ast-monkey-traverse-with-lookahead

Utility library to traverse AST, reports upcoming values

Install

The latest version is ESM only: Node 12+ is needed to use it and it must be imported instead of required. If your project is not on ESM yet and you want to use require, use an older version of this program, 2.1.0.

npm i ast-monkey-traverse-with-lookahead

Quick Take

import { strict as assert } from "assert";

import { traverse } from "ast-monkey-traverse-with-lookahead";

const input = [
  {
    a: "b",
  },
  {
    c: "d",
  },
  {
    e: "f",
  },
];
const gathered = [];

// callback interface:
traverse(
  input,
  (key1, val1, innerObj) => {
    gathered.push([key1, val1, innerObj]);
  },
  1 // <---------------- report one upcoming value
);

assert.deepEqual(gathered, [
  // ===================
  [
    {
      a: "b",
    },
    undefined,
    {
      depth: 0,
      path: "0",
      parent: [
        {
          a: "b",
        },
        {
          c: "d",
        },
        {
          e: "f",
        },
      ],
      parentType: "array",
      next: [
        [
          "a",
          "b",
          {
            depth: 1,
            path: "0.a",
            parent: {
              a: "b",
            },
            parentType: "object",
          },
        ],
      ],
    },
  ],
  // ===================
  [
    "a",
    "b",
    {
      depth: 1,
      path: "0.a",
      parent: {
        a: "b",
      },
      parentType: "object",
      next: [
        [
          {
            c: "d",
          },
          undefined,
          {
            depth: 0,
            path: "1",
            parent: [
              {
                a: "b",
              },
              {
                c: "d",
              },
              {
                e: "f",
              },
            ],
            parentType: "array",
          },
        ],
      ],
    },
  ],
  // ===================
  [
    {
      c: "d",
    },
    undefined,
    {
      depth: 0,
      path: "1",
      parent: [
        {
          a: "b",
        },
        {
          c: "d",
        },
        {
          e: "f",
        },
      ],
      parentType: "array",
      next: [
        [
          "c",
          "d",
          {
            depth: 1,
            path: "1.c",
            parent: {
              c: "d",
            },
            parentType: "object",
          },
        ],
      ],
    },
  ],
  // ===================
  [
    "c",
    "d",
    {
      depth: 1,
      path: "1.c",
      parent: {
        c: "d",
      },
      parentType: "object",
      next: [
        [
          {
            e: "f",
          },
          undefined,
          {
            depth: 0,
            path: "2",
            parent: [
              {
                a: "b",
              },
              {
                c: "d",
              },
              {
                e: "f",
              },
            ],
            parentType: "array",
          },
        ],
      ],
    },
  ],
  // ===================
  [
    {
      e: "f",
    },
    undefined,
    {
      depth: 0,
      path: "2",
      parent: [
        {
          a: "b",
        },
        {
          c: "d",
        },
        {
          e: "f",
        },
      ],
      parentType: "array",
      next: [
        [
          "e",
          "f",
          {
            depth: 1,
            path: "2.e",
            parent: {
              e: "f",
            },
            parentType: "object",
          },
        ],
      ],
    },
  ],
  // ===================
  [
    "e",
    "f",
    {
      depth: 1,
      path: "2.e",
      parent: {
        e: "f",
      },
      parentType: "object",
      next: [],
    },
  ],
  // ===================
]);

Documentation

Please visit codsen.com for a full description of the API.

Contributing

To report bugs or request features or assistance, raise an issue on GitHub.

Licence

MIT License

Copyright (c) 2010-2022 Roy Revelt and other contributors