stb_textedit.h: proposal for upstream PR to allow custom move-left/move-right handlers (following #473)

stb_textedit.h

@@ -1,5 +1,6 @@
 // [ImGui] this is a slightly modified version of stb_truetype.h 1.8
 // [ImGui] - fixed some minor warnings
+// [ImGui] - added STB_TEXTEDIT_MOVEWORDLEFT/STB_TEXTEDIT_MOVEWORDRIGHT custom handler (#473)
 
 // stb_textedit.h - v1.8  - public domain - Sean Barrett
 // Development of this library was sponsored by RAD Game Tools
@@ -151,15 +152,17 @@
 //    STB_TEXTEDIT_K_REDO        keyboard input to perform redo
 //
 // Optional:
-//    STB_TEXTEDIT_K_INSERT      keyboard input to toggle insert mode
-//    STB_TEXTEDIT_IS_SPACE(ch)  true if character is whitespace (e.g. 'isspace'),
-//                                 required for WORDLEFT/WORDRIGHT
-//    STB_TEXTEDIT_K_WORDLEFT    keyboard input to move cursor left one word // e.g. ctrl-LEFT
-//    STB_TEXTEDIT_K_WORDRIGHT   keyboard input to move cursor right one word // e.g. ctrl-RIGHT
-//    STB_TEXTEDIT_K_LINESTART2  secondary keyboard input to move cursor to start of line
-//    STB_TEXTEDIT_K_LINEEND2    secondary keyboard input to move cursor to end of line
-//    STB_TEXTEDIT_K_TEXTSTART2  secondary keyboard input to move cursor to start of text
-//    STB_TEXTEDIT_K_TEXTEND2    secondary keyboard input to move cursor to end of text
+//    STB_TEXTEDIT_K_INSERT              keyboard input to toggle insert mode
+//    STB_TEXTEDIT_IS_SPACE(ch)          true if character is whitespace (e.g. 'isspace'),
+//                                          required for default WORDLEFT/WORDRIGHT handlers
+//    STB_TEXTEDIT_MOVEWORDLEFT(obj,i)   custom handler for WORDLEFT, returns index to move cursor to
+//    STB_TEXTEDIT_MOVEWORDRIGHT(obj,i)  custom handler for WORDRIGHT, returns index to move cursor to
+//    STB_TEXTEDIT_K_WORDLEFT            keyboard input to move cursor left one word // e.g. ctrl-LEFT
+//    STB_TEXTEDIT_K_WORDRIGHT           keyboard input to move cursor right one word // e.g. ctrl-RIGHT
+//    STB_TEXTEDIT_K_LINESTART2          secondary keyboard input to move cursor to start of line
+//    STB_TEXTEDIT_K_LINEEND2            secondary keyboard input to move cursor to end of line
+//    STB_TEXTEDIT_K_TEXTSTART2          secondary keyboard input to move cursor to start of text
+//    STB_TEXTEDIT_K_TEXTEND2            secondary keyboard input to move cursor to end of text
 //
 // Todo:
 //    STB_TEXTEDIT_K_PGUP        keyboard input to move cursor up a page
@@ -618,9 +621,9 @@ static int is_word_boundary( STB_TEXTEDIT_STRING *_str, int _idx )
    return _idx > 0 ? (STB_TEXTEDIT_IS_SPACE( STB_TEXTEDIT_GETCHAR(_str,_idx-1) ) && !STB_TEXTEDIT_IS_SPACE( STB_TEXTEDIT_GETCHAR(_str, _idx) ) ) : 1;
 }
 
-static int stb_textedit_move_to_word_previous( STB_TEXTEDIT_STRING *_str, STB_TexteditState *_state )
+#ifndef STB_TEXTEDIT_MOVEWORDLEFT
+static int stb_textedit_move_to_word_previous( STB_TEXTEDIT_STRING *_str, int c )
 {
-   int c = _state->cursor - 1;
    while( c >= 0 && !is_word_boundary( _str, c ) )
       --c;
 
@@ -629,11 +632,13 @@ static int stb_textedit_move_to_word_previous( STB_TEXTEDIT_STRING *_str, STB_Te
 
    return c;
 }
+#define STB_TEXTEDIT_MOVEWORDLEFT stb_textedit_move_to_word_previous
+#endif
 
-static int stb_textedit_move_to_word_next( STB_TEXTEDIT_STRING *_str, STB_TexteditState *_state )
+#ifndef STB_TEXTEDIT_MOVEWORDRIGHT
+static int stb_textedit_move_to_word_next( STB_TEXTEDIT_STRING *_str, int c )
 {
    const int len = STB_TEXTEDIT_STRINGLEN(_str);
-   int c = _state->cursor+1;
    while( c < len && !is_word_boundary( _str, c ) )
       ++c;
 
@@ -642,6 +647,9 @@ static int stb_textedit_move_to_word_next( STB_TEXTEDIT_STRING *_str, STB_Texted
 
    return c;
 }
+#define STB_TEXTEDIT_MOVEWORDRIGHT stb_textedit_move_to_word_next
+#endif
+
 #endif
 
 // update selection and cursor to match each other
@@ -763,21 +771,12 @@ retry:
          state->has_preferred_x = 0;
          break;
 
-#ifdef STB_TEXTEDIT_IS_SPACE
+#ifdef STB_TEXTEDIT_MOVEWORDLEFT
       case STB_TEXTEDIT_K_WORDLEFT:
          if (STB_TEXT_HAS_SELECTION(state))
             stb_textedit_move_to_first(state);
          else {
-            state->cursor = stb_textedit_move_to_word_previous(str, state);
-            stb_textedit_clamp( str, state );
-         }
-         break;
-
-      case STB_TEXTEDIT_K_WORDRIGHT:
-         if (STB_TEXT_HAS_SELECTION(state)) 
-            stb_textedit_move_to_last(str, state);
-         else {
-            state->cursor = stb_textedit_move_to_word_next(str, state);
+            state->cursor = STB_TEXTEDIT_MOVEWORDLEFT(str, state->cursor-1);
             stb_textedit_clamp( str, state );
          }
          break;
@@ -786,17 +785,28 @@ retry:
          if( !STB_TEXT_HAS_SELECTION( state ) )
             stb_textedit_prep_selection_at_cursor(state);
 
-         state->cursor = stb_textedit_move_to_word_previous(str, state);
+         state->cursor = STB_TEXTEDIT_MOVEWORDLEFT(str, state->cursor-1);
          state->select_end = state->cursor;
 
          stb_textedit_clamp( str, state );
          break;
+#endif
+
+#ifdef STB_TEXTEDIT_MOVEWORDRIGHT
+      case STB_TEXTEDIT_K_WORDRIGHT:
+         if (STB_TEXT_HAS_SELECTION(state)) 
+            stb_textedit_move_to_last(str, state);
+         else {
+            state->cursor = STB_TEXTEDIT_MOVEWORDRIGHT(str, state->cursor+1);
+            stb_textedit_clamp( str, state );
+         }
+         break;
 
       case STB_TEXTEDIT_K_WORDRIGHT | STB_TEXTEDIT_K_SHIFT:
          if( !STB_TEXT_HAS_SELECTION( state ) )
             stb_textedit_prep_selection_at_cursor(state);
 
-         state->cursor = stb_textedit_move_to_word_next(str, state);
+         state->cursor = STB_TEXTEDIT_MOVEWORDRIGHT(str, state->cursor+1);
          state->select_end = state->cursor;
 
          stb_textedit_clamp( str, state );