openjpa-lib/src/main/java/org/apache/openjpa/lib/conf/Value.java - openjpa - Git at Google

 /*
  * 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.openjpa.lib.conf;

 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;

 import org.apache.openjpa.lib.util.Localizer;
 import org.apache.openjpa.lib.util.ParseException;

 /**
  * A configuration value.
  *
  * @author Marc Prud'hommeaux
  * @author Pinaki Poddar
  */
 public abstract class Value implements Cloneable {

     private static final String[] EMPTY_ALIASES = new String[0];
     private static final Localizer s_loc = Localizer.forPackage(Value.class);
     public static final String INVISIBLE = "******";

     private String prop = null;
     private String loadKey = null;
     private String def = null;
     private String[] aliases = null;
     private String getter = null;
     private List<ValueListener> listeners = null;
     private boolean aliasListComprehensive = false;
     private Class scope = null;
     private boolean isDynamic = false;
     private String originalValue = null;
     private Set<String> otherNames = null;
     private boolean _hidden  = false;
     private boolean _private = false;

     /**
      * Default constructor.
      */
     public Value() {
     }

     /**
      * Constructor. Supply the property name.
      *
      * @see #setProperty
      */
     public Value(String prop) {
         setProperty(prop);
     }

     /**
      * The property name that will be used when setting or
      * getting this value in a {@link Map}.
      */
     public String getProperty() {
         return prop;
     }

     /**
      * The property name that will be used when setting or
      * getting this value in a {@link Map}.
      */
     public void setProperty(String prop) {
         this.prop = prop;
     }

     /**
      * Adds a moniker that is equivalent to the original property key used
      * during construction.
      *
      * @since 2.0.0
      */
     public void addEquivalentKey(String other) {
         if (otherNames == null)
             otherNames = new HashSet<>();
         otherNames.add(other);
     }

     /**
      * Gets the unmodifiable view of the equivalent keys or an empty set if
      * no equivalent key has been added.
      *
      * @since 2.0.0
      */
     public Set<String> getEquivalentKeys() {
         return otherNames == null ? Collections.EMPTY_SET
             : Collections.unmodifiableSet(otherNames);
     }

     /**
      * Gets unmodifiable view of all the property keys set on this receiver.
      * The 0-th element in the returned list is always the same as the original
      * key returned by {@link #getProperty()} method.
      *
      * @since 2.0.0
      */
     public List<String> getPropertyKeys() {
         List<String> result = new ArrayList<>(1 +
             (otherNames ==null ? 0 : otherNames.size()));
         result.add(getProperty());
         if (otherNames != null)
             result.addAll(otherNames);
         return Collections.unmodifiableList(result);
     }

     /**
      * Affirms if the given key matches the property (or any of its equivalent).
      *
      * @since 2.0.0
      */
     public boolean matches(String p) {
         return getProperty().equals(p) ||
           (otherNames != null && otherNames.contains(p));
     }

     /**
      * The key under which this value was loaded, or null.
      */
     public String getLoadKey() {
         return loadKey;
     }

     /**
      * Sets key under which this value was loaded.
      * @exception if called with a non-null key which is different from an
      * already loaded key.
      */
     public void setLoadKey(String key) {
         if (this.loadKey != null && key != null && !this.loadKey.equals(key))
             throw new ParseException(s_loc.get("multiple-load-key",
                 loadKey, key));
         loadKey = key;
     }

     /**
      * Aliases for the value in the form key1, value1, key2, value2, ...
      * All alias values must be in string form.
      */
     public String[] getAliases() {
         return (aliases == null) ? EMPTY_ALIASES : aliases;
     }

     /**
      * Aliases for the value in the form key1, value1, key2, value2, ...
      * All alias values must be in string form.
      * <p>
      * To avoid potential side-effects, this method copies the array passed in.
      */
     public void setAliases(String[] aliases) {
         String [] aStrings = new String[aliases.length];
         System.arraycopy(aliases, 0, aStrings, 0, aStrings.length);
         this.aliases = aStrings;
     }

     /**
      * Replaces an existing alias, or adds the given alias to the front of the
      * alias list if it does not already exist. All alias values must be in
      * string form.
      */
     public void setAlias(String key, String value) {
         aliases = setAlias(key, value, aliases);
     }

