Allows components to remove a child or access to children in general (#152)

Allows components to remove a child or access to children in general.

Co-authored-by: Felix Heitmann <fheitmann@se-gpu-03.intern.plath.de>
Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

include/ftxui/component/component_base.hpp

@@ -26,9 +26,13 @@ class ComponentBase {
   ComponentBase() = default;
   virtual ~ComponentBase();
 
-  // ComponentBase hierarchy.
+  // Component hierarchy:
   ComponentBase* Parent();
+  Component& ChildAt(size_t i);
+  size_t ChildCount() const;
   void Add(Component children);
+  void Detach();
+  void DetachAllChildren();
 
   // Renders the component.
   virtual Element Render();
@@ -67,7 +71,6 @@ class ComponentBase {
 
  private:
   ComponentBase* parent_ = nullptr;
-  void Detach();
 };
 
 using Component = std::shared_ptr<ComponentBase>;

src/ftxui/component/component.cpp

@@ -1,4 +1,6 @@
+#include <stddef.h>   // for size_t
 #include <algorithm>  // for find_if, max
+#include <cassert>    // for assert
 #include <iterator>   // for begin, end
 #include <utility>    // for move
 
@@ -24,7 +26,6 @@ ComponentBase::~ComponentBase() {
 }
 
 /// @brief Return the parent ComponentBase, or nul if any.
-/// @see Attach
 /// @see Detach
 /// @see Parent
 /// @ingroup component
@@ -32,7 +33,20 @@ ComponentBase* ComponentBase::Parent() {
   return parent_;
 }
 
-/// @brief Add a children.
+/// @brief Access the child at index `i`.
+/// @ingroup component
+Component& ComponentBase::ChildAt(size_t i) {
+  assert(i < ChildCount());
+  return children_[i];
+}
+
+/// @brief Returns the number of children.
+/// @ingroup component
+size_t ComponentBase::ChildCount() const {
+  return children_.size();
+}
+
+/// @brief Add a child.
 /// @@param child The child to be attached.
 /// @ingroup component
 void ComponentBase::Add(Component child) {
@@ -41,6 +55,29 @@ void ComponentBase::Add(Component child) {
   children_.push_back(std::move(child));
 }
 
+/// @brief Detach this child from its parent.
+/// @see Detach
+/// @see Parent
+/// @ingroup component
+void ComponentBase::Detach() {
+  if (!parent_)
+    return;
+  auto it = std::find_if(std::begin(parent_->children_),  //
+                         std::end(parent_->children_),    //
+                         [this](const Component& that) {  //
+                           return this == that.get();
+                         });
+  parent_->children_.erase(it);
+  parent_ = nullptr;
+}
+
+/// @brief Remove all children.
+/// @ingroup component
+void ComponentBase::DetachAllChildren() {
+  while (!children_.empty())
+    children_[0]->Detach();
+}
+
 /// @brief Draw the component.
 /// Build a ftxui::Element to be drawn on the ftxi::Screen representing this
 /// ftxui::ComponentBase.
@@ -129,23 +166,6 @@ CapturedMouse ComponentBase::CaptureMouse(const Event& event) {
   return event.screen_->CaptureMouse();
 }
 
-/// @brief Detach this children from its parent.
-/// @see Attach
-/// @see Detach
-/// @see Parent
-/// @ingroup component
-void ComponentBase::Detach() {
-  if (!parent_)
-    return;
-  auto it = std::find_if(std::begin(parent_->children_),  //
-                         std::end(parent_->children_),    //
-                         [this](const Component& that) {  //
-                           return this == that.get();
-                         });
-  parent_->children_.erase(it);
-  parent_ = nullptr;
-}
-
 }  // namespace ftxui
 
 // Copyright 2020 Arthur Sonzogni. All rights reserved.

src/ftxui/component/component_test.cpp

@@ -1,8 +1,10 @@
-#include <memory>  // for shared_ptr, allocator, make_shared, __shared_ptr_access
+#include <gtest/gtest-message.h>    // for Message
+#include <gtest/gtest-test-part.h>  // for TestPartResult
+#include <memory>  // for shared_ptr, __shared_ptr_access, allocator, make_shared
 
 #include "ftxui/component/captured_mouse.hpp"  // for ftxui
 #include "ftxui/component/component_base.hpp"  // for ComponentBase, Component
-#include "gtest/gtest_pred_impl.h"  // for Test, SuiteApiResolver, TEST, TestFactoryImpl
+#include "gtest/gtest_pred_impl.h"  // for EXPECT_EQ, Test, SuiteApiResolver, TEST, TestFactoryImpl
 
 using namespace ftxui;
 
@@ -30,6 +32,129 @@ TEST(ContainerTest, DeleteChildFirst) {
   parent.reset();
 }
 
