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## net.sf.saxon.functions
Class StringLength

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

All Implemented Interfaces:
  Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

    public class StringLength

extends SystemFunction

Implement the XPath string-length() function

See Also:
  Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.functions.SystemFunction
`operation`

Fields inherited from class net.sf.saxon.expr.FunctionCall
`argument`

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`

Constructor Summary
`StringLength()`

Method Summary
`Item` | `evaluateItem(XPathContext c)` Evaluate in a general context
`IntegerValue[]` | `getIntegerBounds()` For an expression that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis.
`int` | `getIntrinsicDependencies()` Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
`boolean` | `isContextPossiblyUndefined()` Ask whether the context item may possibly be undefined
`Expression` | `preEvaluate(ExpressionVisitor visitor)` Pre-evaluate a function at compile time.
`Expression` | `simplify(ExpressionVisitor visitor)` Simplify and validate.
`Expression` | `typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)` Type-check the expression.

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, promote, replaceSubExpression, setArguments, setFunctionName, 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, 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`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Constructor Detail

### StringLength

    public StringLength()

Method Detail

### simplify

    public Expression simplify(ExpressionVisitor visitor)
                        throws XPathException

  Simplify and validate. This is a pure function so it can be simplified in advance if the arguments are known

  Overrides:
    `simplify` in class `FunctionCall`
  Parameters:
    `visitor` - an expression visitor
  Returns:
    the simplified expression
  Throws:
    `XPathException` - if an error is discovered during expression rewriting

### getIntegerBounds

    public IntegerValue[] getIntegerBounds()

  For an expression that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis. The default implementation returns null, meaning "unknown" or "not applicable". Other implementations return an array of two IntegerValue objects, representing the lower and upper bounds respectively. The values UNBOUNDED_LOWER and UNBOUNDED_UPPER are used by convention to indicate that the value may be arbitrarily large. The values MAX_STRING_LENGTH and MAX_SEQUENCE_LENGTH are used to indicate values limited by the size of a string or the size of a sequence.

  Overrides:
    `getIntegerBounds` in class `Expression`
  Returns:
    the lower and upper bounds of integer values in the result, or null to indicate unknown or not applicable.

### 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 `Expression`
  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(ExpressionVisitor visitor)
                           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`
  Parameters:
    `visitor` - an expression visitor
  Returns:
    the expression, either unchanged, or pre-evaluated
  Throws:
    `XPathException` - if evaluation fails

### typeCheck

    public Expression typeCheck(ExpressionVisitor visitor,
                                ExpressionVisitor.ContextItemType contextItemType)
                         throws XPathException

  Description copied from class: `FunctionCall`
  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 visitor
    `contextItemType` - 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)

### isContextPossiblyUndefined

    public boolean isContextPossiblyUndefined()

  Ask whether the context item may possibly be undefined

  Returns:
    true if it might be undefined

### evaluateItem

    public Item evaluateItem(XPathContext c)
                      throws XPathException

  Evaluate in a general context

  Overrides:
    `evaluateItem` in class `Expression`
  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

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Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.