SongFilter: return "const char *" instead of std::string

src/SongFilter.cxx

@@ -300,12 +300,12 @@ SongFilter::HasOtherThanBase() const
 	return false;
 }
 
-std::string
+const char *
 SongFilter::GetBase() const
 {
 	for (const auto &i : items)
 		if (i.GetTag() == LOCATE_TAG_BASE_TYPE)
 			return i.GetValue();
 
-	return std::string();
+	return nullptr;
 }

src/SongFilter.hxx

@@ -76,8 +76,8 @@ public:
 			return fold_case;
 		}
 
-		const std::string &GetValue() const {
+		const char *GetValue() const {
-			return value;
+			return value.c_str();
 		}
 
 		gcc_pure gcc_nonnull(2)
@@ -149,11 +149,11 @@ public:
 	bool HasOtherThanBase() const;
 
 	/**
-	 * Returns the "base" specification (if there is one) or an
+	 * Returns the "base" specification (if there is one) or
-	 * empty string.
+	 * nullptr.
 	 */
 	gcc_pure
-	std::string GetBase() const;
+	const char *GetBase() const;
 };
 
 /**

src/db/Selection.cxx

@@ -26,8 +26,11 @@ DatabaseSelection::DatabaseSelection(const char *_uri, bool _recursive,
 {
 	/* optimization: if the caller didn't specify a base URI, pick
 	   the one from SongFilter */
-	if (uri.empty() && filter != nullptr)
+	if (uri.empty() && filter != nullptr) {
-		uri = filter->GetBase();
+		auto base = filter->GetBase();
+		if (base != nullptr)
+			uri = base;
+	}
 }
 
 bool

src/db/plugins/ProxyDatabasePlugin.cxx

@@ -263,18 +263,18 @@ SendConstraints(mpd_connection *connection, const SongFilter::Item &item)
 
 		return mpd_search_add_base_constraint(connection,
 						      MPD_OPERATOR_DEFAULT,
-						      item.GetValue().c_str());
+						      item.GetValue());
 #endif
 
 	case LOCATE_TAG_FILE_TYPE:
 		return mpd_search_add_uri_constraint(connection,
 						     MPD_OPERATOR_DEFAULT,
-						     item.GetValue().c_str());
+						     item.GetValue());
 
 	case LOCATE_TAG_ANY_TYPE:
 		return mpd_search_add_any_tag_constraint(connection,
 							 MPD_OPERATOR_DEFAULT,
-							 item.GetValue().c_str());
+							 item.GetValue());
 
 	default:
 		tag = Convert(TagType(item.GetTag()));
@@ -284,7 +284,7 @@ SendConstraints(mpd_connection *connection, const SongFilter::Item &item)
 		return mpd_search_add_tag_constraint(connection,
 						     MPD_OPERATOR_DEFAULT,
 						     tag,
-						     item.GetValue().c_str());
+						     item.GetValue());
 	}
 }
 

src/db/plugins/upnp/UpnpDatabasePlugin.cxx

@@ -303,7 +303,7 @@ UpnpDatabase::SearchSongs(const ContentDirectoryService &server,
 					} else {
 						cond += " = ";
 					}
-					dquote(cond, item.GetValue().c_str());
+					dquote(cond, item.GetValue());
 				}
 				cond += ')';
 			}
@@ -339,7 +339,7 @@ UpnpDatabase::SearchSongs(const ContentDirectoryService &server,
 			} else {
 				cond += " = ";
 			}
-			dquote(cond, item.GetValue().c_str());
+			dquote(cond, item.GetValue());
 		}
 	}