+TEST(ContainerTest, Detach) {
+  auto parent = Make();
+  auto child_1 = Make();
+  auto child_2 = Make();
+  auto child_3 = Make();
+  parent->Add(child_1);
+  parent->Add(child_2);
+  parent->Add(child_3);
+
+  EXPECT_EQ(parent->ChildCount(), 3u);
+  EXPECT_EQ(child_1->Parent(), parent.get());
+  EXPECT_EQ(child_2->Parent(), parent.get());
+  EXPECT_EQ(child_3->Parent(), parent.get());
+
+  child_2->Detach();
+
+  EXPECT_EQ(parent->ChildCount(), 2u);
+  EXPECT_EQ(child_1->Parent(), parent.get());
+  EXPECT_EQ(child_2->Parent(), nullptr);
+  EXPECT_EQ(child_3->Parent(), parent.get());
+
+  child_2->Detach();
+
+  EXPECT_EQ(parent->ChildCount(), 2u);
+  EXPECT_EQ(child_1->Parent(), parent.get());
+  EXPECT_EQ(child_2->Parent(), nullptr);
+  EXPECT_EQ(child_3->Parent(), parent.get());
+
+  child_1->Detach();
+
+  EXPECT_EQ(parent->ChildCount(), 1u);
+  EXPECT_EQ(child_1->Parent(), nullptr);
+  EXPECT_EQ(child_2->Parent(), nullptr);
+  EXPECT_EQ(child_3->Parent(), parent.get());
+
+  child_3->Detach();
+
+  EXPECT_EQ(parent->ChildCount(), 0u);
+  EXPECT_EQ(child_1->Parent(), nullptr);
+  EXPECT_EQ(child_2->Parent(), nullptr);
+  EXPECT_EQ(child_3->Parent(), nullptr);
+}
+
+TEST(ContainerTest, DetachAllChild) {
+  auto parent = Make();
+  auto child_1 = Make();
+  auto child_2 = Make();
+  auto child_3 = Make();
+  parent->Add(child_1);
+  parent->Add(child_2);
+  parent->Add(child_3);
+
+  EXPECT_EQ(parent->ChildCount(), 3u);
+  EXPECT_EQ(child_1->Parent(), parent.get());
+  EXPECT_EQ(child_2->Parent(), parent.get());
+  EXPECT_EQ(child_3->Parent(), parent.get());
+
+  parent->DetachAllChild();
+
+  EXPECT_EQ(parent->ChildCount(), 0u);
+  EXPECT_EQ(child_1->Parent(), nullptr);
+  EXPECT_EQ(child_2->Parent(), nullptr);
+  EXPECT_EQ(child_3->Parent(), nullptr);
+}
+
+TEST(ContainerTest, Add) {
+  auto parent = Make();
+  auto child_1 = Make();
+  auto child_2 = Make();
+
+  EXPECT_EQ(parent->ChildCount(), 0u);
+  EXPECT_EQ(child_1->Parent(), nullptr);
+  EXPECT_EQ(child_2->Parent(), nullptr);
+
+  parent->Add(child_1);
+
+  EXPECT_EQ(parent->ChildCount(), 1u);
+  EXPECT_EQ(child_1->Parent(), parent.get());
+  EXPECT_EQ(child_2->Parent(), nullptr);
+
+  parent->Add(child_1);
+
+  EXPECT_EQ(parent->ChildCount(), 1u);
+  EXPECT_EQ(child_1->Parent(), parent.get());
+  EXPECT_EQ(child_2->Parent(), nullptr);
+
+  parent->Add(child_2);
+
+  EXPECT_EQ(parent->ChildCount(), 2u);
+  EXPECT_EQ(child_1->Parent(), parent.get());
+  EXPECT_EQ(child_2->Parent(), parent.get());
+}
+
+TEST(ContainerTest, ChildAt) {
+  auto parent = Make();
+  auto child_1 = Make();
+  auto child_2 = Make();
+
+  EXPECT_EQ(parent->ChildCount(), 0u);
+
+  parent->Add(child_1);
+
+  EXPECT_EQ(parent->ChildCount(), 1u);
+  EXPECT_EQ(parent->ChildAt(0u), child_1);
+
+  parent->Add(child_2);
+
+  EXPECT_EQ(parent->ChildCount(), 2u);
+  EXPECT_EQ(parent->ChildAt(0u), child_1);
+  EXPECT_EQ(parent->ChildAt(1u), child_2);
+
+  parent->Add(child_1);
+
+  EXPECT_EQ(parent->ChildCount(), 2u);
+  EXPECT_EQ(parent->ChildAt(0u), child_2);
+  EXPECT_EQ(parent->ChildAt(1u), child_1);
+
+  child_1->Detach();
+
+  EXPECT_EQ(parent->ChildCount(), 1u);
+  EXPECT_EQ(parent->ChildAt(0u), child_2);
+}
+
 // Copyright 2020 Arthur Sonzogni. All rights reserved.
 // Use of this source code is governed by the MIT license that can be found in
 // the LICENSE file.