https://github.com/grantila/json-cst
Parse JSON into CST (Concrete Syntax Tree)
https://github.com/grantila/json-cst
Last synced: 2 months ago
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Parse JSON into CST (Concrete Syntax Tree)
- Host: GitHub
- URL: https://github.com/grantila/json-cst
- Owner: grantila
- License: mit
- Created: 2022-04-28T21:29:01.000Z (over 3 years ago)
- Default Branch: master
- Last Pushed: 2022-05-02T17:39:33.000Z (over 3 years ago)
- Last Synced: 2025-06-12T15:07:28.679Z (4 months ago)
- Language: TypeScript
- Size: 370 KB
- Stars: 4
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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# json-cst
This package parses a JSON into CST (Concrete Syntax Tree), similar to an AST but more low-level and with ties to the lexer tokens. It uses `json-lexer` to parse the file into tokens. The speed is practically the same as [`json-to-ast`](https://www.npmjs.com/package/json-to-ast) (it's ~10% faster than `json-to-ast`), but it's far smaller (even including `json-lexer`). Pure package is 7x smaller, install size 12x smaller, bundling it makes it 6x smaller according to bundlephobia ([json-to-ast](https://bundlephobia.com/package/json-to-ast@2.1.0) vs [json-cst](https://bundlephobia.com/package/json-cst@1.0.0)).
It comes with TypeScript typings.
# Install
`npm i json-cst` or `yarn add json-cst`
This is a [pure ESM][pure-esm] package, and requires Node.js >=14.13.1
# Simple usage
### Exports
The package exports `parse(json: string, options: ParseCstOptions): CstNode`.
`options` is an optional object which can contain `includeValueTokens: true` to include the value tokens in the result, meaning, for objects and arrays, they will include the slice of tokens for the beginning and end of the object/array.
### Definition
The tokens are parsed into a hierarchy of nodes, each with a "kind" property:
```ts
type CstKindLiteral = 'literal'; // null, true, false
type CstKindNumber = 'number';
type CstKindString = 'string';
type CstKindObjectPropertyColon = 'object-property-colon';
type CstKindObjectProperty = 'object-property';
type CstKindObject = 'object';
type CstKindArrayElement = 'array-element';
type CstKindArray = 'array';
```
And the `CstNode` returned by `parse()` is a `CstValueNode`, i.e. one of:
- `CstNodeLiteral`
- `CstNodeNumber`
- `CstNodeString`
- `CstNodeObject`
- `CstNodeArray`
Other nodes are:
- `CstNodeObjectProperty`
- `CstNodeObjectPropertyColon`
- `CstNodeArrayElement`
Each token contain a `{ range: CstTokenRange }` where
```ts
interface CstTokenRange {
start: number;
end: number;
}
```
Each of the primitive tokens `CstNodeLiteral`, `CstNodeNumber` and `CstNodeString` contain `{ token: Token }` being the raw token from `json-lexer`.
Object and array tokens `CstNodeObject` and `CstNodeArray` contain a property `children` being an array of either `CstNodeObjectProperty` or `CstNodeArrayElement`.
A `CstNodeObjectProperty` has a `keyToken` property being the lexer token for the property name, and a `valueNode` being a `CstNode`. A `CstNodeArrayElement` also has a `valueNode`.
See [`types.ts`](https://github.com/grantila/json-cst/blob/master/lib/types.ts) for exact typings.
[npm-image]: https://img.shields.io/npm/v/json-cst.svg
[npm-url]: https://npmjs.org/package/json-cst
[downloads-image]: https://img.shields.io/npm/dm/json-cst.svg
[build-image]: https://img.shields.io/github/workflow/status/grantila/json-cst/Master.svg
[build-url]: https://github.com/grantila/json-cst/actions?query=workflow%3AMaster
[coverage-image]: https://coveralls.io/repos/github/grantila/json-cst/badge.svg?branch=master
[coverage-url]: https://coveralls.io/github/grantila/json-cst?branch=master
[lgtm-image]: https://img.shields.io/lgtm/grade/javascript/g/grantila/json-cst.svg?logo=lgtm&logoWidth=18
[lgtm-url]: https://lgtm.com/projects/g/grantila/json-cst/context:javascript
[pure-esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c