add 'g' and 'G' commands to go to first and last line in buffer

src/core/Buffer.h

@@ -19,7 +19,7 @@ public:
             INVALID_CODE_POINT = 0xFFFFFFFFu,
         };
 
-        Iterator(Buffer * buffer)
+        Iterator(const Buffer * buffer)
         {
             m_buffer = buffer;
             m_offset = 0u;
@@ -87,7 +87,7 @@ public:
         size_t offset() const { return m_offset; }
 
     protected:
-        Buffer * m_buffer;
+        const Buffer * m_buffer;
         size_t m_offset;
         size_t m_line;
     };
@@ -114,6 +114,8 @@ public:
     void insert_code_point(uint32_t code_point, bool adjust_iterators = true);
     void erase_code_point(const Buffer::Iterator & position);
     std::string filename() const { return m_filename; }
+    Iterator begin() const { return Iterator(this); }
+    Iterator end() const { return *m_eof_iterator; }
 
 protected:
     bool m_eol_at_eof;

src/gui/BufferPane.cc

@@ -333,6 +333,9 @@ void BufferPane::handle_key(uint32_t keyval)
         case '$':
             cursor_move(CursorMovement::EOL);
             break;
+        case 'G':
+            cursor_move(CursorMovement::LAST_LINE);
+            break;
         case 'a':
             if (**m_iterator != '\n')
             {
@@ -341,6 +344,9 @@ void BufferPane::handle_key(uint32_t keyval)
             m_buffer->enter_insert_mode(*m_iterator);
             m_window->request_redraw();
             break;
+        case 'g':
+            cursor_move(CursorMovement::FIRST_LINE);
+            break;
         case 'h':
             cursor_move(CursorMovement::LEFT);
             break;
@@ -419,6 +425,28 @@ void BufferPane::cursor_move(CursorMovement which)
     case CursorMovement::EOL:
         moved = m_iterator->go_end_of_line(m_buffer->insert_mode());
         break;
+    case CursorMovement::FIRST_LINE:
+        {
+            auto it = m_buffer->begin();
+            if (it != *m_iterator)
+            {
+                *m_iterator = it;
+                moved = true;
+            }
+        }
+        break;
+    case CursorMovement::LAST_LINE:
+        {
+            auto it = m_buffer->end();
+            it.go_back();
+            it.go_start_of_line();
+            if (it != *m_iterator)
+            {
+                *m_iterator = it;
+                moved = true;
+            }
+        }
+        break;
     }
     if (moved)
     {
@@ -446,6 +474,12 @@ void BufferPane::cursor_move(CursorMovement which)
         case CursorMovement::EOL:
             m_target_column = INT_MAX;
             break;
+        case CursorMovement::FIRST_LINE:
+            m_cursor_screen_row = 0;
+            break;
+        case CursorMovement::LAST_LINE:
+            m_cursor_screen_row = m_rows;
+            break;
         }
         m_cursor_screen_row = determine_new_cursor_screen_row();
         m_window->request_redraw();

src/gui/BufferPane.h

@@ -25,6 +25,8 @@ protected:
         DOWN,
         SOL,
         EOL,
+        FIRST_LINE,
+        LAST_LINE,
     };
 
     int effective_scroll_offset()