AsBooleanTransformation.java

/*
 * Copyright 2000-2016 JetBrains s.r.o.
 *
 * 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 org.jetbrains.plugins.groovy.codeInspection.changeToOperator.transformations;

import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiType;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.jetbrains.plugins.groovy.codeInspection.changeToOperator.ChangeToOperatorInspection.Options;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.GrIfStatement;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.GrWhileStatement;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrBinaryExpression;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrConditionalExpression;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrMethodCall;
import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrUnaryExpression;

import static java.util.Objects.requireNonNull;
import static org.jetbrains.plugins.groovy.codeInspection.GrInspectionUtil.replaceExpression;
import static org.jetbrains.plugins.groovy.lang.lexer.GroovyTokenTypes.mLNOT;
import static org.jetbrains.plugins.groovy.lang.psi.impl.utils.ParenthesesUtils.PREFIX_PRECEDENCE;
import static org.jetbrains.plugins.groovy.lang.psi.impl.utils.ParenthesesUtils.checkPrecedence;

/**
 * e.g.
 * !a.asBoolean()    -> !a
 * a.asBoolean()     -> !!a
 * if(a.asBoolean()) -> if(a)
 */
class AsBooleanTransformation extends Transformation {
  public static final String NEGATION = mLNOT.toString();
  public static final String DOUBLE_NEGATION = NEGATION + NEGATION;

  @Nullable
  protected String getPrefix(@NotNull GrMethodCall methodCall, @NotNull Options options) {
    if (isImplicitlyBoolean(methodCall)) {
      return "";
    }
    else if (options.useDoubleNegation()) {
      return DOUBLE_NEGATION;
    }
    else {
      return null;
    }
  }

  @Override
  public void apply(@NotNull GrMethodCall methodCall, @NotNull Options options) {
    replaceExpression(methodCall, getPrefix(methodCall, options) + requireNonNull(getBase(methodCall)).getText());
  }

  @Override
  public boolean couldApplyInternal(@NotNull GrMethodCall methodCall, @NotNull Options options) {
    return getBase(methodCall) != null
           && methodCall.getExpressionArguments().length == 0
           && getPrefix(methodCall, options) != null
           && methodCall.getClosureArguments().length == 0;
  }

  @Override
  protected boolean needParentheses(@NotNull GrMethodCall methodCall, @NotNull Options options) {
    String prefix = getPrefix(methodCall, options);
    return DOUBLE_NEGATION.equals(prefix) && checkPrecedence(PREFIX_PRECEDENCE, methodCall);
  }

  private static boolean isImplicitlyBoolean(GrMethodCall methodCall) {
    PsiElement parent = methodCall.getParent();
    if (parent instanceof GrIfStatement || parent instanceof GrWhileStatement) return true;
    if (parent instanceof GrConditionalExpression && ((GrConditionalExpression)parent).getCondition().equals(methodCall)) return true;
    if (parent instanceof GrUnaryExpression && PsiType.BOOLEAN.equals(((GrUnaryExpression)parent).getType())) return true;
    if (parent instanceof GrBinaryExpression && PsiType.BOOLEAN.equals(((GrBinaryExpression)parent).getType())) return true;
    return false;
  }
}