package client.net.sf.saxon.ce.expr.instruct;
import client.net.sf.saxon.ce.Controller;
import client.net.sf.saxon.ce.expr.*;
import client.net.sf.saxon.ce.om.StructuredQName;
import client.net.sf.saxon.ce.om.ValueRepresentation;
import client.net.sf.saxon.ce.trace.Location;
import client.net.sf.saxon.ce.trans.XPathException;
import client.net.sf.saxon.ce.type.TypeHierarchy;
import client.net.sf.saxon.ce.value.SequenceType;
import java.util.Iterator;
/**
* This object represents the compiled form of a user-written function
* (the source can be either an XSLT stylesheet function or an XQuery function).
*
* <p>It is assumed that type-checking, of both the arguments and the results,
* has been handled at compile time. That is, the expression supplied as the body
* of the function must be wrapped in code to check or convert the result to the
* required type, and calls on the function must be wrapped at compile time to check or
* convert the supplied arguments.
*/
public class UserFunction extends Procedure {
private StructuredQName functionName;
private boolean tailCalls = false;
// indicates that the function contains tail calls, not necessarily recursive ones.
private boolean tailRecursive = false;
// indicates that the function contains tail calls on itself
private UserFunctionParameter[] parameterDefinitions;
private SequenceType resultType;
protected int evaluationMode = ExpressionTool.UNDECIDED;
/**
* Create a user-defined function (the body must be added later)
*/
public UserFunction() {}
/**
* Set the function name
* @param name the function name
*/
public void setFunctionName(StructuredQName name) {
functionName = name;
}
/**
* Get the function name
* @return the function name, as a StructuredQName
*/
public StructuredQName getFunctionName() {
return functionName;
}
/**
* Get a name identifying the object of the expression, for example a function name, template name,
* variable name, key name, element name, etc. This is used only where the name is known statically.
*
*/
public StructuredQName getObjectName() {
return functionName;
}
/**
* Determine the preferred evaluation mode for this function
*/
public void computeEvaluationMode() {
if (tailRecursive) {
// If this function contains tail calls, we evaluate it eagerly, because
// the caller needs to know whether a tail call was returned or not: if we
// return a Closure, the tail call escapes into the wild and can reappear anywhere...
evaluationMode = ExpressionTool.eagerEvaluationMode(getBody());
} else {
evaluationMode = ExpressionTool.lazyEvaluationMode(getBody());
}
}
/**
* Set the definitions of the declared parameters for this function
* @param params an array of parameter definitions
*/
public void setParameterDefinitions(UserFunctionParameter[] params) {
parameterDefinitions = params;
}
/**
* Get the definitions of the declared parameters for this function
* @return an array of parameter definitions
*/
public UserFunctionParameter[] getParameterDefinitions() {
return parameterDefinitions;
}
/**
* Set the declared result type of the function
* @param resultType the declared return type
*/
public void setResultType(SequenceType resultType) {
this.resultType = resultType;
}
/**
* Indicate whether the function contains a tail call
* @param tailCalls true if the function contains a tail call (on any function)
* @param recursiveTailCalls true if the function contains a tail call (on itself)
*/
public void setTailRecursive(boolean tailCalls, boolean recursiveTailCalls) {
this.tailCalls = tailCalls;
tailRecursive = recursiveTailCalls;
}
/**
* Determine whether the function contains tail calls (on this or other functions)
* @return true if the function contains tail calls
*/
public boolean containsTailCalls() {
return tailCalls;
}
/**
* Determine whether the function contains a tail call, calling itself
* @return true if the function contains a directly-recursive tail call
*/
public boolean isTailRecursive() {
return tailRecursive;
}
/**
* Get the type of value returned by this function
* @param th the type hierarchy cache
* @return the declared result type, or the inferred result type
* if this is more precise
*/
public SequenceType getResultType(TypeHierarchy th) {
if (resultType == SequenceType.ANY_SEQUENCE) {
// see if we can infer a more precise result type. We don't do this if the function contains
// calls on further functions, to prevent infinite regress.
if (!containsUserFunctionCalls(getBody())) {
resultType = SequenceType.makeSequenceType(
getBody().getItemType(th), getBody().getCardinality());
}
}
return resultType;
}
/**
* Get the declared result type
* @return the declared result type
*/
public SequenceType getDeclaredResultType() {
return resultType;
}
/**
* Determine whether a given expression contains calls on user-defined functions
* @param exp the expression to be tested
* @return true if the expression contains calls to user functions.
