Refactor the way output is handled in CommandLineInterface -- now it will be…

Refactor the way output is handled in CommandLineInterface -- now it will be stored in-memory until all code generators have completed, then dumped to disk all at once.  While this means that protoc uses more memory, the code is much simpler, and handles insertions much faster.  Also, this made it easier to implement a useful feature:  insertions will be indented to match the insertion point line.  Therefore, when inserting into Python code, you don't have to figure out how much to indent your inserted code.  The refactoring should also make it easier to implement output-to-jar at some point.

src/google/protobuf/compiler/command_line_interface.h

@@ -174,9 +174,9 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   // -----------------------------------------------------------------
 
   class ErrorPrinter;
-  class DiskOutputDirectory;
-  class ErrorReportingFileOutput;
-  class InsertionOutputStream;
+  class MemoryOutputDirectory;
+  class SubOutputDirectory;
+  class MemoryOutputStream;
 
   // Clear state from previous Run().
   void Clear();
@@ -212,7 +212,8 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   // Generate the given output file from the given input.
   struct OutputDirective;  // see below
   bool GenerateOutput(const vector<const FileDescriptor*>& parsed_files,
-                      const OutputDirective& output_directive);
+                      const OutputDirective& output_directive,
+                      OutputDirectory* parent_output_directory);
   bool GeneratePluginOutput(const vector<const FileDescriptor*>& parsed_files,
                             const string& plugin_name,
                             const string& parameter,

src/google/protobuf/compiler/command_line_interface_unittest.cc

@@ -933,7 +933,10 @@ TEST_F(CommandLineInterfaceTest, OutputWriteError) {
   Run("protocol_compiler --test_out=$tmpdir "
       "--proto_path=$tmpdir foo.proto");
 
-  ExpectErrorSubstring("MockCodeGenerator detected write error.");
+  // MockCodeGenerator no longer detects an error because we actually write to
+  // an in-memory location first, then dump to disk at the end.  This is no
+  // big deal.
+  //   ExpectErrorSubstring("MockCodeGenerator detected write error.");
 
 #if defined(_WIN32) && !defined(__CYGWIN__)
   // Windows with MSVCRT.dll produces EPERM instead of EISDIR.

src/google/protobuf/compiler/mock_code_generator.cc

@@ -50,7 +50,7 @@ static const char* kSecondInsertionPointName = "second_mock_insertion_point";
 static const char* kFirstInsertionPoint =
     "# @@protoc_insertion_point(first_mock_insertion_point) is here\n";
 static const char* kSecondInsertionPoint =
-    "# @@protoc_insertion_point(second_mock_insertion_point) is here\n";
+    "  # @@protoc_insertion_point(second_mock_insertion_point) is here\n";
 
 MockCodeGenerator::MockCodeGenerator(const string& name)
     : name_(name) {}
@@ -94,7 +94,9 @@ void MockCodeGenerator::ExpectGenerated(
     EXPECT_EQ(GetOutputFileContent(insertion_list[i], "first_insert",
                                    file, first_message_name),
               lines[1 + i]);
-    EXPECT_EQ(GetOutputFileContent(insertion_list[i], "second_insert",
+    // Second insertion point is indented, so the inserted text should
+    // automatically be indented too.
+    EXPECT_EQ("  " + GetOutputFileContent(insertion_list[i], "second_insert",
                                           file, first_message_name),
               lines[2 + insertion_list.size() + i]);
   }

src/google/protobuf/compiler/plugin.proto

@@ -123,6 +123,13 @@ message CodeGeneratorResponse {
     // insertion_point "package_level_decls" 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.
+    //
     // If |insertion_point| is present, |name| must also be present.
     optional string insertion_point = 2;