| /* |
| * Copyright (C) 2021 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef SRC_PROTOZERO_FILTERING_FILTER_BYTECODE_GENERATOR_H_ |
| #define SRC_PROTOZERO_FILTERING_FILTER_BYTECODE_GENERATOR_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include <string> |
| #include <vector> |
| |
| namespace protozero { |
| |
| // Creates a filter bytecode that can be passed to the FilterBytecodeParser. |
| // This class is typically only used by offline tools (e.g. the proto_filter |
| // cmdline tool). See go/trace-filtering for the full filtering design. |
| class FilterBytecodeGenerator { |
| public: |
| FilterBytecodeGenerator(); |
| ~FilterBytecodeGenerator(); |
| |
| // Call at the end of every message. It implicitly starts a new message, there |
| // is no corresponding BeginMessage(). |
| void EndMessage(); |
| |
| // All the methods below must be called in monotonic field_id order or the |
| // generator will CHECK() and crash. |
| |
| // Allows a simple field (varint, fixed32/64, string or bytes). |
| void AddSimpleField(uint32_t field_id); |
| |
| // Allows a range of simple fields. |range_start| is the id of the first field |
| // in range, |range_len| the number of fields in the range. |
| // AddSimpleFieldRange(N,1) is semantically equivalent to AddSimpleField(N) |
| // (but it takes 2 words to encode, rather than just one). |
| void AddSimpleFieldRange(uint32_t range_start, uint32_t range_len); |
| |
| // Adds a nested field. |message_index| is the index of the message that the |
| // parser must recurse into. This implies that at least |message_index| calls |
| // to Begin/EndMessage will be made. |
| // The Serialize() method will fail if any field points to an index that is |
| // out of range (e.g., if message_index = 5 but only 3 EndMessage() calls were |
| // made). |
| void AddNestedField(uint32_t field_id, uint32_t message_index); |
| |
| // Returns the filter bytecode, which is a buffer containing a sequence of |
| // varints and a checksum. The returned string can be passed to |
| // FilterBytecodeParser.Load(). |
| std::string Serialize(); |
| |
| private: |
| uint32_t num_messages_ = 0; |
| uint32_t last_field_id_ = 0; |
| uint32_t max_msg_index_ = 0; |
| bool endmessage_called_ = false; |
| |
| std::vector<uint32_t> bytecode_; |
| }; |
| |
| } // namespace protozero |
| |
| #endif // SRC_PROTOZERO_FILTERING_FILTER_BYTECODE_GENERATOR_H_ |