LengthOneStringsInConcatenationInspection.java

/*
 * Copyright 2003-2011 Dave Griffith, Bas Leijdekkers
 *
 * 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.siyeh.ig.performance;

import com.intellij.codeInspection.ProblemDescriptor;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.text.StringUtil;
import com.intellij.psi.*;
import com.intellij.util.IncorrectOperationException;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import com.siyeh.ig.InspectionGadgetsFix;
import com.siyeh.ig.PsiReplacementUtil;
import com.siyeh.ig.psiutils.ExpressionUtils;
import com.siyeh.ig.psiutils.TypeUtils;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;

public class LengthOneStringsInConcatenationInspection
  extends BaseInspection {

  @Override
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message(
      "length.one.strings.in.concatenation.display.name");
  }

  @Override
  @NotNull
  public String getID() {
    return "SingleCharacterStringConcatenation";
  }

  @Override
  @NotNull
  public String buildErrorString(Object... infos) {
    final String string = (String)infos[0];
    final String escapedString = StringUtil.escapeStringCharacters(string);
    return InspectionGadgetsBundle.message(
      "expression.can.be.replaced.problem.descriptor",
      escapedString);
  }

  @Override
  public InspectionGadgetsFix buildFix(Object... infos) {
    return new ReplaceStringsWithCharsFix();
  }

  private static class ReplaceStringsWithCharsFix
    extends InspectionGadgetsFix {

    @Override
    @NotNull
    public String getFamilyName() {
      return InspectionGadgetsBundle.message(
        "length.one.strings.in.concatenation.replace.quickfix");
    }

    @Override
    public void doFix(Project project, ProblemDescriptor descriptor)
      throws IncorrectOperationException {
      final PsiExpression expression =
        (PsiExpression)descriptor.getPsiElement();
      final String text = expression.getText();
      final int length = text.length();
      final String character = text.substring(1, length - 1);
      final String charLiteral;
      if ("\'".equals(character)) {
        charLiteral = "'\\''";
      }
      else if ("\\\"".equals(character)) {
        charLiteral = "'\"'";
      }
      else {
        charLiteral = '\'' + character + '\'';
      }
      PsiReplacementUtil.replaceExpression(expression, charLiteral);
    }
  }

  @Override
  public BaseInspectionVisitor buildVisitor() {
    return new LengthOneStringsInConcatenationVisitor();
  }

  private static class LengthOneStringsInConcatenationVisitor
    extends BaseInspectionVisitor {

    @Override
    public void visitLiteralExpression(
      @NotNull PsiLiteralExpression expression) {
      super.visitLiteralExpression(expression);
      final PsiType type = expression.getType();
      if (!TypeUtils.isJavaLangString(type)) {
        return;
      }
      final String value = (String)expression.getValue();
      if (value == null || value.length() != 1) {
        return;
      }
      if (!ExpressionUtils.isStringConcatenationOperand(expression) &&
          !isArgumentOfStringAppend(expression)) {
        return;
      }
      registerError(expression, value);
    }

    static boolean isArgumentOfStringAppend(PsiExpression expression) {
      final PsiElement parent = expression.getParent();
      if (parent == null) {
        return false;
      }
      if (!(parent instanceof PsiExpressionList)) {
        return false;
      }
      final PsiElement grandparent = parent.getParent();
      if (!(grandparent instanceof PsiMethodCallExpression)) {
        return false;
      }
      final PsiMethodCallExpression call =
        (PsiMethodCallExpression)grandparent;
      final PsiReferenceExpression methodExpression =
        call.getMethodExpression();
      @NonNls final String name = methodExpression.getReferenceName();
      if (!"append".equals(name) && !"insert".equals(name)) {
        return false;
      }
      final PsiMethod method = call.resolveMethod();
      if (method == null) {
        return false;
      }
      final PsiClass methodClass = method.getContainingClass();
      if (methodClass == null) {
        return false;
      }
      final String className = methodClass.getQualifiedName();
      return CommonClassNames.JAVA_LANG_STRING_BUFFER.equals(className) ||
             CommonClassNames.JAVA_LANG_STRING_BUILDER.equals(className);
    }
  }
}