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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 Saxonica Limited
// 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.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.expr;
import net.sf.saxon.expr.oper.OperandArray;
import net.sf.saxon.expr.parser.*;
import net.sf.saxon.lib.NamespaceConstant;
import net.sf.saxon.om.*;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.NoDynamicContextException;
import net.sf.saxon.trans.UncheckedXPathException;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.JavaExternalObjectType;
import net.sf.saxon.value.SequenceType;
import java.util.Collections;
/**
* Abstract superclass for calls to system-defined and user-defined functions
*/
public abstract class FunctionCall extends Expression {
private OperandArray operanda;
/**
* Set the data structure for the operands of this expression. This must be created during initialisation of the
* expression and must not be subsequently changed
*
* @param operanda the data structure for expression operands
*/
protected void setOperanda(OperandArray operanda) {
this.operanda = operanda;
}
/**
* Get the data structure holding the operands of this expression.
*
* @return the data structure holding expression operands
*/
public OperandArray getOperanda() {
return operanda;
}
@Override
public Iterable operands() {
if (operanda != null) {
return operanda.operands();
} else {
// happens during expression tree construction
return Collections.emptyList();
}
}
/**
* Get the target function to be called
*
* @param context the dynamic evaluation context
* @return the target function
* @throws XPathException if the target function cannot be determined
*/
public abstract Function getTargetFunction(XPathContext context) throws XPathException;
/**
* Get the qualified of the function being called
*
* @return the qualified name. May be null if the function is anonymous.
*/
public abstract StructuredQName getFunctionName();
/**
* Determine the number of actual arguments supplied in the function call
*
* @return the arity (the number of arguments)
*/
public final int getArity() {
return getOperanda().getNumberOfOperands();
}
/**
* Method called by the expression parser when all arguments have been supplied
*
* @param args the expressions contained in the argument list of the function call
*/
public void setArguments(Expression[] args) {
setOperanda(new OperandArray(this, args));
}
protected void setOperanda(Expression[] args, OperandRole[] roles) {
setOperanda(new OperandArray(this, args, roles));
}
/**
* Get the expressions supplied as actual arguments to the function
*
* @return the array of expressions supplied in the argument list of the function call. The array
* is newly constructed to ensure that modifications to the array have no effect.
*/
public Expression[] getArguments() {
Expression[] result = new Expression[getArity()];
int i = 0;
for (Operand o : operands()) {
result[i++] = o.getChildExpression();
}
return result;
}
/**
* Get the expression supplied as the Nth argument
*
* @param n the required argument, zero-based
* @return the expression supplied in the relevant position
* @throws java.lang.IllegalArgumentException if the value of n is out of range
*/
public Expression getArg(int n) {
return getOperanda().getOperandExpression(n);
}
/**
* Set the expression to be used as the Nth argument
*
* @param n the required argument, zero-based
* @param child the expression to be used in the relevant position
* @throws java.lang.IllegalArgumentException if the value of n is out of range
*/
public void setArg(int n, Expression child) {
getOperanda().setOperand(n, child);
adoptChildExpression(child);
}
/**
* Simplify the arguments of the function.
* Called from the simplify() method of each function.
*
* @param env the static context
* @return the result of simplifying the arguments of the expression
* @throws net.sf.saxon.trans.XPathException if an error occurs
*/
protected final Expression simplifyArguments(StaticContext env) throws XPathException {
for (int i = 0; i < getArguments().length; i++) {
Expression exp = getArg(i).simplify();
if (exp != getArg(i)) {
adoptChildExpression(exp);
setArg(i, exp);
}
}
return this;
}
/**
* Type-check the expression. This also calls preEvaluate() to evaluate the function
* if all the arguments are constant; functions that do not require this behavior
* can override the preEvaluate method.
*/
/*@NotNull*/
@Override
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
typeCheckChildren(visitor, contextInfo);
checkArguments(visitor);
return preEvaluateIfConstant(visitor);
}
protected Expression preEvaluateIfConstant(ExpressionVisitor visitor) throws XPathException {
Optimizer opt = visitor.obtainOptimizer();
if (opt.isOptionSet(OptimizerOptions.CONSTANT_FOLDING)) {
boolean fixed = true;
for (Operand o : operands()) {
if (!(o.getChildExpression() instanceof Literal)) {
fixed = false;
}
}
if (fixed) {
try {
return preEvaluate(visitor);
} catch (NoDynamicContextException err) {
// Early evaluation failed, typically because the implicit timezone is not yet known.
