src/main/java/com/google/devtools/build/docgen/skylark/SkylarkMethodDoc.java

// Copyright 2014 The Bazel Authors. All rights reserved.
//
// 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
//
//    http://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.devtools.build.docgen.skylark;

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
import com.google.devtools.build.lib.skylarkinterface.SkylarkSignature;
import com.google.devtools.build.lib.skylarkinterface.SkylarkSignature.Param;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

/**
 * An abstract class containing documentation for a Skylark method.
 */
abstract class SkylarkMethodDoc extends SkylarkDoc {
  /**
   * Returns whether the Skylark method is documented.
   */
  public abstract boolean documented();

  /**
   * Returns a string representing the method signature of the Skylark method, which contains
   * HTML links to the documentation of parameter types if available.
   */
  public abstract String getSignature();

  /**
   * Returns a string containing additional documentation about the method's return value.
   *
   * <p>Returns an empty string by default.
   */
  public String getReturnTypeExtraMessage() {
    return "";
  }

  /**
   * Returns a list containing the documentation for each of the method's parameters.
   */
  public List<SkylarkParamDoc> getParams() {
    return ImmutableList.<SkylarkParamDoc>of();
  }

  private String getParameterString(Method method) {
    return Joiner.on(", ").join(Iterables.transform(
        ImmutableList.copyOf(method.getParameterTypes()), new Function<Class<?>, String>() {
          @Override
          public String apply(Class<?> input) {
            return getTypeAnchor(input);
          }
        }));
  }

  protected String getSignature(String objectName, String methodName, Method method) {
    String args = method.getAnnotation(SkylarkCallable.class).structField()
        ? "" : "(" + getParameterString(method) + ")";

    return String.format("%s %s.%s%s",
        getTypeAnchor(method.getReturnType()), objectName, methodName, args);
  }

  protected String getSignature(String objectName, SkylarkSignature method) {
    List<String> argList = new ArrayList<>();
    for (Param param : adjustedMandatoryPositionals(method)) {
      argList.add(param.name());
    }
    for (Param param : method.optionalPositionals()) {
      argList.add(formatOptionalParameter(param));
    }
    for (Param param : method.extraPositionals()) {
      argList.add("*" + param.name());
    }
    if (argList.size() > 0 && method.extraPositionals().length == 0
        && (method.optionalNamedOnly().length > 0 || method.mandatoryNamedOnly().length > 0)) {
      argList.add("*");
    }
    for (Param param : method.mandatoryNamedOnly()) {
      argList.add(param.name());
    }
    for (Param param : method.optionalNamedOnly()) {
      argList.add(formatOptionalParameter(param));
    }
    for (Param param : method.extraKeywords()) {
      argList.add("**" + param.name());
    }
    String args = "(" + Joiner.on(", ").join(argList) + ")";
    if (!objectName.equals(TOP_LEVEL_ID)) {
      return String.format("%s %s.%s%s\n",
          getTypeAnchor(method.returnType()), objectName, method.name(), args);
    } else {
      return String.format("%s %s%s\n",
          getTypeAnchor(method.returnType()), method.name(), args);
    }
  }

  private String formatOptionalParameter(Param param) {
    String defaultValue = param.defaultValue();
    return String.format("%s=%s", param.name(),
        (defaultValue == null || defaultValue.isEmpty()) ? "&hellip;" : defaultValue);
  }
}