From a643b23486d77b6b9bdfbe9f58a17673d62eaac6 Mon Sep 17 00:00:00 2001
From: ocornut <omarcornut@gmail.com>
Date: Mon, 30 Nov 2020 09:43:10 +0100
Subject: [PATCH] ImStrv: added imconfig class extension example, added natvis
 description.

---
 imconfig.h                  | 9 +++++++++
 imgui.h                     | 9 +++++----
 misc/debuggers/imgui.natvis | 5 +++++
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/imconfig.h b/imconfig.h
index c854832e..976f9ecd 100644
--- a/imconfig.h
+++ b/imconfig.h
@@ -90,6 +90,15 @@
         operator MyVec4() const { return MyVec4(x,y,z,w); }
 */
 
+//---- Define constructor to convert your string type to ImStrv (which is a non-owning begin/end pair)
+// This will be inlined as part of ImStrv class declaration.
+// This has two benefits: you won't need to use .c_str(), if length is already computed it is faster.
+//#include <string>
+//#include <string_view>
+//#define IM_STR_CLASS_EXTRA    ImStrv(const std::string& s)      { Begin = s.c_str(); End = Begin + s.length(); }
+//#define IM_STR_CLASS_EXTRA    ImStrv(const std::string_view& s) { Begin = s.data(); End = Begin + s.length(); }
+//#define IM_STR_CLASS_EXTRA    ImStrv(const MyString& s)         { Begin = s.Data; End = s.end(); }
+
 //---- Use 32-bit vertex indices (default is 16-bit) is one way to allow large meshes with more than 64K vertices.
 // Your renderer backend will need to support it (most example renderer backends support both 16/32-bit indices).
 // Another way to allow large meshes while keeping 16-bit indices is to handle ImDrawCmd::VtxOffset in your renderer.
diff --git a/imgui.h b/imgui.h
index ad9801bb..0d286445 100644
--- a/imgui.h
+++ b/imgui.h
@@ -269,7 +269,8 @@ struct ImVec4
 #endif
 };
 
-// String view class.
+// String view (non-owning pair of begin/end pointers, not necessarily zero-terminated)
+// ImStrv are used as function parameters instead of passing a pair of const char*.
 #define IMGUI_HAS_IMSTR
 struct ImStrv
 {
@@ -280,9 +281,9 @@ struct ImStrv
     ImStrv(const char* b, const char* e){ Begin = b; End = e ? e : b + strlen(b); }
     inline size_t length() const        { return (size_t)(End - Begin); }
     inline bool empty() const           { return Begin == End; }    // == "" or == NULL
-    inline operator bool() const        { return Begin != NULL; }   // != NULL
-#ifdef IM_IMSTR_CLASS_EXTRA
-    IM_IMSTR_CLASS_EXTRA     // Define additional constructors and implicit cast operators in imconfig.h to convert back and forth between your string types and ImStrv.
+    inline operator bool() const        { return Begin != NULL; }   // return true when valid ("" is valid, NULL construction is not)
+#ifdef IM_STR_CLASS_EXTRA
+    IM_STR_CLASS_EXTRA     // Define additional constructor in imconfig.h to convert your string types (e.g. std::string, std::string_view) to ImStrV.
 #endif
     // private: bool operator==(ImStrv) { return false; } // [DEBUG] Uncomment to catch undesirable uses of operators
     // private: bool operator!=(ImStrv) { return false; }
diff --git a/misc/debuggers/imgui.natvis b/misc/debuggers/imgui.natvis
index 13b63600..7d0c9dd1 100644
--- a/misc/debuggers/imgui.natvis
+++ b/misc/debuggers/imgui.natvis
@@ -51,6 +51,11 @@ More information at: https://docs.microsoft.com/en-us/visualstudio/debugger/crea
   </Expand>
 </Type>
 
+<!-- String view (non zero-terminated begin/end pair) -->
+<Type Name="ImStrv">
+  <DisplayString>{Begin,[End-Begin]s} ({End-Begin,d})</DisplayString>
+</Type>
+
 <Type Name="ImGuiWindow">
   <DisplayString>{{Name {Name,s} Active {(Active||WasActive)?1:0,d} Child {(Flags &amp; 0x01000000)?1:0,d} Popup {(Flags &amp; 0x04000000)?1:0,d} Hidden {(Hidden)?1:0,d}}</DisplayString>
 </Type>