core/json/stream

This module provides a bunch of functions to work with JSON in a stream form. The submodules contain different classes to parse, filter and assemble JSON in a stream form.

Usage

import { convertIfDate } from 'core/json';
import { from, pick, streamArrray } from 'core/json/stream';

const
  parser = streamArrray(pick(from('{"data": [1, 2, 3]}'), 'data'), {reviver: convertIfDate});

for await (const val of parser) {
  // {index: 0, value: 1}
  // {index: 1, value: 2}
  // {index: 2, value: 3}
  console.log(val);
}

Functions

from

Parses the specified iterable object as a JSON stream and yields tokens via a Generator. See core/json/stream/parser for more information.

import { from } from 'core/json/stream';

const
  parser = from('{"data": [1, 2, 3]}');

for await (const token of parser) {
  console.log(token);
}

filter

Takes the specified iterable object of tokens and filters it via the specified filter. See core/json/stream/filters for more information.

import { from, filter } from 'core/json/stream';

const
  parser = filter(from('{"total": 3, "data": [1, 2, 3]}'), 'data');

for await (const token of parser) {
  console.log(token);
}

pick

Takes the specified iterable object of tokens and pick from it value that matches the specified selector. See core/json/stream/filters for more information.

import { from, pick } from 'core/json/stream';

const
  parser = pick(from('{"total": 3, "data": [1, 2, 3]}'), 'data');

for await (const token of parser) {
  console.log(token);
}

andPick

Takes the specified iterable object of tokens that has already been pick or pickAnd applied to, and picks from it a value that matches the specified selector. Use this function when you need to combine two or more Pick-s from a one token stream.

import { intoIter } from 'core/iter';
import { sequence } from 'core/iter/combinators';
import { from, pick, andPick, assemble, streamArray } from 'core/json/stream';

const tokens = intoIter(from(JSON.stringify({
  total: 3,
  data: [
    {user: 'Bob', age: 21},
    {user: 'Ben', age: 24},
    {user: 'Rob', age: 28}
  ]
})));

const seq = sequence(
  assemble(pick(tokens, 'total')),
  streamArray(andPick(tokens, 'data'))
);

for await (const val of seq) {
  console.log(val);
}

assemble

Takes the specified iterable object of tokens and yields an assembled item from it. See core/json/stream/assembler for more information.

import { from, assemble } from 'core/json/stream';

const
  parser = assemble(from('{"total": 3, "data": [1, 2, 3]}'));

for await (const val of parser) {
  // {total: 3, data: [1, 2, 3]}
  console.log(val);
}

streamObject

Takes the specified iterable object of tokens representing an object and yields assembled object items. See core/json/stream/streamers for more information.

import { from, streamObject } from 'core/json/stream';

const
  parser = streamObject(from('{"total": 3, "data": [1, 2, 3]}'));

for await (const val of parser) {
  // {key: 'total', value: 3}
  // {key: 'data', value: [1, 2, 3]}
  console.log(val);
}

streamArray

Takes the specified iterable object of tokens representing an array and yields assembled array items. See core/json/stream/streamers for more information.

import { from, streamArray } from 'core/json/stream';

const
  parser = streamArray(from('[1, 2, 3]'));

for await (const val of parser) {
  // {index: 0, value: 1}
  // {index: 1, value: 2]}
  // {index: 2, value: 3}
  console.log(val);
}