     /**
      * Set an alias into a current alias list, returning the new list.
      */
     protected String[] setAlias(String key, String value, String[] aliases) {
         if (aliases == null)
             aliases = EMPTY_ALIASES;
         for (int i = 0; i < aliases.length; i += 2) {
             if (key.equals(aliases[i])) {
                 aliases[i + 1] = value;
                 return aliases;
             }
         }

         // add as new alias
         String[] newAliases = new String[aliases.length + 2];
         System.arraycopy(aliases, 0, newAliases, 2, aliases.length);
         newAliases[0] = key;
         newAliases[1] = value;
         return newAliases;
     }

     /**
      * Whether or not the alias list defines all possible settings for this
      * value. If so, an error will be generated when attempting to invoke
      * any method on this value with an unknown option.
      */
     public boolean isAliasListComprehensive() {
         return aliasListComprehensive;
     }

     /**
      * Whether or not the alias list defines all possible settings for this
      * value. If so, an error will be generated when attempting to invoke
      * any method on this value with an unknown option.
      */
     public void setAliasListComprehensive(boolean aliasListIsComprehensive) {
         this.aliasListComprehensive = aliasListIsComprehensive;
     }

     /**
      * Alias the given setting.
      */
     public String alias(String str) {
         return alias(str, aliases, false);
     }

     /**
      * Alias the given setting.
      */
     protected String alias(String str, String[] aliases, boolean nullNotFound) {
         if (str != null)
             str = str.trim();
         if (aliases == null || aliases.length == 0)
             return (nullNotFound) ? null : str;

         boolean empty = str != null && str.length() == 0;
         for (int i = 1; i < aliases.length; i += 2)
             if (Objects.equals(str, aliases[i])
                 || (empty && aliases[i] == null))
                 return aliases[i - 1];
         return (nullNotFound) ? null : str;
     }

     /**
      * Unalias the given setting.
      */
     public String unalias(String str) {
         return unalias(str, aliases, false);
     }

     /**
      * Unalias the given setting.
      */
     protected String unalias(String str, String[] aliases,
         boolean nullNotFound) {
         if (str != null)
             str = str.trim();

         boolean empty = str != null && str.length() == 0;
         if (str == null || (empty && def != null))
             str = def;
         if (aliases != null)
             for (int i = 0; i < aliases.length; i += 2)
                 if (Objects.equals(str, aliases[i])
                     || Objects.equals(str, aliases[i + 1])
                     || (empty && aliases[i] == null))
                     return aliases[i + 1];

         if (isAliasListComprehensive() && aliases != null)
             throw new ParseException(s_loc.get("invalid-enumerated-config",
                 getProperty(), str, Arrays.asList(aliases)));

         return (nullNotFound) ? null : str;
     }

     /**
      * The default value for the property as a string.
      */
     public String getDefault() {
         return def;
     }

     /**
      * The default value for the property as a string.
      */
     public void setDefault(String def) {
         this.def = def;
     }

     /**
      * The name of the getter method for the instantiated value of this
      * property(as opposed to the string value)
      */
     public String getInstantiatingGetter() {
         return getter;
     }

     /**
      * The name of the getter method for the instantiated value of this
      * property(as opposed to the string value). If the string starts with
      * <code>this.</code>, then the getter will be looked up on the value
      * instance itself. Otherwise, the getter will be looked up on the
      * configuration instance.
      */
     public void setInstantiatingGetter(String getter) {
         this.getter = getter;
     }

     /**
      * A class defining the scope in which this value is defined. This will
      * be used by the configuration framework to look up metadata about
      * the value.
      */
     public Class getScope() {
         return scope;
     }

     /**
      * A class defining the scope in which this value is defined. This will
      * be used by the configuration framework to look up metadata about
      * the value.
      */
     public void setScope(Class cls) {
         scope = cls;
     }

     /**
      * Return a stringified version of this value. If the current value has
      * a short alias key, the alias key is returned.
      */
     public String getString() {
         return alias(getInternalString());
     }

