An instruction derived from an xsl:attribute element in stylesheet, or from
an attribute constructor in XQuery, in cases where the attribute name is not known
statically
checkPermittedContents
public void checkPermittedContents(SchemaType parentType,
StaticContext env,
boolean whole)
throws XPathException
Check that any elements and attributes constructed or returned by this expression are acceptable
in the content model of a given complex type. It's always OK to say yes, since the check will be
repeated at run-time. The process of checking element and attribute constructors against the content
model of a complex type also registers the type of content expected of those constructors, so the
static validation can continue recursively.
- checkPermittedContents in interface Expression
computeSpecialProperties
public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is
bit-signficant. These properties are used for optimizations. In general, if
property bit is set, it is true, but if it is unset, the value is unknown.
- computeSpecialProperties in interface SimpleNodeConstructor
- a set of flags indicating static properties of this expression
copy
public Expression copy()
Copy an expression. This makes a deep copy.
- copy in interface Expression
- the copy of the original expression
explain
public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree
is written to the supplied output destination.
- explain in interface Expression
getCardinality
public int getCardinality()
Get the static cardinality of this expression
- getCardinality in interface Expression
- the static cardinality (exactly one)
getItemType
public ItemType getItemType(TypeHierarchy th)
Get the static type of this expression
- getItemType in interface Instruction
th
- the type hierarchy cache
- the static type of the item returned by this expression
getNameExpression
public Expression getNameExpression()
Get the expression used to compute the name of the attribute
- the expression used to compute the name of the attribute
getNamespaceExpression
public Expression getNamespaceExpression()
Get the expression used to compute the namespace part of the name of the attribute
- the expression used to compute the namespace part of the name of the attribute
getNamespaceResolver
public NamespaceResolver getNamespaceResolver()
Get the namespace resolver used to resolve any prefix in the name of the attribute
- the namespace resolver if one has been saved; or null otherwise
optimize
public Expression optimize(ExpressionVisitor visitor,
ItemType contextItemType)
throws XPathException
Perform optimisation of an expression and its subexpressions. This is the third and final
phase of static optimization.
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 SimpleNodeConstructor
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)
promoteInst
protected void promoteInst(PromotionOffer offer)
throws XPathException
Offer promotion for subexpressions. The offer will be accepted if the subexpression
is not dependent on the factors (e.g. the context item) identified in the PromotionOffer.
By default the offer is not accepted - this is appropriate in the case of simple expressions
such as constant values and variable references where promotion would give no performance
advantage. This method is always called at compile time.
- promoteInst in interface SimpleNodeConstructor
offer
- details of the offer, for example the offer to move
expressions that don't depend on the context to an outer level in
the containing expression
replaceSubExpression
public boolean replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression
- replaceSubExpression in interface SimpleNodeConstructor
original
- the original subexpressionreplacement
- the replacement subexpression
- true if the original subexpression is found
setRejectDuplicates
public void setRejectDuplicates()
Indicate that two attributes with the same name are not acceptable.
(This option is set in XQuery, but not in XSLT)