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From jdil...@apache.org
Subject cvs commit: incubator-geronimo/modules/common/src/java/org/apache/geronimo/common StringValueParser.java
Date Sun, 24 Aug 2003 20:13:22 GMT
jdillon     2003/08/24 13:13:22

  Added:       modules/common/src/java/org/apache/geronimo/common
                        StringValueParser.java
  Log:
   o forgot this one, moved from twiddle to common
  
  Revision  Changes    Path
  1.1                  incubator-geronimo/modules/common/src/java/org/apache/geronimo/common/StringValueParser.java
  
  Index: StringValueParser.java
  ===================================================================
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2003 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution,
   *    if any, must include the following acknowledgment:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowledgment may appear in the software itself,
   *    if and wherever such third-party acknowledgments normally appear.
   *
   * 4. The names "Apache" and "Apache Software Foundation" and
   *    "Apache Geronimo" must not be used to endorse or promote products
   *    derived from this software without prior written permission. For
   *    written permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache",
   *    "Apache Geronimo", nor may "Apache" appear in their name, without
   *    prior written permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   * ====================================================================
   */
  
  package org.apache.geronimo.common;
  
  import java.util.Map;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.apache.commons.jexl.JexlHelper;
  import org.apache.commons.jexl.JexlContext;
  import org.apache.commons.jexl.Expression;
  import org.apache.commons.jexl.ExpressionFactory;
  import org.apache.commons.jexl.resolver.FlatResolver;
  
  /**
   * Handles pasring expressions from a string.
   *
   * @version <code>$Revision: 1.1 $ $Date: 2003/08/24 20:13:22 $</code>
   */
  public class StringValueParser
  {
      private static final Log log = LogFactory.getLog(StringValueParser.class);
      
      protected JexlContext context;
      
      public StringValueParser(final Map vars)
      {
          if (vars == null) {
              throw new NullArgumentException("vars");
          }
          
          context = JexlHelper.createContext();
          context.setVars(vars);
          
          if (log.isTraceEnabled()) {
              log.trace("Using variables: " + context.getVars());
          }
      }
      
      public StringValueParser()
      {
          this(System.getProperties());
      }
      
      public Map getVariables()
      {
          return context.getVars();
      }
      
      public Object getVariable(final Object name)
      {
          if (name == null) {
              throw new NullArgumentException("name");
          }
          
          return getVariables().get(name);
      }
      
      public Object setVariable(final Object name, final Object value)
      {
          if (name == null) {
              throw new NullArgumentException("name");
          }
          
          return getVariables().put(name, value);
      }
      
      public Object unsetVariable(final Object name)
      {
          if (name == null) {
              throw new NullArgumentException("name");
          }
          
          return getVariables().remove(name);
      }
      
      public void addVariables(final Map map)
      {
          if (map == null) {
              throw new NullArgumentException("map");
          }
          
          getVariables().putAll(map);
      }
      
      private FlatResolver resolver = new FlatResolver(true);
      
      protected Expression createExpression(final String expression) throws Exception
      {
          assert expression != null;
          Expression expr = ExpressionFactory.createExpression(expression);
          expr.addPreResolver(resolver);
          return expr;
      }
      
      public Object evaluate(final String expression) throws Exception
      {
          if (expression == null) {
              throw new NullArgumentException("expression");
          }
          
          boolean trace = log.isTraceEnabled();
          if (trace) {
              log.trace("Evaluating expression: " + expression);
          }
          
          Expression expr = createExpression(expression);
          Object obj = expr.evaluate(context);
          if (trace) {
              log.trace("Result: " + obj);
          }
          
          return obj;
      }
      
      public String parse(final String input)
      {
          if (input == null) {
              throw new NullArgumentException("input");
          }
          
          boolean trace = log.isTraceEnabled();
          if (trace) {
              log.trace("Parsing input: " + input);
          }
          
          StringBuffer buff = new StringBuffer();
  
          int cur = 0;
          int prefixLoc = 0;
          int suffixLoc = 0;
  
          while (cur < input.length()) {
              prefixLoc = input.indexOf("${", cur);
  
              if (prefixLoc < 0) {
                  break;
              }
  
              suffixLoc = input.indexOf("}", prefixLoc);
              if (suffixLoc < 0) {
                  throw new RuntimeException("Missing '}': " + input);
              }
              
              String expr = input.substring(prefixLoc + 2, suffixLoc);
              buff.append(input.substring(cur, prefixLoc));
              
              try {
                  buff.append(evaluate(expr));
              }
              catch (Exception e) {
                  throw new RuntimeException("Failed to evaluate: " + expr, e);
              }
              
              cur = suffixLoc + 1;
          }
          
          buff.append(input.substring(cur));
          
          if (trace) {
              log.trace("Parsed result: " + buff);
          }
          
          return buff.toString();
      }
  }
  
  
  

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