     /**
      * Set this value from the given string. If the given string is null or
      * empty and a default is defined, the default is used. If the given
      * string(or default) is an alias key, it will be converted to the
      * corresponding value internally.
      * <br>
      * If this Value is being set to a non-default value for the first time
      * (as designated by <code>originalString</code> being null), then the
      * value is remembered as <em>original</em>. This original value is used
      * for equality and hashCode computation if this Value is
      * {@link #isDynamic() dynamic}.
      *
      */
     public void setString(String val) {
     	assertChangeable();
         String str = unalias(val);
         try {
             setInternalString(str);
             if (originalValue == null && val != null && !isDefault(val)) {
             	originalValue = getString();
             }
         } catch (ParseException pe) {
             throw pe;
         } catch (RuntimeException re) {
             throw new ParseException(prop + ": " + val, re);
         }
     }

     /**
      * Set this value as an object.
      * <br>
      * If this Value is being set to a non-default value for the first time
      * (as designated by <code>originalString</code> being null), then the
      * value is remembered as <em>original</em>. This original value is used
      * for equality and hashCode computation if this Value is
      * {@link #isDynamic() dynamic}.
      *
      */
     public void setObject(Object obj) {
         // if setting to null set as string to get defaults into play
         if (obj == null && def != null)
             setString(null);
         else {
             try {
                 setInternalObject(obj);
                 if (originalValue == null && obj != null && !isDefault(obj)) {
                 	originalValue = getString();
                 }
             } catch (ParseException pe) {
                 throw pe;
             } catch (RuntimeException re) {
                 throw new ParseException(prop + ": " + obj, re);
             }
         }
     }

     /**
      * Gets the original value. Original value denotes the Stringified form of
      * this Value, from which it has been set, if ever. If this Value has never
      * been set to a non-default value, then returns the default value, which
      * itself can be null.
      *
      * @since 1.1.0
      */
     public String getOriginalValue() {
     	return (originalValue == null) ? getDefault() : originalValue;
     }

     boolean isDefault(Object val) {
     	return val != null && val.toString().equals(getDefault());
     }

     /**
      * Returns the type of the property that this Value represents.
      */
     public abstract Class<?> getValueType();

     /**
      * Return the internal string form of this value.
      */
     protected abstract String getInternalString();

     /**
      * Set this value from the given string.
      */
     protected abstract void setInternalString(String str);

     /**
      * Set this value from an object.
      */
     protected abstract void setInternalObject(Object obj);

     /**
      * Gets unmodifable list of listeners for value changes.
      */
     public List<ValueListener> getListeners() {
         return Collections.unmodifiableList(this.listeners);
     }

     /**
      * Listener for value changes.
      */
     public void addListener(ValueListener listener) {
     	if (listener == null)
     		return;
     	if (listeners == null)
     		listeners = new ArrayList<>();
         listeners.add(listener);
     }

     public void removeListener(ValueListener listener) {
     	if (listener == null)
     		return;
         listeners.remove(listener);
     }

     /**
      * Subclasses should call this method when their internal value changes.
      */
     public void valueChanged() {
         if (listeners == null)
         	return;
         for (ValueListener listener : listeners) {
         	listener.valueChanged(this);
         }
     }

     /**
      * Asserts if this receiver can be changed.
      * Subclasses <em>must</em> invoke this method before changing its
      * internal state.
      *
      * This receiver can not be changed if all of the following is true
      * <LI>this receiver is not dynamic
      * <LI>ValueListener attached to this receiver is a Configuration
      * <LI>Configuration is read-only
      */
     protected void assertChangeable() {
     	if (!isDynamic() && containsReadOnlyConfigurationAsListener()) {
         	throw new RuntimeException(s_loc.get("veto-change",
         		this.getProperty()).toString());
        	}
     }

     boolean containsReadOnlyConfigurationAsListener() {
     	if (listeners == null)
     		return false;
     	for (ValueListener listener : listeners) {
     		if (listener instanceof Configuration
     		&& ((Configuration)listener).isReadOnly())
     			return true;
     	}
     	return false;
     }

     /**
      * Sets if this receiver can be mutated even when the configuration it
      * belongs to has been {@link Configuration#isReadOnly() frozen}.
      *
      * @since 1.1.0
      */
     public void setDynamic(boolean flag) {
     	isDynamic = flag;
     }

     /**
      * Affirms if this receiver can be mutated even when the configuration it
      * belongs to has been {@link Configuration#isReadOnly() frozen}.
      *
      * @since 1.1.0
      */
     public boolean isDynamic() {
     	return isDynamic;
     }

