net.sf.saxon.expr
Class IdentityComparison
- EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator
public final class IdentityComparison
IdentityComparison: a boolean expression that compares two nodes
for equals, not-equals, greater-than or less-than based on identity and
document ordering
computeCardinality , computeSpecialProperties , displayOperator , equals , explain , getOperands , getOperator , hashCode , isAssociative , isCommutative , isInverse , iterateSubExpressions , optimize , promote , replaceSubExpression , setFlattened , simplify , toString , typeCheck |
addToPathMap , adoptChildExpression , checkPermittedContents , computeCardinality , computeDependencies , computeSpecialProperties , computeStaticProperties , copy , display , doPromotion , dynamicError , effectiveBooleanValue , evaluateAsString , evaluateItem , explain , explain , findParentOf , getCardinality , getColumnNumber , getConstructType , getContainer , getDependencies , getExecutable , getHostLanguage , getImplementationMethod , getInstructionInfo , getIntrinsicDependencies , getItemType , getLineNumber , getLocationId , getLocationProvider , getPublicId , getSlotsUsed , getSpecialProperties , getSystemId , hasLoopingSubexpression , implementsStaticTypeCheck , iterate , iterateEvents , iterateSubExpressions , markTailFunctionCalls , optimize , process , promote , replaceSubExpression , resetLocalStaticProperties , setContainer , setFiltered , setFlattened , setLocationId , simplify , staticTypeCheck , suppressValidation , toString , typeCheck , typeError |
IdentityComparison
public IdentityComparison(Expression p1,
int op,
Expression p2)
Create an identity comparison identifying the two operands and the operator
p1
- the left-hand operandop
- the operator, as a token returned by the Tokenizer (e.g. Token.LT)p2
- the right-hand operand
copy
public Expression copy()
Copy an expression. This makes a deep copy.
- copy in interface Expression
- the copy of the original expression
effectiveBooleanValue
public boolean effectiveBooleanValue(XPathContext context)
throws XPathException
Get the effective boolean value of the expression. This returns false if the value
is the empty sequence, a zero-length string, a number equal to zero, or the boolean
false. Otherwise it returns true.
- effectiveBooleanValue in interface Expression
context
- The context in which the expression is to be evaluated
- the effective boolean value
XPathException
- if any dynamic error occurs evaluating the
expression
isGenerateIdEmulation
public boolean isGenerateIdEmulation()
Test the flag that indicates different empty-sequence behavior when emulating
comparison of two generate-id's
- true if this function is being used to compare generate-id() output
optimize
public Expression optimize(ExpressionVisitor visitor,
ItemType contextItemType)
throws XPathException
Perform optimisation of an expression and its subexpressions.
This method is called after all references to functions and variables have been resolved
to the declaration of the function or variable, and after all type checking has been done.
- optimize in interface BinaryExpression
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 to
Type.ITEM_TYPE
- the original expression, rewritten if appropriate to optimize execution
XPathException
- if an error is discovered during this phase
(typically a type error)
setGenerateIdEmulation
public void setGenerateIdEmulation(boolean flag)
Set flag to indicate different empty-sequence behavior when emulating
comparison of two generate-id's
flag
- true if this function is being used to compare generate-id() output