content: /*
   * Copyright 1999-2012 Alibaba Group.
   *  
   * 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.
   */
  /**
   * (created at 2011-7-19)
   */
  package com.alibaba.cobar.route.function;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  
  import com.alibaba.cobar.config.model.rule.RuleAlgorithm;
  import com.alibaba.cobar.parser.ast.expression.Expression;
  import com.alibaba.cobar.parser.ast.expression.primary.function.FunctionExpression;
  import com.alibaba.cobar.parser.util.Pair;
  import com.alibaba.cobar.parser.util.PairUtil;
  import com.alibaba.cobar.util.StringUtil;
  
  /**
   * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
   */
  public final class PartitionByString extends PartitionFunction implements RuleAlgorithm {
      public PartitionByString(String functionName) {
          this(functionName, null);
      }
  
      public PartitionByString(String functionName, List<Expression> arguments) {
          super(functionName, arguments);
      }
  
      private int hashSliceStart = 0;
      /** 0 means str.length(), -1 means str.length()-1 */
      private int hashSliceEnd = 8;
  
      public void setHashLength(int hashLength) {
          setHashSlice(String.valueOf(hashLength));
      }
  
      public void setHashSlice(String hashSlice) {
          Pair<Integer, Integer> p = PairUtil.sequenceSlicing(hashSlice);
          hashSliceStart = p.getKey();
          hashSliceEnd = p.getValue();
      }
  
      @Override
      public Object evaluationInternal(Map<? extends Object, ? extends Object> parameters) {
          return calculate(parameters)[0];
      }
  
      @Override
      public Integer[] calculate(Map<? extends Object, ? extends Object> parameters) {
          Integer[] rst = new Integer[1];
          Object arg = arguments.get(0).evaluation(parameters);
          if (arg == UNEVALUATABLE) {
              throw new IllegalArgumentException("argument is UNEVALUATABLE");
          }
          String key = String.valueOf(arg);
          int start = hashSliceStart >= 0 ? hashSliceStart : key.length() + hashSliceStart;
          int end = hashSliceEnd > 0 ? hashSliceEnd : key.length() + hashSliceEnd;
          long hash = StringUtil.hash(key, start, end);
          rst[0] = partitionIndex(hash);
          return rst;
      }
  
      @Override
      public FunctionExpression constructFunction(List<Expression> arguments) {
          if (arguments == null || arguments.size() != 1) {
              throw new IllegalArgumentException("function " + getFunctionName() + " must have 1 argument but is "
                      + arguments);
          }
          Object[] args = new Object[arguments.size()];
          int i = -1;
          for (Expression arg : arguments) {
              args[++i] = arg;
          }
          return (FunctionExpression) constructMe(args);
      }
  
      @Override
      public RuleAlgorithm constructMe(Object... objects) {
          List<Expression> args = new ArrayList<Expression>(objects.length);
          for (Object obj : objects) {
              args.add((Expression) obj);
          }
          PartitionByString partitionFunc = new PartitionByString(functionName, args);
          partitionFunc.hashSliceStart = hashSliceStart;
          partitionFunc.hashSliceEnd = hashSliceEnd;
          partitionFunc.count = count;
          partitionFunc.length = length;
          return partitionFunc;
      }
  
      @Override
      public void initialize() {
          init();
      }
  
  }
  