net.sf.saxon.expr
public class PatternMatchExpression extends Expression
Constructor Summary | |
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PatternMatchExpression(Pattern pattern)
Create a pattern match expression |
Method Summary | |
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protected int | computeCardinality()
Get the cardinality of this expression |
Expression | copy()
Copy an expression. |
boolean | effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression. |
Item | evaluateItem(XPathContext context)
Evaluate an expression as a single item. |
void | explain(ExpressionPresenter destination)
Diagnostic print of expression structure. |
int | getIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived
from the dependencies of its subexpressions. |
ItemType | getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible. |
Pattern | getPattern()
Get the underlying pattern |
Iterator<Expression> | iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions. |
Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Perform type checking of an expression and its subexpressions. |
Parameters: pattern the pattern to be matched
Returns: the value @link {StaticProperty#EXACTLY_ONE}
Returns: the copy of the original expression
Parameters: context The context in which the expression is to be evaluated
Returns: the effective boolean value
Throws: net.sf.saxon.trans.XPathException if any dynamic error occurs evaluating the expression
Parameters: context The context in which the expression is to be evaluated
Returns: the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
Throws: net.sf.saxon.trans.XPathException if any dynamic error occurs evaluating the expression
Returns: a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
This method should always return a result, though it may be the best approximation that is available at the time.
Parameters: th the type hierarchy cache
Returns: a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)
Returns: the pattern
Returns: an iterator containing the sub-expressions of this expression
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)
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.
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 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)