Add experimental support for gd/gu for visually moving cursor down/up

Author: mawww

src/coord.hh

@@ -75,14 +75,15 @@ struct DisplayCoord : LineAndColumn<DisplayCoord, LineCount, ColumnCount>
 struct BufferCoordAndTarget : BufferCoord
 {
     [[gnu::always_inline]]
-    constexpr BufferCoordAndTarget(LineCount line = 0, ByteCount column = 0, ColumnCount target = -1)
-        : BufferCoord{line, column}, target{target} {}
+    constexpr BufferCoordAndTarget(LineCount line = 0, ByteCount column = 0, ColumnCount target = -1, ColumnCount display_target=-1)
+        : BufferCoord{line, column}, target{target}, display_target{display_target} {}
 
     [[gnu::always_inline]]
-    constexpr BufferCoordAndTarget(BufferCoord coord, ColumnCount target = -1)
-        : BufferCoord{coord}, target{target} {}
+    constexpr BufferCoordAndTarget(BufferCoord coord, ColumnCount target = -1, ColumnCount display_target=-1)
+        : BufferCoord{coord}, target{target}, display_target{display_target} {}
 
     ColumnCount target;
+    ColumnCount display_target;
 };
 
 constexpr size_t hash_value(const BufferCoordAndTarget& val)

src/input_handler.cc

@@ -1494,7 +1494,7 @@ class Insert : public InputMode
                 buffer.insert(sel.max().line + inserted_count + 1,
                               String{'\n', CharCount{count}});
                 for (int i = 0; i < count; ++i)
-                    new_sels.push_back({sel.max().line + inserted_count + i + 1});
+                    new_sels.push_back(BufferCoord{sel.max().line + inserted_count + i + 1});
                 inserted_count += count;
             }
             selections.set(std::move(new_sels),
@@ -1512,7 +1512,7 @@ class Insert : public InputMode
                 buffer.insert(sel.min().line + inserted_count,
                               String{'\n', CharCount{count}});
                 for (int i = 0; i < count; ++i)
-                    new_sels.push_back({sel.min().line + inserted_count + i});
+                    new_sels.push_back(BufferCoord{sel.min().line + inserted_count + i});
                 inserted_count += count;
             }
             selections.set(std::move(new_sels),

src/normal.cc

@@ -234,12 +234,12 @@ void goto_commands(Context& context, NormalParams params)
     else
     {
         on_next_key_with_autoinfo(context, "goto", KeymapMode::Goto,
-                                 [](Key key, Context& context) {
+                                  [params](Key key, Context& context) {
             auto cp = key.codepoint();
             if (not cp or key == Key::Escape)
                 return;
             auto& buffer = context.buffer();
-            switch (to_lower(*cp))
+            switch (auto lower_cp = to_lower(*cp); lower_cp)
             {
             case 'g':
             case 'k':
@@ -297,6 +297,30 @@ void goto_commands(Context& context, NormalParams params)
                 context.change_buffer(*target);
                 break;
             }
+            case 'd':
+            case 'u':
+            {
+                auto offset = (lower_cp == 'd' ? 1_line : -1_line) * std::max(params.count, 1);
+                select(context, mode, [&](Context& context, Selection& sel) -> Optional<Selection> {
+                    if (context.has_window())
+                    {
+                        auto& cursor = sel.cursor();
+                        auto& window = context.window();
+                        if (auto display_coord = window.display_coord(cursor))
+                        {
+                            if (cursor.display_target == -1)
+                                cursor.display_target = display_coord->column;
+                            display_coord->column = cursor.display_target;
+                            if (auto buffer_coord = window.buffer_coord(*display_coord + offset))
+                                return Selection{BufferCoordAndTarget{*buffer_coord, -1, cursor.display_target}};
+                        }
+                    }
+                    const ColumnCount tabstop = context.options()["tabstop"].get<int>();
+                    return Selection{context.buffer().offset_coord(sel.cursor(), offset, tabstop)};
+                });
+                break;
+            }
+
             case 'f':
             {
                 static constexpr char forbidden[] = { '\'', '\\', '\0' };

src/selection.hh

@@ -27,6 +27,7 @@ struct BasicSelection
 
     BasicSelection() = default;
     BasicSelection(BufferCoord pos) : BasicSelection(pos,pos) {}
+    BasicSelection(BufferCoordAndTarget pos) : BasicSelection(pos,pos) {}
     BasicSelection(BufferCoord anchor, BufferCoordAndTarget cursor)
         : m_anchor{anchor}, m_cursor{cursor} {}
 
@@ -62,6 +63,7 @@ struct Selection : BasicSelection
 {
     Selection() = default;
     Selection(BufferCoord pos) : BasicSelection(pos,pos) {}
+    Selection(BufferCoordAndTarget pos) : BasicSelection(pos,pos) {}
     Selection(BufferCoord anchor, BufferCoordAndTarget cursor, CaptureList captures = {})
         : BasicSelection{anchor, cursor}, m_captures(std::move(captures)) {}
     CaptureList& captures() { return m_captures; }

src/window.cc

@@ -303,9 +303,9 @@ Optional<BufferCoord> Window::buffer_coord(DisplayCoord coord) const
         m_display_buffer.lines().empty())
         return {};
     if (coord <= 0_line)
-        coord = {};
+        return {};
     if ((size_t)coord.line >= m_display_buffer.lines().size())
-        coord = DisplayCoord{(int)m_display_buffer.lines().size()-1, INT_MAX};
+        return {};
 
     return find_buffer_coord(m_display_buffer.lines()[(int)coord.line],
                              buffer(), coord.column);