Package net.sf.saxon.query

Class XQueryFunctionLibrary

java.lang.Object
net.sf.saxon.query.XQueryFunctionLibrary
All Implemented Interfaces:
FunctionLibrary, XQueryFunctionBinder
public class XQueryFunctionLibrary extends Object implements FunctionLibrary, XQueryFunctionBinder
An XQueryFunctionLibrary is a function library containing all the user-defined functions available for use within a particular XQuery module: that is, the functions declared in that module, and the functions imported from other modules. It also contains (transiently during compilation) entries for functions that have been referenced but not yet declared, because the body of a function may contain a reference to another function declared later in the same module.

  • Constructor Details

    • XQueryFunctionLibrary

      public XQueryFunctionLibrary(Configuration config)
      Create an XQueryFunctionLibrary
      Parameters:
      config - the Saxon configuration

  • Method Details

    • setConfiguration

      public void setConfiguration(Configuration config)
      Set the Configuration options
      Specified by:
      setConfiguration in interface FunctionLibrary
      Parameters:
      config - the Saxon configuration

    • getConfiguration

      public Configuration getConfiguration()
      Get the Configuration options
      Returns:
      the Saxon configuration

    • declareFunction

      public void declareFunction(XQueryFunction function) throws XPathException
      Register a user-defined XQuery function
      Parameters:
      function - the function to be registered
      Throws:
      XPathException - if there is an existing function with the same name and arity

    • getFunctionItem

      public FunctionItem getFunctionItem(SymbolicName.F functionName, StaticContext staticContext) throws XPathException
      Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.

      This supports the function-lookup() function in XPath 3.0.

      Specified by:
      getFunctionItem in interface FunctionLibrary
      Parameters:
      functionName - the qualified name of the function being called
      staticContext - the static context to be used by the function, in the event that it is a system function with dependencies on the static context
      Returns:
      if a function of this name and arity is available for calling, then a corresponding function item; or null if the function does not exist
      Throws:
      XPathException - in the event of certain errors, for example attempting to get a function that is private

    • isAvailable

      public boolean isAvailable(SymbolicName.F functionName, Schema schema, int languageLevel)
      Test whether a function with a given name and arity is available

      This supports the function-available() function in XSLT.

      Specified by:
      isAvailable in interface FunctionLibrary
      Parameters:
      functionName - the qualified name of the function being called
      schema - the schema in question (constructor functions are available in some schemas and not others)
      languageLevel - the XPath language level times 10 (31 = XPath 3.1)
      Returns:
      true if a function of this name and arity is available for calling

    • getNamespaces

      public Iterable<NamespaceUri> getNamespaces()

    • getFunctionsForNamespace

      public ImmutableHashTrieMap<String,ZenoChain<XQueryFunction>> getFunctionsForNamespace(NamespaceUri ns)

    • addFunctions

      public void addFunctions(NamespaceUri ns, ImmutableHashTrieMap<String,ZenoChain<XQueryFunction>> functions) throws XPathException
      Throws:
      XPathException

    • bind

      public Expression bind(SymbolicName.F functionName, Expression[] arguments, Map<StructuredQName,Integer> keywords, StaticContext env, List<String> reasons) throws XPathException
      Identify a (namespace-prefixed) function appearing in the expression. This method is called by the XQuery parser to resolve function calls found within the query.

      Note that a function call may appear earlier in the query than the definition of the function to which it is bound. Unlike XSLT, we cannot search forwards to find the function definition. Binding of function calls is therefore a two-stage process; at the time the function call is parsed, we simply register it as pending; subsequently at the end of query parsing all the pending function calls are resolved. Another consequence of this is that we cannot tell at the time a function call is parsed whether it is a call to an internal (XSLT or XQuery) function or to an extension function written in Java.

      Specified by:
      bind in interface FunctionLibrary
      Parameters:
      functionName - the QName of the function being called
      arguments - Contains the expressions supplied statically in arguments to the function call. The intention is that the static type of the arguments (obtainable via getItemType() and getCardinality()) may be used as part of the binding algorithm. In some cases it may be possible for the function to be pre-evaluated at compile time, for example if these expressions are all constant values.

