Hotkeys to jump between changes

inc/hotkeys.dat

@@ -18,5 +18,7 @@ DAT_CAT_START(GlobalCommand, GLB, global, "Global Commands")
     DAT_CMD(GLB_TextPageUp,             OS::Key::PageUp,    OS::KeyMods::None,                      "Page up text")
     DAT_CMD(GLB_TextBeginning,          OS::Key::Home,      OS::KeyMods::Ctrl,                      "Beginning of text")
     DAT_CMD(GLB_TextEnd,                OS::Key::End,       OS::KeyMods::Ctrl,                      "End of text")
+    DAT_CMD(GLB_TextNextChange,         OS::Key::Down,      OS::KeyMods::Alt,                       "Jump to next change")
+    DAT_CMD(GLB_TextPrevChange,         OS::Key::Up,        OS::KeyMods::Alt,                       "Jump to previous change")
     DAT_CMD(GLB_Close,                  OS::Key::W,         OS::KeyMods::Ctrl,                      "Close Gap / close command")
 DAT_CAT_END(GlobalCommand, GLB)

src/diff-text.cpp

@@ -160,6 +160,37 @@ namespace Diff
         {
             return window.idx_buf[circular_window_mask(idx, window.cap)];
         }
+
+        bool is_change(const DiffTextView* widget, int64_t idx)
+        {
+            const EditType type = widget->diffs.lines[idx].type;
+            return type != EditType::Eq and type != EditType::Skip;
+        }
+
+        // Head of the change region after 'from', or 'from' if there isn't one.
+        int64_t next_change_idx(const DiffTextView* widget, int64_t from)
+        {
+            const int64_t size = static_cast<int64_t>(widget->diffs.size);
+            int64_t idx = from;
+            // Step out of the region we're in, then on to the head of the next one.
+            while (idx < size and is_change(widget, idx)) ++idx;
+            while (idx < size and not is_change(widget, idx)) ++idx;
+            // Nothing below us; stay put rather than running off to the end of the file.
+            return idx < size ? idx : from;
+        }
+
+        // Head of the change region before 'from', or 'from' if there isn't one.
+        int64_t prev_change_idx(const DiffTextView* widget, int64_t from)
+        {
+            // 'from' indexes the scroll view, which outruns 'diffs' when there is no diff to show.
+            int64_t idx = std::min(from, static_cast<int64_t>(widget->diffs.size)) - 1;
+            // Step back to the region above us, then on to its head.
+            while (idx >= 0 and not is_change(widget, idx)) --idx;
+            // Nothing above us; stay put rather than running off to the start of the file.
+            if (idx < 0) return from;
+            while (idx >= 0 and is_change(widget, idx)) --idx;
+            return idx + 1;
+        }
     } // namespace [anon]
 
     // Creation.
@@ -534,6 +565,24 @@ namespace Diff
                 widget->scroll->scroll_to(off);
                 resp.scroll_changed = true;
             }
+
+            if (hotkey(*state, Hotkey::GLB_TextNextChange))
+            {
+                UI::Widgets::IndexedScrollOffset off = widget->scroll->position();
+                off.offset.y = 0.f;
+                off.idx = std::min(next_change_idx(widget, off.idx), scroll_size.v_size - 1);
+                widget->scroll->scroll_to(off);
+                resp.scroll_changed = true;
+            }
+
+            if (hotkey(*state, Hotkey::GLB_TextPrevChange))
+            {
+                UI::Widgets::IndexedScrollOffset off = widget->scroll->position();
+                off.offset.y = 0.f;
+                off.idx = std::max(prev_change_idx(widget, off.idx), int64_t(0));
+                widget->scroll->scroll_to(off);
+                resp.scroll_changed = true;
+            }
         }
         font_ctx.render_whitespace(Config::system_effects().render_whitespace);
         font_ctx.whitespace_color(colors.whitespace);