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30 
31 // Author: kenton@google.com (Kenton Varda)
32 //  Based on original Protocol Buffers design by
33 //  Sanjay Ghemawat, Jeff Dean, and others.
34 //
35 // Defines the abstract interface implemented by each of the language-specific
36 // code generators.
37 
38 #ifndef GOOGLE_PROTOBUF_COMPILER_CODE_GENERATOR_H__
39 #define GOOGLE_PROTOBUF_COMPILER_CODE_GENERATOR_H__
40 
41 #include <google/protobuf/stubs/common.h>
42 #include <string>
43 #include <vector>
44 #include <utility>
45 
46 namespace google {
47 namespace protobuf {
48 
49 namespace io { class ZeroCopyOutputStream; }
50 class FileDescriptor;
51 
52 namespace compiler {
53 
54 // Defined in this file.
55 class CodeGenerator;
56 class GeneratorContext;
57 
58 // The abstract interface to a class which generates code implementing a
59 // particular proto file in a particular language.  A number of these may
60 // be registered with CommandLineInterface to support various languages.
61 class LIBPROTOC_EXPORT CodeGenerator {
62  public:
CodeGenerator()63   inline CodeGenerator() {}
64   virtual ~CodeGenerator();
65 
66   // Generates code for the given proto file, generating one or more files in
67   // the given output directory.
68   //
69   // A parameter to be passed to the generator can be specified on the
70   // command line.  This is intended to be used by Java and similar languages
71   // to specify which specific class from the proto file is to be generated,
72   // though it could have other uses as well.  It is empty if no parameter was
73   // given.
74   //
75   // Returns true if successful.  Otherwise, sets *error to a description of
76   // the problem (e.g. "invalid parameter") and returns false.
77   virtual bool Generate(const FileDescriptor* file,
78                         const string& parameter,
79                         GeneratorContext* generator_context,
80                         string* error) const = 0;
81 
82  private:
83   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CodeGenerator);
84 };
85 
86 // CodeGenerators generate one or more files in a given directory.  This
87 // abstract interface represents the directory to which the CodeGenerator is
88 // to write and other information about the context in which the Generator
89 // runs.
90 class LIBPROTOC_EXPORT GeneratorContext {
91  public:
GeneratorContext()92   inline GeneratorContext() {}
93   virtual ~GeneratorContext();
94 
95   // Opens the given file, truncating it if it exists, and returns a
96   // ZeroCopyOutputStream that writes to the file.  The caller takes ownership
97   // of the returned object.  This method never fails (a dummy stream will be
98   // returned instead).
99   //
100   // The filename given should be relative to the root of the source tree.
101   // E.g. the C++ generator, when generating code for "foo/bar.proto", will
102   // generate the files "foo/bar.pb.h" and "foo/bar.pb.cc"; note that
103   // "foo/" is included in these filenames.  The filename is not allowed to
104   // contain "." or ".." components.
105   virtual io::ZeroCopyOutputStream* Open(const string& filename) = 0;
106 
107   // Similar to Open() but the output will be appended to the file if exists
108   virtual io::ZeroCopyOutputStream* OpenForAppend(const string& filename);
109 
110   // Creates a ZeroCopyOutputStream which will insert code into the given file
111   // at the given insertion point.  See plugin.proto (plugin.pb.h) for more
112   // information on insertion points.  The default implementation
113   // assert-fails -- it exists only for backwards-compatibility.
114   //
115   // WARNING:  This feature is currently EXPERIMENTAL and is subject to change.
116   virtual io::ZeroCopyOutputStream* OpenForInsert(
117       const string& filename, const string& insertion_point);
118 
119   // Returns a vector of FileDescriptors for all the files being compiled
120   // in this run.  Useful for languages, such as Go, that treat files
121   // differently when compiled as a set rather than individually.
122   virtual void ListParsedFiles(vector<const FileDescriptor*>* output);
123 
124  private:
125   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(GeneratorContext);
126 };
127 
128 // The type GeneratorContext was once called OutputDirectory. This typedef
129 // provides backward compatibility.
130 typedef GeneratorContext OutputDirectory;
131 
132 // Several code generators treat the parameter argument as holding a
133 // list of options separated by commas.  This helper function parses
134 // a set of comma-delimited name/value pairs: e.g.,
135 //   "foo=bar,baz,qux=corge"
136 // parses to the pairs:
137 //   ("foo", "bar"), ("baz", ""), ("qux", "corge")
138 extern void ParseGeneratorParameter(const string&,
139             vector<pair<string, string> >*);
140 
141 }  // namespace compiler
142 }  // namespace protobuf
143 
144 }  // namespace google
145 #endif  // GOOGLE_PROTOBUF_COMPILER_CODE_GENERATOR_H__
146