net.sf.saxon.expr
public final class Atomizer extends UnaryExpression implements DivisibleInstruction
Nested Class Summary | |
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static class | Atomizer.AtomizingFunction
Implement the mapping function. |
Constructor Summary | |
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Atomizer(Expression sequence)
Constructor |
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()
Determine the static cardinality of the expression |
int | computeSpecialProperties()
Determine the special properties of this expression |
Expression | copy()
Copy an expression. |
String | displayExpressionName()
Diagnostic print of expression structure. |
Item | evaluateItem(XPathContext context)
Evaluate as an Item. |
static ItemType | getAtomizedItemType(Expression operand, boolean alwaysUntyped, TypeHierarchy th)
Compute the type that will result from atomizing the result of a given expression |
static SequenceIterator | getAtomizingIterator(SequenceIterator base)
Get an iterator that returns the result of atomizing the sequence delivered by the supplied
iterator |
ItemType | getItemType(TypeHierarchy th)
Determine the data type of the items returned by the expression, if possible |
SequenceIterator | iterate(XPathContext context)
Iterate over the sequence of values |
Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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void | process(XPathContext context)
Process the instruction, without returning any tail calls |
void | processLeft(Stack<XPathContext> contextStack, Stack state)
In streaming mode, process the first half of the instruction (for example, to start a new document or element) |
void | processRight(Stack<XPathContext> contextStack, Stack state)
In streaming mode, process the right half of the instruction (for example, to end a new document or element)
Note that unlike other divisible instructions this one doesn't push the result to the current output
destination, it leaves a sequenceIterator over the result on the stack. |
Expression | simplify(ExpressionVisitor visitor)
Simplify an expression |
Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the expression |
Parameters: sequence the sequence to be atomized
The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.
Parameters: pathMap the PathMap to which the expression should be added pathMapNodeSet the PathMapNodeSet to which the paths embodied in this expression should be added
Returns: the pathMapNodeSet representing the points in the source document that are both reachable by this expression, and that represent possible results of this expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.
Returns: NON_CREATIVE.
Returns: the copy of the original expression
Parameters: operand the given expression alwaysUntyped true if it is known that nodes will always be untyped th the type hierarchy cache
Returns: the item type of the result of evaluating the operand expression, after atomization
Parameters: base the supplied iterator, the input to atomization
Returns: an iterator that returns atomic values, the result of the atomization
Parameters: th the type hierarchy cache
Returns: a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER. For this class, the result is always an atomic type, but it might be more specific.
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: net.sf.saxon.trans.XPathException if an error is discovered during this phase (typically a type error)
Parameters: context The dynamic context, giving access to the current node, the current variables, etc.
Parameters: contextStack state a stack on which the instruction can save state information during the call on processLeft()
Parameters: contextStack state a stack on which the instruction can save state information during the call on processLeft()
Parameters: visitor an expression visitor