net.sf.saxon.instruct

Class UseAttributeSets

public class UseAttributeSets extends Instruction

This instruction corresponds to a use-attribute-sets attribute on a literal result element, xsl:element, or xsl:copy.
Constructor Summary
UseAttributeSets(AttributeSet[] sets)
Create a use-attribute-sets expression
Method Summary
Expressioncopy()
Copy an expression.
booleanequals(Object obj)
Test whether this UseAttributeSets expression is equal to another
voidexplain(ExpressionPresenter out)
Diagnostic print of expression structure.
intgetIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemTypegetItemType(TypeHierarchy th)
Get the item type of the items returned by evaluating this instruction
inthashCode()
Compute a hashcode
Expressionoptimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
TailCallprocessLeavingTail(XPathContext context)
ProcessLeavingTail: called to do the real work of this instruction.
Expressionsimplify(ExpressionVisitor visitor)
Simplify an expression.
ExpressiontypeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Perform type checking of an expression and its subexpressions.

Constructor Detail

UseAttributeSets

public UseAttributeSets(AttributeSet[] sets)
Create a use-attribute-sets expression

Parameters: sets the set of attribute sets to be expanded

Method Detail

copy

public Expression copy()
Copy an expression. This makes a deep copy.

Returns: the copy of the original expression

equals

public boolean equals(Object obj)
Test whether this UseAttributeSets expression is equal to another

Parameters: obj the other expression

explain

public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

getIntrinsicDependencies

public int getIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions. For example, position() has an intrinsic dependency on the context position, while (position()+1) does not. The default implementation of the method returns 0, indicating "no dependencies".

Returns: a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

getItemType

public ItemType getItemType(TypeHierarchy th)
Get the item type of the items returned by evaluating this instruction

Parameters: th the type hierarchy cache

Returns: the static item type of the instruction

hashCode

public int hashCode()
Compute a hashcode

optimize

public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType)
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.

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)

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.

Parameters: context The dynamic context of the transformation, giving access to the current node, the current variables, etc.

Returns: null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.

simplify

public Expression simplify(ExpressionVisitor visitor)
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.

Parameters: visitor an expression visitor

Returns: the simplified expression

Throws: net.sf.saxon.trans.XPathException if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Perform type checking of an expression and its subexpressions.

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.

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)