a40f54f847
* Add all option to babel-plugin-syntax-flow The Flow parser has some conditional logic based on whether types should be parsed or not, which is based on either (a) the @flow pragma in the docblock of the file of (b) the `all` configuration, provided via command line or .flowconfig. This commit adds the ability to provide the `all` configuration to Babel as well, via the syntax-flow plugin. This should be set to `true` if the project uses all=true. * Parse @flow pragma The Flow parser has some conditional logic based on whether types should be parsed or not, which is based on either (a) the @flow pragma in the docblock of the file of (b) the `all` configuration, provided via command line or .flowconfig. This commit parses the @flow (or @noflow) pragma from the first comment in the source file. Directives are allowed to appear before the comment. * WIP: add tests for explicit type arguments This commit includes tests which have unexpected output, but will change to the expected output as later commits add parsing support for various features. * Parse type arguments in new expressions * Parse type arguments in call expressions * Parse optional call expressions with explicit type args * Add explicit type arguments to babel-types Flow calls these typeArguments instead of typeParameters, which clearly separates formal/actual parameters, and mirrors the existing arguments key. The existing definitions to support TypeScript also included Flow's TypeParameterInstantiation node type, which I've moved to the the new field. * Add support for explicit type arguments to babel-generator * Add test for explicit type args to transform-flow-strip-types plugin * Oops. Forgot to regenerate the babel-types README. * Fix Flow parser shouldParseTypes() function I was looking at `options.all`, but the correct property ws `options.flowAll`. Oops! * Remove typeapp_call from whitelist of expected failures Now that Babylon parses this syntax extension, we can remove the typeapp_call tests from the list of expected differences. Note that I am using the `flowAll` option, mirroring the behavior of the Flow tests, which assume types without requiring the `@flow` pragma. * Use Babylon plugin options instead of parser options * Parse optional call expressions type arguments unambiguously
Woah, what's going on here?
A monorepo, muhahahahahaha. See the monorepo design doc for reasoning.
Core Packages
| Package | Version | Dependencies |
|---|---|---|
@babel/core |
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babylon |
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@babel/traverse |
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@babel/generator |
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@babel/core is the Babel compiler itself; it exposes the babel.transform method, where transformedCode = transform(src).code.
The compiler can be broken down into 3 parts:
- The parser:
babylon - The transformer[s]: All the plugins/presets
- These all use
@babel/traverseto traverse through the AST
- These all use
- The generator:
@babel/generator
The flow goes like this:
input string -> babylon parser -> AST -> transformer[s] -> AST -> @babel/generator -> output string
Check out the babel-handbook for more information on this.
Other
| Package | Version | Dependencies |
|---|---|---|
@babel/cli |
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@babel/types |
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@babel/polyfill |
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@babel/runtime |
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@babel/register |
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@babel/template |
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@babel/helpers |
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@babel/code-frame |
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@babel/cliis the CLI tool that runs@babel/coreand helps with outputting to a directory, a file, stdout and more (also includes@babel/nodecli). Check out the docs.@babel/typesis used to validate, build and change AST nodes.@babel/polyfillis literally a wrapper aroundcore-jsand regenerator-runtime. Check out the docs.@babel/runtimeis similar to the polyfill except that it doesn't modify the global scope and is to be used with@babel/plugin-transform-runtime(usually in library/plugin code). Check out the docs.@babel/registeris a way to automatically compile files with Babel on the fly by binding to Node.jsrequire. Check out the docs.@babel/templateis a helper function that allows constructing AST nodes from a string presentation of the code; this eliminates the tedium of using@babel/typesfor building AST nodes.@babel/helpersis a set of pre-made@babel/templatefunctions that are used in some Babel plugins.@babel/code-frameis a standalone package used to generate errors that print the source code and point to error locations.
Presets
After Babel 6, the default transforms were removed; if you don't specify any plugins/presets, Babel will just return the original source code.
The transformer[s] used in Babel are the independent pieces of code that transform specific things. For example: the es2015-arrow-functions transform specifically changes arrow functions into regular functions. A preset is simply an array of plugins that make it easier to run a whole a set of transforms without specifying each one manually.
| Package | Version | Dependencies | Description |
|---|---|---|---|
@babel/preset-env |
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automatically determines plugins and polyfills you need based on your supported environments |
You can find community maintained presets on npm
Plugins
Plugins are the heart of Babel and what make it work.
You can find community plugins on npm.
Transform Plugins
There are many kinds of plugins: ones that convert ES6/ES2015 to ES5, transform to ES3, minification, JSX, flow, experimental features, and more. Check out our website for more.
Syntax Plugins
These just enable the transform plugins to be able to parse certain features (the transform plugins already include the syntax plugins so you don't need both): @babel/plugin-syntax-x. Check out our website for more.
Helpers
These are mostly for internal use in various plugins: @babel/helper-x.