06736f0df5
Summary: Release notes: the side-effect detection system within pure scopes has been improved This PR revamps the entire `evaluatePure` system. The old system had so many small issues with it was the cause of many edge-cases that were hard to patch up. Specifically, the PR makes the following changes: - `realm.evaluatePure` -> `realm.evaluateWithPureScope` and now can only be used a single instance. Nesting further `realm.evaluateWithPureScope` calls will trigger an invariant and is strictly forbidden. Furthermore, it now only takes a single argument – the function you're wrapped around. - All places that used pure scope wrappers have been updated to conditionally enable it depending if the `realm.isInPureScope()` returns `true` or `false`. - `realm.evaluateFunctionForPureEffects` has been added, this works like `evaluateForEffects` except it requires a root function and a callback for side-effects. The callback for side-effects works like the old callback that was `evaluatePure`. - `realm.evaluateFunctionForPureEffectsInGlobalEnv` has been added a convenience wrapper around `realm.evaluateFunctionForPureEffects`. - When we leak bindings, we no longer set their value to `undefined` or `realm.intrinsics.undefined`. We now set the value to a special "leaked abstract", specifically – `realm.intrinsics.__leakedValue` – like `topValue` and `bottomValue`. Unsurprisingly, this now fixes a host of bugs that existed before. Including fixes for https://github.com/facebook/prepack/issues/2598, https://github.com/facebook/prepack/issues/2579, https://github.com/facebook/prepack/issues/2446, https://github.com/facebook/prepack/issues/2599 and probably many other issues too. The logic for detection of side-effects works very differently from before but after speaking to sebmarkbage last week, he pointed me in this direction to track side-effects rather than how we did it before. We now find side-effects from a given set of effects, rather than in an ad-hoc manor as mutations occur on objects/bindings. This PR requires https://github.com/facebook/prepack/pull/2596 as a dependency as it re-uses the logic. Closes https://github.com/facebook/prepack/pull/2587. Fixes https://github.com/facebook/prepack/issues/2598. Fixes https://github.com/facebook/prepack/issues/2579. Fixes https://github.com/facebook/prepack/issues/2446. Fixes https://github.com/facebook/prepack/issues/2599. Pull Request resolved: https://github.com/facebook/prepack/pull/2600 Differential Revision: D10368159 Pulled By: trueadm fbshipit-source-id: ded248f5cfd8648913cae9b9c697d723a82c59ab |
||
---|---|---|
.circleci | ||
assets | ||
bin | ||
fb-www | ||
flow-libs | ||
flow-typed/npm | ||
fuzzer | ||
scripts | ||
src | ||
test | ||
website | ||
.eslintignore | ||
.eslintrc | ||
.flowconfig | ||
.gitignore | ||
.gitmodules | ||
.prettierrc | ||
.watchmanconfig | ||
babel.config.js | ||
CODE_OF_CONDUCT.md | ||
CONTRIBUTING.md | ||
LICENSE | ||
package.json | ||
PATENTS | ||
README.md | ||
webpack.config.js | ||
yarn.lock |
Prepack
Prepack is a partial evaluator for JavaScript. Prepack rewrites a JavaScript bundle, resulting in JavaScript code that executes more efficiently. For initialization-heavy code, Prepack works best in an environment where JavaScript parsing is effectively cached.
See the official prepack.io website for an introduction and an interactive REPL playground.
How to use Prepack
Install the CLI via npm,
$ npm install -g prepack
Or if you prefer yarn, make sure you get yarn first,
$ npm install -g yarn
and then install the Prepack CLI via yarn:
$ yarn global add prepack
You may need to prepend
(pun intended!) the command with sudo
in some cases.
Let the party begin
To compile a file and print the output to the console:
$ prepack script.js
If you want to compile a file and output to another file:
$ prepack script.js --out script-processed.js
Detailed instructions and the API can be found at Prepack CLI: Getting Started
Plugins to other tools
The following are a few plugins to other tools. They have been created and are maintained separately from Prepack itself. If you run into any issues with those plugins, please ask the plugin maintainers for support.
- A Rollup plugin for Prepack
- A Webpack plugin for Prepack
- A Parcel plugin for Prepack
- A Visual Studio code plugin for Prepack
- A babel plugin which transforms Flow annotations into prepack model declarations.
Status
- test262 status on master branch
- code coverage report for serialization tests
- To see the status for a pull request, look for the message All checks have passed or All checks have failed. Click on Show all checks, Details, Artifacts, and then test262-status.txt or coverage-report-sourcemapped/index.html.
How to get the code
- Clone repository and make it your current directory.
git submodule init
git submodule update --init
- Get yarn and node, then do
yarn
Note: For development work you really need yarn
, as many scripts require it.
How to build, lint, type check
- Get the code
yarn build
You can later runyarn watch
in the background to just compile changed files on the fly.yarn lint
yarn flow
How to run tests
- Get the code
- Make sure the code is built, either by running
yarn build
oryarn watch
yarn test
You can run individual test suites as follows:
yarn test-serializer
This tests the interpreter and serializer. All tests should pass.yarn test-test262
This tests conformance against the test262 suite. Not all will pass, increasing conformance is work in progress.
How to run the interpreter
- Get the code
- Make sure the code is built, either by running
yarn build
oryarn watch
yarn repl
This starts an interactive interpreter session.
How to run Prepack
-
Get the code
-
Make sure the code is built, either by running
yarn build
oryarn watch
. -
Have a JavaScript file handy that you want to prepack, for example:
echo "function hello() { return 'hello'; } function world() { return 'world'; } s = hello() + ' ' + world();" >/tmp/sample.js
-
cat /tmp/sample.js | yarn prepack-cli
Try--help
for more options.
How to validate changes
Instead of building, linting, type checking, testing separately, the following does everything together:
yarn validate
How to edit the website
The content for prepack.io resides in the website directory of this repository. To make changes, submit a pull request, just like for any code changes.
In order to run the website locally at localhost:8000:
- Build prepack into the website:
yarn build && mv prepack.min.js website/js
- Run
python -m SimpleHTTPServer
(Python 2) orpython -m http.server
(Python 3) from thewebsite/
directory
How to contribute
To read more about the project, check out this suggested reading wiki
For more information about contributing pull requests and issues, see our Contribution Guidelines.
License
Prepack is BSD-licensed. We also provide an additional patent grant.