inline `Platform.select`

Summary: We are already inlining `Platform.OS`. This diff adds support to inline calls to `Platform.select` with an object literal as first argument. The transform will replace the call with the property value corresponding to the platform, or `undefined` if it does not exist.

Reviewed By: frantic

Differential Revision: D3385391

fbshipit-source-id: bb068d17948ed84e381707faeaa0450399c2f306

packager/react-packager/src/JSTransformer/worker/__tests__/inline-test.js

@@ -141,6 +141,113 @@ describe('inline constants', () => {
       normalize(code.replace(/require\('react-native'\)\.Platform\.OS/, '"android"')));
   });
 
+  it('inlines Platform.select in the code if Platform is a global and the argument is an object literal', () => {
+    const code = `function a() {
+      var a = Platform.select({ios: 1, android: 2});
+      var b = a.Platform.select({ios: 1, android: 2});
+    }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'ios'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/Platform\.select[^;]+/, '1')));
+  });
+
+  it('replaces Platform.select in the code if Platform is a top level import', () => {
+    const code = `
+      var Platform = require('Platform');
+      function a() {
+        Platform.select({ios: 1, android: 2});
+        var b = a.Platform.select({});
+      }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'android'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/Platform\.select[^;]+/, '2')));
+  });
+
+  it('replaces Platform.select in the code if Platform is a top level import from react-native', () => {
+    const code = `
+      var Platform = require('react-native').Platform;
+      function a() {
+        Platform.select({ios: 1, android: 2});
+        var b = a.Platform.select({});
+      }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'ios'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/Platform\.select[^;]+/, '1')));
+  });
+
+  it('replaces require("Platform").select in the code', () => {
+    const code = `function a() {
+      var a = require('Platform').select({ios: 1, android: 2});
+      var b = a.require('Platform').select({});
+    }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'android'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/Platform\.select[^;]+/, '2')));
+  });
+
+  it('replaces React.Platform.select in the code if React is a global', () => {
+    const code = `function a() {
+      var a = React.Platform.select({ios: 1, android: 2});
+      var b = a.React.Platform.select({});
+    }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'ios'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/React\.Platform\.select[^;]+/, '1')));
+  });
+
+  it('replaces ReactNative.Platform.select in the code if ReactNative is a global', () => {
+    const code = `function a() {
+      var a = ReactNative.Platform.select({ios: 1, android: 2});
+      var b = a.ReactNative.Platform.select({});
+    }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'ios'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/ReactNative\.Platform\.select[^;]+/, '1')));
+  });
+
+  it('replaces React.Platform.select in the code if React is a top level import', () => {
+    const code = `
+      var React = require('React');
+      function a() {
+        var a = React.Platform.select({ios: 1, android: 2});
+        var b = a.React.Platform.select({});
+      }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'ios'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/React\.Platform\.select[^;]+/, '1')));
+  });
+
+  it('replaces require("React").Platform.select in the code', () => {
+    const code = `function a() {
+      var a = require('React').Platform.select({ios: 1, android: 2});
+      var b = a.require('React').Platform.select({});
+    }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'android'});
+    expect(toString(ast)).toEqual(
+      normalize(code.replace(/require\('React'\)\.Platform\.select[^;]+/, '2')));
+  });
+
+  it('replaces ReactNative.Platform.select in the code if ReactNative is a top level import', () => {
+    const code = `
+      var ReactNative = require('react-native');
+      function a() {
+        var a = ReactNative.Plaftform.select({ios: 1, android: 2});
+        var b = a.ReactNative.Platform.select;
+      }`;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'android'});
+    expect(toString(ast)).toEqual(normalize(code.replace(/ReactNative.Platform\.select[^;]+/, '2')));
+  });
+
+  it('replaces require("react-native").Platform.select in the code', () => {
+    const code = `
+      var a = require('react-native').Platform.select({ios: 1, android: 2});
+      var b = a.require('react-native').Platform.select({});
+    `;
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'android'});
+    expect(toString(ast)).toEqual(
+      normalize(code.replace(/require\('react-native'\)\.Platform\.select[^;]+/, '2')));
+  });
+
+  it('replaces non-existing properties with `undefined`', () => {
+    const code = 'var a = Platform.select({ios: 1, android: 2})';
+    const {ast} = inline('arbitrary.js', {code}, {platform: 'doesnotexist'});
+    expect(toString(ast)).toEqual(
+      normalize(code.replace(/Platform\.select[^;]+/, 'undefined')));
+  });
+
   it('replaces process.env.NODE_ENV in the code', () => {
     const code = `function a() {
       if (process.env.NODE_ENV === 'production') {

packager/react-packager/src/JSTransformer/worker/inline.js

@@ -15,6 +15,7 @@ const React = {name: 'React'};
 const ReactNative = {name: 'ReactNative'};
 const platform = {name: 'Platform'};
 const os = {name: 'OS'};
+const select = {name: 'select'};
 const requirePattern = {name: 'require'};
 
 const env = {name: 'env'};
@@ -63,11 +64,29 @@ const isProcessEnvNodeEnv = (node, scope) =>
   t.isIdentifier(node.object.object, processId) &&
   isGlobal(scope.getBinding(processId.name));
 
+const isPlatformSelect = (node, scope) =>
+  t.isMemberExpression(node.callee) &&
+  t.isIdentifier(node.callee.object, platform) &&
+  t.isIdentifier(node.callee.property, select) &&
+  isImportOrGlobal(node.callee.object, scope, [platform]);
+
+const isReactPlatformSelect = (node, scope) =>
+  t.isMemberExpression(node.callee) &&
+  t.isIdentifier(node.callee.property, select) &&
+  t.isMemberExpression(node.callee.object) &&
+  t.isIdentifier(node.callee.object.property, platform) &&
+  isImportOrGlobal(node.callee.object.object, scope, [React, ReactNative]);
+
 const isDev = (node, parent, scope) =>
   t.isIdentifier(node, dev) &&
   isGlobal(scope.getBinding(dev.name)) &&
   !(t.isMemberExpression(parent));
 
+function findProperty(objectExpression, key) {
+  const property = objectExpression.properties.find(p => p.key.name === key);
+  return property ? property.value : t.identifier('undefined');
+}
+
 const inlinePlugin = {
   visitor: {
     Identifier(path, state) {
@@ -86,6 +105,19 @@ const inlinePlugin = {
           t.stringLiteral(state.opts.dev ? 'development' : 'production'));
       }
     },
+    CallExpression(path, state) {
+      const node = path.node;
+      const scope = path.scope;
+      const arg = node.arguments[0];
+
+      if (isPlatformSelect(node, scope) || isReactPlatformSelect(node, scope)) {
+        const replacement = t.isObjectExpression(arg)
+          ? findProperty(arg, state.opts.platform)
+          : node;
+
+        path.replaceWith(replacement);
+      }
+    }
   },
 };