## net.sf.saxon.sql
Class SQLColumn.ColumnInstruction

    java.lang.Object
      net.sf.saxon.expr.ComputedExpression
          net.sf.saxon.instruct.Instruction
              net.sf.saxon.instruct.GeneralVariable
                  net.sf.saxon.sql.SQLColumn.ColumnInstruction

All Implemented Interfaces:
  Binding, Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator, TailCallReturner

Enclosing class:
  SQLColumn

protected static class SQLColumn.ColumnInstruction
extends GeneralVariable

See Also:
  Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.instruct.GeneralVariable
`nameCode, referenceCount`

Fields inherited from class net.sf.saxon.expr.ComputedExpression
`locationId, staticProperties`

Fields inherited from interface net.sf.saxon.expr.Expression
`EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD`

Constructor Summary
`SQLColumn.ColumnInstruction()`

Method Summary
`ValueRepresentation` `evaluateVariable(XPathContext context)` Evaluate the variable (method exists only to satisfy the interface)
`InstructionInfo` `getInstructionInfo()` Get InstructionInfo for this expression
`TailCall` `processLeavingTail(XPathContext context)` ProcessLeavingTail: called to do the real work of this instruction.

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

`display, evaluateItem, getCardinality, getInstructionNameCode, getItemType, getLocalSlotNumber, getNameCode, getRequiredType, getSelectExpression, getSelectValue, getSlotNumber, getVariableFingerprint, getVariableName, init, isAssignable, isGlobal, isRequiredParam, isTunnelParam, iterate, iterateSubExpressions, optimize, promoteInst, setAssignable, setNameCode, setReferenceCount, setRequiredParam, setRequiredType, setSelectExpression, setSlotNumber, setTunnel, setVariableName, simplify, typeCheck`

Methods inherited from class net.sf.saxon.instruct.Instruction
`appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, createsNewNodes, dynamicError, evaluateAsString, getImplementationMethod, getSourceLocator, isXSLT, process, promote`

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

`adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, effectiveBooleanValue, getColumnNumber, getConstructType, getDependencies, getExecutable, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError`

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

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

Constructor Detail

### SQLColumn.ColumnInstruction

    public SQLColumn.ColumnInstruction()

Method Detail

### getInstructionInfo

    public InstructionInfo getInstructionInfo()

  Description copied from class: `ComputedExpression`
  Get InstructionInfo for this expression

  Specified by:
    `getInstructionInfo` in interface `InstructionInfoProvider`
  Overrides:
    `getInstructionInfo` in class `Instruction`

### processLeavingTail

    public TailCall processLeavingTail(XPathContext context)

  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.

### evaluateVariable

    public ValueRepresentation evaluateVariable(XPathContext context)
                                         throws XPathException

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

  Throws:
    `XPathException`