com.google.api.codegen.transformer.py.PythonSamplePrintArgTransformer.java Source code

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Here is the source code for com.google.api.codegen.transformer.py.PythonSamplePrintArgTransformer.java

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/* Copyright 2018 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.api.codegen.transformer.py;

import static com.google.api.codegen.viewmodel.PrintArgView.ArgSegmentView;
import static com.google.api.codegen.viewmodel.PrintArgView.TextSegmentView;
import static com.google.api.codegen.viewmodel.PrintArgView.VariableSegmentView;
import static com.google.common.base.Preconditions.checkArgument;

import com.google.api.codegen.config.ProtoTypeRef;
import com.google.api.codegen.config.TypeModel;
import com.google.api.codegen.transformer.MethodContext;
import com.google.api.codegen.transformer.OutputTransformer;
import com.google.api.codegen.viewmodel.OutputView;
import com.google.api.codegen.viewmodel.PrintArgView;
import com.google.api.tools.framework.model.ProtoElement;
import com.google.api.tools.framework.model.ProtoFile;
import com.google.api.tools.framework.model.TypeRef;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import java.util.ArrayList;
import java.util.List;

public class PythonSamplePrintArgTransformer implements OutputTransformer.PrintArgTransformer {

    /**
     * Converts the {@code VariableView} to a {@link com.google.api.codegen.viewmodel.PrintArgView}
     * that knows how to print proto types nicely. Has effects only when the variable is an enum.
     *
     * <p>In python, calling {@code print(x)} or {@code print(''.format(x))} would only get an int
     * when {@code x} is an enum. To print the enum name of the value, we need to convert the enum
     * value to it's name.
     *
     * <p>When the type of the enum value {@code x} is a top-level enum {@code EnumType}, we can call
     * {@code print(enums.EnumType(x).name)} to print the name of {@code x}.
     *
     * <p>When the type of the enum value {@code x} is a nested enum {@code MessageType.EnumType}, we
     * can call {@code print(enums.MessageType.EnumType(x).name)} to print the name of {@code x}.
     */
    @Override
    public PrintArgView generatePrintArg(MethodContext context, OutputView.VariableView variableView) {
        if (variableView.type() == null || !variableView.type().isEnum()) {
            return PrintArgView.newBuilder()
                    .segments(ImmutableList.<ArgSegmentView>of(VariableSegmentView.of(variableView))).build();
        }
        ImmutableList<ArgSegmentView> segments = ImmutableList.of(
                TextSegmentView.of(getEnumTypeClassName(context, variableView.type()) + "("),
                VariableSegmentView.of(variableView), TextSegmentView.of(").name"));
        return PrintArgView.newBuilder().segments(segments).build();
    }

    private static String getEnumTypeClassName(MethodContext context, TypeModel type) {
        checkArgument(type instanceof ProtoTypeRef, "%s: type %s is not a proto type",
                context.getMethodModel().getSimpleName(), type);
        checkArgument(((ProtoTypeRef) type).isEnum(), "%s: type %s is not an enum type",
                context.getMethodModel().getSimpleName(), type);
        TypeRef protoType = ((ProtoTypeRef) type).getProtoType();
        ProtoElement t = protoType.getEnumType();
        List<String> names = new ArrayList<>();
        while (!(t instanceof ProtoFile)) {
            names.add(t.getSimpleName());
            t = t.getParent();
        }
        names.add("enums");
        StringBuilder builder = new StringBuilder();
        for (String name : Lists.reverse(names)) {
            builder.append(name).append(".");
        }
        return builder.substring(0, builder.length() - 1);
    }
}