fix deleting current candidate

src/rime/common.h

@@ -14,7 +14,6 @@
 #include <list>
 #include <map>
 #include <memory>
-#include <optional>
 #include <set>
 #include <string>
 #include <unordered_map>

src/rime/context.cc

@@ -143,27 +143,26 @@ bool Context::Highlight(size_t index) {
   return true;
 }
 
-bool Context::DeleteCandidate(std::optional<size_t> index) {
-  if (composition_.empty())
-    return false;
-  Segment& seg(composition_.back());
-  auto cand = index ? seg.GetCandidateAt(*index) : seg.GetSelectedCandidate();
+bool Context::DeleteCandidate(an<Candidate> cand) {
   if (!cand)
     return false;
   DLOG(INFO) << "Deleting candidate: " << cand->text();
-  if (index) {
-    seg.selected_index = *index;
-  }
   delete_notifier_(this);
   return true;  // CAVEAT: this doesn't mean anything is deleted for sure
 }
 
 bool Context::DeleteCandidate(size_t index) {
-  return DeleteCandidate(std::optional{index});
+  if (composition_.empty())
+    return false;
+  Segment& seg(composition_.back());
+  return DeleteCandidate(seg.GetCandidateAt(index));
 }
 
 bool Context::DeleteCurrentSelection() {
-  return DeleteCandidate({});
+  if (composition_.empty())
+    return false;
+  Segment& seg(composition_.back());
+  return DeleteCandidate(seg.GetSelectedCandidate());
 }
 
 bool Context::ConfirmCurrentSelection() {

src/rime/context.h

@@ -94,7 +94,7 @@ class RIME_API Context {
 
  private:
   string GetSoftCursor() const;
-  bool DeleteCandidate(std::optional<size_t> index);
+  bool DeleteCandidate(an<Candidate> cand);
 
   string input_;
   size_t caret_pos_ = 0;