     /**
      * Use {@link #getOriginalValue() original value} instead of
      * {@link #getString() current value} because they are one and the same
      * for non-dynamic Values and ensures that modifying dynamic Values do not
      * impact equality or hashCode contract.
      */
     @Override
     public int hashCode() {
         String str = (isDynamic()) ? getOriginalValue() : getString();
         int strHash = (str == null) ? 0 : str.hashCode();
         int propHash = (prop == null) ? 0 : prop.hashCode();
         return strHash ^ propHash;
     }

     /**
      * Use {@link #getOriginalValue() original value} instead of
      * {@link #getString() current value} because they are one and the same
      * for non-dynamic Values and ensures that modifying dynamic Values do not
      * impact equality or hashCode contract.
      */
     @Override
     public boolean equals(Object other) {
         if (other == this)
             return true;
         if (!(other instanceof Value))
             return false;

         Value o = (Value) other;
         String thisStr = (isDynamic()) ? getOriginalValue() : getString();
         String thatStr = (isDynamic()) ? o.getOriginalValue() : o.getString();
         return (isDynamic() == o.isDynamic())
             && Objects.equals(prop, o.getProperty())
             && Objects.equals(thisStr, thatStr);
     }

     @Override
     public Object clone() {
         try {
             return super.clone();
         } catch (CloneNotSupportedException cnse) {
             return null;
         }
     }

     /**
      * Affirms if the value for this Value is visible.
      * Certain sensitive value such as password can be made invisible
      * so that it is not returned to the user code.
      */
     public boolean isHidden() {
         return _hidden;
     }

     /**
      * Hides the value of this Value from being output to the caller.
      */
     public void hide() {
         _hidden = true;
     }

     /**
      * Affirms if this Value is used for internal purpose only and not exposed as a supported property.
      * @see Configuration#getPropertyKeys()
      */
     public boolean isPrivate() {
         return _private;
     }

     /**
      * Marks this Value for internal purpose only.
      */
     public void makePrivate() {
         _private = true;
     }

     /**
      * Get the actual data stored in this value.
      */
     public abstract Object get();

     @Override
     public String toString() {
         return getProperty()+ ":" + get() + "[" + getValueType().getName() + "]";
     }
 }
	/*
	* 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.openjpa.lib.conf;

	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collections;
	import java.util.HashSet;
	import java.util.List;
	import java.util.Map;
	import java.util.Objects;
	import java.util.Set;

	import org.apache.openjpa.lib.util.Localizer;
	import org.apache.openjpa.lib.util.ParseException;

	/**
	* A configuration value.
	*
	* @author Marc Prud'hommeaux
	* @author Pinaki Poddar
	*/
	public abstract class Value implements Cloneable {

	private static final String[] EMPTY_ALIASES = new String[0];
	private static final Localizer s_loc = Localizer.forPackage(Value.class);
	public static final String INVISIBLE = "******";

	private String prop = null;
	private String loadKey = null;
	private String def = null;
	private String[] aliases = null;
	private String getter = null;
	private List<ValueListener> listeners = null;
	private boolean aliasListComprehensive = false;
	private Class scope = null;
	private boolean isDynamic = false;
	private String originalValue = null;
	private Set<String> otherNames = null;
	private boolean _hidden = false;
	private boolean _private = false;

	/**
	* Default constructor.
	*/
	public Value() {
	}

	/**
	* Constructor. Supply the property name.
	*
	* @see #setProperty
	*/
	public Value(String prop) {
	setProperty(prop);
	}

	/**
	* The property name that will be used when setting or
	* getting this value in a {@link Map}.
	*/
	public String getProperty() {
	return prop;
	}

	/**
	* The property name that will be used when setting or
	* getting this value in a {@link Map}.
	*/
	public void setProperty(String prop) {
	this.prop = prop;
	}

	/**
	* Adds a moniker that is equivalent to the original property key used
	* during construction.
	*
	* @since 2.0.0
	*/
	public void addEquivalentKey(String other) {
	if (otherNames == null)
	otherNames = new HashSet<>();
	otherNames.add(other);
	}

	/**
	* Gets the unmodifiable view of the equivalent keys or an empty set if
	* no equivalent key has been added.
	*
	* @since 2.0.0
	*/
	public Set<String> getEquivalentKeys() {
	return otherNames == null ? Collections.EMPTY_SET
	: Collections.unmodifiableSet(otherNames);
	}

