net.sf.saxon.functions

Class FormatNumber

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.FormatNumber

All Implemented Interfaces:

Callable, Function, GroundedValue, Item, Sequence

public class FormatNumber
extends SystemFunction
implements Callable

Implementation of format-number() function. Note this has no dependency on number formatting in the JDK.

Constructor Summary

Constructors

Constructor and Description
FormatNumber()

Method Summary

Modifier and Type	Method and Description
static java.math.BigDecimal	adjustToDecimal(double value, int precision) Convert a double to a BigDecimal.
StringValue	call(XPathContext context, Sequence[] arguments) Call the format-number function, supplying two or three arguments
Expression	fixArguments(Expression... arguments) Allow the function to create an optimized call based on the values of the actual arguments.
static java.lang.String	formatExponential(DoubleValue value) Format a double as required by the adaptive serialization method
protected DecimalSymbols	getNamedDecimalFormat(DecimalFormatManager dfm, java.lang.String lexicalName) Get a decimal format, given its lexical QName

Methods inherited from class net.sf.saxon.functions.SystemFunction

dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, getArity, getCardinality, getCompilerName, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getIntegerBounds, getNetCost, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, importAttributes, isTrustedResultType, makeCall, makeFunction, makeFunctionCall, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, typeCheckCaller

Methods inherited from class net.sf.saxon.functions.AbstractFunction

atomize, deepEquals, effectiveBooleanValue, getAnnotations, getStringValue, getStringValueCS, isArray, isMap, makeNewContext, simplify, typeCheck

Methods inherited from class net.sf.saxon.om.AbstractItem

getLength, head, isStreamed, itemAt, iterate, reduce, subsequence

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.sf.saxon.om.Function

iterate

Methods inherited from interface net.sf.saxon.om.Item

head

Methods inherited from interface net.sf.saxon.om.GroundedValue

getLength, head, itemAt, reduce, subsequence

Constructor Detail

FormatNumber

public FormatNumber()

Method Detail

fixArguments

public Expression fixArguments(Expression... arguments)
                        throws XPathException

Allow the function to create an optimized call based on the values of the actual arguments. This handles the case where the decimal format name is supplied as a literal (or defaulted), and the picture string is also supplied as a literal.

Overrides:

fixArguments in class SystemFunction

Parameters:

arguments - the supplied arguments to the function call

Returns:

either a function call on this function, or an expression that delivers the same result, or null indicating that no optimization has taken place

Throws:

XPathException - if an error is detected

adjustToDecimal

public static java.math.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 appropriate, 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

call

public StringValue call(XPathContext context,
                        Sequence[] arguments)
                 throws XPathException

Call the format-number function, supplying two or three arguments

Specified by:

call in interface Callable

Specified by:

call in interface Function

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences.

Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility methd SequenceTool.toGroundedValue().

If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

Returns:

the result of the function

Throws:

XPathException - if any dynamic error occurs

getNamedDecimalFormat

protected DecimalSymbols getNamedDecimalFormat(DecimalFormatManager dfm,
                                               java.lang.String lexicalName)
                                        throws XPathException

Get a decimal format, given its lexical QName

Parameters:

dfm - the decimal format manager

lexicalName - the lexical QName (or EQName) of the decimal format

Returns:

the decimal format

Throws:

XPathException - if the lexical QName is invalid or if no decimal format is found.

formatExponential

public static java.lang.String formatExponential(DoubleValue value)

Format a double as required by the adaptive serialization method

Parameters:

value - the value to be formatted

Returns:

the formatted value