array-of-arrays-into-ast^2.1.0

Turns an array of arrays of data into a nested tree of plain objects

Install via npm

npm i array-of-arrays-into-ast

Consume via a require():

const { generateAst } = require("array-of-arrays-into-ast");

or as an ES Module:

import { generateAst } from "array-of-arrays-into-ast";

Install as a script, via CDN

Put this in your HTML:

<script src="https://cdn.jsdelivr.net/npm/array-of-arrays-into-ast/dist/array-of-arrays-into-ast.umd.js"></script>

Then, you’ll get a global variable arrayOfArraysIntoAst in your Global object and you consume it like this:

const { generateAst } = arrayOfArraysIntoAst;

Trivia

This program has 10 assertions in its unit tests. That's less than all unit test assertions' median (44) and less than geometric mean (72).

§ Quick Take

import { strict as assert } from "assert";
import { generateAst } from "array-of-arrays-into-ast";

assert.deepEqual(
  generateAst([[1, 2, 3], [1, 2], [5]]),
  {
    1: [
      {
        2: [
          {
            3: [null],
          },
          null,
        ],
      },
    ],
    5: [null],
  }
);

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§ Purpose

It consumes array of arrays and produces a trie -like AST from them. This library was a piece of a one experimental code generator of ours.

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§ API

generateAst(
  inputArr,
  [opts]
)

§ API - Input

Input argument	Type	Obligatory?	Description
`input`	Array of zero or more arrays	yes	Source of data to put into an AST
`otps`	Plain object	no	An Optional Options Object. See its API below.

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§ An Optional Options Object

Type: object - an Optional Options Object.

`options` object's key	Type	Default	Description
`dedupe`	Boolean	`true`	Skip duplicates

Here are all defaults in one place for copying:

{
  dedupe: true,
}

When unused, Optional Options Object can also be passed as a null or undefined value.

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§ API - Output

Type	Description
Plain object	AST of the input

§ `opts.dedupe`

If you generate the AST with default settings, dedupe setting will be active and duplicate paths won't be created:

import generateAst from "array-of-arrays-into-ast";
const res = generateAst([[1], [1], [1]]);
console.log(
  `${`\u001b[${33}m${`res`}\u001b[${39}m`} = ${JSON.stringify(res, null, 4)}`
);
// res = {
//   1: [null]
// }

Now, see what happens when you turn off opts.dedupe:

import generateAst from "array-of-arrays-into-ast";
const res = generateAst([[1], [1], [1]], { dedupe: false });
console.log(
  `${`\u001b[${33}m${`res`}\u001b[${39}m`} = ${JSON.stringify(res, null, 4)}`
);
// res = {
//   1: [null, null, null]
// }
}

Notice how entries for each branch were created.

Generally, we don't see the reason why you'd want duplicates, but the setting is there if you ever need it. 👍🏻

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§ Principles

Every object's key will have a value of array.

null inside that array means it's the tip of the branch.
An object inside that array means the branch continues.

Simples.

§ Compared vs. `datastructures-js`

There are libraries that produce and manage trie data structures, for example, datastructures-js . In particular case, the problem is, the data structure is abstracted behind the let trie = ds.trie(); and you can't access it directly, traversing the nested tree of arrays and objects.

datastructures-js trie would limit to search(), traverse() and count() methods. However, we need to recursively traverse every node and look up and down, what's around it.

Here's where this library comes in. It doesn't abstract the data it's producing - you get a nested plain object which you can traverse and further process any way you like, using a vast ocean of object- processing libraries.

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