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# ts-xpath

This is a modified version of [js-xpath](https://github.com/dimagi/js-xpath). It is adapted for use with TypeScript and is compiled using `npm run build`.

## Usage

```bash
npm install ts-xpath
```

```typescript
import { XPathParser } from 'ts-xpath';

let parser = new XPathParser();
let parsed = parser.parse("//node");
```

`xpath-models.ts` provides a default `XPathModels` which does not support the hashtag preprocessor. If you want to support hashtags within xpaths, you can use:

```typescript
let hashtagConfig: XPathModels.HashtagConfig = {
  isValidNamespace: (namespace: string) => boolean,
  hashtagToXPath: (hashtagExpr: string) => string | null,
  toHashtag: (xpath: IXPathExpression) => string | null
}
parser.hashtagConfig = hashtagConfig;
```

hashtags use the format `#namespace/arbitrarily/long/path` and do not support filtering

## Tests

- Run `yarn test` to run tests.

## Known Limitations

- Filter expressions are not supported due to a known bug in jison.
- See the failing tests for examples of expressions that are known not to work.

## Build

This is built using a [fork of](https://github.com/GerHobbelt/jison) [jison](http://zaach.github.com/jison/). To build the parser file yourself run:

`$ yarn build` - This will build both the distribution (`webpack`) package in dist/ and rebuild the Jison parser (`src/jison/xpath.js`) from the `src/jison/` files.
`$ yarn jison` - Rebuild `parser.js` from the Jison specification files.

For more information on jison see the jison project website at: http://zaach.github.com/jison/.