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, LocationProvider, SaxonLocator, InstructionInfo, Locator
public class Substring
- extends SystemFunction
This class implements the XPath substring() function
- See Also:
- Serialized Form
Fields inherited from class net.sf.saxon.expr.Expression |
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD |
Methods inherited from class net.sf.saxon.functions.SystemFunction |
addContextDocumentArgument, addDocToPathMap, checkArguments, computeCardinality, computeSpecialProperties, copy, equals, getDetails, getErrorCodeForTypeErrors, getImplementationMethod, getItemType, getOperation, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault |
Methods inherited from class net.sf.saxon.expr.FunctionCall |
addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString |
Methods inherited from class net.sf.saxon.expr.Expression |
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError |
Substring
public Substring()
typeCheck
public Expression typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
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:
typeCheck
in class FunctionCall
- Parameters:
visitor
- an expression visitorcontextItemType
- the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPE
- Returns:
- the original expression, rewritten to perform necessary run-time type checks,
and to perform other type-related optimizations
- Throws:
XPathException
- if an error is discovered during this phase
(typically a type error)
evaluateItem
public Item evaluateItem(XPathContext context)
throws XPathException
- Evaluate the function
- 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 valuestart
- 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 valuestart
- 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.
Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.