1 /*
2  * Copyright (C) 2010 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 _INIT_PARSER_H_
18 #define _INIT_PARSER_H_
19 
20 #include <map>
21 #include <memory>
22 #include <string>
23 #include <vector>
24 
25 #include "result.h"
26 
27 //  SectionParser is an interface that can parse a given 'section' in init.
28 //
29 //  You can implement up to 4 functions below, with ParseSection being mandatory. The first two
30 //  functions return Result<Success> indicating if they have an error. It will be reported along
31 //  with the filename and line number of where the error occurred.
32 //
33 //  1) ParseSection
34 //    This function is called when a section is first encountered.
35 //
36 //  2) ParseLineSection
37 //    This function is called on each subsequent line until the next section is encountered.
38 //
39 //  3) EndSection
40 //    This function is called either when a new section is found or at the end of the file.
41 //    It indicates that parsing of the current section is complete and any relevant objects should
42 //    be committed.
43 //
44 //  4) EndFile
45 //    This function is called at the end of the file.
46 //    It indicates that the parsing has completed and any relevant objects should be committed.
47 
48 namespace android {
49 namespace init {
50 
51 class SectionParser {
52   public:
53     virtual ~SectionParser() {}
54     virtual Result<Success> ParseSection(std::vector<std::string>&& args,
55                                          const std::string& filename, int line) = 0;
56     virtual Result<Success> ParseLineSection(std::vector<std::string>&&, int) { return Success(); };
57     virtual Result<Success> EndSection() { return Success(); };
58     virtual void EndFile(){};
59 };
60 
61 class Parser {
62   public:
63     //  LineCallback is the type for callbacks that can parse a line starting with a given prefix.
64     //
65     //  They take the form of bool Callback(std::vector<std::string>&& args, std::string* err)
66     //
67     //  Similar to ParseSection() and ParseLineSection(), this function returns bool with false
68     //  indicating a failure and has an std::string* err parameter into which an error string can
69     //  be written.
70     using LineCallback = std::function<Result<Success>(std::vector<std::string>&&)>;
71 
72     Parser();
73 
74     bool ParseConfig(const std::string& path);
75     bool ParseConfig(const std::string& path, size_t* parse_errors);
76     void AddSectionParser(const std::string& name, std::unique_ptr<SectionParser> parser);
77     void AddSingleLineParser(const std::string& prefix, LineCallback callback);
78 
79   private:
80     void ParseData(const std::string& filename, const std::string& data, size_t* parse_errors);
81     bool ParseConfigFile(const std::string& path, size_t* parse_errors);
82     bool ParseConfigDir(const std::string& path, size_t* parse_errors);
83 
84     std::map<std::string, std::unique_ptr<SectionParser>> section_parsers_;
85     std::vector<std::pair<std::string, LineCallback>> line_callbacks_;
86 };
87 
88 }  // namespace init
89 }  // namespace android
90 
91 #endif
92