88 lines
2.8 KiB
Markdown
88 lines
2.8 KiB
Markdown
### node-source-walk [](https://npmjs.org/package/node-source-walk) [](https://npmjs.org/package/node-source-walk)
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> Synchronously execute a callback on every node of a file's AST and stop walking whenever you see fit.
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`npm install --save node-source-walk`
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### Usage
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```javascript
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var Walker = require('node-source-walk');
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var walker = new Walker();
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// Assume src is the string contents of myfile.js
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// or the AST of an outside parse of myfile.js
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walker.walk(src, function(node) {
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if (node.type === whateverImLookingFor) {
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// No need to keep traversing since we found what we wanted
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walker.stopWalking();
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}
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});
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```
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By default, Walker will use `babylon` (supporting ES6, JSX, Flow, and all other available babylon plugins) and the `sourceType: module`, but you can change any of the defaults as follows:
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```js
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var walker = new Walker({
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sourceType: 'script',
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// If you don't like experimental plugins
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plugins: [
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'jsx',
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'flow'
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]
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});
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```
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* The supplied options are passed through to the parser, so you can configure it according to babylon's documentation: https://github.com/babel/babylon
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### Swap out the parser
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If you want to supply your own parser, you can do:
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```js
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var walker = new Walker({
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parser: mySweetParser
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});
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```
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* The custom parser must have a `.parse` method that takes in a string and returns an object/AST.
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* All of the other options supplied to the Walker constructor will be passed along as parser options to your chosen parser.
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### Public Members
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`walk(src, cb)`
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* Recursively walks the given `src` from top to bottom
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* `src`: the contents of a file **OR** its (already parsed) AST
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* `cb`: a function that is called for every visited node.
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* The argument passed to `cb` will be the currently visited node.
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`moonwalk(node, cb)`
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* Recursively walks up an AST starting from the given node. This is a traversal that's in the opposite direction of `walk` and `traverse`.
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* `node`: a valid AST node
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* `cb`: a function that is called for every node (specifically via visiting the parent(s) of every node recursively).
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* The argument passed to `cb` will be the currently visited node.
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`stopWalking()`
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* Halts further walking of the AST until another manual call of `walk` or `moonwalk`.
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* This is super-beneficial when dealing with large source files (or ASTs)
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`traverse(node, cb)`
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* Allows you to traverse an AST node and execute a callback on it
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* Callback should expect the first argument to be an AST node, similar to `walk`'s callback.
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`parse(src)`
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* Uses the options supplied to Walker to parse the given source code string and return its AST
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using the configured parser (or babylon by default).
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## License
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MIT
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