	/**
	* Gets unmodifiable view of all the property keys set on this receiver.
	* The 0-th element in the returned list is always the same as the original
	* key returned by {@link #getProperty()} method.
	*
	* @since 2.0.0
	*/
	public List<String> getPropertyKeys() {
	List<String> result = new ArrayList<>(1 +
	(otherNames ==null ? 0 : otherNames.size()));
	result.add(getProperty());
	if (otherNames != null)
	result.addAll(otherNames);
	return Collections.unmodifiableList(result);
	}

	/**
	* Affirms if the given key matches the property (or any of its equivalent).
	*
	* @since 2.0.0
	*/
	public boolean matches(String p) {
	return getProperty().equals(p) \|\|
	(otherNames != null && otherNames.contains(p));
	}

	/**
	* The key under which this value was loaded, or null.
	*/
	public String getLoadKey() {
	return loadKey;
	}

	/**
	* Sets key under which this value was loaded.
	* @exception if called with a non-null key which is different from an
	* already loaded key.
	*/
	public void setLoadKey(String key) {
	if (this.loadKey != null && key != null && !this.loadKey.equals(key))
	throw new ParseException(s_loc.get("multiple-load-key",
	loadKey, key));
	loadKey = key;
	}

	/**
	* Aliases for the value in the form key1, value1, key2, value2, ...
	* All alias values must be in string form.
	*/
	public String[] getAliases() {
	return (aliases == null) ? EMPTY_ALIASES : aliases;
	}

	/**
	* Aliases for the value in the form key1, value1, key2, value2, ...
	* All alias values must be in string form.
	* <p>
	* To avoid potential side-effects, this method copies the array passed in.
	*/
	public void setAliases(String[] aliases) {
	String [] aStrings = new String[aliases.length];
	System.arraycopy(aliases, 0, aStrings, 0, aStrings.length);
	this.aliases = aStrings;
	}

	/**
	* Replaces an existing alias, or adds the given alias to the front of the
	* alias list if it does not already exist. All alias values must be in
	* string form.
	*/
	public void setAlias(String key, String value) {
	aliases = setAlias(key, value, aliases);
	}

	/**
	* Set an alias into a current alias list, returning the new list.
	*/
	protected String[] setAlias(String key, String value, String[] aliases) {
	if (aliases == null)
	aliases = EMPTY_ALIASES;
	for (int i = 0; i < aliases.length; i += 2) {
	if (key.equals(aliases[i])) {
	aliases[i + 1] = value;
	return aliases;
	}
	}

	// add as new alias
	String[] newAliases = new String[aliases.length + 2];
	System.arraycopy(aliases, 0, newAliases, 2, aliases.length);
	newAliases[0] = key;
	newAliases[1] = value;
	return newAliases;
	}

	/**
	* Whether or not the alias list defines all possible settings for this
	* value. If so, an error will be generated when attempting to invoke
	* any method on this value with an unknown option.
	*/
	public boolean isAliasListComprehensive() {
	return aliasListComprehensive;
	}

	/**
	* Whether or not the alias list defines all possible settings for this
	* value. If so, an error will be generated when attempting to invoke
	* any method on this value with an unknown option.
	*/
	public void setAliasListComprehensive(boolean aliasListIsComprehensive) {
	this.aliasListComprehensive = aliasListIsComprehensive;
	}

	/**
	* Alias the given setting.
	*/
	public String alias(String str) {
	return alias(str, aliases, false);
	}

	/**
	* Alias the given setting.
	*/
	protected String alias(String str, String[] aliases, boolean nullNotFound) {
	if (str != null)
	str = str.trim();
	if (aliases == null \|\| aliases.length == 0)
	return (nullNotFound) ? null : str;

	boolean empty = str != null && str.length() == 0;
	for (int i = 1; i < aliases.length; i += 2)
	if (Objects.equals(str, aliases[i])
	\|\| (empty && aliases[i] == null))
	return aliases[i - 1];
	return (nullNotFound) ? null : str;
	}

	/**
	* Unalias the given setting.
	*/
	public String unalias(String str) {
	return unalias(str, aliases, false);
	}