      The conventions of the XPath language demand that the results of a function depend only on the values of the expressions supplied as arguments, and not on the form of those expressions. For example, the result of f(4) is expected to be the same as f(2+2). The actual expression is supplied here to enable the binding mechanism to select the most efficient possible implementation (including compile-time pre-evaluation where appropriate).

      keywords - May be null if no keywords are used in the function call. Otherwise, a map identifying the keywords appearing in the function call, and the 0-based position at which they appeared.
      env - The static context of the function call
      reasons - If no matching function is found by the function library, it may add a diagnostic explanation to this list explaining why none of the available functions could be used.
      Returns:
      an Expression representing the function call. This will normally be a FunctionCall, but it may be rewritten as some other expression.
      Throws:
      XPathException - if a matching function was identified, but the call is incorrect, for example because it uses incorrect argument keywords

    • getDeclaration

      public XQueryFunction getDeclaration(StructuredQName functionName, int staticArgs)
      Get the function declaration corresponding to a given function name and arity
      Specified by:
      getDeclaration in interface XQueryFunctionBinder
      Parameters:
      functionName - the name of the function as a QName
      staticArgs - the number of expressions supplied as arguments in the function call
      Returns:
      the XQueryFunction if there is one, or null if not.

    • getDeclarationByKey

      public XQueryFunction getDeclarationByKey(SymbolicName.F functionKey)
      Get the function declaration corresponding to a given function name and arity, supplied in the form "{uri}local/arity"
      Parameters:
      functionKey - a string in the form "{uri}local/arity" identifying the required function
      Returns:
      the XQueryFunction if there is one, or null if not.

    • processAllFunctions

      public void processAllFunctions(Consumer<XQueryFunction> action) throws XPathException
      Process all the functions defined in this module
      Parameters:
      action - an action to be performed on every function defined in this module including those imported from elsewhere.
      Throws:
      XPathException - if any of the defined actions fails with an UncheckedXPathException

    • fixupGlobalFunctions

      protected void fixupGlobalFunctions(QueryModule env) throws XPathException
      Fixup all references to global functions. This method is called on completion of query parsing. Each XQueryFunction is required to bind all references to that function to the object representing the run-time executable code of the function.

      This method is for internal use.

      Parameters:
      env - the static context for the main query body.
      Throws:
      XPathException - if an error occurs

    • optimizeGlobalFunctions

      protected void optimizeGlobalFunctions(QueryModule topModule) throws XPathException
      Optimize the body of all global functions. This may involve inlining functions calls
      Parameters:
      topModule - the top level module of the compilation unit whose functions are to be optimized; functions in separately-compiled imported libraries are unaffected.
      Throws:
      XPathException - if an error occurs

    • explainGlobalFunctions

      public void explainGlobalFunctions(ExpressionPresenter out) throws XPathException
      Output "explain" information about each declared function
      Parameters:
      out - the ExpressionPresenter that renders the output
      Throws:
      XPathException - if things go wrong

    • getUserDefinedFunction

      public UserFunction getUserDefinedFunction(NamespaceUri uri, String localName, int arity)
      Get the function with a given name and arity. This method is provided so that XQuery functions can be called directly from a Java application. Note that there is no type checking or conversion of arguments when this is done: the arguments must be provided in exactly the form that the function signature declares them.
      Parameters:
      uri - the uri of the function name
      localName - the local part of the function name
      arity - the number of arguments.
      Returns:
      the function identified by the URI, local name, and arity; or null if there is no such function

    • copy

      public FunctionLibrary copy()
      This method creates a copy of a FunctionLibrary: if the original FunctionLibrary allows new functions to be added, then additions to this copy will not affect the original, or vice versa.
      Specified by:
      copy in interface FunctionLibrary
      Returns:
      a copy of this function library. This must be an instance of the original class.