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java.lang.Object net.sf.saxon.expr.Expression com.saxonica.functions.hof.PartialApply
public class PartialApply
This expression class implements the operation of currying (or performing partial application) of a function. That is, it takes a function and a set of argument bindings as input, and produces a new function as output.
Field Summary |
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Fields inherited from class net.sf.saxon.expr.Expression |
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EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD |
Constructor Summary | |
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PartialApply(Expression base,
Expression[] boundArguments)
Create a partial function application expression |
Method Summary | |
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protected int |
computeCardinality()
Compute the static cardinality of this expression |
Expression |
copy()
Copy an expression. |
Item |
evaluateItem(XPathContext context)
Evaluate this experssion at run-time |
void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
Expression |
getBaseExpression()
|
Expression[] |
getBoundArguments()
|
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible. |
Iterator<Expression> |
iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
Expression |
promote(PromotionOffer offer,
Expression parent)
Offer promotion for this subexpression. |
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform type checking of an expression and its subexpressions. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public PartialApply(Expression base, Expression[] boundArguments)
base
- the expression that returns the function to be calledboundArguments
- an array in which each element is either an expression to be bound to the corresponding
argument, or null to represent a placeholder ("?" in the source syntax)Method Detail |
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public Expression getBaseExpression()
public Expression[] getBoundArguments()
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
Expression
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.
If the implementation returns a value other than "this", then it is required to ensure that the location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.
typeCheck
in class Expression
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
XPathException
- if an error is discovered during this phase
(typically a type error)public ItemType getItemType(TypeHierarchy th)
Expression
This method should always return a result, though it may be the best approximation that is available at the time.
getItemType
in class Expression
th
- the type hierarchy cache
public Iterator<Expression> iterateSubExpressions()
Expression
iterateSubExpressions
in class Expression
public Expression promote(PromotionOffer offer, Expression parent) throws XPathException
Expression
This method must be overridden for any Expression that has subexpressions.
promote
in class Expression
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 expressionparent
- the containing expression in the expression tree
XPathException
- if any error is detectedpublic boolean replaceSubExpression(Expression original, Expression replacement)
Expression
replaceSubExpression
in class Expression
original
- the original subexpressionreplacement
- the replacement subexpression
public void explain(ExpressionPresenter out)
Expression
explain
in class Expression
out
- the expression presenter used to display the structureprotected int computeCardinality()
Expression
computeCardinality
in class Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public Expression copy()
Expression
copy
in class Expression
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in class Expression
context
- The XPath dynamic evaluation context
XPathException
- if a dynamic error occurs during evaluation of the function.
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