Fix Clamp crash when entries_ size is zero (#306)

Run ftxui_example_homescreen on Windows, then select compiler tab, crash on origin code.

Co-authored-by: chenpeizhe <peizhe.chen@horizon.ai>

CMakeLists.txt

@@ -23,17 +23,18 @@ else()
 endif()
 
 add_library(screen
+  include/ftxui/screen/box.hpp
+  include/ftxui/screen/color.hpp
+  include/ftxui/screen/color_info.hpp
+  include/ftxui/screen/screen.hpp
+  include/ftxui/screen/string.hpp
   src/ftxui/screen/box.cpp
   src/ftxui/screen/color.cpp
   src/ftxui/screen/color_info.cpp
   src/ftxui/screen/screen.cpp
   src/ftxui/screen/string.cpp
   src/ftxui/screen/terminal.cpp
-  include/ftxui/screen/box.hpp
+  src/ftxui/screen/util.hpp
-  include/ftxui/screen/color.hpp
-  include/ftxui/screen/color_info.hpp
-  include/ftxui/screen/screen.hpp
-  include/ftxui/screen/string.hpp
 )
 
 add_library(dom

src/ftxui/component/menu.cpp

@@ -14,6 +14,7 @@
 #include "ftxui/component/screen_interactive.hpp"  // for Component
 #include "ftxui/dom/elements.hpp"  // for operator|, Element, reflect, text, nothing, select, vbox, Elements, focus
 #include "ftxui/screen/box.hpp"  // for Box
+#include "ftxui/screen/util.hpp"
 #include "ftxui/util/ref.hpp"  // for Ref, ConstStringListRef, ConstStringRef
 
 namespace ftxui {
@@ -74,7 +75,7 @@ class MenuBase : public ComponentBase {
       if (event == Event::TabReverse && size())
         *selected_ = (*selected_ + size() - 1) % size();
 
-      *selected_ = std::clamp(*selected_, 0, size() - 1);
+      *selected_ = util::clamp(*selected_, 0, size() - 1);
 
       if (*selected_ != old_selected) {
         focused_entry() = *selected_;
@@ -131,7 +132,7 @@ class MenuBase : public ComponentBase {
     if (event.mouse().button == Mouse::WheelDown)
       (*selected_)++;
 
-    *selected_ = std::clamp(*selected_, 0, size() - 1);
+    *selected_ = util::clamp(*selected_, 0, size() - 1);
 
     if (*selected_ != old_selected)
       option_->on_change();
@@ -140,8 +141,8 @@ class MenuBase : public ComponentBase {
 
   void Clamp() {
     boxes_.resize(size());
-    *selected_ = std::clamp(*selected_, 0, size() - 1);
+    *selected_ = util::clamp(*selected_, 0, size() - 1);
-    focused_entry() = std::clamp(focused_entry(), 0, size() - 1);
+    focused_entry() = util::clamp(focused_entry(), 0, size() - 1);
   }
 
   bool Focusable() const final { return entries_.size(); }

src/ftxui/component/radiobox.cpp

@@ -14,6 +14,7 @@
 #include "ftxui/component/screen_interactive.hpp"  // for Component
 #include "ftxui/dom/elements.hpp"  // for operator|, reflect, text, Element, hbox, vbox, Elements, focus, nothing, select
 #include "ftxui/screen/box.hpp"    // for Box
+#include "ftxui/screen/util.hpp"
 #include "ftxui/util/ref.hpp"  // for Ref, ConstStringListRef
 
 namespace ftxui {
@@ -91,7 +92,7 @@ class RadioboxBase : public ComponentBase {
       if (event == Event::TabReverse && size())
         hovered_ = (hovered_ + size() - 1) % size();
 
-      hovered_ = std::clamp(hovered_, 0, size() - 1);
+      hovered_ = util::clamp(hovered_, 0, size() - 1);
 
       if (hovered_ != old_hovered) {
         focused_entry() = hovered_;
@@ -145,7 +146,7 @@ class RadioboxBase : public ComponentBase {
     if (event.mouse().button == Mouse::WheelDown)
       (hovered_)++;
 
-    hovered_ = std::clamp(hovered_, 0, size() - 1);
+    hovered_ = util::clamp(hovered_, 0, size() - 1);
 
     if (hovered_ != old_hovered)
       option_->on_change();
@@ -155,9 +156,9 @@ class RadioboxBase : public ComponentBase {
 
   void Clamp() {
     boxes_.resize(size());
-    *selected_ = std::clamp(*selected_, 0, size() - 1);
+    *selected_ = util::clamp(*selected_, 0, size() - 1);
-    focused_entry() = std::clamp(focused_entry(), 0, size() - 1);
+    focused_entry() = util::clamp(focused_entry(), 0, size() - 1);
-    hovered_ = std::clamp(hovered_, 0, size() - 1);
+    hovered_ = util::clamp(hovered_, 0, size() - 1);
   }
 
   bool Focusable() const final { return entries_.size(); }

src/ftxui/component/toggle.cpp

@@ -12,6 +12,7 @@
 #include "ftxui/component/mouse.hpp"  // for Mouse, Mouse::Left, Mouse::Pressed
 #include "ftxui/dom/elements.hpp"  // for operator|, Element, Elements, hbox, reflect, separator, text, focus, nothing, select
 #include "ftxui/screen/box.hpp"    // for Box
+#include "ftxui/screen/util.hpp"
 #include "ftxui/util/ref.hpp"  // for Ref, ConstStringListRef
 
 namespace ftxui {
@@ -68,7 +69,7 @@ class ToggleBase : public ComponentBase {
     if (event == Event::TabReverse && size())
       *selected_ = (*selected_ + size() - 1) % size();
 
-    *selected_ = std::clamp(*selected_, 0, size() - 1);
+    *selected_ = util::clamp(*selected_, 0, size() - 1);
 
     if (old_selected != *selected_) {
       focused_entry() = *selected_;
@@ -108,8 +109,8 @@ class ToggleBase : public ComponentBase {
 
   void Clamp() {
     boxes_.resize(size());
-    *selected_ = std::clamp(*selected_, 0, size() - 1);
+    *selected_ = util::clamp(*selected_, 0, size() - 1);
-    focused_entry() = std::clamp(focused_entry(), 0, size() - 1);
+    focused_entry() = util::clamp(focused_entry(), 0, size() - 1);
   }
 
   bool Focusable() const final { return size(); }

src/ftxui/screen/util.hpp

@@ -0,0 +1,15 @@
+namespace ftxui {
+namespace util {
+
+// Similar to std::clamp, but allow hi to be lower than lo.
+template <class T>
+constexpr const T& clamp(const T& v, const T& lo, const T& hi) {
+  return v < lo ? lo : hi < v ? hi : v;
+}
+
+}  // namespace util
+}  // namespace ftxui
+
+// Copyright 2022 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.

tools/license_headers.cpp

@@ -1,4 +1,4 @@
 
-// Copyright 2021 Arthur Sonzogni. All rights reserved.
+// Copyright 2022 Arthur Sonzogni. All rights reserved.
 // Use of this source code is governed by the MIT license that can be found in
 // the LICENSE file.