| // Copyright 2018 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef SQL_STATEMENT_ID_H_ |
| #define SQL_STATEMENT_ID_H_ |
| |
| #include <cstddef> |
| |
| #include "sql/sql_export.h" |
| |
| namespace sql { |
| |
| // Identifies a compiled SQLite statement in a statement cache. |
| // |
| // This is a value type with the same performance characteristics as |
| // std::string_view. Instances are thread-unsafe, but not thread-hostile. |
| // |
| // StatementID instances should be constructed by using the SQL_FROM_HERE |
| // macro, which produces an unique ID based on the source file name and line. |
| class SQL_EXPORT StatementID { |
| public: |
| // Creates an ID representing a line in the source tree. |
| // |
| // SQL_FROM_HERE should be preferred to calling this constructor directly. |
| // |
| // |source_file| should point to a C-style string that lives for the duration |
| // of the program. |
| explicit StatementID(const char* source_file, size_t source_line) noexcept |
| : source_file_(source_file), source_line_(source_line) {} |
| |
| // Copying intentionally allowed. |
| StatementID(const StatementID&) noexcept = default; |
| StatementID& operator=(const StatementID&) noexcept = default; |
| |
| // Facilitates storing StatementID instances in maps. |
| bool operator<(const StatementID& rhs) const noexcept; |
| |
| private: |
| // Instances cannot be immutable because they support being used as map keys. |
| // |
| // It seems tempting to merge source_file_ and source_line_ in a single |
| // source_location_ member, and to have SQL_FROM_HERE use C++ preprocessor |
| // magic to generate strings like "sql/connection.cc:42". This causes a |
| // non-trivial binary size increase, because Chrome uses -fmerge-constants and |
| // SQL_FROM_HERE tends to be used many times in the same few files. |
| const char* source_file_; |
| size_t source_line_; |
| }; |
| |
| } // namespace sql |
| |
| // Produces a StatementID based on the current line in the source tree. |
| #define SQL_FROM_HERE sql::StatementID(__FILE__, __LINE__) |
| |
| #endif // SQL_STATEMENT_ID_H_ |