net.sf.saxon.functions

Class SystemFunctionCall

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.SystemFunctionCall

All Implemented Interfaces:

SourceLocator, Callable, IdentityComparable, InstructionInfo

Direct Known Subclasses:

Abs, AccessorFn, AccumulatorFn, Adjust, Aggregate, Available, AvailableEnvironmentVariables, BaseURI, BooleanFn, Ceiling, CodepointEqual, CodepointsToString, CollatingFunction, Collection, CompileTimeFunction, Concat, CurrentDateTime, CurrentGroup, CurrentGroupingKey, CurrentMergeGroup, CurrentMergeKey, CurrentOutputUri, DateTimeConstructor, Doc, DocAvailable, DocumentFn, DocumentUriFn, EnvironmentVariable, Error, EscapeURI, False, FilterFn, Floor, FoldingFunction, FoldRightFn, ForEachFn, ForEachPairFn, FormatDate, FormatInteger, FormatNumber, FunctionArity, FunctionLookup, FunctionName, GenerateId, HasChildren, Id, Idref, Innermost, InScopePrefixes, InsertBefore, JsonToXMLFn, KeyFn, Lang, Last, LocalNameFn, LowerCase, Matches, NameFn, NamespaceForPrefix, NamespaceUriFn, Nilled, NodeNameFn, NormalizeSpace_0, NormalizeSpace_1, NormalizeUnicode, NotFn, NumberFn, Outermost, ParseXml, ParseXmlFragment, Path, Position, Put, QNameFn, RegexGroup, Remove, Replace, ResolveQName, ResolveURI, Reverse, Root, Round, RoundHalfToEven, Serialize, SerializeJsonFn, SnapshotFn, StreamAvailable, StringFn, StringLength, StringToCodepoints, Subsequence, Substring, SystemProperty, Tokenize, Trace, Translate, TreatFn, True, UnparsedEntity, UnparsedTextFunction, UpperCase, UriCollection, XMLToJsonFn, XMLToJsonTransform

public abstract class SystemFunctionCall
extends FunctionCall
implements Callable

Abstract superclass for calls to functions in the standard function library

Field Summary

Fields

Modifier and Type	Field and Description
protected int	operation

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

argument

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

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
SystemFunctionCall()

Method Summary

Methods

Modifier and Type	Method and Description
protected void	addContextDocumentArgument(int pos, String augmentedName) Add an implicit argument referring to the context document.
PathMap.PathMapNodeSet	addDocToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodes) Add a representation of a doc() call or similar function to a PathMap.
void	bindStaticContext(StaticContext env) Bind aspects of the static context on which the particular function depends
void	checkArguments(ExpressionVisitor visitor) Method called during static type checking
int	computeCardinality() Determine the cardinality of the function.
int	computeSpecialProperties() Determine the special properties of this expression.
Expression	copy() Copy an expression.
static boolean	equalOrNull(Object x, Object y) Return true if two objects are equal or if both are null
boolean	equals(Object o) Determine whether two expressions are equivalent
protected NodeInfo	getContextNode(XPathContext context) Helper method for subclasses: get the context item if it is a node, throwing appropriate errors if not
Callable	getConvertingCallable()
NodeInfo	getDefaultArgumentNode(XPathContext context, Sequence[] arguments, String funcName)
StandardFunction.Entry	getDetails() Get the details of the function signature
String	getErrorCodeForTypeErrors() Return the error code to be used for type errors.
FunctionItemType	getFunctionItemType(TypeHierarchy th) Get the item type of the function item
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
ItemType	getItemType() Determine the item type of the value returned by the function
int	getOperation()
protected SequenceType	getRequiredType(int arg) Get the required type of the nth argument
static FunctionCall	makeSystemFunction(String name, Expression[] arguments) Make a system function call (one in the standard function namespace).
Iterable<Operand>	operands() Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
Expression	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Perform optimisation of an expression and its subexpressions.
void	setDetails(StandardFunction.Entry entry) Set the details of this type of function
String	toShortString() Produce a short string identifying the expression for use in error messages
protected void	useContextItemAsDefault(ExpressionVisitor visitor) Set "." as the default value for the first and only argument.

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

addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, preEvaluate, promote, replaceOperand, setArguments, setFunctionName, simplifyArguments, toString, typeCheck

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

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getConfiguration, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExpressionCompiler, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLocationId, getObjectName, getPosture, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, simplify, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError, unordered

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.saxon.expr.Callable

call

Field Detail

operation

protected int operation

Constructor Detail

SystemFunctionCall

public SystemFunctionCall()

Method Detail

getConvertingCallable

public Callable getConvertingCallable()

makeSystemFunction

public static FunctionCall makeSystemFunction(String name,
                              Expression[] arguments)

Make a system function call (one in the standard function namespace).

