Add use_react_native_codegen!

Summary:
Consolidate CocoaPods codegen scripts under a single `use_react_native_codegen!` method in `react_native_pods.rb`.

This is the first step towards making the codegen scripts library-agnostic. There are still a handful of hardcoded assumptions in place (e.g. the output directory structure, the use of a separate directory for components), but with some work one would be able to add codegen support to arbitrary CocoaPods podspecs.

The codegen script no longer takes a CODEGEN_PATH argument, and will instead attempt to use the local react-native-codegen package if available, and fallback to using the node_modules/react-native-codegen package if not.

## Usage

The `use_react_native_codegen!` method has two arguments:

- `spec`, a pod [Specification](https://www.rubydoc.info/github/CocoaPods/Core/Pod/Specification) object.
- `options`, an optional object. Supported keys:
  - `:srcs_dir`, the path to your JavaScript sources. Your native module or component specs should be located somewhere in this directory.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D25728053

fbshipit-source-id: feec587b656d5b220598ce6196ea6bb34a9580a9

Libraries/FBReactNativeSpec/FBReactNativeSpec.podspec

@@ -4,44 +4,19 @@
 # LICENSE file in the root directory of this source tree.
 
 require "json"
+require_relative "../../scripts/react_native_pods.rb"
 
 package = JSON.parse(File.read(File.join(__dir__, "..", "..", "package.json")))
 version = package['version']
 
 source = { :git => 'https://github.com/facebook/react-native.git' }
-codegen_path_prefix = ".."
 if version == '1000.0.0'
   # This is an unpublished version, use the latest commit hash of the react-native repo, which we’re presumably in.
   source[:commit] = `git rev-parse HEAD`.strip
-  codegen_path_prefix = "packages"
 else
   source[:tag] = "v#{version}"
 end
 
-react_native_path = File.join(__dir__, "..", "..")
-srcs_dir = File.join(__dir__, "..")
-codegen_script_path = File.join(react_native_path, "scripts", "generate-specs.sh")
-codegen_path = File.join(react_native_path, codegen_path_prefix, "react-native-codegen")
-codegen_command = "CODEGEN_PATH=#{codegen_path} sh '#{codegen_script_path}' | tee \"${SCRIPT_OUTPUT_FILE_0}\""
-modules_output_dir = File.join(__dir__, "FBReactNativeSpec")
-components_output_dir = File.join(react_native_path, "ReactCommon", "react", "renderer", "components", "rncore")
-generated_filenames = [ "FBReactNativeSpec.h", "FBReactNativeSpec-generated.mm" ]
-generated_files = generated_filenames.map { |filename| File.join(modules_output_dir, filename) }
-
-if ENV['USE_FABRIC'] == '1'
-  components_generated_filenames = [
-    "ComponentDescriptors.h",
-    "EventEmitters.cpp",
-    "EventEmitters.h",
-    "Props.cpp",
-    "Props.h",
-    "RCTComponentViewHelpers.h",
-    "ShadowNodes.cpp",
-    "ShadowNodes.h"
-  ]
-  generated_files = generated_files.concat(components_generated_filenames.map { |filename| File.join(components_output_dir, filename) })
-end
-
 folly_compiler_flags = '-DFOLLY_NO_CONFIG -DFOLLY_MOBILE=1 -DFOLLY_USE_LIBCPP=1 -Wno-comma -Wno-shorten-64-to-32'
 folly_version = '2020.01.13.00'
 
@@ -72,12 +47,5 @@ Pod::Spec.new do |s|
   s.dependency "React-jsi", version
   s.dependency "ReactCommon/turbomodule/core", version
 
-  s.prepare_command = "mkdir -p #{modules_output_dir} #{components_output_dir} && touch #{generated_files.reduce() { |str, file| str + " " + file }}"
-  s.script_phase = {
-    :name => 'Generate Specs',
-    :input_files => [srcs_dir],
-    :output_files => ["$(DERIVED_FILE_DIR)/codegen.log"],
-    :script => codegen_command,
-    :execution_position => :before_compile
-  }
+  use_react_native_codegen! (s)
 end

packages/rn-tester/Podfile.lock

@@ -798,7 +798,7 @@ SPEC CHECKSUMS:
   CocoaLibEvent: 2fab71b8bd46dd33ddb959f7928ec5909f838e3f
   DoubleConversion: cde416483dac037923206447da6e1454df403714
   FBLazyVector: fe973c09b2299b5e8154186ecf1f6554b4f70987
-  FBReactNativeSpec: 259a715466e53b411664fdfbe166dbde93ece5b6
+  FBReactNativeSpec: cc83b1f9c1a764577c37a7009d002b8afb36f192
   Flipper: be611d4b742d8c87fbae2ca5f44603a02539e365
   Flipper-DoubleConversion: 38631e41ef4f9b12861c67d17cb5518d06badc41
   Flipper-Folly: e4493b013c02d9347d5e0cb4d128680239f6c78a

scripts/generate-specs.sh

@@ -7,16 +7,10 @@
 # This script collects the JavaScript spec definitions for core
 # native modules and components, then uses react-native-codegen
 # to generate native code.
-# The script will use the local react-native-codegen package by
-# default. Optionally, set the CODEGEN_PATH to point to the
-# desired codegen library (e.g. when using react-native-codegen
-# from npm).
 #
 # Usage:
 #   ./scripts/generate-specs.sh
 #
-# Examples:
-#  CODEGEN_PATH=.. ./scripts/generate-specs.sh
 
