Prev Class | Next Class | Frames | No Frames |
Summary: Nested | Field | Method | Constr | Detail: Nested | Field | Method | Constr |
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.UnaryExpression
net.sf.saxon.expr.NegateExpression
public class NegateExpression
extends UnaryExpression
Field Summary |
Fields inherited from class net.sf.saxon.expr.UnaryExpression | |
operand |
Fields inherited from class net.sf.saxon.expr.Expression | |
EVALUATE_METHOD , ITERATE_METHOD , PROCESS_METHOD , locationId , staticProperties |
Constructor Summary | |
|
Method Summary | |
Expression |
|
protected String |
|
Item |
|
ItemType |
|
void |
|
Expression |
|
Methods inherited from class net.sf.saxon.expr.UnaryExpression | |
computeCardinality , computeSpecialProperties , displayExpressionName , displayOperator , equals , explain , getBaseExpression , getItemType , hashCode , iterateSubExpressions , optimize , promote , replaceSubExpression , simplify , toString , typeCheck |
public NegateExpression(Expression base)
Create a NegateExpression
- Parameters:
base
- the expression that computes the value whose sign is to be reversed
public Expression copy()
Copy an expression. This makes a deep copy.
- Overrides:
- copy in interface Expression
- Returns:
- the copy of the original expression
protected String displayOperator(Configuration config)
- Overrides:
- displayOperator in interface UnaryExpression
public Item evaluateItem(XPathContext context) throws XPathException
Evaluate the expression.
- Specified by:
- evaluateItem in interface EvaluableItem
- Overrides:
- evaluateItem in interface Expression
public ItemType getItemType(TypeHierarchy th)
Determine the data type of the expression, if this is known statically
- Overrides:
- getItemType in interface UnaryExpression
- Parameters:
th
- the type hierarchy cache
public void setBackwardsCompatible(boolean compatible)
Set whether the expression is to be evaluated in XPath 1.0 compatibility mode
- Parameters:
compatible
- true if XPath 1.0 compatibility mode is enabled
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Perform type checking of an expression and its subexpressions. This is the second phase of static optimization. This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression. This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared. If the implementation returns a value other than "this", then it is required to ensure that the parent pointer and location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.
- Overrides:
- typeCheck in interface UnaryExpression
- Parameters:
visitor
- an expression visitorcontextItemType
- 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 toType.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)