Function getMaskedContext

code/new-context-api/public/app.js:11675–11707

(workInProgress, unmaskedContext)

  }

  function getMaskedContext(workInProgress, unmaskedContext) {
    var type = workInProgress.type;
    var contextTypes = type.contextTypes;
    if (!contextTypes) {
      return emptyObject;
    }

    // Avoid recreating masked context unless unmasked context has changed.
    // Failing to do this will result in unnecessary calls to componentWillReceiveProps.
    // This may trigger infinite loops if componentWillReceiveProps calls setState.
    var instance = workInProgress.stateNode;
    if (instance && instance.__reactInternalMemoizedUnmaskedChildContext === unmaskedContext) {
      return instance.__reactInternalMemoizedMaskedChildContext;
    }

    var context = {};
    for (var key in contextTypes) {
      context[key] = unmaskedContext[key];
    }

    {
      var name = getComponentName(workInProgress) || 'Unknown';
      checkPropTypes(contextTypes, context, 'context', name, ReactDebugCurrentFiber.getCurrentFiberStackAddendum);
    }

    // Cache unmasked context so we can avoid recreating masked context unless necessary.
    // Context is created before the class component is instantiated so check for instance.
    if (instance) {
      cacheContext(workInProgress, unmaskedContext, context);
    }

    return context;
  }

  function hasContextChanged() {
    return didPerformWorkStackCursor.current;