 # shellcheck disable=SC2038
 
@@ -25,7 +19,6 @@ set -e
 THIS_DIR=$(cd -P "$(dirname "$(readlink "${BASH_SOURCE[0]}" || echo "${BASH_SOURCE[0]}")")" && pwd)
 TEMP_DIR=$(mktemp -d /tmp/react-native-codegen-XXXXXXXX)
 RN_DIR=$(cd "$THIS_DIR/.." && pwd)
-CODEGEN_PATH="${CODEGEN_PATH:-$(cd "$RN_DIR/packages/react-native-codegen" && pwd)}"
 YARN_BINARY="${YARN_BINARY:-$(command -v yarn)}"
 USE_FABRIC="${USE_FABRIC:-0}"
 
@@ -48,6 +41,18 @@ main() {
 
   SCHEMA_FILE="$TEMP_DIR/schema.json"
 
+  CODEGEN_REPO_PATH="$RN_DIR/packages/react-native-codegen"
+  CODEGEN_NPM_PATH="$RN_DIR/../react-native-codegen"
+
+  if [ -d "$CODEGEN_REPO_PATH" ]; then
+    CODEGEN_PATH=$(cd "$CODEGEN_REPO_PATH" && pwd)
+  elif [ -d "$CODEGEN_NPM_PATH" ]; then
+    CODEGEN_PATH=$(cd "$CODEGEN_NPM_PATH" && pwd)
+  else
+    echo "Error: Could not determine react-native-codegen location. Try running 'yarn install' or 'npm install' in your project root." 1>&2
+    exit 1
+  fi
+
   if [ ! -d "$CODEGEN_PATH/lib" ]; then
     describe "Building react-native-codegen package"
     pushd "$CODEGEN_PATH" >/dev/null || exit
@@ -61,7 +66,7 @@ main() {
 
   describe "Generating native code from schema (iOS)"
   pushd "$RN_DIR" >/dev/null || exit
-    USE_FABRIC="$USE_FABRIC" "$YARN_BINARY" --silent node scripts/generate-specs-cli.js ios "$SCHEMA_FILE" "$OUTPUT_DIR"
+    "$YARN_BINARY" --silent node scripts/generate-specs-cli.js ios "$SCHEMA_FILE" "$OUTPUT_DIR"
   popd >/dev/null || exit
 
   mkdir -p "$COMPONENTS_DIR" "$MODULES_DIR"

scripts/react_native_pods.rb

@@ -4,7 +4,7 @@
 # LICENSE file in the root directory of this source tree.
 
 def use_react_native! (options={})
-  # The prefix to the react-native
+  # The prefix to react-native
   prefix = options[:path] ||= "../node_modules/react-native"
 
   # Include Fabric dependencies
@@ -144,3 +144,51 @@ def react_native_post_install(installer)
 
   exclude_architectures(installer)
 end
+
+def use_react_native_codegen!(spec, options={})
+  # The path to react-native (e.g. react_native_path)
+  prefix = options[:path] ||= File.join(__dir__, "..")
+
+  # The path to JavaScript files
+  srcs_dir = options[:srcs_dir] ||= File.join(prefix, "Libraries")
+
+  # Library name (e.g. FBReactNativeSpec)
+  library_name = spec.name
+  modules_output_dir = File.join(prefix, "Libraries/#{library_name}/#{library_name}")
+
+  # Run the codegen as part of the Xcode build pipeline.
+  spec.script_phase = {
+    :name => 'Generate Specs',
+    :input_files => [srcs_dir],
+    :output_files => ["$(DERIVED_FILE_DIR)/codegen.log"],
+    :script => "sh '#{File.join(__dir__, "generate-specs.sh")}' | tee \"${SCRIPT_OUTPUT_FILE_0}\"",
+    :execution_position => :before_compile
+  }
+
+  # Since the generated files are not guaranteed to exist when CocoaPods is run, we need to create
+  # empty files to ensure the references are included in the resulting Pods Xcode project.
+  mkdir_command = "mkdir -p #{modules_output_dir}"
+  generated_filenames = [ "#{library_name}.h", "#{library_name}-generated.mm" ]
+  generated_files = generated_filenames.map { |filename| File.join(modules_output_dir, filename) }
+
+  if ENV['USE_FABRIC'] == '1'
+    # We use a different library name for components, as well as an additional set of files.
+    # Eventually, we want these to be part of the same library as #{library_name} above.
+    components_library_name = "rncore"
+    components_output_dir = File.join(prefix, "ReactCommon/react/renderer/components/#{components_library_name}")
+    mkdir_command += " #{components_output_dir}"
+    components_generated_filenames = [
+      "ComponentDescriptors.h",
+      "EventEmitters.cpp",
+      "EventEmitters.h",
+      "Props.cpp",
+      "Props.h",
+      "RCTComponentViewHelpers.h",
+      "ShadowNodes.cpp",
+      "ShadowNodes.h"
+    ]
+    generated_files = generated_files.concat(components_generated_filenames.map { |filename| File.join(components_output_dir, filename) })
+  end
+
+  spec.prepare_command = "#{mkdir_command} && touch #{generated_files.reduce() { |str, file| str + " " + file }}"
+end