list.js

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

function getDefaultName(type) {
  return 'Array<' + getTypeName(type) + '>';
}

function list(type, name) {

  if (process.env.NODE_ENV !== 'production') {
    assert(isFunction(type), function () { return 'Invalid argument type ' + assert.stringify(type) + ' supplied to list(type, [name]) combinator (expected a type)'; });
    assert(isTypeName(name), function () { return 'Invalid argument name ' + assert.stringify(name) + ' supplied to list(type, [name]) combinator (expected a string)'; });
  }

  var displayName = name || getDefaultName(type);
  var typeNameCache = getTypeName(type);
  var identity = isIdentity(type); // the list is identity iif type is identity

  function List(value, path) {

    if (process.env.NODE_ENV === 'production') {
      if (identity) {
        return value; // just trust the input if elements must not be hydrated
      }
    }

    if (process.env.NODE_ENV !== 'production') {
      path = path || [displayName];
      assert(isArray(value), function () { return 'Invalid value ' + assert.stringify(value) + ' supplied to ' + path.join('/') + ' (expected an array of ' + typeNameCache + ')'; });
    }

    var idempotent = true; // will remain true if I can reutilise the input
    var ret = []; // make a temporary copy, will be discarded if idempotent remains true
    for (var i = 0, len = value.length; i < len; i++ ) {
      var actual = value[i];
      var instance = create(type, actual, ( process.env.NODE_ENV !== 'production' ? path.concat(i + ': ' + typeNameCache) : null ));
      idempotent = idempotent && ( actual === instance );
      ret.push(instance);
    }

    if (idempotent) { // implements idempotency
      ret = value;
    }

    if (process.env.NODE_ENV !== 'production') {
      Object.freeze(ret);
    }

    return ret;
  }

  List.meta = {
    kind: 'list',
    type: type,
    name: name,
    identity: identity
  };

  List.displayName = displayName;

  List.is = function (x) {
    return isArray(x) && x.every(function (e) {
      return is(e, type);
    });
  };

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

  return List;
}

list.getDefaultName = getDefaultName;
module.exports = list;