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java.lang.Object net.sf.saxon.expr.Expression net.sf.saxon.expr.FunctionCall net.sf.saxon.functions.SystemFunction
public abstract class SystemFunction
Abstract superclass for system-defined and user-defined functions
Field Summary | |
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protected int |
operation
|
Fields inherited from class net.sf.saxon.expr.FunctionCall |
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argument |
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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SystemFunction()
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Method Summary | |
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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. |
boolean |
equals(Object o)
Determine whether two expressions are equivalent |
StandardFunction.Entry |
getDetails()
Get the details of the function signature |
String |
getErrorCodeForTypeErrors()
Return the error code to be used for type errors. |
int |
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). |
ItemType |
getItemType(TypeHierarchy th)
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). |
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType 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(ExpressionVisitor visitor)
Set "." as the default value for the first and only argument. |
Methods inherited from class net.sf.saxon.expr.FunctionCall |
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addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Field Detail |
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protected int operation
Constructor Detail |
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public SystemFunction()
Method Detail |
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public static FunctionCall makeSystemFunction(String name, Expression[] arguments)
name
- The local name of the function.arguments
- the arguments to the function call
public void setDetails(StandardFunction.Entry entry)
entry
- information giving details of the function signaturepublic StandardFunction.Entry getDetails()
public int getOperation()
public int getImplementationMethod()
getImplementationMethod
in class Expression
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
public void checkArguments(ExpressionVisitor visitor) throws XPathException
checkArguments
in class FunctionCall
visitor
- the expression visitor
XPathException
- if the arguments are incorrectpublic Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
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.
optimize
in class FunctionCall
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 Expression copy()
copy
in class Expression
public boolean equals(Object o)
equals
in class FunctionCall
public String getErrorCodeForTypeErrors()
protected SequenceType getRequiredType(int arg)
arg
- the number of the argument whose type is requested, zero-based
public ItemType getItemType(TypeHierarchy th)
getItemType
in class Expression
th
- the type hierarchy cache
public int computeCardinality()
computeCardinality
in class Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public int computeSpecialProperties()
computeSpecialProperties
in class Expression
protected final void useContextItemAsDefault(ExpressionVisitor visitor)
visitor
- the expression visitorprotected final void addContextDocumentArgument(int pos, String augmentedName) throws XPathException
pos
- the position of the argument whose default value is ".", zero-basedaugmentedName
- 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.
XPathException
- if a static error is foundpublic PathMap.PathMapNodeSet addDocToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodes)
pathMap
- the PathMap to which the expression should be addedpathMapNodes
- 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.
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