Class SystemFunction

All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, Locator
Direct Known 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, InScopePrefixes, Insert, IsWholeNumber, ItemAt, KeyFn, Lang, Last, Matches, NamePart, NamespaceForPrefix, Nilled, NormalizeSpace, NormalizeUnicode, NumberFn, Parse, Position, Put, 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
See Also:
  • Field Details

    • operation

      protected int operation
  • Constructor Details

    • SystemFunction

      public SystemFunction()
  • Method Details

    • 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
    • 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
    • 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 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
    • 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(TypeHierarchy th)
      Determine the item type of the value returned by the function
      Specified by:
      getItemType in class Expression
      Parameters:
      th - the type hierarchy cache
      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()
      Set "." as the default value for the first and only argument. Called from subclasses.
    • 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
    • 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