*/
private static boolean containsUserFunctionCalls(Expression exp) {
if (exp instanceof UserFunctionCall) {
return true;
}
Iterator i = exp.iterateSubExpressions();
while (i.hasNext()) {
Expression e = (Expression)i.next();
if (containsUserFunctionCalls(e)) {
return true;
}
}
return false;
}
/**
* Get the required types of an argument to this function
* @param n identifies the argument in question, starting at 0
* @return a SequenceType object, indicating the required type of the argument
*/
public SequenceType getArgumentType(int n) {
return parameterDefinitions[n].getRequiredType();
}
/**
* Get the evaluation mode. The evaluation mode will be computed if this has not already been done
* @return the computed evaluation mode
*/
public int getEvaluationMode() {
if (evaluationMode == ExpressionTool.UNDECIDED) {
computeEvaluationMode();
}
return evaluationMode;
}
/**
* Get the arity of this function
* @return the number of arguments
*/
public int getNumberOfArguments() {
return parameterDefinitions.length;
}
/**
* Ask whether this function is a memo function
* @return false (overridden in a subclass)
*/
public boolean isMemoFunction() {
return false;
}
/**
* Call this function to return a value.
* @param actualArgs the arguments supplied to the function. These must have the correct
* types required by the function signature (it is the caller's responsibility to check this).
* It is acceptable to supply a {@link client.net.sf.saxon.ce.value.Closure} to represent a value whose
* evaluation will be delayed until it is needed. The array must be the correct size to match
* the number of arguments: again, it is the caller's responsibility to check this.
* @param context This provides the run-time context for evaluating the function. It is the caller's
* responsibility to allocate a "clean" context for the function to use; the context that is provided
* will be overwritten by the function.
* @return a Value representing the result of the function.
*/
public ValueRepresentation call(ValueRepresentation[] actualArgs, XPathContextMajor context)
throws XPathException {
if (evaluationMode == ExpressionTool.UNDECIDED) {
// should have been done at compile time
computeEvaluationMode();
}
// Otherwise evaluate the function
context.setStackFrame(getStackFrameMap(), actualArgs);
ValueRepresentation result;
try {
result = ExpressionTool.evaluate(getBody(), evaluationMode, context, 1);
} catch (XPathException err) {
err.maybeSetLocation(getSourceLocator());
throw err;
}
return result;
}
/**
* Call this function in "push" mode, writing the results to the current output destination.
* @param actualArgs the arguments supplied to the function. These must have the correct
* types required by the function signature (it is the caller's responsibility to check this).
* It is acceptable to supply a {@link client.net.sf.saxon.ce.value.Closure} to represent a value whose
* evaluation will be delayed until it is needed. The array must be the correct size to match
* the number of arguments: again, it is the caller's responsibility to check this.
* @param context This provides the run-time context for evaluating the function. It is the caller's
* responsibility to allocate a "clean" context for the function to use; the context that is provided
* will be overwritten by the function.
*/
public void process(ValueRepresentation[] actualArgs, XPathContextMajor context)
throws XPathException {
context.setStackFrame(getStackFrameMap(), actualArgs);
getBody().process(context);
}
/**
* Call this function. This method allows an XQuery function to be called directly from a Java
* application. It creates the environment needed to achieve this
* @param actualArgs the arguments supplied to the function. These must have the correct
* types required by the function signature (it is the caller's responsibility to check this).
* It is acceptable to supply a {@link client.net.sf.saxon.ce.value.Closure} to represent a value whose
* evaluation will be delayed until it is needed. The array must be the correct size to match
* the number of arguments: again, it is the caller's responsibility to check this.
* @param controller This provides the run-time context for evaluating the function. This may
* be used for a series of calls on functions defined in the same module as the XQueryExpression.
* @return a Value representing the result of the function.
*/
public ValueRepresentation call(ValueRepresentation[] actualArgs, Controller controller) throws XPathException {
return call(actualArgs, controller.newXPathContext());
}
public int getConstructType() {
return Location.FUNCTION;
}
}
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is “Incompatible With Secondary Licenses”, as defined by the Mozilla Public License, v. 2.0.