intersection.js

var assert = require('./assert');
var isTypeName = require('./isTypeName');
var isFunction = require('./isFunction');
var isArray = require('./isArray');
var forbidNewOperator = require('./isIdentity');
var is = require('./is');
var getTypeName = require('./getTypeName');
var isIdentity = require('./isIdentity');

function getDefaultName(types) {
  return types.map(getTypeName).join(' & ');
}

function intersection(types, name) {

  if (process.env.NODE_ENV !== 'production') {
    assert(isArray(types) && types.every(isFunction) && types.length >= 2, function () { return 'Invalid argument types ' + assert.stringify(types) + ' supplied to intersection(types, [name]) combinator (expected an array of at least 2 types)'; });
    assert(isTypeName(name), function () { return 'Invalid argument name ' + assert.stringify(name) + ' supplied to intersection(types, [name]) combinator (expected a string)'; });
  }

  var displayName = name || getDefaultName(types);
  var identity = types.every(isIdentity);

  function Intersection(value, path) {

    if (process.env.NODE_ENV !== 'production') {
      if (identity) {
        forbidNewOperator(this, Intersection);
      }
      path = path || [displayName];
      assert(Intersection.is(value), function () { return 'Invalid value ' + assert.stringify(value) + ' supplied to ' + path.join('/'); });
    }

    return value;
  }

  Intersection.meta = {
    kind: 'intersection',
    types: types,
    name: name,
    identity: identity
  };

  Intersection.displayName = displayName;

  Intersection.is = function (x) {
    return types.every(function (type) {
      return is(x, type);
    });
  };

  Intersection.update = function (instance, patch) {
    return Intersection(assert.update(instance, patch));
  };

  return Intersection;
}

intersection.getDefaultName = getDefaultName;
module.exports = intersection;