ObjC Support a runtime import override.

Option to add a prefix to generated #imports incase ObjC Protos are
used in a build system where one wants to avoid adding a header
search path and have more complete imports.

objectivec/README.md

@@ -172,6 +172,12 @@ supported keys are:
     lot of proto files included in it; and having multiple lines makes things
     easier to read.
 
+  * `runtime_import_prefix`: The `value` used for this key to be used as a
+    prefix on `#import`s of runtime provided headers in the generated files.
+    When integrating ObjC protos into a build system, this can be used to avoid
+    having to add the runtime directory to the header search path since the
+    generate `#import` will be more complete.
+
 Contributing
 ------------
 

src/google/protobuf/compiler/objectivec/objectivec_file.cc

@@ -242,6 +242,7 @@ void FileGenerator::GenerateHeader(io::Printer *printer) {
     ImportWriter import_writer(
         options_.generate_for_named_framework,
         options_.named_framework_to_proto_path_mappings_path,
+        options_.runtime_import_prefix,
         is_bundled_proto_);
     const string header_extension(kHeaderExtension);
     for (int i = 0; i < file_->public_dependency_count(); i++) {
@@ -355,6 +356,7 @@ void FileGenerator::GenerateSource(io::Printer *printer) {
     ImportWriter import_writer(
         options_.generate_for_named_framework,
         options_.named_framework_to_proto_path_mappings_path,
+        options_.runtime_import_prefix,
         is_bundled_proto_);
     const string header_extension(kHeaderExtension);
 
@@ -596,7 +598,8 @@ void FileGenerator::PrintFileRuntimePreamble(
       "// source: $filename$\n"
       "\n",
       "filename", file_->name());
-  ImportWriter::PrintRuntimeImports(printer, headers_to_import, true);
+  ImportWriter::PrintRuntimeImports(
+      printer, headers_to_import, options_.runtime_import_prefix, true);
   printer->Print("\n");
 }
 

src/google/protobuf/compiler/objectivec/objectivec_generator.cc

@@ -127,6 +127,13 @@ bool ObjectiveCGenerator::GenerateAll(const std::vector<const FileDescriptor*>&
       // with generate_for_named_framework, or the relative path to it's include
       // path otherwise.
       generation_options.named_framework_to_proto_path_mappings_path = options[i].second;
+    } else if (options[i].first == "runtime_import_prefix") {
+      // Path to use as a prefix on #imports of runtime provided headers in the
+      // generated files. When integrating ObjC protos into a build system,
+      // this can be used to avoid having to add the runtime directory to the
+      // header search path since the generate #import will be more complete.
+      generation_options.runtime_import_prefix =
+          StripSuffixString(options[i].second, "/");
     } else {
       *error = "error: Unknown generator option: " + options[i].first;
       return false;

src/google/protobuf/compiler/objectivec/objectivec_helpers.cc

@@ -1566,10 +1566,12 @@ bool ParseSimpleFile(
 ImportWriter::ImportWriter(
   const string& generate_for_named_framework,
   const string& named_framework_to_proto_path_mappings_path,
+  const string& runtime_import_prefix,
   bool include_wkt_imports)
     : generate_for_named_framework_(generate_for_named_framework),
       named_framework_to_proto_path_mappings_path_(
           named_framework_to_proto_path_mappings_path),
+      runtime_import_prefix_(runtime_import_prefix),
       include_wkt_imports_(include_wkt_imports),
       need_to_parse_mapping_file_(true) {
 }
@@ -1618,7 +1620,7 @@ void ImportWriter::Print(io::Printer* printer) const {
   bool add_blank_line = false;
 
   if (!protobuf_imports_.empty()) {
-    PrintRuntimeImports(printer, protobuf_imports_);
+    PrintRuntimeImports(printer, protobuf_imports_, runtime_import_prefix_);
     add_blank_line = true;
   }
 
@@ -1654,7 +1656,20 @@ void ImportWriter::Print(io::Printer* printer) const {
 void ImportWriter::PrintRuntimeImports(
     io::Printer* printer,
     const std::vector<string>& header_to_import,
+    const string& runtime_import_prefix,
     bool default_cpp_symbol) {
+
+  // Given an override, use that.
+  if (!runtime_import_prefix.empty()) {
+    for (const auto& header : header_to_import) {
+      printer->Print(
+          " #import \"$import_prefix$/$header$\"\n",
+          "import_prefix", runtime_import_prefix,
+          "header", header);
+    }
+    return;
+  }
+
   const string framework_name(ProtobufLibraryFrameworkName);
   const string cpp_symbol(ProtobufFrameworkImportSymbol(framework_name));
 

src/google/protobuf/compiler/objectivec/objectivec_helpers.h

@@ -53,6 +53,7 @@ struct Options {
   std::vector<string> expected_prefixes_suppressions;
   string generate_for_named_framework;
   string named_framework_to_proto_path_mappings_path;
+  string runtime_import_prefix;
 };
 
 // Escape C++ trigraphs by escaping question marks to "\?".
@@ -279,6 +280,7 @@ class PROTOC_EXPORT ImportWriter {
  public:
   ImportWriter(const string& generate_for_named_framework,
                const string& named_framework_to_proto_path_mappings_path,
+               const string& runtime_import_prefix,
                bool include_wkt_imports);
   ~ImportWriter();
 
@@ -287,6 +289,7 @@ class PROTOC_EXPORT ImportWriter {
 
   static void PrintRuntimeImports(io::Printer *printer,
                                   const std::vector<string>& header_to_import,
+                                  const string& runtime_import_prefix,
                                   bool default_cpp_symbol = false);
 
  private:
@@ -305,6 +308,7 @@ class PROTOC_EXPORT ImportWriter {
 
   const string generate_for_named_framework_;
   const string named_framework_to_proto_path_mappings_path_;
+  const string runtime_import_prefix_;
   const bool include_wkt_imports_;
   std::map<string, string> proto_file_to_framework_name_;
   bool need_to_parse_mapping_file_;