Stamp factory which allows extra properties

compose2.js

const assign = require('@stamp/core/assign')
const compose = require('@stamp/compose')
const isStamp = require('@stamp/is/stamp')
const merge = require('@stamp/core/merge')

const STAMP_DESCRIPTOR_VOID = {
  'methods': {},
  'properties': {},
  'deepProperties': {},
  'propertyDescriptors': {},
  'staticProperties': {},
  'staticDeepProperties': {},
  'staticPropertyDescriptors': {},
  'initializers': [],
  'composers': [],
  'configuration': {},
  'deepConfiguration': {}
}

const compose2 = compose.bind({
  composers: [extraComposer]
})

function extraComposer ({stamp, composables}) {
  for (let i = 0; i < composables.length; ++i) {
    const composable = composables[i]
    const descriptor = isStamp(composable) ? composable.compose : composable

    for (let key in descriptor) {
      if (key in STAMP_DESCRIPTOR_VOID) {
        continue
      }

      if (!(key in stamp.compose)) {
        stamp.compose[key] = descriptor[key]

        continue
      }

      if (Array.isArray(stamp.compose[key])) {
        stamp.compose[key].push(...descriptor[key])

        continue
      }

      if (/deep|Deep/.test(key)) {
        merge(stamp.compose[key], descriptor[key])

        continue
      }

      assign(stamp.compose[key], descriptor[key])
    }
  }
}

module.exports = compose2

example.js

const s = compose2({
  foobar: {
    foo: {
      bar: ['bar']
    }
  },
  deepFoobar: {
    foo: {
      bar: ['bar']
    }
  }
}).compose({
  foobar: {
    foo: {
      bar: ['BAR']
    }
  },
  deepFoobar: {
    foo: {
      bar: ['BAR']
    }
  }
})

// { [Function: Stamp]
//   compose:
//    { [Function: _compose]
//      composers: [ [Function: extraComposer] ],
//      foobar: { foo: { bar: [ 'BAR' ] } },
//      deepFoobar: { foo: { bar: [ 'bar', 'BAR' ] } } } }