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1 /*
2  * Copyright (C) 2023 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef SRC_TRACE_PROCESSOR_PERFETTO_SQL_ENGINE_PERFETTO_SQL_PREPROCESSOR_H_
18 #define SRC_TRACE_PROCESSOR_PERFETTO_SQL_ENGINE_PERFETTO_SQL_PREPROCESSOR_H_
19 
20 #include <optional>
21 #include <string>
22 #include <unordered_map>
23 #include <unordered_set>
24 #include <vector>
25 
26 #include "perfetto/base/status.h"
27 #include "perfetto/ext/base/flat_hash_map.h"
28 #include "perfetto/ext/base/status_or.h"
29 #include "src/trace_processor/sqlite/sql_source.h"
30 #include "src/trace_processor/sqlite/sqlite_tokenizer.h"
31 
32 namespace perfetto::trace_processor {
33 
34 // Preprocessor for PerfettoSQL statements. The main responsiblity of this
35 // class is to perform similar functions to the C/C++ preprocessor (e.g.
36 // expanding macros). It is also responsible for splitting the given SQL into
37 // statements.
38 class PerfettoSqlPreprocessor {
39  public:
40   struct Macro {
41     bool replace;
42     std::string name;
43     std::vector<std::string> args;
44     SqlSource sql;
45   };
46 
47   // Creates a preprocessor acting on the given SqlSource.
48   explicit PerfettoSqlPreprocessor(
49       SqlSource,
50       const base::FlatHashMap<std::string, Macro>&);
51 
52   // Preprocesses the next SQL statement. Returns true if a statement was
53   // successfully preprocessed and false if EOF was reached or the statement was
54   // not preprocessed correctly.
55   //
56   // Note: if this function returns false, callers *must* call |status()|: it
57   // is undefined behaviour to not do so.
58   bool NextStatement();
59 
60   // Returns the error status for the parser. This will be |base::OkStatus()|
61   // until an unrecoverable error is encountered.
status()62   const base::Status& status() const { return status_; }
63 
64   // Returns the most-recent preprocessed SQL statement.
65   //
66   // Note: this function must not be called unless |NextStatement()| returned
67   // true.
statement()68   SqlSource& statement() { return *statement_; }
69 
70  private:
71   struct MacroInvocation {
72     const Macro* macro;
73     std::unordered_map<std::string, SqlSource> arg_bindings;
74   };
75 
76   base::StatusOr<SqlSource> RewriteInternal(
77       const SqlSource&,
78       const std::unordered_map<std::string, SqlSource>& arg_bindings);
79 
80   base::StatusOr<MacroInvocation> ParseMacroInvocation(
81       SqliteTokenizer& tokenizer,
82       SqliteTokenizer::Token& token,
83       const SqliteTokenizer::Token& name_token,
84       const std::unordered_map<std::string, SqlSource>& arg_bindings);
85 
86   SqliteTokenizer global_tokenizer_;
87   const base::FlatHashMap<std::string, Macro>* macros_ = nullptr;
88   std::unordered_set<std::string> seen_macros_;
89   std::optional<SqlSource> statement_;
90   base::Status status_;
91 };
92 
93 }  // namespace perfetto::trace_processor
94 
95 #endif  // SRC_TRACE_PROCESSOR_PERFETTO_SQL_ENGINE_PERFETTO_SQL_PREPROCESSOR_H_
96