net.sf.saxon.instruct.UserFunction Maven / Gradle / Ivy
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package net.sf.saxon.instruct;
import net.sf.saxon.Controller;
import net.sf.saxon.trace.Location;
import net.sf.saxon.evpull.EventIterator;
import net.sf.saxon.expr.*;
import net.sf.saxon.om.*;
import net.sf.saxon.sort.SortExpression;
import net.sf.saxon.sort.TupleSorter;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.Type;
import net.sf.saxon.type.TypeHierarchy;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.value.Value;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
/**
* This object represents the compiled form of a user-written function
* (the source can be either an XSLT stylesheet function or an XQuery function).
*
* 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 memoFunction = false;
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;
private int evaluationMode = ExpressionTool.UNDECIDED;
private boolean isUpdating = false;
/**
* Create a user-defined function with no body (the body must be added later)
*/
public UserFunction() {}
/**
* Create a user-defined function
* @param body the expression comprising the body of the function, which is evaluated to compute the result
* of the function
*/
public UserFunction(Expression body) {
setBody(body);
}
/**
* 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 || memoFunction) {
// 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...
// Eager evaluation also makes sense if it's a memo function.
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;
}
/**
* Set whether this is an updating function (as defined in XQuery Update)
* @param isUpdating true if this is an updating function
*/
public void setUpdating(boolean isUpdating) {
this.isUpdating = isUpdating;
}
/**
* Ask whether this is an updating function (as defined in XQuery Update)
* @return true if this is an updating function
*/
public boolean isUpdating() {
return isUpdating;
}
/**
* 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;
}
/**
* 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;
}
/**
* Mark this function as a memo function (or not)
* @param isMemo true if this is a memo function
*/
public void setMemoFunction(boolean isMemo) {
memoFunction = isMemo;
}
/**
* Ask whether this function is a memo function
* @return true if this function is marked as a memo function
*/
public boolean isMemoFunction() {
return memoFunction;
}
/**
* Gather the direct contributing callees of this function. A callee is a function that this one
* calls. A contributing callee is a function whose output is added directly to the output of this
* function without further processing (other than by attaching it to a parent element or document
* node). A direct contributing callee is a function that is called directly, rather than indirectly.
* @param result the list into which the callees are gathered.
*/
public void gatherDirectContributingCallees(Set result) {
Expression body = getBody();
gatherDirectContributingCallees(body, result);
}
private void gatherDirectContributingCallees(Expression exp, Set result) {
Iterator kids = exp.iterateSubExpressions();
while (kids.hasNext()) {
Expression kid = (Expression)kids.next();
if (kid instanceof UserFunctionCall) {
result.add(((UserFunctionCall)kid).getFunction());
} else if (kid instanceof Assignation) {
gatherDirectContributingCallees(((Assignation)kid).getAction(), result);
// } else if (kid instanceof IfExpression) {
// gatherDirectContributingCallees(((IfExpression)kid).getThenExpression(), result);
// gatherDirectContributingCallees(((IfExpression)kid).getElseExpression(), result);
} else if (kid instanceof Choose) {
Expression[] actions = ((Choose)kid).getActions();
for (int c=0; c