bindings.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {devModeEqual} from '../change_detection/change_detection_util';
import {assertDataInRange, assertLessThan, assertNotSame} from '../util/assert';
import {throwErrorIfNoChangesMode} from './errors';
import {LView} from './interfaces/view';
import {getCheckNoChangesMode} from './state';
import {NO_CHANGE} from './tokens';
import {isDifferent} from './util/misc_utils';



// TODO(misko): consider inlining
/** Updates binding and returns the value. */
export function updateBinding(lView: LView, bindingIndex: number, value: any): any {
  return lView[bindingIndex] = value;
}


/** Gets the current binding value. */
export function getBinding(lView: LView, bindingIndex: number): any {
  ngDevMode && assertDataInRange(lView, bindingIndex);
  ngDevMode &&
      assertNotSame(lView[bindingIndex], NO_CHANGE, 'Stored value should never be NO_CHANGE.');
  return lView[bindingIndex];
}

/** Updates binding if changed, then returns whether it was updated. */
export function bindingUpdated(lView: LView, bindingIndex: number, value: any): boolean {
  ngDevMode && assertNotSame(value, NO_CHANGE, 'Incoming value should never be NO_CHANGE.');
  ngDevMode &&
      assertLessThan(bindingIndex, lView.length, `Slot should have been initialized to NO_CHANGE`);

  const oldValue = lView[bindingIndex];
  if (isDifferent(oldValue, value)) {
    if (ngDevMode && getCheckNoChangesMode()) {
      // View engine didn't report undefined values as changed on the first checkNoChanges pass
      // (before the change detection was run).
      const oldValueToCompare = oldValue !== NO_CHANGE ? oldValue : undefined;
      if (!devModeEqual(oldValueToCompare, value)) {
        throwErrorIfNoChangesMode(oldValue === NO_CHANGE, oldValueToCompare, value);
      }
    }
    lView[bindingIndex] = value;
    return true;
  }

  return false;
}

/** Updates 2 bindings if changed, then returns whether either was updated. */
export function bindingUpdated2(lView: LView, bindingIndex: number, exp1: any, exp2: any): boolean {
  const different = bindingUpdated(lView, bindingIndex, exp1);
  return bindingUpdated(lView, bindingIndex + 1, exp2) || different;
}

/** Updates 3 bindings if changed, then returns whether any was updated. */
export function bindingUpdated3(
    lView: LView, bindingIndex: number, exp1: any, exp2: any, exp3: any): boolean {
  const different = bindingUpdated2(lView, bindingIndex, exp1, exp2);
  return bindingUpdated(lView, bindingIndex + 2, exp3) || different;
}

/** Updates 4 bindings if changed, then returns whether any was updated. */
export function bindingUpdated4(
    lView: LView, bindingIndex: number, exp1: any, exp2: any, exp3: any, exp4: any): boolean {
  const different = bindingUpdated2(lView, bindingIndex, exp1, exp2);
  return bindingUpdated2(lView, bindingIndex + 2, exp3, exp4) || different;
}