{"dist":{"shasum":"8689d09e883f13795fe2eb50a5eec6585dc64c43","tarball":"https://registry.npmjs.org/@parcel/babylon-walk/-/babylon-walk-2.0.0-nightly.2001.tgz","fileCount":9,"integrity":"sha512-2tb/L9J9/i1BLn/FWibJiubMo57D7SpOD1si1nmPl2rasHVeSXyz53JeabvO5/ju8UTH+/HdMkSTUeqtQTLtPA==","signatures":[{"sig":"MEUCIC7341niCRyD4SS7G45EX9xOCD8E2dhaeAcWJlbTNBL6AiEA0xChIT/gblPwLBiwcwEHGH/1h28zAOBpZ9mJDbabfnU=","keyid":"SHA256:jl3bwswu80PjjokCgh0o2w5c2U4LhQAE57gj9cz1kzA"}],"unpackedSize":33025,"npm-signature":"-----BEGIN PGP SIGNATURE-----\r\nVersion: OpenPGP.js v3.0.4\r\nComment: https://openpgpjs.org\r\n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\nQzZm\r\n=mgij\r\n-----END PGP SIGNATURE-----\r\n"},"main":"lib/index.js","name":"@parcel/babylon-walk","author":{"name":"Timothy Gu","email":"timothygu99@gmail.com"},"readme":"# babylon-walk\n\nLightweight AST traversal tools for [Babylon] ASTs.\n\nBabylon is the parser used by the [Babel] project, which supplies the wonderful [babel-traverse] module for walking Babylon ASTs. Problem is, babel-traverse is very heavyweight, as it is designed to supply utilities to make all sorts of AST transformations possible. For simple AST walking without transformation, babel-traverse brings a lot of overhead.\n\nThis module loosely implements the API of Acorn parser's [walk module], which is a lightweight AST walker for the ESTree AST format.\n\nIn my tests, babylon-walk's ancestor walker (the most complex walker provided by this module) is about 8 times faster than babel-traverse, if the visitors are cached and the same AST is used for all runs. It is about 16 times faster if a fresh AST is used every run.\n\n[![Dependency Status](https://img.shields.io/david/pugjs/babylon-walk.svg)](https://david-dm.org/pugjs/babylon-walk)\n[![NPM version](https://img.shields.io/npm/v/babylon-walk.svg)](https://www.npmjs.com/package/babylon-walk)\n\n[babylon]: https://github.com/babel/babylon\n[babel]: https://babeljs.io/\n[babel-traverse]: https://github.com/thejameskyle/babel-handbook/blob/master/translations/en/plugin-handbook.md#toc-babel-traverse\n[walk module]: https://github.com/ternjs/acorn#distwalkjs\n\n## Installation\n\n```sh\n$ npm install babylon-walk\n```\n\n## API\n\n```js\nvar walk = require('babylon-walk');\n```\n\n### walk.simple(node, visitors, state)\n\nDo a simple walk over the AST. `node` should be the AST node to walk, and `visitors` an object containing Babel [visitors]. Each visitor function will be called as `(node, state)`, where `node` is the AST node, and `state` is the same `state` passed to `walk.simple`.\n\nWhen `walk.simple` is called with a fresh set of visitors, it will first \"explode\" the visitors (e.g. expanding `Visitor(node, state) {}` to `Visitor() { enter(node, state) {} }`). This exploding process can take some time, so it is recommended to [cache your visitors] and communicate state leveraging the `state` parameter. (One difference between the linked article and babylon-walk is that the state is only accessible through the `state` variable, never as `this`.)\n\nAll [babel-types] aliases (e.g. `Expression`) and the union syntax (e.g. `'Identifier|AssignmentPattern'(node, state) {}`) work.\n\n### walk.ancestor(node, visitors, state)\n\nDo a simple walk over the AST, but memoizing the ancestors of the node and making them available to the visitors. `node` should be the AST node to walk, and `visitors` an object containing Babel [visitors]. Each visitor function will be called as `(node, state, ancestors)`, where `node` is the AST node, `state` is the same `state` passed to `walk.ancestor`, and `ancestors` is an array of ancestors to the node (with the outermost node being `[0]` and the current node being `[ancestors.length - 1]`). If `state` is not specified in the call to `walk.ancestor`, the `state` parameter will be set to `ancestors`.\n\nWhen `walk.ancestor` is called with a fresh set of visitors, it will first \"explode\" the visitors (e.g. expanding `Visitor(node, state) {}` to `Visitor() { enter(node, state) {} }`). This exploding process can take some time, so it is recommended to [cache your visitors] and communicate state leveraging the `state` parameter. (One difference between the linked article and babylon-walk is that the state is only accessible through the `state` variable, never as `this`.)\n\nAll [babel-types] aliases (e.g. `Expression`) and the union syntax (e.g. `'Identifier|AssignmentPattern'(node, state) {}`) work.