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Simple Apache Accumulo examples.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.accumulo.examples.simple.constraints;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.apache.accumulo.core.constraints.Constraint;
import org.apache.accumulo.core.data.ColumnUpdate;
import org.apache.accumulo.core.data.Mutation;

/**
 * This class is an accumulo constraint that ensures values are numeric strings. See
 * docs/examples/README.constraint for instructions.
 */
public class NumericValueConstraint implements Constraint {

  static final short NON_NUMERIC_VALUE = 1;
  static final String VIOLATION_MESSAGE = "Value is not numeric";

  private static final List VIOLATION_LIST = Collections
      .unmodifiableList(Arrays.asList(NON_NUMERIC_VALUE));

  private boolean isNumeric(byte bytes[]) {
    for (byte b : bytes) {
      boolean ok = (b >= '0' && b <= '9');
      if (!ok)
        return false;
    }

    return true;
  }

  @Override
  public List check(Environment env, Mutation mutation) {
    Collection updates = mutation.getUpdates();

    for (ColumnUpdate columnUpdate : updates) {
      if (!isNumeric(columnUpdate.getValue()))
        return VIOLATION_LIST;
    }

    return null;
  }

  @Override
  public String getViolationDescription(short violationCode) {

    switch (violationCode) {
      case NON_NUMERIC_VALUE:
        return "Value is not numeric";
    }

    return null;
  }

}