keichi / binary-parser

A blazing-fast declarative parser builder for binary data
MIT License
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Directly embed parse result of wrapped object? #212

Closed wpyoga closed 1 year ago

wpyoga commented 1 year ago

When I call wrapped with an empty string "" as the name argument, the parsed object is directly embedded into the current object, much like when I call nest without the optional name parameter.

This is very useful for my use case. Is this intentional behavior? If it is, I will submit a patch for the readme. And then I will also submit a patch to make the name parameter optional for the wrapped function.

wpyoga commented 1 year ago

This is a working example:

import { Parser } from 'binary-parser';

const myParser = new Parser()
  .uint8('messageId')
  .uint8('reportCount')
  .array('reports', {
    length: 'reportCount',
    type: new Parser()
      .uint8('reportId')
      .uint8('reportLength')
      .wrapped('', {
        length: 'reportLength',
        wrapper: (buffer) => buffer,
        type: new Parser()
          .nest('basicReport', {
            type: new Parser()
              .uint8('dataPoint1')
              .uint8('dataPoint2')
              .uint8('dataPoint3')
              .uint8('dataPoint4'),
          })
          .array('extendedReport', {
            readUntil: 'eof',
            type: new Parser()
              .uint8('dataType')
              .uint8('dataLength')
              .buffer('data', { length: 'dataLength' }),
          }),
      }),
  });

const buf = Buffer.from(
  '1002f11012345678a003303132a101dfa20255aaf21201020304a003343536a202aa55a101eb',
  'hex'
);

console.dir(myParser.parse(buf), { depth: null });

It will output:

{
  messageId: 16,
  reportCount: 2,
  reports: [
    {
      reportId: 241,
      reportLength: 16,
      basicReport: {
        dataPoint1: 18,
        dataPoint2: 52,
        dataPoint3: 86,
        dataPoint4: 120
      },
      extendedReport: [
        {
          dataType: 160,
          dataLength: 3,
          data: Buffer(3) [Uint8Array] [ 48, 49, 50 ]
        },
        {
          dataType: 161,
          dataLength: 1,
          data: Buffer(1) [Uint8Array] [ 223 ]
        },
        {
          dataType: 162,
          dataLength: 2,
          data: Buffer(2) [Uint8Array] [ 85, 170 ]
        }
      ]
    },
    {
      reportId: 242,
      reportLength: 18,
      basicReport: { dataPoint1: 1, dataPoint2: 2, dataPoint3: 3, dataPoint4: 4 },
      extendedReport: [
        {
          dataType: 160,
          dataLength: 3,
          data: Buffer(3) [Uint8Array] [ 52, 53, 54 ]
        },
        {
          dataType: 162,
          dataLength: 2,
          data: Buffer(2) [Uint8Array] [ 170, 85 ]
        },
        {
          dataType: 161,
          dataLength: 1,
          data: Buffer(1) [Uint8Array] [ 235 ]
        }
      ]
    }
  ]
}

Notice that the wrapped object is directly embedded into the parent object.

keichi commented 1 year ago

Yes, this is expected and should be documented. I would appreciate your PR!

wpyoga commented 1 year ago

Thank you for making this very useful library!