src/compiler/objective_c_generator.cc

/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * 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,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <map>
#include <sstream>

#include "src/compiler/config.h"
#include "src/compiler/objective_c_generator.h"
#include "src/compiler/objective_c_generator_helpers.h"

#include <google/protobuf/compiler/objectivec/objectivec_helpers.h>

using ::google::protobuf::compiler::objectivec::ClassName;
using ::grpc::protobuf::io::Printer;
using ::grpc::protobuf::MethodDescriptor;
using ::grpc::protobuf::ServiceDescriptor;
using ::grpc::string;
using ::std::map;

namespace grpc_objective_c_generator {
namespace {

void PrintProtoRpcDeclarationAsPragma(Printer *printer,
                                      const MethodDescriptor *method,
                                      map<string, string> vars) {
  vars["client_stream"] = method->client_streaming() ? "stream " : "";
  vars["server_stream"] = method->server_streaming() ? "stream " : "";

  printer->Print(vars,
      "#pragma mark $method_name$($client_stream$$request_type$)"
      " returns ($server_stream$$response_type$)\n\n");
}

void PrintMethodSignature(Printer *printer,
                          const MethodDescriptor *method,
                          const map<string, string>& vars) {
  // TODO(jcanizales): Print method comments.

  printer->Print(vars, "- ($return_type$)$method_name$With");
  if (method->client_streaming()) {
    printer->Print("RequestsWriter:(id<GRXWriter>)requestWriter");
  } else {
    printer->Print(vars, "Request:($request_class$ *)request");
  }

  // TODO(jcanizales): Put this on a new line and align colons.
  if (method->server_streaming()) {
    printer->Print(vars, " eventHandler:(void(^)(BOOL done, "
      "$response_class$ *response, NSError *error))eventHandler");
  } else {
    printer->Print(vars, " handler:(void(^)($response_class$ *response, "
      "NSError *error))handler");
  }
}

void PrintSimpleSignature(Printer *printer,
                          const MethodDescriptor *method,
                          map<string, string> vars) {
  vars["method_name"] =
      grpc_generator::LowercaseFirstLetter(vars["method_name"]);
  vars["return_type"] = "void";
  PrintMethodSignature(printer, method, vars);
}

void PrintAdvancedSignature(Printer *printer,
                            const MethodDescriptor *method,
                            map<string, string> vars) {
  vars["method_name"] = "RPCTo" + vars["method_name"];
  vars["return_type"] = "ProtoRPC *";
  PrintMethodSignature(printer, method, vars);
}

inline map<string, string> GetMethodVars(const MethodDescriptor *method) {
  map<string,string> res;
  res["method_name"] = method->name();
  res["request_type"] = method->input_type()->name();
  res["response_type"] = method->output_type()->name();
  res["request_class"] = ClassName(method->input_type());
  res["response_class"] = ClassName(method->output_type());
  return res;
}

void PrintMethodDeclarations(Printer *printer,
                             const MethodDescriptor *method) {
  map<string, string> vars = GetMethodVars(method);

  PrintProtoRpcDeclarationAsPragma(printer, method, vars);

  PrintSimpleSignature(printer, method, vars);
  printer->Print(";\n\n");
  PrintAdvancedSignature(printer, method, vars);
  printer->Print(";\n\n\n");
}

void PrintSimpleImplementation(Printer *printer,
                               const MethodDescriptor *method,
                               map<string, string> vars) {
  printer->Print("{\n");
  printer->Print(vars, "  [[self RPCTo$method_name$With");
  if (method->client_streaming()) {
    printer->Print("RequestsWriter:requestWriter");
  } else {
    printer->Print("Request:request");
  }
  if (method->server_streaming()) {
    printer->Print(" eventHandler:eventHandler] start];\n");
  } else {
    printer->Print(" handler:handler] start];\n");
  }
  printer->Print("}\n");
}

