net.sf.saxon.expr
public final class IdentityComparison extends BinaryExpression
Constructor Summary | |
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IdentityComparison(Expression p1, int op, Expression p2)
Create an identity comparison identifying the two operands and the operator |
Method Summary | |
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Expression | copy()
Copy an expression. |
boolean | effectiveBooleanValue(XPathContext context) |
Item | evaluateItem(XPathContext context)
Evaluate the expression |
ItemType | getItemType(TypeHierarchy th)
Determine the data type of the expression |
boolean | isGenerateIdEmulation()
Test the flag that indicates different empty-sequence behavior when emulating
comparison of two generate-id's |
Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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void | setGenerateIdEmulation(boolean flag)
Set flag to indicate different empty-sequence behavior when emulating
comparison of two generate-id's |
Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the expression |
Parameters: p1 the left-hand operand op the operator, as a token returned by the Tokenizer (e.g. Token.LT) p2 the right-hand operand
Returns: the copy of the original expression
Parameters: th the type hierarchy cache
Returns: Type.BOOLEAN
Returns: true if this function is being used to compare generate-id() output
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.
Parameters: visitor an expression visitor contextItemType 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 ITEM_TYPE
Returns: the original expression, rewritten if appropriate to optimize execution
Throws: XPathException if an error is discovered during this phase (typically a type error)
Parameters: flag true if this function is being used to compare generate-id() output