net.sf.saxon.functions
Class Substring

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.functions.SystemFunction
              net.sf.saxon.functions.Substring

All Implemented Interfaces:

Serializable, SourceLocator, EvaluableItem, SequenceIterable, InstructionInfoProvider

public class Substring
extends SystemFunction

This class implements the XPath substring() function

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

Substring()

Method Summary

Item	evaluateItem(XPathContext context) Evaluate the function
static CharSequence	substring(StringValue sv, NumericValue start) Implement the substring function with two arguments.
static CharSequence	substring(StringValue sv, NumericValue start, NumericValue len, XPathContext context) Implement the substring function with three arguments.

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

addDocToPathMap, checkArguments, 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, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, toString, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, evaluateAsString, 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

Substring

public Substring()

Method Detail

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate the function

Specified by:

evaluateItem in interface EvaluableItem

Overrides:

evaluateItem in class Expression

Parameters:

context - 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

substring

public static CharSequence 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 CharSequence substring(StringValue sv,
                                     NumericValue start,
                                     NumericValue len,
                                     XPathContext context)

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)

context - the XPath dynamic context. Provided because some arithmetic computations require it

Returns:

the substring starting at this position.