void PrintAdvancedImplementation(Printer *printer,
                                 const MethodDescriptor *method,
                                 map<string, string> vars) {
  printer->Print("{\n");
  printer->Print(vars, "  return [self RPCToMethod:@\"$method_name$\"\n");

  printer->Print("            requestsWriter:");
  if (method->client_streaming()) {
    printer->Print("requestWriter\n");
  } else {
    printer->Print("[GRXWriter writerWithValue:request]\n");
  }

  printer->Print(vars, "             responseClass:[$response_class$ class]\n");

  printer->Print("        responsesWriteable:[GRXWriteable ");
  if (method->server_streaming()) {
    printer->Print("writeableWithStreamHandler:eventHandler]];\n");
  } else {
    printer->Print("writeableWithSingleValueHandler:handler]];\n");
  }

  printer->Print("}\n");
}

void PrintMethodImplementations(Printer *printer,
                                const MethodDescriptor *method) {
  map<string, string> vars = GetMethodVars(method);

  PrintProtoRpcDeclarationAsPragma(printer, method, vars);

  // TODO(jcanizales): Print documentation from the method.
  PrintSimpleSignature(printer, method, vars);
  PrintSimpleImplementation(printer, method, vars);

  printer->Print("// Returns a not-yet-started RPC object.\n");
  PrintAdvancedSignature(printer, method, vars);
  PrintAdvancedImplementation(printer, method, vars);
}

} // namespace

string GetHeader(const ServiceDescriptor *service) {
  string output;
  {
    // Scope the output stream so it closes and finalizes output to the string.
    grpc::protobuf::io::StringOutputStream output_stream(&output);
    Printer printer(&output_stream, '$');
  
    printer.Print("@protocol GRXWriteable;\n");
    printer.Print("@protocol GRXWriter;\n\n");

    map<string, string> vars = {{"service_class", ServiceClassName(service)}};

    printer.Print(vars, "@protocol $service_class$ <NSObject>\n\n");

    for (int i = 0; i < service->method_count(); i++) {
      PrintMethodDeclarations(&printer, service->method(i));
    }
    printer.Print("@end\n\n");

    printer.Print("// Basic service implementation, over gRPC, that only does"
        " marshalling and parsing.\n");
    printer.Print(vars, "@interface $service_class$ :"
      " ProtoService<$service_class$>\n");
    printer.Print("- (instancetype)initWithHost:(NSString *)host"
      " NS_DESIGNATED_INITIALIZER;\n");
    printer.Print("@end\n");
  }
  return output;
}

string GetSource(const ServiceDescriptor *service) {
  string output;
  {
    // Scope the output stream so it closes and finalizes output to the string.
    grpc::protobuf::io::StringOutputStream output_stream(&output);
    Printer printer(&output_stream, '$');

    map<string, string> vars = {{"service_name", service->name()},
                                {"service_class", ServiceClassName(service)},
                                {"package", service->file()->package()}};

    printer.Print(vars,
        "static NSString *const kPackageName = @\"$package$\";\n");
    printer.Print(vars,
        "static NSString *const kServiceName = @\"$service_name$\";\n\n");

    printer.Print(vars, "@implementation $service_class$\n\n");
  
    printer.Print("// Designated initializer\n");
    printer.Print("- (instancetype)initWithHost:(NSString *)host {\n");
    printer.Print("  return (self = [super initWithHost:host"
        " packageName:kPackageName serviceName:kServiceName]);\n");
    printer.Print("}\n\n");
    printer.Print("// Override superclass initializer to disallow different"
        " package and service names.\n");
    printer.Print("- (instancetype)initWithHost:(NSString *)host\n");
    printer.Print("                 packageName:(NSString *)packageName\n");
    printer.Print("                 serviceName:(NSString *)serviceName {\n");
    printer.Print("  return [self initWithHost:host];\n");
    printer.Print("}\n\n\n");

    for (int i = 0; i < service->method_count(); i++) {
      PrintMethodImplementations(&printer, service->method(i));
    }

    printer.Print("@end\n");
  }
  return output;
}

} // namespace grpc_objective_c_generator