feat,refactor(dict): tweak to reduce peak memory usage

- Use smart pointer
- Release memory in time

This may save about 12% memory usage when compiling dict.

src/rime/dict/dict_compiler.cc

@@ -236,9 +236,9 @@ bool DictCompiler::BuildTable(int table_index,
     for (const auto& s : collector.syllabary) {
       syllable_to_id[s] = syllable_id++;
     }
-    for (RawDictEntry& r : collector.entries) {
+    for (auto r : collector.entries) {
       Code code;
-      for (const auto& s : r.raw_code) {
+      for (const auto& s : r->raw_code) {
         code.push_back(syllable_to_id[s]);
       }
       DictEntryList* ls = vocabulary.LocateEntries(code);
@@ -248,10 +248,12 @@ bool DictCompiler::BuildTable(int table_index,
       }
       auto e = New<DictEntry>();
       e->code.swap(code);
-      e->text.swap(r.text);
-      e->weight = log(r.weight > 0 ? r.weight : DBL_EPSILON);
+      e->text.swap(r->text);
+      e->weight = log(r->weight > 0 ? r->weight : DBL_EPSILON);
       ls->push_back(e);
     }
+    // release memory in time to reduce peak memory usage
+    vector<of<RawDictEntry>>().swap(collector.entries);
     if (settings->sort_order() != "original") {
       vocabulary.SortHomophones();
     }

src/rime/dict/entry_collector.cc

@@ -206,7 +206,7 @@ void EntryCollector::CreateEntry(const string &word,
     words[e.text][code_str] += e.weight;
     total_weight[e.text] += e.weight;
   }
-  entries.push_back(e);
+  entries.emplace_back(New<RawDictEntry>(e));
   ++num_entries;
 }
 
@@ -240,10 +240,10 @@ void EntryCollector::Dump(const string& file_name) const {
     out << "# - " << syllable << std::endl;
   }
   out << std::endl;
-  for (const RawDictEntry& e : entries) {
-    out << e.text << '\t'
-        << e.raw_code.ToString() << '\t'
-        << e.weight << std::endl;
+  for (const auto &e : entries) {
+    out << e->text << '\t'
+        << e->raw_code.ToString() << '\t'
+        << e->weight << std::endl;
   }
   out.close();
 }

src/rime/dict/entry_collector.h

@@ -35,7 +35,7 @@ class EntryCollector : public PhraseCollector {
  public:
   Syllabary syllabary;
   bool build_syllabary = true;
-  vector<RawDictEntry> entries;
+  vector<of<RawDictEntry>> entries;
   size_t num_entries = 0;
   ReverseLookupTable stems;