	/**
	* Unalias the given setting.
	*/
	protected String unalias(String str, String[] aliases,
	boolean nullNotFound) {
	if (str != null)
	str = str.trim();

	boolean empty = str != null && str.length() == 0;
	if (str == null \|\| (empty && def != null))
	str = def;
	if (aliases != null)
	for (int i = 0; i < aliases.length; i += 2)
	if (Objects.equals(str, aliases[i])
	\|\| Objects.equals(str, aliases[i + 1])
	\|\| (empty && aliases[i] == null))
	return aliases[i + 1];

	if (isAliasListComprehensive() && aliases != null)
	throw new ParseException(s_loc.get("invalid-enumerated-config",
	getProperty(), str, Arrays.asList(aliases)));

	return (nullNotFound) ? null : str;
	}

	/**
	* The default value for the property as a string.
	*/
	public String getDefault() {
	return def;
	}

	/**
	* The default value for the property as a string.
	*/
	public void setDefault(String def) {
	this.def = def;
	}

	/**
	* The name of the getter method for the instantiated value of this
	* property(as opposed to the string value)
	*/
	public String getInstantiatingGetter() {
	return getter;
	}

	/**
	* The name of the getter method for the instantiated value of this
	* property(as opposed to the string value). If the string starts with
	* <code>this.</code>, then the getter will be looked up on the value
	* instance itself. Otherwise, the getter will be looked up on the
	* configuration instance.
	*/
	public void setInstantiatingGetter(String getter) {
	this.getter = getter;
	}

	/**
	* A class defining the scope in which this value is defined. This will
	* be used by the configuration framework to look up metadata about
	* the value.
	*/
	public Class getScope() {
	return scope;
	}

	/**
	* A class defining the scope in which this value is defined. This will
	* be used by the configuration framework to look up metadata about
	* the value.
	*/
	public void setScope(Class cls) {
	scope = cls;
	}

	/**
	* Return a stringified version of this value. If the current value has
	* a short alias key, the alias key is returned.
	*/
	public String getString() {
	return alias(getInternalString());
	}

	/**
	* Set this value from the given string. If the given string is null or
	* empty and a default is defined, the default is used. If the given
	* string(or default) is an alias key, it will be converted to the
	* corresponding value internally.
	* <br>
	* If this Value is being set to a non-default value for the first time
	* (as designated by <code>originalString</code> being null), then the
	* value is remembered as <em>original</em>. This original value is used
	* for equality and hashCode computation if this Value is
	* {@link #isDynamic() dynamic}.
	*
	*/
	public void setString(String val) {
	assertChangeable();
	String str = unalias(val);
	try {
	setInternalString(str);
	if (originalValue == null && val != null && !isDefault(val)) {
	originalValue = getString();
	}
	} catch (ParseException pe) {
	throw pe;
	} catch (RuntimeException re) {
	throw new ParseException(prop + ": " + val, re);
	}
	}

	/**
	* Set this value as an object.
	* <br>
	* If this Value is being set to a non-default value for the first time
	* (as designated by <code>originalString</code> being null), then the
	* value is remembered as <em>original</em>. This original value is used
	* for equality and hashCode computation if this Value is
	* {@link #isDynamic() dynamic}.
	*
	*/
	public void setObject(Object obj) {
	// if setting to null set as string to get defaults into play
	if (obj == null && def != null)
	setString(null);
	else {
	try {
	setInternalObject(obj);
	if (originalValue == null && obj != null && !isDefault(obj)) {
	originalValue = getString();
	}
	} catch (ParseException pe) {
	throw pe;
	} catch (RuntimeException re) {
	throw new ParseException(prop + ": " + obj, re);
	}
	}
	}

	/**
	* Gets the original value. Original value denotes the Stringified form of
	* this Value, from which it has been set, if ever. If this Value has never
	* been set to a non-default value, then returns the default value, which
	* itself can be null.
	*
	* @since 1.1.0
	*/
	public String getOriginalValue() {
	return (originalValue == null) ? getDefault() : originalValue;
	}

	boolean isDefault(Object val) {
	return val != null && val.toString().equals(getDefault());
	}

	/**
	* Returns the type of the property that this Value represents.
	*/
	public abstract Class<?> getValueType();

	/**
	* Return the internal string form of this value.
	*/
	protected abstract String getInternalString();

	/**
	* Set this value from the given string.
	*/
	protected abstract void setInternalString(String str);

	/**
	* Set this value from an object.
	*/
	protected abstract void setInternalObject(Object obj);

