Add string view overloads (#1154)

This is better ergonomic, as `std::string_view` is lightweight and accept more conversion than `const std::string&`.

Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

include/ftxui/screen/screen.hpp

@@ -68,7 +68,7 @@ class Screen : public Image {
 
   // Store an hyperlink in the screen. Return the id of the hyperlink. The id is
   // used to identify the hyperlink when the user click on it.
-  uint8_t RegisterHyperlink(const std::string& link);
+  uint8_t RegisterHyperlink(std::string_view link);
   const std::string& Hyperlink(uint8_t id) const;
 
   using SelectionStyle = std::function<void(Pixel&)>;

include/ftxui/screen/string.hpp

@@ -4,27 +4,32 @@
 #ifndef FTXUI_SCREEN_STRING_HPP
 #define FTXUI_SCREEN_STRING_HPP
 
-#include <string>  // for string, wstring, to_string
-#include <vector>  // for vector
+#include <string>       // for string, wstring, to_string
+#include <string_view>  // for string_view
+#include <vector>       // for vector
 
 namespace ftxui {
-std::string to_string(const std::wstring& s);
-std::wstring to_wstring(const std::string& s);
+std::string to_string(std::wstring_view s);
+std::wstring to_wstring(std::string_view s);
 
 template <typename T>
 std::wstring to_wstring(T s) {
-  return to_wstring(std::to_string(s));
+  return to_wstring(std::string_view(std::to_string(s)));
+}
+template <>
+inline std::wstring to_wstring(const char* s) {
+  return to_wstring(std::string_view(s));
 }
 
-int string_width(const std::string&);
+int string_width(std::string_view);
 
 // Split the string into a its glyphs. An empty one is inserted ater fullwidth
 // ones.
-std::vector<std::string> Utf8ToGlyphs(const std::string& input);
+std::vector<std::string> Utf8ToGlyphs(std::string_view input);
 
 // Map every cells drawn by |input| to their corresponding Glyphs. Half-size
 // Glyphs takes one cell, full-size Glyphs take two cells.
-std::vector<int> CellToGlyphIndex(const std::string& input);
+std::vector<int> CellToGlyphIndex(std::string_view input);
 
 }  // namespace ftxui