Protocol Buffer runtime library and 'protoc' plugin

lib/protobuf/plugin/plugin.proto

+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: kenton@google.com (Kenton Varda)
+//
+// WARNING:  The plugin interface is currently EXPERIMENTAL and is subject to
+//   change.
+//
+// protoc (aka the Protocol Compiler) can be extended via plugins.  A plugin is
+// just a program that reads a CodeGeneratorRequest from stdin and writes a
+// CodeGeneratorResponse to stdout.
+//
+// Plugins written using C++ can use google/protobuf/compiler/plugin.h instead
+// of dealing with the raw protocol defined here.
+//
+// A plugin executable needs only to be placed somewhere in the path.  The
+// plugin should be named "protoc-gen-$NAME", and will then be used when the
+// flag "--${NAME}_out" is passed to protoc.
+
+package google.protobuf.compiler;
+
+import "descriptor.proto";
+
+// An encoded CodeGeneratorRequest is written to the plugin's stdin.
+message CodeGeneratorRequest {
+  // The .proto files that were explicitly listed on the command-line.  The
+  // code generator should generate code only for these files.  Each file's
+  // descriptor will be included in proto_file, below.
+  repeated string file_to_generate = 1;
+
+  // The generator parameter passed on the command-line.
+  optional string parameter = 2;
+
+  // FileDescriptorProtos for all files in files_to_generate and everything
+  // they import.  The files will appear in topological order, so each file
+  // appears before any file that imports it.
+  //
+  // protoc guarantees that all proto_files will be written after
+  // the fields above, even though this is not technically guaranteed by the
+  // protobuf wire format.  This theoretically could allow a plugin to stream
+  // in the FileDescriptorProtos and handle them one by one rather than read
+  // the entire set into memory at once.  However, as of this writing, this
+  // is not similarly optimized on protoc's end -- it will store all fields in
+  // memory at once before sending them to the plugin.
+  repeated FileDescriptorProto proto_file = 15;
+}
+
+// The plugin writes an encoded CodeGeneratorResponse to stdout.
+message CodeGeneratorResponse {
+  // Error message.  If non-empty, code generation failed.  The plugin process
+  // should exit with status code zero even if it reports an error in this way.
+  //
+  // This should be used to indicate errors in .proto files which prevent the
+  // code generator from generating correct code.  Errors which indicate a
+  // problem in protoc itself -- such as the input CodeGeneratorRequest being
+  // unparseable -- should be reported by writing a message to stderr and
+  // exiting with a non-zero status code.
+  optional string error = 1;
+
+  // Represents a single generated file.
+  message File {
+    // The file name, relative to the output directory.  The name must not
+    // contain "." or ".." components and must be relative, not be absolute (so,
+    // the file cannot lie outside the output directory).  "/" must be used as
+    // the path separator, not "\".
+    //
+    // If the name is omitted, the content will be appended to the previous
+    // file.  This allows the generator to break large files into small chunks,
+    // and allows the generated text to be streamed back to protoc so that large
+    // files need not reside completely in memory at one time.  Note that as of
+    // this writing protoc does not optimize for this -- it will read the entire
+    // CodeGeneratorResponse before writing files to disk.
+    optional string name = 1;
+
+    // If non-empty, indicates that the named file should already exist, and the
+    // content here is to be inserted into that file at a defined insertion
+    // point.  This feature allows a code generator to extend the output
+    // produced by another code generator.  The original generator may provide
+    // insertion points by placing special annotations in the file that look
+    // like:
+    //   @@protoc_insertion_point(NAME)
+    // The annotation can have arbitrary text before and after it on the line,
+    // which allows it to be placed in a comment.  NAME should be replaced with
+    // an identifier naming the point -- this is what other generators will use
+    // as the insertion_point.  Code inserted at this point will be placed
+    // immediately above the line containing the insertion point (thus multiple
+    // insertions to the same point will come out in the order they were added).
+    // The double-@ is intended to make it unlikely that the generated code
+    // could contain things that look like insertion points by accident.
+    //
+    // For example, the C++ code generator places the following line in the
+    // .pb.h files that it generates:
+    //   // @@protoc_insertion_point(namespace_scope)
+    // This line appears within the scope of the file's package namespace, but
+    // outside of any particular class.  Another plugin can then specify the
+    // insertion_point "namespace_scope" to generate additional classes or
+    // other declarations that should be placed in this scope.
+    //
+    // Note that if the line containing the insertion point begins with
+    // whitespace, the same whitespace will be added to every line of the
+    // inserted text.  This is useful for languages like Python, where
+    // indentation matters.  In these languages, the insertion point comment
+    // should be indented the same amount as any inserted code will need to be
+    // in order to work correctly in that context.
+    //
+    // The code generator that generates the initial file and the one which
+    // inserts into it must both run as part of a single invocation of protoc.
+    // Code generators are executed in the order in which they appear on the
+    // command line.
+    //
+    // If |insertion_point| is present, |name| must also be present.
+    optional string insertion_point = 2;
+
+    // The file contents.
+    optional string content = 15;
+  }
+  repeated File file = 15;
+}