net.sf.saxon.expr
Class Atomizer
- EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator
public final class Atomizer
An Atomizer is an expression corresponding essentially to the fn:data() function: it
maps a sequence by replacing nodes with their typed values
computeCardinality , computeSpecialProperties , displayExpressionName , displayOperator , equals , explain , getBaseExpression , getItemType , hashCode , iterateSubExpressions , optimize , promote , replaceSubExpression , 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 |
Atomizer
public Atomizer(Expression sequence,
Configuration config)
Constructor
sequence
- the sequence to be atomizedconfig
- the Configuration. Used only for optimization, may be null. Atomization is faster if
it is known in advance that all nodes will be untyped.
addToPathMap
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap,
PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited
by an expression in a source tree.
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.
- addToPathMap in interface Expression
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
- the PathMapNodeSet to which the paths embodied in this expression should be added
- 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.
copy
public Expression copy()
Copy an expression. This makes a deep copy.
- copy in interface Expression
- the copy of the original expression
displayExpressionName
public String displayExpressionName()
Diagnostic print of expression structure. The abstract expression tree
is written to the supplied output destination.
- displayExpressionName in interface UnaryExpression
getAtomizedItemType
public static ItemType getAtomizedItemType(Expression operand,
boolean alwaysUntyped,
TypeHierarchy th)
Compute the type that will result from atomizing the result of a given expression
operand
- the given expressionalwaysUntyped
- true if it is known that nodes will always be untypedth
- the type hierarchy cache
- the item type of the result of evaluating the operand expression, after atomization
getAtomizingIterator
public static SequenceIterator getAtomizingIterator(SequenceIterator base)
Get an iterator that returns the result of atomizing the sequence delivered by the supplied
iterator
base
- the supplied iterator, the input to atomization
- an iterator that returns atomic values, the result of the atomization
getItemType
public ItemType getItemType(TypeHierarchy th)
Determine the data type of the items returned by the expression, if possible
- getItemType in interface UnaryExpression
th
- the type hierarchy cache
- 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.
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 UnaryExpression
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)