net.sf.saxon.functions

Class SystemFunction

Implemented Interfaces:
EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator
Known Direct Subclasses:
Adjust, Aggregate, Available, BaseURI, BooleanFn, CodepointEqual, CodepointsToString, CollatingFunction, Collection, CompileTimeFunction, Component, Concat, Current, CurrentDateTime, CurrentGroup, DateTimeConstructor, Doc, DocAvailable, Document, Error, EscapeURI, Evaluate, Existence, ForceCase, FormatDate, FormatNumber, Id, Idref, Insert, InScopePrefixes, IsWholeNumber, ItemAt, KeyFn, Lang, Last, Matches, NamePart, NamespaceForPrefix, Nilled, NormalizeSpace, NormalizeUnicode, NumberFn, Parse, Position, QNameFn, RegexGroup, Remove, Replace, ResolveQName, ResolveURI, Reverse, Root, Rounding, Serialize, StringFn, StringJoin, StringLength, StringToCodepoints, Subsequence, Substring, SystemProperty, Tokenize, Trace, Translate, TreatFn, UnparsedEntity, UnparsedText

public abstract class SystemFunction
extends FunctionCall

Abstract superclass for system-defined and user-defined functions

Field Summary

protected int
operation

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

argument

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Method Summary

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
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.
StandardFunction.Entry
getDetails()
Get the details of the function signature
String
getErrorCodeForTypeErrors()
Return the error code to be used for type errors.
ItemType
getItemType(TypeHierarchy th)
Determine the item type of the value returned by the function
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).
Expression
optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
void
setDetails(StandardFunction.Entry entry)
Set the details of this type of function
protected void
useContextItemAsDefault()
Set "." as the default value for the first and only argument.

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

addExternalFunctionCallToPathMap, checkArgumentCount, checkArguments, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, optimize, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck

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

addToPathMap, adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Field Details

operation

protected int operation

Method Details

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.

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

checkArguments

public void checkArguments(ExpressionVisitor visitor)
            throws XPathException
Method called during static type checking
Overrides:
checkArguments in interface FunctionCall

computeCardinality

public int computeCardinality()
Determine the cardinality of the function.
Overrides:
computeCardinality in interface Expression

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 interface Expression

copy

public Expression copy()
Copy an expression. This makes a deep copy.
Overrides:
copy in interface Expression
Returns:
the copy of the original expression

getDetails

public StandardFunction.Entry getDetails()
Get the details of the function signature
Returns:
information about the function signature

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()

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the item type of the value returned by the function
Overrides:
getItemType in interface Expression
Parameters:
th - the type hierarchy cache

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

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.

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ItemType 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 interface 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)

setDetails

public void setDetails(StandardFunction.Entry entry)
Set the details of this type of function
Parameters:
entry - information giving details of the function signature

useContextItemAsDefault

protected final void useContextItemAsDefault()
Set "." as the default value for the first and only argument. Called from subclasses.