Lang

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

All Implemented Interfaces:

java.io.Serializable, javax.xml.transform.SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, org.xml.sax.Locator
```
public class Lang
extends SystemFunction
```
See Also:

Serialized Form

Field Summary
- Fields inherited from class net.sf.saxon.expr.Expression
  EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
- Fields inherited from class net.sf.saxon.expr.FunctionCall
  argument
- Fields inherited from class net.sf.saxon.functions.SystemFunction
  operation

Constructor Summary

Constructors
Constructor Description

Lang()

Constructors
Constructor	Description
`Lang()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Item`	`evaluateItem(XPathContext c)`	Evaluate in a general context
`int`	`getIntrinsicDependencies()`	Determine the dependencies
`static boolean`	`isLang(java.lang.String arglang, NodeInfo target)`	Test whether the context node has the given language attribute
`Expression`	`preEvaluate(ExpressionVisitor visitor)`	preEvaluate: this method suppresses compile-time evaluation by doing nothing
`Expression`	`typeCheck(ExpressionVisitor visitor, ItemType contextItemType)`	Type-check the expression.

Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterate, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError

Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString

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

Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, addDocToPathMap, checkArguments, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault

- Constructor Detail
  - Lang
```
public Lang()
```
- Method Detail
  - preEvaluate
```
public Expression preEvaluate(ExpressionVisitor visitor)
```
    preEvaluate: this method suppresses compile-time evaluation by doing nothing
    
    Overrides:
    
    preEvaluate in class FunctionCall
    
    Parameters:
    
    visitor - an expression visitor
    
    Returns:
    
    the result of the early evaluation, or the original expression, or potentially a simplified expression
  - typeCheck
```
public Expression typeCheck(ExpressionVisitor visitor,
                            ItemType 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)
  - evaluateItem
```
public Item evaluateItem(XPathContext c)
                  throws XPathException
```
    Evaluate in a general context
    
    Specified by:
    
    evaluateItem in interface EvaluableItem
    
    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
  - getIntrinsicDependencies
```
public int getIntrinsicDependencies()
```
    Determine the 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
  - isLang
```
public static boolean isLang(java.lang.String arglang,
                             NodeInfo target)
```
    Test whether the context node has the given language attribute
    
    Parameters:
    
    arglang - the language being tested
    
    target - the target node

Class Lang

Field Summary

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

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

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

Constructor Summary

Method Summary

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

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

Methods inherited from class java.lang.Object

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

Constructor Detail

Lang

Method Detail

preEvaluate

typeCheck

evaluateItem

getIntrinsicDependencies

isLang