net.sf.saxon.functions
Class StringLength
java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.FunctionCall
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.StringLength
- All Implemented Interfaces:
- Serializable, SourceLocator, Container, Expression, InstructionInfoProvider
public class StringLength
- extends SystemFunction
Implement the XPath string-length() function
- See Also:
- Serialized Form
Methods inherited from class net.sf.saxon.functions.SystemFunction |
addContextDocumentArgument, checkArguments, computeCardinality, computeSpecialProperties, display, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, main, makeSystemFunction, setDetails, useContextItemAsDefault |
Methods inherited from class net.sf.saxon.expr.FunctionCall |
checkArgumentCount, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, optimize, promote, setArguments, setFunctionNameCode, simplifyArguments, typeCheck |
Methods inherited from class net.sf.saxon.expr.ComputedExpression |
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
StringLength
public StringLength()
simplify
public Expression simplify(StaticContext env)
throws XPathException
- Simplify and validate.
This is a pure function so it can be simplified in advance if the arguments are known
- Specified by:
simplify
in interface Expression
- Overrides:
simplify
in class FunctionCall
- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression
rewriting
getIntrinsicDependencies
public int getIntrinsicDependencies()
- Determine the intrinsic dependencies of an expression, that is, those which are not derived
from the dependencies of its subexpressions. For example, position() has an intrinsic dependency
on the context position, while (position()+1) does not. The default implementation
of the method returns 0, indicating "no dependencies".
- Overrides:
getIntrinsicDependencies
in class ComputedExpression
- Returns:
- a set of bit-significant flags identifying the "intrinsic"
dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
preEvaluate
public Expression preEvaluate(StaticContext env)
throws XPathException
- Pre-evaluate a function at compile time. Functions that do not allow
pre-evaluation, or that need access to context information, can override this method.
- Overrides:
preEvaluate
in class FunctionCall
- Throws:
XPathException
setShortcut
public void setShortcut()
- setShortCut() - used by optimizer when we only need to know if the length is non-zero
evaluateItem
public Item evaluateItem(XPathContext c)
throws XPathException
- Evaluate in a general context
- Specified by:
evaluateItem
in interface Expression
- Overrides:
evaluateItem
in class ComputedExpression
- Parameters:
c
- 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