Make NTString nullable

src/clang_cursor.cc

@@ -228,12 +228,12 @@ std::string ClangCursor::get_type_description() const {
   return ::ToString(clang_getTypeSpelling(type));
 }
 
-std::string ClangCursor::get_comments() const {
+NTString ClangCursor::get_comments() const {
   if (!g_index_comments)
-    return "";
+    return {};
   CXSourceRange range = clang_Cursor_getCommentRange(cx_cursor);
   if (clang_Range_isNull(range))
-    return "";
+    return {};
 
   unsigned start_column;
   clang_getSpellingLocation(clang_getRangeStart(range), nullptr, nullptr,
@@ -286,7 +286,9 @@ std::string ClangCursor::get_comments() const {
   }
   while (ret.size() && isspace(ret.back()))
     ret.pop_back();
-  return ret;
+  if (ret.empty())
+    return {};
+  return static_cast<std::string_view>(ret);
 }
 
 std::string ClangCursor::ToString() const {

src/clang_cursor.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "position.h"
+#include "ntstring.h"
 
 #include <clang-c/Index.h>
 #include <optional.h>
@@ -79,7 +80,7 @@ class ClangCursor {
   bool is_valid_kind() const;
 
   std::string get_type_description() const;
-  std::string get_comments() const;
+  NTString get_comments() const;
 
   std::string ToString() const;
 

src/messages/cquery_random.cc

@@ -15,7 +15,7 @@ REGISTER_IPC_MESSAGE(Ipc_CqueryRandom);
 
 const double kDeclWeight = 3;
 const double kDamping = 0.1;
-const double kAlpha = 0.3;
+const double kAlpha = 2.80777024202851936522;
 
 template <typename Q>
 struct Kind;

src/ntstring.h

@@ -9,32 +9,26 @@
 class Reader;
 class Writer;
 
-// Null-terminated string
+// Nullable null-terminated string, which is null if default constructed,
+// but non-null if assigned.
 // This is used in Query{Func,Type,Var}::def to reduce memory footprint.
 class NTString {
   using size_type = std::string::size_type;
   std::unique_ptr<char[]> str;
 
  public:
-  NTString() : str(new char[1]()) {}
+  NTString() = default;
-  NTString(const NTString& o) : str(new char[strlen(o.c_str()) + 1]) {
-    strcpy(str.get(), o.c_str());
-  }
   NTString(NTString&& o) = default;
-  NTString(std::string_view sv) {
+  NTString(const NTString& o) { *this = o; }
-    *this = sv;
+  NTString(std::string_view sv) { *this = sv; }
-  }
 
-  operator std::string_view() const { return str.get(); }
   const char* c_str() const { return str.get(); }
-  std::string_view substr(size_type pos, size_type cnt) const {
+  operator std::string_view() const {
-    return std::string_view(c_str() + pos, cnt);
+    if (c_str())
-  }
+      return c_str();
-  bool empty() const { return !str || str.get()[0] == '\0'; }
+    return {};
-  size_type find(const char* s) {
-    const char *p = strstr(c_str(), s);
-    return p ? std::string::size_type(p - c_str()) : std::string::npos;
   }
+  bool empty() const { return !str || *c_str() == '\0'; }
 
   void operator=(std::string_view sv) {
     str = std::unique_ptr<char[]>(new char[sv.size() + 1]);
@@ -45,6 +39,7 @@ class NTString {
     *this = static_cast<std::string_view>(o);
   }
   bool operator==(const NTString& o) const {
-    return strcmp(c_str(), o.c_str()) == 0;
+    return str && o.str ? strcmp(c_str(), o.c_str()) == 0
+      : c_str() == o.c_str();
   }
 };

src/query.cc

@@ -40,8 +40,10 @@ optional<QueryType::Def> ToQuery(const IdMap& id_map,
   result.short_name_offset = type.short_name_offset;
   result.short_name_size = type.short_name_size;
   result.kind = type.kind;
-  result.hover = type.hover;
+  if (!type.hover.empty())
-  result.comments = type.comments;
+    result.hover = type.hover;
+  if (!type.comments.empty())
+    result.comments = type.comments;
   result.file = id_map.primary_file;
   result.spell = id_map.ToQuery(type.spell);
   result.extent = id_map.ToQuery(type.extent);
@@ -64,8 +66,10 @@ optional<QueryFunc::Def> ToQuery(const IdMap& id_map,
   result.short_name_size = func.short_name_size;
   result.kind = func.kind;
   result.storage = func.storage;
-  result.hover = func.hover;
+  if (!func.hover.empty())
-  result.comments = func.comments;
+    result.hover = func.hover;
+  if (!func.comments.empty())
+    result.comments = func.comments;
   result.file = id_map.primary_file;
   result.spell = id_map.ToQuery(func.spell);
   result.extent = id_map.ToQuery(func.extent);
@@ -84,13 +88,13 @@ optional<QueryVar::Def> ToQuery(const IdMap& id_map, const IndexVar::Def& var) {
   result.detailed_name = var.detailed_name;
   result.short_name_offset = var.short_name_offset;
   result.short_name_size = var.short_name_size;
-  result.hover = var.hover;
+  if (!var.hover.empty())
-  result.comments = var.comments;
+    result.hover = var.hover;
+  if (!var.comments.empty())
+    result.comments = var.comments;
   result.file = id_map.primary_file;
-  if (var.spell)
+  result.spell = id_map.ToQuery(var.spell);
-    result.spell = id_map.ToQuery(*var.spell);
+  result.extent = id_map.ToQuery(var.extent);
-  if (var.extent)
-    result.extent = id_map.ToQuery(*var.extent);
   result.variable_type = id_map.ToQuery(var.variable_type);
   if (result.parent_id)
     switch (var.parent_kind) {