ComponentKit/Core/Scope/CKComponentScope.mm

/*
 *  Copyright (c) 2014-present, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 *
 */

#import "CKComponentScope.h"

#import "CKAnalyticsListener.h"
#import "CKComponentScopeHandle.h"
#import "CKComponentScopeRoot.h"
#import "CKThreadLocalComponentScope.h"
#import "CKTreeNode.h"

#import <ComponentKit/CKRenderHelpers.h>
#import <ComponentKit/CKCoalescedSpecSupport.h>

static auto toInitialStateCreator(id (^initialStateCreator)(void), Class componentClass) {
  return initialStateCreator ?: ^{
    return [componentClass initialState];
  };
}

CKComponentScope::~CKComponentScope()
{
  if (_threadLocalScope != nullptr) {
    [_node.scopeHandle resolveAndRegisterInScopeRoot:_threadLocalScope->newScopeRoot];

    if (_threadLocalScope->systraceListener) {
      auto const componentTypeName = _node.scopeHandle.componentTypeName ?: "UnkownTypeName";
      RCCAssertWithCategory(objc_getClass(componentTypeName) != nil,
                            [NSString stringWithUTF8String:componentTypeName],
                            @"Creating an action from a scope should always yield a class");

      [_threadLocalScope->systraceListener didBuildComponent:componentTypeName];
    }

    _threadLocalScope->pop(YES, YES);
  }
}

CKComponentScope::CKComponentScope(Class __unsafe_unretained componentClass, id identifier, id (^initialStateCreator)(void)) noexcept
{
  RCCAssert(class_isMetaClass(object_getClass(componentClass)), @"Expected %@ to be a meta class", componentClass);
  RCCWarnWithCategory(
    [componentClass conformsToProtocol:@protocol(CKReusableComponentProtocol)] == NO,
    NSStringFromClass(componentClass),
    @"Reusable components shouldn't use scopes.");
  RCCAssertWithCategory(
    identifier == nil ||
    class_isMetaClass(object_getClass(identifier)) ||
    [identifier conformsToProtocol:@protocol(CKComponentProtocol)] == NO,
    NSStringFromClass(componentClass),
    @"Identifier should never be an instance of CKComponent. Identifiers should be **constant**.");
  RCCAssertWithCategory(
    identifier != componentClass,
    NSStringFromClass(componentClass),
    @"Passing the component class as the identifier is redundant.");

  _threadLocalScope = CKThreadLocalComponentScope::currentScope();
  if (_threadLocalScope != nullptr) {
    RCCWarnWithCategory(
      [componentClass isSubclassOfClass:[CKComponent class]] == _threadLocalScope->enforceCKComponentSubclasses,
      NSStringFromClass(componentClass),
      @"Component type doesn't match the TLS's type. Have you created the component **outside** a component provider function?");

    const auto componentTypeName = class_getName(componentClass);

    [_threadLocalScope->systraceListener willBuildComponent:componentTypeName];

    const auto& pair = _threadLocalScope->stack.top();
    const auto childPair = [CKTreeNode childPairForPair:pair
                                                newRoot:_threadLocalScope->newScopeRoot
                                      componentTypeName:componentTypeName
                                             identifier:identifier
                                                   keys:_threadLocalScope->keys.top()
                                         initialStateCreator:toInitialStateCreator(initialStateCreator, componentClass)
                                                stateUpdates:_threadLocalScope->stateUpdates
                                         requiresScopeHandle:YES];
    _node = childPair.node;

    const auto ancestorHasStateUpdate =
        _threadLocalScope->coalescingMode == RCComponentCoalescingModeComposite &&
         _threadLocalScope->buildTrigger == CKBuildTriggerStateUpdate &&
        (_threadLocalScope->ancestorHasStateUpdate.top() ||
           CKRender::componentHasStateUpdate(
               _node,
               pair.previousNode,
               _threadLocalScope->buildTrigger,
             _threadLocalScope->stateUpdates));

    _threadLocalScope->push({.node = childPair.node, .previousNode = childPair.previousNode}, YES, ancestorHasStateUpdate);
  }
  RCCAssertWithCategory(_threadLocalScope != nullptr,
                        NSStringFromClass(componentClass),
                        @"Component with scope must be created inside component provider function.");
}

id CKComponentScope::state(void) const noexcept
{
  return _node.state;
}

CKTreeNodeIdentifier CKComponentScope::identifier(void) const noexcept
{
  return _node.nodeIdentifier;
}

void CKComponentScope::replaceState(const CKComponentScope &scope, id state) noexcept
{
  [scope._node.scopeHandle replaceState:state];
}

CKComponentStateUpdater CKComponentScope::stateUpdater(void) const noexcept
{
  // We must capture `node` in a local, since `this` may be destroyed by the time the block executes.
  CKTreeNode *const node = _node;
  return ^(id (^stateUpdate)(id), NSDictionary<NSString *, id> *userInfo, CKUpdateMode mode) {
    [node.scopeHandle updateState:stateUpdate
                         metadata:{.userInfo = userInfo}
                             mode:mode];
  };
}

CKTreeNode *CKComponentScope::node(void) const noexcept
{
  return _node;
}