ShiftUtils.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.ipp.shift;

import com.intellij.psi.PsiExpression;
import com.intellij.psi.PsiLiteralExpression;
import com.intellij.psi.PsiType;

class ShiftUtils {

  private ShiftUtils() {
    super();
  }

  public static boolean isPowerOfTwo(PsiExpression rhs) {
    if (!(rhs instanceof PsiLiteralExpression)) {
      return false;
    }
    final PsiLiteralExpression literal = (PsiLiteralExpression)rhs;
    final Object value = literal.getValue();
    if (!(value instanceof Number)) {
      return false;
    }
    if (value instanceof Double || value instanceof Float) {
      return false;
    }
    int intValue = ((Number)value).intValue();
    if (intValue <= 0) {
      return false;
    }
    while (intValue % 2 == 0) {
      intValue >>= 1;
    }
    return intValue == 1;
  }

  public static int getLogBase2(PsiExpression rhs) {
    final PsiLiteralExpression literal = (PsiLiteralExpression)rhs;
    final Object value = literal.getValue();
    int intValue = ((Number)value).intValue();
    int log = 0;
    while (intValue % 2 == 0) {
      intValue >>= 1;
      log++;
    }
    return log;
  }

  public static int getExpBase2(PsiExpression rhs) {
    final PsiLiteralExpression literal = (PsiLiteralExpression)rhs;
    final Object value = literal.getValue();
    if (value == null) {
      return 0;
    }
    final int intValue = ((Number)value).intValue() & 31;
    int exp = 1;
    for (int i = 0; i < intValue; i++) {
      exp <<= 1;
    }
    return exp;
  }

  public static boolean isIntegral(PsiType lhsType) {
    return lhsType != null &&
           (lhsType.equals(PsiType.INT)
            || lhsType.equals(PsiType.SHORT)
            || lhsType.equals(PsiType.LONG)
            || lhsType.equals(PsiType.BYTE));
  }

  public static boolean isIntLiteral(PsiExpression rhs) {
    if (!(rhs instanceof PsiLiteralExpression)) {
      return false;
    }
    final PsiLiteralExpression literal = (PsiLiteralExpression)rhs;
    final Object value = literal.getValue();
    if (!(value instanceof Number)) {
      return false;
    }
    return !(value instanceof Double) && !(value instanceof Float);
  }
}