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## org.apache.xpath.operations
Class Operation

    java.lang.Object
      |
      +--org.apache.xpath.Expression
            |
            +--org.apache.xpath.operations.Operation

Direct Known Subclasses:
  And, Div, Equals, Gt, Gte, Lt, Lte, Minus, Mod, Mult, NotEquals, Or, Plus, Quo

public class Operation
extends Expression
implements ExpressionOwner

The baseclass for a binary operation.

See Also:
  Serialized Form

Constructor Summary
`Operation()`

Method Summary
`void` | `callVisitors(ExpressionOwner owner, XPathVisitor visitor)`
`boolean` | `canTraverseOutsideSubtree()` Tell if this expression or it's subexpressions can traverse outside the current subtree.
`boolean` | `deepEquals(Expression expr)`
`XObject` | `execute(XPathContext xctxt)` Execute a binary operation by calling execute on each of the operands, and then calling the operate method on the derived class.
`void` | `fixupVariables(java.util.Vector vars, int globalsSize)` This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
`Expression` | `getExpression()`
`Expression` | `getLeftOperand()`
`Expression` | `getRightOperand()`
`XObject` | `operate(XObject left, XObject right)` Apply the operation to two operands, and return the result.
`void` | `setExpression(Expression exp)`
`void` | `setLeftRight(Expression l, Expression r)` Set the left and right operand expressions for this operation.

Methods inherited from class org.apache.xpath.Expression
`asIterator, asIteratorRaw, asNode, assertion, bool, error, execute, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isStableNumber, num, warn, xstr`

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

Constructor Detail

### Operation

    public Operation()

Method Detail

### fixupVariables

    public void fixupVariables(java.util.Vector vars,
                               int globalsSize)

  This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
  Parameters:
    `vars` - List of QNames that correspond to variables. This list should be searched backwards for the first qualified name that corresponds to the variable reference qname. The position of the QName in the vector from the start of the vector will be its position in the stack frame (but variables above the globalsTop value will need to be offset to the current stack frame).
  Overrides:
    fixupVariables in class Expression

### canTraverseOutsideSubtree

    public boolean canTraverseOutsideSubtree()

  Tell if this expression or it's subexpressions can traverse outside the current subtree.
  Returns:
    true if traversal outside the context node's subtree can occur.
  Overrides:
    canTraverseOutsideSubtree in class Expression

### setLeftRight

    public void setLeftRight(Expression l,
                             Expression r)

  Set the left and right operand expressions for this operation.
  Parameters:
    `l` - The left expression operand.
    `r` - The right expression operand.

### execute

    public XObject execute(XPathContext xctxt)
                    throws TransformerException

  Execute a binary operation by calling execute on each of the operands, and then calling the operate method on the derived class.
  Parameters:
    `xctxt` - The runtime execution context.
  Returns:
    The XObject result of the operation.
  Throws:
    TransformerException -
  Overrides:
    execute in class Expression

### operate

    public XObject operate(XObject left,
                           XObject right)
                    throws TransformerException

  Apply the operation to two operands, and return the result.
  Parameters:
    `left` - non-null reference to the evaluated left operand.
    `right` - non-null reference to the evaluated right operand.
  Returns:
    non-null reference to the XObject that represents the result of the operation.
  Throws:
    TransformerException -

### getLeftOperand

    public Expression getLeftOperand()

  Returns:
    the left operand of binary operation, as an Expression.

### getRightOperand

    public Expression getRightOperand()

  Returns:
    the right operand of binary operation, as an Expression.

### callVisitors

    public void callVisitors(ExpressionOwner owner,
                             XPathVisitor visitor)

  See Also:
    `XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)`

### getExpression

    public Expression getExpression()

  Specified by:
    getExpression in interface ExpressionOwner
  See Also:
    `ExpressionOwner.getExpression()`

### setExpression

    public void setExpression(Expression exp)

  Specified by:
    setExpression in interface ExpressionOwner
  See Also:
    `ExpressionOwner.setExpression(Expression)`

### deepEquals

    public boolean deepEquals(Expression expr)

  Overrides:
    deepEquals in class Expression
  See Also:
    `Expression.deepEquals(Expression)`

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Copyright © 2002 Apache XML Project. All Rights Reserved.