net.sf.saxon.functions

Class Substring

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.Substring

All Implemented Interfaces:

Callable, Function, GroundedValue, Item, Sequence

public class Substring
extends SystemFunction
implements Callable

This class implements the XPath substring() function

Constructor Summary

Constructors

Constructor and Description
Substring()

Method Summary

Modifier and Type	Method and Description
ZeroOrOne<StringValue>	call(XPathContext context, Sequence[] arguments) Evaluate the expression
java.lang.String	getCompilerName() Get the (local) name of a class that can be used to generate bytecode for this system function
static UnicodeString	substring(StringValue sv, NumericValue start) Implement the substring function with two arguments.
static UnicodeString	substring(StringValue sv, NumericValue start, NumericValue len) Implement the substring function with three arguments.
Expression	typeCheckCaller(FunctionCall caller, ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression.

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

dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, 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

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

Substring

public Substring()

Method Detail

typeCheckCaller

public Expression typeCheckCaller(FunctionCall caller,
                                  ExpressionVisitor visitor,
                                  ContextItemStaticInfo contextInfo)
                           throws XPathException

Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.

Overrides:

typeCheckCaller in class SystemFunction

Throws:

XPathException

substring

public static UnicodeString substring(StringValue sv,
                                      NumericValue start)

Implement the substring function with two arguments.

Parameters:

sv - the string value

start - the numeric offset (1-based) of the first character to be included in the result (if not an integer, the XPath rules apply)

Returns:

the substring starting at this position.

substring

public static UnicodeString substring(StringValue sv,
                                      NumericValue start,
                                      NumericValue len)

Implement the substring function with three arguments.

Parameters:

sv - the string value

start - the numeric offset (1-based) of the first character to be included in the result (if not an integer, the XPath rules apply)

len - the length of the required substring (again, XPath rules apply)

Returns:

the substring starting at this position.

call

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

Evaluate the expression

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

Returns:

the result of the evaluation, in the form of a Sequence

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression

getCompilerName

public java.lang.String getCompilerName()

Description copied from class: SystemFunction

Get the (local) name of a class that can be used to generate bytecode for this system function

Overrides:

getCompilerName in class SystemFunction

Returns:

the name of a bytecode generation class, or null if there is no bytecode support for this function