com.salesforce.reactivegrpccommon.ReactiveGrpcGenerator Maven / Gradle / Ivy

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/*
 *  Copyright (c) 2017, salesforce.com, inc.
 *  All rights reserved.
 *  Licensed under the BSD 3-Clause license.
 *  For full license text, see LICENSE.txt file in the repo root  or https://opensource.org/licenses/BSD-3-Clause
 */

package com.salesforce.reactivegrpccommon;

import com.google.common.base.Strings;
import com.google.protobuf.DescriptorProtos.FileDescriptorProto;
import com.google.protobuf.DescriptorProtos.FileOptions;
import com.google.protobuf.DescriptorProtos.MethodDescriptorProto;
import com.google.protobuf.DescriptorProtos.ServiceDescriptorProto;
import com.google.protobuf.compiler.PluginProtos;
import com.salesforce.jprotoc.Generator;
import com.salesforce.jprotoc.GeneratorException;
import com.salesforce.jprotoc.ProtoTypeMap;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * Abstract class for protoc generators generating Reactive Streams bindings for gRPC.
 */
public abstract class ReactiveGrpcGenerator extends Generator {

    protected abstract String getClassPrefix();

    @Override
    public Stream generate(PluginProtos.CodeGeneratorRequest request) throws GeneratorException {
        final ProtoTypeMap typeMap = ProtoTypeMap.of(request.getProtoFileList());

        List protosToGenerate = request.getProtoFileList().stream()
                .filter(protoFile -> request.getFileToGenerateList().contains(protoFile.getName()))
                .collect(Collectors.toList());

        List services = findServices(protosToGenerate, typeMap);
        List files = generateFiles(services);
        return files.stream();
    }

    private List findServices(List protos, ProtoTypeMap typeMap) {
        List contexts = new ArrayList<>();

        for (FileDescriptorProto fileProto : protos) {
            for (ServiceDescriptorProto serviceProto : fileProto.getServiceList()) {
                ServiceContext serviceContext = buildServiceContext(serviceProto, typeMap);
                serviceContext.protoName = fileProto.getName();
                serviceContext.packageName = extractPackageName(fileProto);
                contexts.add(serviceContext);
            }
        }

        return contexts;
    }

    private String extractPackageName(FileDescriptorProto proto) {
        FileOptions options = proto.getOptions();
        if (options != null) {
            String javaPackage = options.getJavaPackage();
            if (!Strings.isNullOrEmpty(javaPackage)) {
                return javaPackage;
            }
        }

        return Strings.nullToEmpty(proto.getPackage());
    }

    private ServiceContext buildServiceContext(ServiceDescriptorProto serviceProto, ProtoTypeMap typeMap) {
        ServiceContext serviceContext = new ServiceContext();
        serviceContext.fileName = getClassPrefix() + serviceProto.getName() + "Grpc.java";
        serviceContext.className = getClassPrefix() + serviceProto.getName() + "Grpc";
        serviceContext.serviceName = serviceProto.getName();
        serviceContext.deprecated = serviceProto.getOptions() != null && serviceProto.getOptions().getDeprecated();

        int i = 0;
        for (MethodDescriptorProto methodProto : serviceProto.getMethodList()) {
            MethodContext methodContext = buildMethodContext(methodProto, typeMap, i++);
            serviceContext.methods.add(methodContext);
        }

        return serviceContext;
    }

    private MethodContext buildMethodContext(MethodDescriptorProto methodProto, ProtoTypeMap typeMap, int methodNumber) {
        MethodContext methodContext = new MethodContext();
        methodContext.methodName = lowerCaseFirst(methodProto.getName());
        methodContext.methodNumber = methodNumber;
        methodContext.inputType = typeMap.toJavaTypeName(methodProto.getInputType());
        methodContext.outputType = typeMap.toJavaTypeName(methodProto.getOutputType());
        methodContext.deprecated = methodProto.getOptions() != null && methodProto.getOptions().getDeprecated();
        methodContext.isManyInput = methodProto.getClientStreaming();
        methodContext.isManyOutput = methodProto.getServerStreaming();
        if (!methodProto.getClientStreaming() && !methodProto.getServerStreaming()) {
            methodContext.reactiveCallsMethodName = "oneToOne";
            methodContext.grpcCallsMethodName = "asyncUnaryCall";
        }
        if (!methodProto.getClientStreaming() && methodProto.getServerStreaming()) {
            methodContext.reactiveCallsMethodName = "oneToMany";
            methodContext.grpcCallsMethodName = "asyncServerStreamingCall";
        }
        if (methodProto.getClientStreaming() && !methodProto.getServerStreaming()) {
            methodContext.reactiveCallsMethodName = "manyToOne";
            methodContext.grpcCallsMethodName = "asyncClientStreamingCall";
        }
        if (methodProto.getClientStreaming() && methodProto.getServerStreaming()) {
            methodContext.reactiveCallsMethodName = "manyToMany";
            methodContext.grpcCallsMethodName = "asyncBidiStreamingCall";
        }
        return methodContext;
    }

    private String lowerCaseFirst(String s) {
        return Character.toLowerCase(s.charAt(0)) + s.substring(1);
    }

    private List generateFiles(List services) {
        return services.stream()
                .map(this::buildFile)
                .collect(Collectors.toList());
    }

    private PluginProtos.CodeGeneratorResponse.File buildFile(ServiceContext context) {
        String content = applyTemplate(getClassPrefix() + "Stub.mustache", context);
        return PluginProtos.CodeGeneratorResponse.File
                .newBuilder()
                .setName(absoluteFileName(context))
                .setContent(content)
                .build();
    }

    private String absoluteFileName(ServiceContext ctx) {
        String dir = ctx.packageName.replace('.', '/');
        if (Strings.isNullOrEmpty(dir)) {
            return ctx.fileName;
        } else {
            return dir + "/" + ctx.fileName;
        }
    }

    /**
     * Template class for proto Service objects.
     */
    private class ServiceContext {
        // CHECKSTYLE DISABLE VisibilityModifier FOR 7 LINES
        public String fileName;
        public String protoName;
        public String packageName;
        public String className;
        public String serviceName;
        public boolean deprecated;
        public List methods = new ArrayList<>();
    }

    /**
     * Template class for proto RPC objects.
     */
    private class MethodContext {
        // CHECKSTYLE DISABLE VisibilityModifier FOR 9 LINES
        public String methodName;
        public String inputType;
        public String outputType;
        public boolean deprecated;
        public boolean isManyInput;
        public boolean isManyOutput;
        public String reactiveCallsMethodName;
        public String grpcCallsMethodName;
        public int methodNumber;

        // This method mimics the upper-casing method ogf gRPC to ensure compatibility
        // See https://github.com/grpc/grpc-java/blob/v1.8.0/compiler/src/java_plugin/cpp/java_generator.cpp#L58
        public String methodNameUpperUnderscore() {
            StringBuilder s = new StringBuilder();
            for (int i = 0; i < methodName.length(); i++) {
                char c = methodName.charAt(i);
                s.append(Character.toUpperCase(c));
                if ((i < methodName.length() - 1) && Character.isLowerCase(c) && Character.isUpperCase(methodName.charAt(i + 1))) {
                    s.append('_');
                }
            }
            return s.toString();
        }
    }
}