function declare()

in composer.js [149:179]

• 17 lines of code
• 13 McCabe index (conditional complexity)

function declare (combinators, prefix) {
  if (arguments.length > 2) throw new ComposerError('Too many arguments in "declare"')
  if (!isObject(combinators)) throw new ComposerError('Invalid argument "combinators" in "declare"', combinators)
  if (prefix !== undefined && typeof prefix !== 'string') throw new ComposerError('Invalid argument "prefix" in "declare"', prefix)
  const composer = {}
  for (let key in combinators) {
    const type = prefix ? prefix + '.' + key : key
    const combinator = combinators[key]
    if (!isObject(combinator) || (combinator.args !== undefined && !Array.isArray(combinator.args))) {
      throw new ComposerError(`Invalid "${type}" combinator specification in "declare"`, combinator)
    }
    for (let arg of combinator.args || []) {
      if (typeof arg.name !== 'string') throw new ComposerError(`Invalid "${type}" combinator specification in "declare"`, combinator)
    }
    composer[key] = function () {
      const composition = { type, '.combinator': () => combinator }
      const skip = (combinator.args && combinator.args.length) || 0
      if (!combinator.components && (arguments.length > skip)) {
        throw new ComposerError(`Too many arguments in "${type}" combinator`)
      }
      for (let i = 0; i < skip; ++i) {
        composition[combinator.args[i].name] = arguments[i]
      }
      if (combinator.components) {
        composition.components = Array.prototype.slice.call(arguments, skip)
      }
      return new Composition(composition)
    }
  }
  return composer
}