[escher/ion] Factorize code for removing a code point in text field/area

escher/include/escher/text_area.h

@@ -75,7 +75,7 @@ protected:
     void insertText(const char * s, int textLength, char * location);
     void insertSpacesAtLocation(int numberOfSpaces, char * location);
 
-    CodePoint removeCodePoint(const char * * position);
+    CodePoint removeCodePoint(char * * position);
     size_t removeRemainingLine(const char * position, int direction);
     char operator[](size_t index) {
       assert(index < m_bufferSize);

escher/src/text_area.cpp

@@ -199,29 +199,17 @@ void TextArea::Text::insertSpacesAtLocation(int numberOfSpaces, char * location)
   }
 }
 
-CodePoint TextArea::Text::removeCodePoint(const char * * position) {
+CodePoint TextArea::Text::removeCodePoint(char * * position) {
   assert(m_buffer != nullptr);
   assert(m_buffer <= *position && *position < m_buffer + m_bufferSize);
 
-  // Find the beginning of the previous code point
-  UTF8Decoder decoder(m_buffer, *position);
-  CodePoint deletedCodePoint = decoder.previousCodePoint();
-  const char * newCursorLocation = decoder.stringPosition();
-  assert(newCursorLocation < *position);
+  CodePoint removedCodePoint = 0;
+  int removedSize = UTF8Helper::RemovePreviousCodePoint(m_buffer, *position, &removedCodePoint);
+  assert(removedSize > 0);
 
-  // Shift the buffer
-  int codePointSize = *position - newCursorLocation;
-  assert(codePointSize == UTF8Decoder::CharSizeOfCodePoint(deletedCodePoint));
-  assert(newCursorLocation >= m_buffer);
-  for (size_t i = newCursorLocation - m_buffer; i < m_bufferSize; i++) {
-    m_buffer[i] = m_buffer[i + codePointSize];
-    if (m_buffer[i] == 0) {
-      break;
-    }
-  }
   // Set the new cursor position
-  *position = newCursorLocation;
-  return deletedCodePoint;
+  *position = *position - removedSize;
+  return removedCodePoint;
 }
 
 size_t TextArea::Text::removeRemainingLine(const char * location, int direction) {
@@ -401,7 +389,7 @@ bool TextArea::TextArea::ContentView::removeCodePoint() {
     return false;
   }
   bool lineBreak = false;
-  const char * cursorLoc = cursorLocation();
+  char * cursorLoc = const_cast<char *>(cursorLocation());
   lineBreak = m_text.removeCodePoint(&cursorLoc) == '\n';
   setCursorLocation(cursorLoc); // Update the cursor
   layoutSubviews(); // Reposition the cursor

escher/src/text_field.cpp

@@ -143,35 +143,28 @@ KDSize TextField::ContentView::minimalSizeForOptimalDisplay() const {
 
 bool TextField::ContentView::removeCodePoint() {
   assert(m_isEditing);
-  if (cursorLocation() <= m_draftTextBuffer) {
+
+  // Remove the code point if possible
+  CodePoint removedCodePoint = 0;
+  int removedSize = UTF8Helper::RemovePreviousCodePoint(m_draftTextBuffer, const_cast<char *>(cursorLocation()), &removedCodePoint);
+  if (removedSize == 0) {
     assert(cursorLocation() == m_draftTextBuffer);
     return false;
   }
-  UTF8Decoder decoder(m_draftTextBuffer, cursorLocation());
-  decoder.previousCodePoint();
-  const char * newCursorLocation = decoder.stringPosition();
 
-  assert(newCursorLocation < cursorLocation());
-  int removedCodePointLength = cursorLocation() - newCursorLocation;
-  m_currentDraftTextLength-= removedCodePointLength;
+  // Update the draft buffer length
+  m_currentDraftTextLength-= removedSize;
+  assert(m_draftTextBuffer[m_currentDraftTextLength] == 0);
 
+  // Reload the view and set the cursor location
   if (m_horizontalAlignment > 0.0f) {
     reloadRectFromPosition(m_draftTextBuffer);
   }
-
-  setCursorLocation(newCursorLocation);
+  assert(cursorLocation() - removedSize >= m_draftTextBuffer);
+  setCursorLocation(cursorLocation() - removedSize);
   if (m_horizontalAlignment == 0.0f) {
     reloadRectFromPosition(cursorLocation());
   }
-
-  for (char * k = const_cast<char *>(cursorLocation()); k < m_draftTextBuffer + m_currentDraftTextLength + removedCodePointLength; k++) {
-    *k = *(k+removedCodePointLength);
-    if (*k == 0) {
-      break;
-    }
-  }
-
-  assert(m_draftTextBuffer[m_currentDraftTextLength] == 0);
   layoutSubviews();
   return true;
 }

ion/include/ion/unicode/utf8_helper.h

@@ -43,6 +43,10 @@ const char *  PerformAtCodePoints(const char * string, CodePoint c, CodePointAct
 bool PreviousCodePointIs(const char * buffer, const char * location, CodePoint c);
 bool CodePointIs(const char * location, CodePoint c);
 
+// Shift the buffer and return the number of bytes removed.
+int RemovePreviousCodePoint(const char * text, char * location, CodePoint * c);
+
+
 };
 
 #endif

ion/src/shared/unicode/utf8_helper.cpp

@@ -169,4 +169,27 @@ bool CodePointIs(const char * location, CodePoint c) {
   return decoder.nextCodePoint() == c;
 }
 
+int RemovePreviousCodePoint(const char * text, char * location, CodePoint * c) {
+  assert(c != nullptr);
+  if (location <= text) {
+    assert(location == text);
+    return 0;
+  }
+
+  // Find the previous code point
+  UTF8Decoder decoder(text, location);
+  *c = decoder.previousCodePoint();
+
+  // Shift the buffer
+  int codePointSize = UTF8Decoder::CharSizeOfCodePoint(*c);
+  char * iterator = location - codePointSize;
+  assert(iterator >= text);
+  do {
+    *iterator = *(iterator + codePointSize);
+    iterator++;
+  } while (*(iterator - 1) != 0); // Stop shifting after writing a null terminating char.
+
+  return codePointSize;
+}
+
 };