## net.sf.saxon.expr.instruct
Class Assign

    java.lang.Object
      net.sf.saxon.expr.Expression
          net.sf.saxon.expr.instruct.Instruction
              net.sf.saxon.expr.instruct.GeneralVariable
                  net.sf.saxon.expr.instruct.Assign

All Implemented Interfaces:
  Serializable, SourceLocator, LocationProvider, SaxonLocator, Binding, BindingReference, EvaluableItem, TailCallReturner, SequenceIterable, InstructionInfo, Locator

    public class Assign

extends GeneralVariable
implements BindingReference

saxon:assign element in stylesheet. The saxon:assign element has mandatory attribute name and optional attribute expr. It also allows xsl:extension-element-prefixes etc.

See Also:
  Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.instruct.GeneralVariable
`evaluationMode, referenceCount, slotNumber, variableQName`

Fields inherited from class net.sf.saxon.expr.Expression
`EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD`

Constructor Summary
`Assign()`

Method Summary
`ValueRepresentation` `evaluateVariable(XPathContext context)` Evaluate the variable (method exists only to satisfy the interface)
`void` `explain(ExpressionPresenter out)` Diagnostic print of expression structure.
`void` `fixup(Binding binding)` Fix up this binding reference to a binding
`int` `getInstructionNameCode()` Get the name of this instruction for diagnostic and tracing purposes
`int` `getIntrinsicDependencies()` Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
`TailCall` `processLeavingTail(XPathContext context)` ProcessLeavingTail: called to do the real work of this instruction.
`Expression` `promote(PromotionOffer offer, Expression parent)` Offer promotion for this subexpression.
`void` `setStaticType(SequenceType type, Value constantValue, int properties)` Fix up the static type of this variable reference; optionally, supply a constant value for the variable.

Methods inherited from class net.sf.saxon.expr.instruct.GeneralVariable

`copy, evaluateItem, getCardinality, getEvaluationMode, getItemType, getLocalSlotNumber, getRequiredType, getSelectExpression, getSelectValue, getSlotNumber, getVariableQName, init, isAssignable, isGlobal, isImplicitlyRequiredParam, isRequiredParam, isTunnelParam, iterate, iterateSubExpressions, optimize, promoteInst, replaceSubExpression, setAssignable, setImplicitlyRequiredParam, setReferenceCount, setRequiredParam, setRequiredType, setSelectExpression, setSlotNumber, setTunnel, setVariableQName, simplify, typeCheck`

Methods inherited from class net.sf.saxon.expr.instruct.Instruction
`assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, createsNewNodes, dynamicError, evaluateAsString, getConstructType, getExpressionName, getImplementationMethod, getInstructionName, getIteratorFromProcessMethod, getSourceLocator, isXSLT, process`

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

`addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getColumnNumber, getColumnNumber, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError`

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

Methods inherited from interface javax.xml.transform.SourceLocator
`getColumnNumber, getLineNumber, getPublicId, getSystemId`

Constructor Detail

### Assign

    public Assign()

Method Detail

### setStaticType

    public void setStaticType(SequenceType type,
                              Value constantValue,
                              int properties)

  Description copied from interface: `BindingReference`
  Fix up the static type of this variable reference; optionally, supply a constant value for the variable. Also supplies other static properties of the expression to which the variable is bound, for example whether it is an ordered node-set.

  Specified by:
    `setStaticType` in interface `BindingReference`

### fixup

    public void fixup(Binding binding)

  Description copied from interface: `BindingReference`
  Fix up this binding reference to a binding

  Specified by:
    `fixup` in interface `BindingReference`

### getIntrinsicDependencies

    public int getIntrinsicDependencies()

  Description copied from class: `Expression`
  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

### promote

    public Expression promote(PromotionOffer offer,
                              Expression parent)
                       throws XPathException

  Offer promotion for this subexpression. This needs careful handling in the case of saxon:assign

  Overrides:
    `promote` in class `Instruction`
  Parameters:
    `offer` - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression
    `parent` -
  Returns:
    if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
  Throws:
    `XPathException` - if any error is detected

### getInstructionNameCode

    public int getInstructionNameCode()

  Get the name of this instruction for diagnostic and tracing purposes

  Overrides:
    `getInstructionNameCode` in class `GeneralVariable`
  Returns:
    the name of this instruction, as a name pool name code

### processLeavingTail

    public TailCall processLeavingTail(XPathContext context)
                                throws XPathException

  Description copied from class: `Instruction`
  ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.

  Specified by:
    `processLeavingTail` in interface `TailCallReturner`
  Specified by:
    `processLeavingTail` in class `Instruction`
  Parameters:
    `context` - The dynamic context of the transformation, giving access to the current node, the current variables, etc.
  Returns:
    null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.
  Throws:
    `XPathException`

### evaluateVariable

    public ValueRepresentation evaluateVariable(XPathContext context)
                                         throws XPathException

  Evaluate the variable (method exists only to satisfy the interface)

  Specified by:
    `evaluateVariable` in interface `Binding`
  Parameters:
    `context` - the XPath dynamic evaluation context
  Returns:
    the result of evaluating the variable
  Throws:
    `XPathException`

### explain

    public void explain(ExpressionPresenter out)

  Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

  Overrides:
    `explain` in class `GeneralVariable`
  Parameters:
    `out` - the expression presenter used to display the structure

Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.