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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
   *
   *    https://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.cayenne.exp.parser;
  
  import java.io.IOException;
  import java.util.List;
  
  import org.apache.cayenne.exp.Expression;
  
  /**
   * @since 4.0
   */
  public abstract class ASTFunctionCall extends EvaluatedNode {
  
      protected String functionName;
  
      ASTFunctionCall(int id, String functionName) {
          super(id);
          setFunctionName(functionName);
      }
  
      public ASTFunctionCall(int id, String functionName, Object... nodes) {
          this(id, functionName);
          setFunctionName(functionName);
          int len = nodes.length;
          for (int i = 0; i < len; i++) {
              jjtAddChild(wrapChild(nodes[i]), i);
          }
  
          connectChildren();
      }
  
      @Override
      public int getType() {
          return Expression.FUNCTION_CALL;
      }
  
      public boolean needParenthesis() {
          return true;
      }
  
      public String getFunctionName() {
          return functionName;
      }
  
      protected void setFunctionName(String functionName) {
          this.functionName = functionName;
      }
  
      @Override
      protected String getExpressionOperator(int index) {
          return ",";
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
          if (o == null || getClass() != o.getClass()) return false;
          if (!super.equals(o)) return false;
          ASTFunctionCall that = (ASTFunctionCall) o;
          return functionName.equals(that.functionName);
      }
  
      @Override
      public int hashCode() {
          return 31 * super.hashCode() + functionName.hashCode();
      }
  
      protected void appendFunctionNameAsString(Appendable out) throws IOException {
          out.append(nameToCamelCase(getFunctionName()));
      }
  
      @Override
      public void appendAsString(Appendable out) throws IOException {
          appendFunctionNameAsString(out);
          if(parent == null) {
              // else call to super method will append parenthesis
              out.append("(");
          }
          super.appendAsString(out);
          if(parent == null) {
              out.append(")");
          }
      }
  
      @Override
      public void appendAsEJBQL(List<Object> parameterAccumulator, Appendable out, String rootId) throws IOException {
          out.append(getFunctionName());
          out.append("(");
          super.appendChildrenAsEJBQL(parameterAccumulator, out, rootId);
          out.append(")");
      }
  
      /**
       *
       * @param functionName in UPPER_UNDERSCORE convention
       * @return functionName in camelCase convention
       */
      protected static String nameToCamelCase(String functionName) {
          String[] parts = functionName.split("_");
          StringBuilder sb = new StringBuilder();
          boolean first = true;
          for(String part : parts) {
              if(first) {
                  sb.append(part.toLowerCase());
                  first = false;
              } else {
                  char[] chars = part.toLowerCase().toCharArray();
                  chars[0] = Character.toTitleCase(chars[0]);
                  sb.append(chars);
              }
          }
          return sb.toString();
      }
  }
  