editor: add 'delete_forward' and 'delete' key-binding

This also renames 'backspace' to 'delete_backward' for consistency.

editor/editor.hpp

@@ -83,7 +83,8 @@ struct buffer {
   inline static constexpr line<C> * incref(line<C> * l);
   inline static constexpr int32_t line_length(line<C> const * const l);
   inline constexpr bool put(uint8_t c);
-  inline constexpr bool backspace();
+  inline constexpr bool delete_backward();
+  inline constexpr bool delete_forward();
   inline constexpr bool cursor_left();
   inline constexpr bool cursor_right();
   inline constexpr bool cursor_up();
@@ -239,7 +240,7 @@ inline constexpr bool buffer<C, R>::put(const uint8_t c)
 }
 
 template <int C, int R>
-inline constexpr bool buffer<C, R>::backspace()
+inline constexpr bool buffer<C, R>::delete_backward()
 {
   if (this->mode == mode::mark) {
     this->mode = mode::normal;
@@ -274,11 +275,48 @@ inline constexpr bool buffer<C, R>::backspace()
     line<C> * l = mutref(this->lines[cur.row]);
     int32_t length = l->length - cur.col;
     move(&l->buf[cur.col-1], &l->buf[cur.col], length);
+    l->length--;
 
     cur.col--;
     scroll_left();
+  }
+
+  return true;
+}
+
+template <int C, int R>
+inline constexpr bool buffer<C, R>::delete_forward()
+{
+  if (this->mode == mode::mark) {
+    this->mode = mode::normal;
+    return mark_delete();
+  }
+
+  editor::cursor& cur = this->cursor;
+
+  if (cur.col < 0 || cur.col > C)
+    return false;
+
+  if (line_length(this->lines[cur.row]) == 0) {
+    if (this->length == 1) return false;
+    decref(this->lines[cur.row]);
+    // shift all lines up by 1
+    int32_t n_lines = this->length - (cur.row + 1);
+    move(&this->lines[cur.row],
+	 &this->lines[cur.row+1],
+	 (sizeof (line<C>*)) * n_lines);
+    this->length--;
+    this->lines[this->length] = nullptr;
+    // no scrolling needed--cursor is already in the correct position
+  } else {
+    //    c
+    // 01234
+    line<C> * l = mutref(this->lines[cur.row]);
+    int32_t length = l->length - cur.col;
+    move(&l->buf[cur.col], &l->buf[cur.col+1], length);
     l->length--;
-    l->buf[l->length] = 0x7f;
+
+    // no scrolling needed--cursor is already in the correct position
   }
 
   return true;

editor/main_saturn.cpp

@@ -92,7 +92,8 @@ inline void keyboard_regular_key(const enum keysym k)
   switch (modifier_state) {
   case MODIFIER_NONE:
     switch (k) {
-    case keysym::BACKSPACE  : buffer.backspace(); break;
+    case keysym::BACKSPACE  : buffer.delete_backward(); break;
+    case keysym::DELETE     : buffer.delete_forward(); break;
     case keysym::ARROW_LEFT : buffer.cursor_left(); break;
     case keysym::ARROW_RIGHT: buffer.cursor_right(); break;
     case keysym::ARROW_UP   : buffer.cursor_up(); break;

editor/test_editor.cpp

@@ -109,10 +109,10 @@ void test_backspace()
   assert(l->length == 1);
   assert(l->buf[0] == 'a');
 
-  assert(b.backspace() == true);
+  assert(b.delete_backward() == true);
   assert(l->length == 0);
 
-  assert(b.backspace() == false);
+  assert(b.delete_backward() == false);
 
   b.put('b');
   b.put('c');
@@ -122,7 +122,7 @@ void test_backspace()
   assert(l->length == 4);
 
   //"bcde"
-  assert(b.backspace() == true);
+  assert(b.delete_backward() == true);
   assert(l->buf[0] == 'b');
   assert(l->buf[1] == 'd');
   assert(l->buf[2] == 'e');
@@ -202,8 +202,8 @@ void test_enter_backspace1()
   b.enter();
   b.enter();
   assert(b.length == 3);
-  b.backspace();
-  b.backspace();
+  b.delete_backward();
+  b.delete_backward();
   assert(b.length == 1);
   b.enter();
   assert(b.length == 2);
@@ -223,7 +223,7 @@ void test_enter_backspace2()
   assert(b.cursor.row == 1);
   assert(b.cursor.col == 0);
   assert(b.length == 2);
-  b.backspace();
+  b.delete_backward();
   assert(b.cursor.row == 0);
   assert(b.cursor.col == 1);
   assert(b.length == 1);
@@ -281,7 +281,7 @@ void test_enter_backspace3()
   assert(b.lines[4] == nullptr);
   assert(b.length == 4);
 
-  b.backspace();
+  b.delete_backward();
   assert(b.length == 3);
   assert(b.lines[0]->buf[0] == 'a');
   assert(b.lines[1]->length == 0);
@@ -731,6 +731,38 @@ void test_shadow_paste_multiline()
   assert(b.lines[4]->buf[2] == 'x');
 }
 
+void test_delete_forward()
+{
+   buffer<8, 8> b {4, 2};
+   b.put('a');
+   b.put('b');
+   b.put('c');
+   b.cursor_left();
+   b.cursor_left();
+   b.delete_forward();
+   assert(b.lines[0]->length == 2);
+   assert(b.lines[0]->buf[0] == 'a');
+   assert(b.lines[0]->buf[1] == 'c');
+
+   //
+   b.cursor_end();
+   b.enter();
+   b.enter();
+   b.put('q');
+   b.put('w');
+   b.cursor_home();
+   b.cursor_up();
+   assert(b.length == 3);
+   b.delete_forward();
+   assert(b.length == 2);
+   assert(b.lines[0]->length == 2);
+   assert(b.lines[0]->buf[0] == 'a');
+   assert(b.lines[0]->buf[1] == 'c');
+   assert(b.lines[1]->length == 2);
+   assert(b.lines[1]->buf[0] == 'q');
+   assert(b.lines[1]->buf[1] == 'w');
+}
+
 int main()
 {
   test_allocate();
@@ -749,6 +781,7 @@ int main()
   test_selection_delete();
   test_shadow_paste_oneline();
   test_shadow_paste_multiline();
+  test_delete_forward();
 
   return 0;
 }