How it works

Here you can read some details about sharec architecture.

The Core

sharec actively uses middleware pattern dividing all the core logic to simple steps. All the steps can be divided on three groups: read, process and write.

From step to step we're passing FlowContext – structure which includes all the data we need: target package data, loaded configs, cache, processing result; and Semaphore – abstraction controlling the whole process:

(context, semaphore) -> readTargetPackage -> ... -> mergeConfigsPackages -> ... -> writeConfigs -> ...

FlowContext is very similary to Request and Response parameters in express or koa middlewares.

With Semaphore steps can send any data to CLI or even terminate the process.

Schema definiton

sharec allows to describe json and yaml based configurations declaratively providing special utilities in sharec-schema package.

Each field can be processed by helper depending on it's type.

Composed schema is a just function, which can process given data structure in a specific way:

const { compose } = require('sharec-schema').actions
const { primitiveAtom } = require('sharec-schema').atoms

const schema = compose({
  field: primitiveAtom,
})

Schema has special operators: $$default to handle fields, which weren't described and $$ignore to exclude fields from the process:

const { compose } = require('sharec-schema').actions
const { primitiveAtom, hashAtom } = require('sharec-schema').atoms

const schema = compose({
  field: hashAtom,
  $$default: primitiveAtom,
  $$ignore: ['foo', 'bar', 'baz'],
})

Fields that have multiple possible types, can be handled by fork operator. It allows to match field with predicate and apply required function:

const isMap = require('lodash/isMap')
const { compose, fork } = require('sharec-schema').actions
const { hashAtom, listConcatAtom, primitiveAtom } = require('sharec-schema').atoms

const defaultJson = compose({
  $$default: fork([[Array.isArray, listConcatAtom], [isMap, hashAtom], primitiveAtom]),
})

To apply required schema it should be mapped by certain file name or regexp:

const { map } = require('sharec-schema').actions
const { createJsonPipe } = require('sharec-schema').pipes
const { babelJson } = require('./schema')

const babelJsonPipe = createJsonPipe([babelJson])

const babelPipe = map(['.babelrc', babelJsonPipe], ['.babelrc.json', babelJsonPipe], ['babelrc.json', babelJsonPipe])