org.jaxen.function.StringFunction Maven / Gradle / Ivy
/*
* $Header$
* $Revision$
* $Date$
*
* ====================================================================
*
* Copyright 2000-2002 bob mcwhirter & James Strachan.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * 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.
*
* * Neither the name of the Jaxen Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS 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 COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* 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 Jaxen Project and was originally
* created by bob mcwhirter and
* James Strachan . For more information on the
* Jaxen Project, please see
* 4.2 string string(object)
*
*
*
*
*
* The string function converts
* an object to a string as follows:
*
*
*
*
* -
*
* A node-set is converted to a string by returning the string-value of the node in the node-set
* that is first in document order. If
* the node-set is empty, an empty string is returned.
*
*
*
* -
*
* A number is converted to a string as follows
*
*
*
*
* -
*
* NaN is converted to the string NaN
*
*
*
* -
*
* positive zero is converted to the string 0
*
*
*
* -
*
*
* negative zero is converted to the string 0
*
*
*
* -
*
* positive infinity is converted to the string Infinity
*
*
*
* -
*
* negative infinity is converted to the string -Infinity
*
*
*
*
* -
*
* if the number is an integer, the number is represented in decimal
* form as a Number with no decimal point and
* no leading zeros, preceded by a minus sign (-) if
* the number is negative
*
*
*
* -
*
* otherwise, the number is represented in decimal form as a Number including a decimal point with at least
* one digit before the decimal point and at least one digit after the
* decimal point, preceded by a minus sign (-) if the
* number is negative; there must be no leading zeros before the decimal
* point apart possibly from the one required digit immediately before
* the decimal point; beyond the one required digit after the decimal
* point there must be as many, but only as many, more digits as are
* needed to uniquely distinguish the number from all other IEEE 754
* numeric values.
*
*
*
*
*
*
*
*
* -
*
* The boolean false value is converted to the string false.
* The boolean true value is converted to the string true.
*
*
*
* -
*
* An object of a type other than the four basic types is converted to a
* string in a way that is dependent on that type.
*
*
*
*
*
*
*
* If the argument is omitted, it defaults to a node-set with the
* context node as its only member.
*
*
*
*
* @author bob mcwhirter (bob @ werken.com)
* @see Section 4.2 of the XPath Specification
*/
@SuppressWarnings({"rawtypes"})
public class StringFunction implements Function
{
private static DecimalFormat format = (DecimalFormat) NumberFormat.getInstance(Locale.ENGLISH);
static {
DecimalFormatSymbols symbols = new DecimalFormatSymbols(Locale.ENGLISH);
symbols.setNaN("NaN");
symbols.setInfinity("Infinity");
format.setGroupingUsed(false);
format.setMaximumFractionDigits(32);
format.setDecimalFormatSymbols(symbols);
}
/**
* Create a new StringFunction object.
*/
public StringFunction() {}
/**
* Returns the string-value of args.get(0)
* or of the context node if args is empty.
*
* @param context the context at the point in the
* expression where the function is called
* @param args list with zero or one element
*
* @return a String
*
* @ if args has more than one item
*/
public Object call(Context context,
List args)
{
int size = args.size();
if ( size == 0 )
{
return evaluate( context.getNodeSet(),
context.getNavigator() );
}
else if ( size == 1 )
{
return evaluate( args.get(0),
context.getNavigator() );
}
throw new RuntimeException( "string() takes at most argument." );
}
/**
* Returns the XPath string-value of obj.
* This operation is only defined if obj is a node, node-set,
* String, Number, or
* Boolean. For other types this function
* returns the empty string.
*
* @param obj the node, node-set, string, number, or boolean
* whose string-value is calculated
* @param nav the navigator used to calculate the string-value
*
* @return a String. May be empty but is never null.
*/
public static String evaluate(Object obj,
Navigator nav)
{
try
{
// Workaround because XOM uses lists for Text nodes
// so we need to check for that first
if (nav != null && nav.isText(obj))
{
return nav.getTextStringValue(obj);
}
if (obj instanceof List)
{
List list = (List) obj;
if (list.isEmpty())
{
return "";
}
// do not recurse: only first list should unwrap
obj = list.get(0);
}
if (nav != null) {
// This stack of instanceof really suggests there's
// a failure to take advantage of polymorphism here
if (nav.isElement(obj))
{
return nav.getElementStringValue(obj);
}
else if (nav.isAttribute(obj))
{
return nav.getAttributeStringValue(obj);
}
else if (nav.isDocument(obj))
{
Iterator childAxisIterator = nav.getChildAxisIterator(obj);
while (childAxisIterator.hasNext())
{
Object descendant = childAxisIterator.next();
if (nav.isElement(descendant))
{
return nav.getElementStringValue(descendant);
}
}
}
else if (nav.isProcessingInstruction(obj))
{
return nav.getProcessingInstructionData(obj);
}
else if (nav.isComment(obj))
{
return nav.getCommentStringValue(obj);
}
else if (nav.isText(obj))
{
return nav.getTextStringValue(obj);
}
else if (nav.isNamespace(obj))
{
return nav.getNamespaceStringValue(obj);
}
}
if (obj instanceof String)
{
return (String) obj;
}
else if (obj instanceof Boolean)
{
return stringValue(((Boolean) obj).booleanValue());
}
else if (obj instanceof Number)
{
return stringValue(((Number) obj).doubleValue());
}
}
catch (Exception e)
{
throw new RuntimeException(e);
}
return "";
}
private static String stringValue(double value)
{
// DecimalFormat formats negative zero as "-0".
// Therefore we need to test for zero explicitly here.
if (value == 0) return "0";
// need to synchronize object for thread-safety
String result = null;
synchronized (format) {
result = format.format(value);
}
return result;
}
private static String stringValue(boolean value)
{
return value ? "true" : "false";
}
}