Parameters:

name - The local name of the function.

arguments - the arguments to the function call

Returns:

a FunctionCall that implements this function, if it exists, or null if the function is unknown.

setDetails

public void setDetails(StandardFunction.Entry entry)

Set the details of this type of function

Parameters:

entry - information giving details of the function signature

getDetails

public StandardFunction.Entry getDetails()

Get the details of the function signature

Returns:

information about the function signature

getOperation

public int getOperation()

getFunctionItemType

public FunctionItemType getFunctionItemType(TypeHierarchy th)

Get the item type of the function item

Parameters:

th - the type hierarchy cache

Returns:

the function item's type

getImplementationMethod

public int getImplementationMethod()

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.

Overrides:

getImplementationMethod in class Expression

Returns:

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

getDefaultArgumentNode

public NodeInfo getDefaultArgumentNode(XPathContext context,
                              Sequence[] arguments,
                              String funcName)
                                throws XPathException

Throws:

XPathException

bindStaticContext

public void bindStaticContext(StaticContext env)
                       throws XPathException

Bind aspects of the static context on which the particular function depends

Parameters:

env - the static context of the function call

Throws:

XPathException - if execution with this static context will inevitably fail

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException

Method called during static type checking

Specified by:

checkArguments in class FunctionCall

Parameters:

visitor - the expression visitor

Throws:

XPathException - if the arguments are incorrect

optimize

public Expression optimize(ExpressionVisitor visitor,
                  ContextItemStaticInfo 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.

Overrides:

optimize in class FunctionCall

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 Type.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)

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

operands

public Iterable<Operand> operands()

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

Overrides:

operands in class FunctionCall

Returns:

an iterator containing the sub-expressions of this expression

equals

public boolean equals(Object o)

Determine whether two expressions are equivalent

Overrides:

equals in class FunctionCall

equalOrNull

public static boolean equalOrNull(Object x,
                  Object y)

Return true if two objects are equal or if both are null

Parameters:

x - the first object

y - the second object

Returns:

true if both x and y are null or if x.equals(y)

getErrorCodeForTypeErrors

public String getErrorCodeForTypeErrors()

Return the error code to be used for type errors. This is overridden for functions such as exactly-one(), one-or-more(), ...

Returns:

the error code to be used for type errors in the function call. Normally XPTY0004, but different codes are used for functions such as exactly-one()

getRequiredType

protected SequenceType getRequiredType(int arg)

Get the required type of the nth argument

Parameters:

arg - the number of the argument whose type is requested, zero-based

Returns:

the required type of the argument as defined in the function signature

getItemType

public ItemType getItemType()

Determine the item type of the value returned by the function

Specified by:

getItemType in class Expression

Returns:

a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)

computeCardinality

public int computeCardinality()

Determine the cardinality of the function.

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

computeSpecialProperties

public int computeSpecialProperties()

Determine the special properties of this expression. The general rule is that a system function call is non-creative if its return type is atomic, or if all its arguments are non-creative. This is overridden for the generate-id() function, which is considered creative if its operand is creative (because the result depends on the identity of the operand)

Overrides:

computeSpecialProperties in class Expression

Returns:

the special properties, as a bit-significant integer

useContextItemAsDefault

protected final void useContextItemAsDefault(ExpressionVisitor visitor)

Set "." as the default value for the first and only argument. Called from subclasses.

Parameters:

visitor - the expression visitor

addContextDocumentArgument

protected final void addContextDocumentArgument(int pos,
                              String augmentedName)
                                         throws XPathException

Add an implicit argument referring to the context document. Called by functions such as id() and key() that take the context document as an implicit argument

Parameters:

pos - the position of the argument whose default value is ".", zero-based

augmentedName - the name to be used for the function call with its extra argument. There are some cases where user function calls cannot supply the argument directly (notably unparsed-entity-uri() and unparsed-entity-public-id()) and in these cases a synthesized function name is used for the new function call.

Throws:

XPathException - if a static error is found

addDocToPathMap

public PathMap.PathMapNodeSet addDocToPathMap(PathMap pathMap,
                                     PathMap.PathMapNodeSet pathMapNodes)

Add a representation of a doc() call or similar function to a PathMap. This is a convenience method called by the addToPathMap() methods for doc(), document(), collection() and similar functions. These all create a new root expression in the path map.

Parameters:

pathMap - the PathMap to which the expression should be added

pathMapNodes - the node in the PathMap representing the focus at the point where this expression is called. Set to null if this expression appears at the top level.

Returns:

the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression

getContextNode

protected NodeInfo getContextNode(XPathContext context)
                           throws XPathException

Helper method for subclasses: get the context item if it is a node, throwing appropriate errors if not

Parameters:

context - the XPath dynamic context

Returns:

the context item if it exists and is a node

Throws:

XPathException - if there is no context item or if the context item is not a node

toShortString

public String toShortString()

Description copied from class: FunctionCall

Produce a short string identifying the expression for use in error messages

Overrides:

toShortString in class FunctionCall

Returns:

a short string, sufficient to identify the expression