Joe Savona
4e104fce8e
Early sketch of a new representation for the middle-phase of the compiler. This is a sea-of-nodes approach, representing instructions and terminals as nodes with direct and control dependencies.
Something like this:
```js
let array = [];
if (cond) {
array.push(value);
}
return array;
```
Would correspond roughly to a graph as follows. Note that the actual representation uses `Instruction` as-is, and maps dependencies into local `Place`s, but for ease of reading i've mapped operands as the node they come from (n0 etc):
```
// instructions before the 'if': note that these are dangling
// (no nodes depends on them) but they would get ordered as control deps of n7, the if node
n0 = ArrayExpression []
n1 = StoreLocal 'array' = n0
// nodes from the consequent
n2 = LoadLocal 'array'
n3 = PropertyLoad n2 . 'push'
n4 = LoadLocal 'value'
n5 = MethodCall n2 . n3 ( n4 )
// if terminal
n6 = LoadLocal 'cond'
n7 = If test=n6 consequent=n5 alternate=(not pictured)
// return terminal
n8 = LoadLocal 'array';
n9 = Return value=n8
exit=n9
```
Note that even if there are multiple returns, there will always be a single "exit" node, which is just the node corresponding to the last statement of the outer block in the original program.
Converting back to HIR is a bit tricky, but shouldn’t be too bad. For all the nodes that correspond to a given block scope we can just emit the nodes to HIR in order, since they’re already in reverse post order. The catch is that nodes for inner block scopes are also mixed in and have to be emitted at the right point. I need to experiment with this more.
What's implemented so far is very basic translation of HIR to ReactiveGraph. The only dependencies created are direct data dependencies and basic control flow, which means that e.g. code inside an if consequent will stay "inside" that consequent, but it's possible for mutations or reassignments to get reordered. The reordering happens because we reverse-postorder the graph after construction, which automatically orders strictly based on dependencies and moves things around otherwise.
There is lots left to do here, including cleaning up the node dependencies and how they map to local Places, establishing other forms of dependencies, etc.
[ghstack-poisoned]
React · 
React is a JavaScript library for building user interfaces.
- Declarative: React makes it painless to create interactive UIs. Design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes. Declarative views make your code more predictable, simpler to understand, and easier to debug.
- Component-Based: Build encapsulated components that manage their own state, then compose them to make complex UIs. Since component logic is written in JavaScript instead of templates, you can easily pass rich data through your app and keep the state out of the DOM.
- Learn Once, Write Anywhere: We don't make assumptions about the rest of your technology stack, so you can develop new features in React without rewriting existing code. React can also render on the server using Node and power mobile apps using React Native.
Learn how to use React in your project.
Installation
React has been designed for gradual adoption from the start, and you can use as little or as much React as you need:
- Use Quick Start to get a taste of React.
- Add React to an Existing Project to use as little or as much React as you need.
- Create a New React App if you're looking for a powerful JavaScript toolchain.
Documentation
You can find the React documentation on the website.
Check out the Getting Started page for a quick overview.
The documentation is divided into several sections:
- Quick Start
- Tutorial
- Thinking in React
- Installation
- Describing the UI
- Adding Interactivity
- Managing State
- Advanced Guides
- API Reference
- Where to Get Support
- Contributing Guide
You can improve it by sending pull requests to this repository.
Examples
We have several examples on the website. Here is the first one to get you started:
import { createRoot } from 'react-dom/client';
function HelloMessage({ name }) {
return <div>Hello {name}</div>;
}
const root = createRoot(document.getElementById('container'));
root.render(<HelloMessage name="Taylor" />);
This example will render "Hello Taylor" into a container on the page.
You'll notice that we used an HTML-like syntax; we call it JSX. JSX is not required to use React, but it makes code more readable, and writing it feels like writing HTML.
Contributing
The main purpose of this repository is to continue evolving React core, making it faster and easier to use. Development of React happens in the open on GitHub, and we are grateful to the community for contributing bugfixes and improvements. Read below to learn how you can take part in improving React.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our contributing guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React.
Good First Issues
To help you get your feet wet and get you familiar with our contribution process, we have a list of good first issues that contain bugs that have a relatively limited scope. This is a great place to get started.
License
React is MIT licensed.