\n\n### walk.recursive(node, visitors, state)\n\nDo a recursive walk over the AST, where the visitors are responsible for continuing the walk on the child nodes of their target node. `node` should be the AST node to walk, and `visitors` an object containing Babel [visitors]. Each visitor function will be called as `(node, state, c)`, where `node` is the AST node, `state` is the same `state` passed to `walk.recursive`, and `c` is a function that takes a single node as argument and continues walking _that_ node. If no visitor for a node is provided, the default walker algorithm will still be used.\n\nWhen `walk.recursive` is called with a fresh set of visitors, it will first \"explode\" the visitors (e.g. expanding `Visitor(node, state) {}` to `Visitor() { enter(node, state) {} }`). This exploding process can take some time, so it is recommended to [cache your visitors] and communicate state leveraging the `state` parameter. (One difference between the linked article and babylon-walk is that the state is only accessible through the `state` variable, never as `this`.)\n\nUnlike other babylon-walk walkers, `walk.recursive` does not call the `exit` visitor, only the `enter` (the default) visitor, of a specific node type.\n\nAll [babel-types] aliases (e.g. `Expression`) and the union syntax (e.g. `'Identifier|AssignmentPattern'(node, state) {}`) work.\n\nIn the following example, we are trying to count the number of functions in the outermost scope. This means, that we can simply walk all the statements and increment a counter if it is a function declaration or expression, and then stop walking. Note that we do not specify a visitor for the `Program` node, and the default algorithm for walking `Program` nodes is used (which is what we want). Also of note is how I bring the `visitors` object outside of `countFunctions` so that the object can be cached to improve performance.\n\n```js\nimport * as t from 'babel-types';\nimport {parse} from 'babylon';\nimport * as walk from 'babylon-walk';\n\nconst visitors = {\n  Statement(node, state, c) {\n    if (t.isVariableDeclaration(node)) {\n      for (let declarator of node.declarations) {\n        // Continue walking the declarator\n        c(declarator);\n      }\n    } else if (t.isFunctionDeclaration(node)) {\n      state.counter++;\n    }\n  },\n\n  VariableDeclarator(node, state) {\n    if (t.isFunction(node.init)) {\n      state.counter++;\n    }\n  },\n};\n\nfunction countFunctions(node) {\n  const state = {\n    counter: 0,\n  };\n  walk.recursive(node, visitors, state);\n  return state.counter;\n}\n\nconst ast = parse(`\n  // Counts\n  var a = () => {};\n\n  // Counts\n  function b() {\n    // Doesn't count\n    function c() {\n    }\n  }\n\n  // Counts\n  const c = function d() {};\n`);\n\ncountFunctions(ast);\n// = 3\n```\n\n### walk.traverse(node, visitors, state)\n\nVisitors get called as `(path, state)`. Every `Path` has these methods (similar to `@babel/traverse`):\n\n- `skip()`\n- `replaceWith(node)`\n- `remove()`\n\n[babel-types]: https://github.com/babel/babel/tree/master/packages/babel-types\n[cache your visitors]: https://github.com/thejameskyle/babel-handbook/blob/master/translations/en/plugin-handbook.md#toc-optimizing-nested-visitors\n[visitors]: https://github.com/thejameskyle/babel-handbook/blob/master/translations/en/plugin-handbook.md#toc-visitors\n\n## Caveat\n\nFor those of you migrating from Acorn to Babylon, there are a few things to be aware of.\n\n1. The visitor caching suggestions do not apply to Acorn's walk module, but do for babylon-walk.\n\n2. babylon-walk does not provide any of the other functions Acorn's walk module provides (e.g. `make`, `findNode*`).\n\n3. babylon-walk does not use a `base` variable. The walker algorithm is the same as what babel-traverse uses.\n   - That means certain nodes that are not walked by Acorn, such as the `property` property of a non-computed `MemberExpression`, are walked by babylon-walk.\n\n## License\n\nMIT\n","source":"src/index.js","engines":{"node":">= 10.0.0"},"funding":{"url":"https://opencollective.com/parcel","type":"opencollective"},"gitHead":"e4c350d2f333e9aa25d75aeb6410cf604667fec2","license":"MIT","_npmUser":{"name":"devongovett","email":"devongovett@gmail.com"},"_npmVersion":"lerna/3.20.2/node@v12.18.3+x64 (linux)","description":"Lightweight Babylon AST traversal","directories":{},"maintainers":[{"name":"devongovett","email":"devongovett@gmail.com"}],"_nodeVersion":"12.18.3","dependencies":{"@babel/types":"^7.0.0","lodash.clone":"^4.5.0"},"publishConfig":{"access":"public"},"_hasShrinkwrap":false,"readmeFilename":"README.md","_npmOperationalInternal":{"tmp":"tmp/babylon-walk_2.0.0-nightly.2001_1598055188916_0.02989451781950936","host":"s3://npm-registry-packages"},"_id":"@parcel/babylon-walk@2.0.0-nightly.2001","version":"2.0.0-nightly.2001"}