclared = binding =>
    isGlobal(binding) || isFlowDeclared(binding);

  const isLeftHandSideOfAssignmentExpression = (node: Ast, parent) =>
    t.isAssignmentExpression(parent) && parent.left === node;

  const isProcessEnvNodeEnv = (node: Ast, scope) =>
    t.isIdentifier(node.property, nodeEnv) &&
    t.isMemberExpression(node.object) &&
    t.isIdentifier(node.object.property, env) &&
    t.isIdentifier(node.object.object, processId) &&
    isGlobal(scope.getBinding(processId.name));

  const isDev = (node: Ast, parent, scope) =>
    t.isIdentifier(node, dev) &&
    isGlobalOrFlowDeclared(scope.getBinding(dev.name)) &&
    !t.isMemberExpression(parent);

  function findProperty(objectExpression, key: string, fallback) {
    const property = objectExpression.properties.find(p => {
      if (t.isIdentifier(p.key) && p.key.name === key) {
        return true;
      }

      if (t.isStringLiteral(p.key) && p.key.value === key) {
        return true;
      }

      return false;
    });
    return property ? property.value : fallback();
  }

  function hasStaticProperties(objectExpression): boolean {
    if (!t.isObjectExpression(objectExpression)) {
      return false;
    }

    return objectExpression.properties.every(p => {
      if (p.computed) {
        return false;
      }

      return t.isIdentifier(p.key) || t.isStringLiteral(p.key);
    });
  }

  return {
    visitor: {
      Identifier(path: Path, state: State): void {
        if (!state.opts.dev && isDev(path.node, path.parent, path.scope)) {
          path.replaceWith(t.booleanLiteral(state.opts.dev));
        }
      },
      MemberExpression(path: Path, state: State): void {
        const node = path.node;
        const scope = path.scope;
        const opts = state.opts;

        if (!isLeftHandSideOfAssignmentExpression(node, path.parent)) {
          if (
            opts.inlinePlatform &&
            isPlatformNode(node, scope, !!opts.isWrapped)
          ) {
            path.replaceWith(t.stringLiteral(opts.platform));
          } else if (!opts.dev && isProcessEnvNodeEnv(node, scope)) {
            path.replaceWith(
              t.stringLiteral(opts.dev ? 'development' : 'production'),
            );
          }
        }
      },
      CallExpression(path: Path, state: State): void {
        const node = path.node;
        const scope = path.scope;
        const arg = node.arguments[0];
        const opts = state.opts;

        if (
          opts.inlinePlatform &&
          isPlatformSelectNode(node, scope, !!opts.isWrapped)
        ) {
          if (hasStaticProperties(arg)) {
            const fallback = () =>
              findProperty(arg, 'native', () =>
                findProperty(arg, 'default', () => t.identifier('undefined')),
              );

            path.replaceWith(findProperty(arg, opts.platform, fallback));
          }
        }
      },
    },
  };
}

module.exports = inlinePlugin;