net.sf.saxon.functions
Class FormatNumber

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.FunctionCall
          extended by net.sf.saxon.functions.SystemFunction
              extended by net.sf.saxon.functions.FormatNumber
All Implemented Interfaces:
Serializable, SourceLocator, EvaluableItem, SequenceIterable, XSLTFunction, InstructionInfoProvider

public class FormatNumber
extends SystemFunction
implements XSLTFunction

XSLT 2.0 implementation of format-number() function - removes the dependence on the JDK.

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
 
Constructor Summary
FormatNumber()
           
 
Method Summary
static BigDecimal adjustToDecimal(double value, int precision)
          Convert a double to a BigDecimal.
 void checkArguments(ExpressionVisitor visitor)
          Method called during static type checking
 CharSequence evaluateAsString(XPathContext context)
          Evaluate in a context where a string is wanted
 Item evaluateItem(XPathContext c)
          Evaluate in a general context
 void fixup(DecimalSymbols dfs)
          Fixup: this is a callback from the DecimalFormatManager used once the xsl:decimal-format element is identified
 Expression preEvaluate(ExpressionVisitor visitor)
          preEvaluate: this method suppresses compile-time evaluation by doing nothing.
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
addDocToPathMap, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, makeSystemFunction, optimize, setDetails
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, simplify, toString, typeCheck
 
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, explain, findParentOf, getCardinality, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, markTailFunctionCalls, process, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

FormatNumber

public FormatNumber()
Method Detail

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException
Description copied from class: SystemFunction
Method called during static type checking

Overrides:
checkArguments in class SystemFunction
Parameters:
visitor - the expression visitor
Throws:
XPathException

fixup

public void fixup(DecimalSymbols dfs)
Fixup: this is a callback from the DecimalFormatManager used once the xsl:decimal-format element is identified

Parameters:
dfs - the decimal symbols to be used

preEvaluate

public Expression preEvaluate(ExpressionVisitor visitor)
                       throws XPathException
preEvaluate: this method suppresses compile-time evaluation by doing nothing. We can't evaluate early because we don't have access to the DecimalFormatManager.

Overrides:
preEvaluate in class FunctionCall
Parameters:
visitor - the expression visitor
Returns:
the result of the early evaluation, or the original expression, or potentially a simplified expression
Throws:
XPathException

evaluateAsString

public CharSequence evaluateAsString(XPathContext context)
                              throws XPathException
Evaluate in a context where a string is wanted

Overrides:
evaluateAsString in class Expression
Parameters:
context - The context in which the expression is to be evaluated
Returns:
the value of the expression, evaluated in the current context. The expression must return a string or (); if the value of the expression is (), this method returns "".
Throws:
XPathException - if any dynamic error occurs evaluating the expression

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException
Evaluate in a general context

Specified by:
evaluateItem in interface EvaluableItem
Overrides:
evaluateItem in class Expression
Parameters:
c - The context in which the expression is to be evaluated
Returns:
the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
Throws:
XPathException - if any dynamic error occurs evaluating the expression

adjustToDecimal

public static BigDecimal adjustToDecimal(double value,
                                         int precision)
Convert a double to a BigDecimal. In general there will be several BigDecimal values that are equal to the supplied value, and the one we want to choose is the one with fewest non-zero digits. The algorithm used is rather pragmatic: look for a string of zeroes or nines, try rounding the number down or up as approriate, then convert the adjusted value to a double to see if it's equal to the original: if not, use the original value unchanged.

Parameters:
value - the double to be converted
precision - 2 for a double, 1 for a float
Returns:
the result of conversion to a double


Copyright (C) Michael H. Kay. All rights reserved.