Package net.sf.saxon.expr

Class DraftFunctionCall

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.DraftExpression

net.sf.saxon.expr.DraftFunctionCall

All Implemented Interfaces:

ExportAgent, Locatable, IdentityComparable, Traceable

public class DraftFunctionCall
extends DraftExpression

This class represents a call to a function in its raw lexical form, before it has been resolved to an actual function. Used in XQuery only, where function references can be forwards references to functions not yet declared.

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor	Description
DraftFunctionCall(String lexicalName, QueryModule queryModule, Expression[] arguments, Map<StructuredQName,Integer> keywordArgs)	Create a function call to a user-written function in a query

Method Summary

Modifier and Type	Method	Description
protected int	computeCardinality()	Determine the cardinality of the result
Expression	copy(RebindingMap rebindings)	Copy an expression.
Item	evaluateItem(XPathContext c)	Call the function, returning the value as an item.
void	export(ExpressionPresenter out)	Diagnostic print of expression structure.
Elaborator	getElaborator()	Make an elaborator for this expression
String	getExpressionName()	Get a name identifying the kind of expression, in terms meaningful to a user.
int	getImplementationMethod()	An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
int	getIntrinsicDependencies()	Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
boolean	isUpdatingExpression()	Determine whether this is an updating expression as defined in the XQuery update specification
SequenceIterator	iterate(XPathContext c)	Call the function, returning an iterator over the results.
Iterable<Operand>	operands()	Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
void	process(Outputter output, XPathContext context)	Process the function call in push mode
Expression	simplify()	The simplify method applied to a DraftFunctionCall when the entire query has been parsed, so all user-defined functions are now known, enabling the name to be resolved.

Methods inherited from class net.sf.saxon.expr.DraftExpression

computeSpecialProperties, getItemType, getStaticType, getStaticUType

Methods inherited from class net.sf.saxon.expr.Expression

adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeStaticProperties, dispatchTailCall, dynamicError, effectiveBooleanValue, equals, evaluateAsString, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStreamerName, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isVacuousExpression, makeElaborator, markTailFunctionCalls, operandList, operandSparseList, optimize, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, supportsLazyEvaluation, suppressValidation, toPattern, toShortString, toString, typeCheck, typeCheckChildren, typeError, unordered, verifyParentPointers, warning, withLocation

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface net.sf.saxon.trace.Traceable

gatherProperties

Constructor Details

DraftFunctionCall

public DraftFunctionCall(String lexicalName,
 QueryModule queryModule,
 Expression[] arguments,
 Map<StructuredQName,Integer> keywordArgs)

Create a function call to a user-written function in a query

Parameters:

lexicalName - The name of the function as written in the source query

queryModule - The query module containing the function definition

arguments - The argument expressions, in order, representing any "?" place marker by a PlaceHolder pseudo-expression

keywordArgs - Mapping from argument keywords (where used) to the zero-based position where the keyword is used

Method Details

operands

public Iterable<Operand> operands()

Description copied from class: Expression

Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.

If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

Overrides:

operands in class Expression

Returns:

an iterator containing the sub-expressions of this expression

getIntrinsicDependencies

public int getIntrinsicDependencies()

Description copied from class: Expression

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".

Overrides:

getIntrinsicDependencies in class Expression

Returns:

an integer containing bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

isUpdatingExpression

public boolean isUpdatingExpression()

Determine whether this is an updating expression as defined in the XQuery update specification

Overrides:

isUpdatingExpression in class Expression

Returns:

true if this is an updating expression

copy

public Expression copy(RebindingMap rebindings)

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Parameters:

rebindings - variable bindings that need to be changed

Returns:

the copy of the original expression

computeCardinality

protected int computeCardinality()

Determine the cardinality of the result

Specified by:

computeCardinality in class Expression

Returns:

the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE. May also return StaticProperty.ALLOWS_ZERO if the result is known to be an empty sequence, or StaticProperty.ALLOWS_MANY if if is known to return a sequence of length two or more.

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException

Call the function, returning the value as an item. This method will be used only when the cardinality is zero or one. If the function is tail recursive, it returns an Object representing the arguments to the next (recursive) call

Overrides:

evaluateItem in class Expression

Parameters:

c - The context in which the expression is to be evaluated

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

iterate

public SequenceIterator iterate(XPathContext c)
                         throws XPathException

Call the function, returning an iterator over the results. (But if the function is tail recursive, it returns an iterator over the arguments of the recursive call)

Overrides:

iterate in class Expression

Parameters:

c - supplies the context for evaluation

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

Throws:

XPathException - if any dynamic error occurs evaluating the expression

process

public void process(Outputter output,
 XPathContext context)
             throws XPathException

Process the function call in push mode

Overrides:

process in class Expression

Parameters:

output - the destination for the result

context - the XPath dynamic context

Throws:

XPathException - if a dynamic error occurs

export

public void export(ExpressionPresenter out)
            throws XPathException

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

export in interface ExportAgent

Specified by:

export in class Expression

Parameters:

out - the expression presenter used to display the structure

Throws:

XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

getExpressionName

public String getExpressionName()

Get a name identifying the kind of expression, in terms meaningful to a user.

Overrides:

getExpressionName in class Expression

Returns:

a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

getImplementationMethod

public int getImplementationMethod()

Description copied from class: Expression

An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.

Specified by:

getImplementationMethod in class Expression

Returns:

the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

getElaborator

public Elaborator getElaborator()

Description copied from class: Expression

Make an elaborator for this expression

Overrides:

getElaborator in class Expression

Returns:

an appropriate Elaborator

simplify

public Expression simplify()
                    throws XPathException

The simplify method applied to a DraftFunctionCall when the entire query has been parsed, so all user-defined functions are now known, enabling the name to be resolved. As well as locating the target function, keyword arguments can be resolved to positional arguments.

Overrides:

simplify in class Expression

Returns:

either a FunctionCall or a CurriedFunction

Throws:

XPathException - if resolution fails