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  package org.apache.cayenne.exp.parser;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.regex.Pattern;
  
  import org.apache.cayenne.CayenneRuntimeException;
  import org.apache.cayenne.util.Util;
  
  /**
   * Superclass of pattern matching nodes. Assumes that subclass is a binary expression with
   * the second operand being a pattern.
   * 
   * @since 1.1
   */
  public abstract class PatternMatchNode extends ConditionNode {
  
      protected transient Pattern pattern;
      protected transient boolean patternCompiled;
      protected boolean ignoringCase;
      protected char escapeChar;
  
      PatternMatchNode(int i, boolean ignoringCase) {
          super(i);
          this.ignoringCase = ignoringCase;
      }
  
      PatternMatchNode(int i, boolean ignoringCase, char escapeChar) {
          super(i);
          this.ignoringCase = ignoringCase;
          setEscapeChar(escapeChar);
      }
  
      SimpleNode wrap(Object pattern) {
          if(pattern instanceof SimpleNode) {
              return (SimpleNode)pattern;
          }
          return new ASTScalar(pattern);
      }
  
      /**
       * <p>This method will return an escape character for the like
       * clause.  The escape character will eventually end up in the
       * query as <code>...(t0.foo LIKE ? &#123;escape '|'&#125;)</code> where the
       * pipe symbol is the escape character.</p>
       * <p>Note that having no escape character is represented as
       * the character 0.</p>
       */
  
      public char getEscapeChar() {
          return escapeChar;
      }
  
      /**
       * <p>This method allows the setting of the escape character.
       * The escape character can be used in a LIKE clause.  The
       * character 0 signifies no escape character.  The escape
       * character '?' is disallowed.</p>
       */
  
      public void setEscapeChar(char value) {
  
          if ('?' == value)
              throw new CayenneRuntimeException("the use of the '?' as an escape character in LIKE clauses is disallowed.");
  
          escapeChar = value;
      }
  
      /**
       * @since 4.2
       */
      public boolean isIgnoringCase() {
          return ignoringCase;
      }
  
      protected boolean matchPattern(String string) {
          return (string != null) && getPattern().matcher(string).find();
      }
  
      protected Pattern getPattern() {
          // compile pattern on demand
          if (!patternCompiled) {
              synchronized (this) {
                  if (!patternCompiled) {
                      pattern = null;
  
                      if (jjtGetNumChildren() < 2) {
                          patternCompiled = true;
                          return null;
                      }
  
                      // precompile pattern
                      Node node = jjtGetChild(1);
                      if(node instanceof ASTScalar) {
                          ASTScalar patternNode = (ASTScalar) node;
                          if (patternNode == null) {
                              patternCompiled = true;
                              return null;
                          }
  
                          String srcPattern = (String) patternNode.getValue();
                          if (srcPattern == null) {
                              patternCompiled = true;
                              return null;
                          }
  
                          pattern = Util.sqlPatternToPattern(srcPattern, ignoringCase);
                          patternCompiled = true;
                      }
                  }
              }
          }
  
          return pattern;
      }
  
      @Override
      public void jjtAddChild(Node n, int i) {
          // reset pattern if the node is modified
          if (i == 1) {
              patternCompiled = false;
          }
  
          super.jjtAddChild(n, i);
      }
  
      @Override
      protected void appendChildrenAsEJBQL(List<Object> parameterAccumulator, Appendable out, String rootId) throws IOException {
          super.appendChildrenAsEJBQL(parameterAccumulator, out, rootId);
  
          if(0 != getEscapeChar()) {
  
              if('\'' == getEscapeChar()) {
                  throw new CayenneRuntimeException("unable to escape an EJBQL like clause with a single quote character");
              }
  
              out.append(" escape '");
              out.append(getEscapeChar());
              out.append("'");
          }
      }
  
  }
  