feat(translator): contextual suggestions in partially selected sentence

src/rime/composition.cc

@@ -5,6 +5,7 @@
 // 2011-06-19 GONG Chen <chen.sst@gmail.com>
 //
 #include <boost/algorithm/string.hpp>
+#include <boost/range/adaptor/reversed.hpp>
 #include <rime/candidate.h>
 #include <rime/composition.h>
 #include <rime/menu.h>
@@ -167,4 +168,16 @@ string Composition::GetDebugText() const {
   return result;
 }
 
+string Composition::GetTextBefore(size_t pos) const {
+  if (empty()) return string();
+  for (const auto& seg : boost::adaptors::reverse(*this)) {
+    if (seg.end <= pos) {
+      if (auto cand = seg.GetSelectedCandidate()) {
+        return cand->text();
+      }
+    }
+  }
+  return string();
+}
+
 }  // namespace rime

src/rime/composition.h

@@ -29,6 +29,8 @@ class Composition : public Segmentation {
   string GetCommitText() const;
   string GetScriptText() const;
   string GetDebugText() const;
+  // Returns text of the last segment before the given position.
+  string GetTextBefore(size_t pos) const;
 };
 
 }  // namespace rime

src/rime/gear/poet.h

@@ -44,14 +44,17 @@ class Poet {
   template <class TranslatorT>
   an<Translation> ContextualWeighted(an<Translation> translation,
                                      const string& input,
+                                     size_t start,
                                      TranslatorT* translator) {
     if (!translator->contextual_suggestions() || !grammar_) {
       return translation;
     }
-    return New<ContextualTranslation>(translation,
-                                      input,
-                                      translator->GetPrecedingText(),
-                                      grammar_.get());
+    auto preceding_text = translator->GetPrecedingText(start);
+    if (preceding_text.empty()) {
+      return translation;
+    }
+    return New<ContextualTranslation>(
+        translation, input, preceding_text, grammar_.get());
   }
 
  private:

src/rime/gear/script_translator.cc

@@ -196,7 +196,7 @@ an<Translation> ScriptTranslator::Query(const string& input,
   }
   auto deduped = New<DistinctTranslation>(result);
   if (contextual_suggestions_) {
-    return poet_->ContextualWeighted(deduped, input, this);
+    return poet_->ContextualWeighted(deduped, input, segment.start, this);
   }
   return deduped;
 }
@@ -218,9 +218,10 @@ string ScriptTranslator::Spell(const Code& code) {
   return result;
 }
 
-string ScriptTranslator::GetPrecedingText() const {
-  return contextual_suggestions_ ?
-      engine_->context()->commit_history().latest_text() : string();
+string ScriptTranslator::GetPrecedingText(size_t start) const {
+  return !contextual_suggestions_ ? string() :
+      start > 0 ? engine_->context()->composition().GetTextBefore(start) :
+      engine_->context()->commit_history().latest_text();
 }
 
 bool ScriptTranslator::Memorize(const CommitEntry& commit_entry) {
@@ -547,9 +548,10 @@ an<Sentence> ScriptTranslation::MakeSentence(Dictionary* dict,
       }
     }
   }
-  if (auto sentence = poet_->MakeSentence(graph,
-                                          syllable_graph.interpreted_length,
-                                          translator_->GetPrecedingText())) {
+  if (auto sentence =
+      poet_->MakeSentence(graph,
+                          syllable_graph.interpreted_length,
+                          translator_->GetPrecedingText(start_))) {
     sentence->Offset(start_);
     sentence->set_syllabifier(syllabifier_);
     return sentence;

src/rime/gear/script_translator.h

@@ -37,7 +37,7 @@ class ScriptTranslator : public Translator,
 
   string FormatPreedit(const string& preedit);
   string Spell(const Code& code);
-  string GetPrecedingText() const;
+  string GetPrecedingText(size_t start) const;
 
   // options
   int max_homophones() const { return max_homophones_; }

src/rime/gear/table_translator.cc

@@ -312,7 +312,7 @@ an<Translation> TableTranslator::Query(const string& input,
   }
   translation = New<DistinctTranslation>(translation);
   if (contextual_suggestions_) {
-    return poet_->ContextualWeighted(translation, input, this);
+    return poet_->ContextualWeighted(translation, input, segment.start, this);
   }
   return translation;
 }
@@ -366,9 +366,10 @@ bool TableTranslator::Memorize(const CommitEntry& commit_entry) {
   return true;
 }
 
-string TableTranslator::GetPrecedingText() const {
-  return contextual_suggestions_ ?
-      engine_->context()->commit_history().latest_text() : string();
+string TableTranslator::GetPrecedingText(size_t start) const {
+  return !contextual_suggestions_ ? string() :
+      start > 0 ? engine_->context()->composition().GetTextBefore(start) :
+      engine_->context()->commit_history().latest_text();
 }
 
 // SentenceSyllabifier
@@ -691,7 +692,7 @@ TableTranslator::MakeSentence(const string& input, size_t start,
   }
   if (auto sentence = poet_->MakeSentence(graph,
                                           input.length(),
-                                          GetPrecedingText())) {
+                                          GetPrecedingText(start))) {
     auto result = Cached<SentenceTranslation>(
         this,
         std::move(sentence),

src/rime/gear/table_translator.h

@@ -29,13 +29,13 @@ class TableTranslator : public Translator,
   TableTranslator(const Ticket& ticket);
 
   virtual an<Translation> Query(const string& input,
-                                        const Segment& segment);
+                                const Segment& segment);
   virtual bool Memorize(const CommitEntry& commit_entry);
 
   an<Translation> MakeSentence(const string& input,
-                                       size_t start,
-                                       bool include_prefix_phrases = false);
-  string GetPrecedingText() const;
+                               size_t start,
+                               bool include_prefix_phrases = false);
+  string GetPrecedingText(size_t start) const;
   UnityTableEncoder* encoder() const { return encoder_.get(); }
 
  protected: