net.sf.saxon.expr
public final class FilterExpression extends Expression implements ContextSwitchingExpression
Field Summary | |
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static int | FILTERED |
Constructor Summary | |
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FilterExpression(Expression start, Expression filter)
Constructor
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Method Summary | |
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PathMap.PathMapNodeSet | addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. |
int | computeCardinality()
Get the static cardinality of this expression
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int | computeDependencies()
Determine which aspects of the context the expression depends on. |
int | computeSpecialProperties()
Get the static properties of this expression (other than its type). |
Expression | copy()
Copy an expression. |
boolean | equals(Object other)
Is this expression the same as another expression?
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void | explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
Expression | getControlledExpression()
Get the subexpression that is evaluated in the new context |
Expression | getControllingExpression()
Get the underlying expression
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Expression | getFilter()
Get the filter expression
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ItemType | getItemType(TypeHierarchy th)
Get the data type of the items returned
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int | hashCode()
get HashCode for comparing two expressions
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boolean | hasLoopingSubexpression(Expression child)
Given an expression that is an immediate child of this expression, test whether
the evaluation of the parent expression causes the child expression to be
evaluated repeatedly
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boolean | isIndependentNumericFilter()
Determine whether the filter is a simple independent numeric, that is, an expression
that satisfies the following conditions: (a) its value is numeric;
(b) the value does not depend on the context item or position;
(c) the cardinality is zero or one.
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boolean | isPositional(TypeHierarchy th)
Determine if the filter is positional
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boolean | isSimpleBooleanFilter()
Test if the filter always returns a singleton boolean
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SequenceIterator | iterate(XPathContext context)
Iterate over the results, returning them in the correct order
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Iterator<Expression> | iterateSameFocusSubExpressions()
Get the immediate sub-expressions of this expression that are evaluated with the
same focus (context item, position, and size) as the parent expression. |
Iterator<Expression> | iterateSubExpressions()
Get the immediate subexpressions of this expression
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Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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Expression | promote(PromotionOffer offer, Expression parent)
Promote this expression if possible
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boolean | replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression
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Expression | simplify(ExpressionVisitor visitor)
Simplify an expression
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String | toString()
The toString() method for an expression attempts to give a representation of the expression
in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
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Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the expression
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Parameters: start A node-set expression denoting the absolute or relative set of nodes from which the navigation path should start. filter An expression defining the filter predicate
Parameters: pathMap the PathMap to which the expression should be added pathMapNodeSet
Returns: the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression
Returns: the cardinality. The method attempts to determine the case where the filter predicate is guaranteed to select at most one item from the sequence being filtered
Returns: the dependencies
Returns: the static properties of the expression, as a bit-significant value
Returns: the copy of the original expression
Parameters: other the expression to be compared with this one
Returns: true if the two expressions are statically equivalent
Parameters: out the ExpressionPresenter to be used
Returns: the subexpression evaluated in the context set by the controlling expression
Returns: the expression being filtered
Returns: the expression acting as the filter predicate
Parameters: th the type hierarchy cache
Returns: an integer representing the data type
Returns: the hash code
Parameters: child the immediate subexpression
Returns: true if the child expression is evaluated repeatedly
Returns: true if the filter is a numeric value that does not depend on the context item or position
Parameters: th the Type Hierarchy (for cached access to type information)
Returns: true if the value of the filter depends on the position of the item against which it is evaluated
Returns: true if the filter is a simple boolean expression
Parameters: context the dynamic context for the evaluation
Returns: an iterator over the expression results
Throws: XPathException if any dynamic error occurs
Returns: an iterator containing those sub-expressions of this expression that are evaluated with the same focus as the parent expression
Returns: the subexpressions, as an array
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: offer details of the promotion that is possible parent
Returns: the promoted expression (or the original expression, unchanged)
Parameters: original the original subexpression replacement the replacement subexpression
Returns: true if the original subexpression is found
Parameters: visitor the expression visitor
Returns: the simplified expression
Throws: XPathException if any failure occurs
Parameters: visitor the expression visitor contextItemType the type of the context item for this expression
Returns: the expression after type-checking (potentially modified to add run-time checks and/or conversions)