	/**
	* Gets unmodifable list of listeners for value changes.
	*/
	public List<ValueListener> getListeners() {
	return Collections.unmodifiableList(this.listeners);
	}

	/**
	* Listener for value changes.
	*/
	public void addListener(ValueListener listener) {
	if (listener == null)
	return;
	if (listeners == null)
	listeners = new ArrayList<>();
	listeners.add(listener);
	}

	public void removeListener(ValueListener listener) {
	if (listener == null)
	return;
	listeners.remove(listener);
	}

	/**
	* Subclasses should call this method when their internal value changes.
	*/
	public void valueChanged() {
	if (listeners == null)
	return;
	for (ValueListener listener : listeners) {
	listener.valueChanged(this);
	}
	}

	/**
	* Asserts if this receiver can be changed.
	* Subclasses <em>must</em> invoke this method before changing its
	* internal state.
	*
	* This receiver can not be changed if all of the following is true
	* <LI>this receiver is not dynamic
	* <LI>ValueListener attached to this receiver is a Configuration
	* <LI>Configuration is read-only
	*/
	protected void assertChangeable() {
	if (!isDynamic() && containsReadOnlyConfigurationAsListener()) {
	throw new RuntimeException(s_loc.get("veto-change",
	this.getProperty()).toString());
	}
	}

	boolean containsReadOnlyConfigurationAsListener() {
	if (listeners == null)
	return false;
	for (ValueListener listener : listeners) {
	if (listener instanceof Configuration
	&& ((Configuration)listener).isReadOnly())
	return true;
	}
	return false;
	}

	/**
	* Sets if this receiver can be mutated even when the configuration it
	* belongs to has been {@link Configuration#isReadOnly() frozen}.
	*
	* @since 1.1.0
	*/
	public void setDynamic(boolean flag) {
	isDynamic = flag;
	}

	/**
	* Affirms if this receiver can be mutated even when the configuration it
	* belongs to has been {@link Configuration#isReadOnly() frozen}.
	*
	* @since 1.1.0
	*/
	public boolean isDynamic() {
	return isDynamic;
	}

	/**
	* Use {@link #getOriginalValue() original value} instead of
	* {@link #getString() current value} because they are one and the same
	* for non-dynamic Values and ensures that modifying dynamic Values do not
	* impact equality or hashCode contract.
	*/
	@Override
	public int hashCode() {
	String str = (isDynamic()) ? getOriginalValue() : getString();
	int strHash = (str == null) ? 0 : str.hashCode();
	int propHash = (prop == null) ? 0 : prop.hashCode();
	return strHash ^ propHash;
	}

	/**
	* Use {@link #getOriginalValue() original value} instead of
	* {@link #getString() current value} because they are one and the same
	* for non-dynamic Values and ensures that modifying dynamic Values do not
	* impact equality or hashCode contract.
	*/
	@Override
	public boolean equals(Object other) {
	if (other == this)
	return true;
	if (!(other instanceof Value))
	return false;

	Value o = (Value) other;
	String thisStr = (isDynamic()) ? getOriginalValue() : getString();
	String thatStr = (isDynamic()) ? o.getOriginalValue() : o.getString();
	return (isDynamic() == o.isDynamic())
	&& Objects.equals(prop, o.getProperty())
	&& Objects.equals(thisStr, thatStr);
	}

	@Override
	public Object clone() {
	try {
	return super.clone();
	} catch (CloneNotSupportedException cnse) {
	return null;
	}
	}

	/**
	* Affirms if the value for this Value is visible.
	* Certain sensitive value such as password can be made invisible
	* so that it is not returned to the user code.
	*/
	public boolean isHidden() {
	return _hidden;
	}

	/**
	* Hides the value of this Value from being output to the caller.
	*/
	public void hide() {
	_hidden = true;
	}

	/**
	* Affirms if this Value is used for internal purpose only and not exposed as a supported property.
	* @see Configuration#getPropertyKeys()
	*/
	public boolean isPrivate() {
	return _private;
	}

	/**
	* Marks this Value for internal purpose only.
	*/
	public void makePrivate() {
	_private = true;
	}

	/**
	* Get the actual data stored in this value.
	*/
	public abstract Object get();

	@Override
	public String toString() {
	return getProperty()+ ":" + get() + "[" + getValueType().getName() + "]";
	}
	}