net.sf.saxon.functions

Class Substring

java.lang.Object

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
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 StringValue	substring(StringValue sv, NumericValue start) Implement the substring function with two arguments.
static StringValue	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, getUniStringArg, hashCode, importAttributes, isSequenceVariadic, isTrustedResultType, makeCall, makeFunction, makeFunctionCall, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, toShortString, toString

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

atomize, deepEquals, effectiveBooleanValue, getAnnotations, getUnicodeStringValue, isArray, isMap, makeNewContext, simplify, typeCheck

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

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

getGenre

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

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

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

asIterable, concatenate, containsNode, materialize

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

makeRepeatable

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

Parameters:

caller - the function call expression calling this function

visitor - the expression visitor

contextInfo - static context information relating to the call

Returns:

a type-checked replacement for the supplied function call

Throws:

XPathException - if an error is detected

substring

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

Evaluate the expression

Specified by:

call in interface Callable

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