// Try again later at run-time.
return this;
}
}
}
return this;
}
/**
* Check the function call against the declared function signature, applying the
* function conversion rules to each argument as necessary
*
* @param target the function being called
* @param visitor an expression visitor
* @throws XPathException if there is a type error
*/
public void checkFunctionCall(Function target,
ExpressionVisitor visitor) throws XPathException {
TypeChecker tc = visitor.getConfiguration().getTypeChecker(visitor.getStaticContext().isInBackwardsCompatibleMode());
SequenceType[] argTypes = target.getFunctionItemType().getArgumentTypes();
if (target.isSequenceVariadic() && getArity() == 1) {
String name = getFunctionName() == null ? "" : getFunctionName().getDisplayName();
RoleDiagnostic role = new RoleDiagnostic(RoleDiagnostic.FUNCTION, name, 0);
setArg(0, tc.staticTypeCheck(
getArg(0),
new SequenceType(argTypes[0].getPrimaryType(), StaticProperty.ALLOWS_ZERO_OR_MORE),
role, visitor));
} else {
int n = target.getArity();
for (int i = 0; i < n; i++) {
String name = getFunctionName() == null ? "" : getFunctionName().getDisplayName();
RoleDiagnostic role = new RoleDiagnostic(RoleDiagnostic.FUNCTION, name, i);
setArg(i, tc.staticTypeCheck(
getArg(i),
argTypes[i],
role, visitor));
}
}
}
/**
* 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.
*
* @param visitor an expression visitor
* @param 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
* {@link net.sf.saxon.type.Type#ITEM_TYPE}
* @return the original expression, rewritten if appropriate to optimize execution
* @throws XPathException if an error is discovered during this phase
* (typically a type error)
*/
/*@NotNull*/
@Override
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException {
optimizeChildren(visitor, contextItemType);
Optimizer opt = visitor.obtainOptimizer();
if (opt.isOptionSet(OptimizerOptions.CONSTANT_FOLDING)) {
boolean fixed = true;
for (Operand o : operands()) {
if (!(o.getChildExpression() instanceof Literal)) {
fixed = false;
break;
}
}
if (fixed) {
return preEvaluate(visitor);
}
}
return this;
}
/**
* Return the estimated cost of evaluating an expression. This is a very crude measure based
* on the syntactic form of the expression (we have no knowledge of data values). We take
* the cost of evaluating a simple scalar comparison or arithmetic expression as 1 (one),
* and we assume that a sequence has length 5. The resulting estimates may be used, for
* example, to reorder the predicates in a filter expression so cheaper predicates are
* evaluated first.
*/
@Override
public int getNetCost() {
return 5;
}
/**
* Pre-evaluate a function at compile time. Functions that do not allow
* pre-evaluation, or that need access to context information, can override this method.
*
* @param visitor an expression visitor
* @return the result of the early evaluation, or the original expression, or potentially
* a simplified expression
* @throws net.sf.saxon.trans.XPathException if evaluation fails
*/
public Expression preEvaluate(ExpressionVisitor visitor) throws XPathException {
if ((getIntrinsicDependencies() & ~StaticProperty.DEPENDS_ON_STATIC_CONTEXT) != 0) {
return this;
}
try {
try {
Literal lit = Literal.makeLiteral(SequenceTool.toGroundedValue(
iterate(visitor.getStaticContext().makeEarlyEvaluationContext())), this);
Optimizer.trace(visitor.getConfiguration(), "Pre-evaluated function call " + toShortString(), lit);
return lit;
} catch (UncheckedXPathException e) {
throw e.getXPathException();
}
} catch (NoDynamicContextException e) {
// early evaluation failed, usually because implicit timezone required
return this;
} catch (UnsupportedOperationException e) {
//e.printStackTrace();
if (e.getCause() instanceof NoDynamicContextException) {
return this;
} else {
throw e;
}
}
}
/**
* Method supplied by each class of function to check arguments during parsing, when all
* the argument expressions have been read
*
* @param visitor the expression visitor
* @throws net.sf.saxon.trans.XPathException if the arguments are incorrect
*/
protected void checkArguments(ExpressionVisitor visitor) throws XPathException {
// default: do nothing
}
/**
* Check number of arguments.
* A convenience routine for use in subclasses.
*
* @param min the minimum number of arguments allowed
* @param max the maximum number of arguments allowed
* @return the actual number of arguments
* @throws net.sf.saxon.trans.XPathException if the number of arguments is out of range
*/
protected int checkArgumentCount(int min, int max) throws XPathException {
int numArgs = getArity();
String msg = null;
if (min == max && numArgs != min) {
msg = "Function " + getDisplayName() + " must have " + pluralArguments(min);
} else if (numArgs < min) {
msg = "Function " + getDisplayName() + " must have at least " + pluralArguments(min);
} else if (numArgs > max) {
msg = "Function " + getDisplayName() + " must have no more than " + pluralArguments(max);
}
if (msg != null) {
XPathException err = new XPathException(msg, "XPST0017");
err.setIsStaticError(true);
err.setLocation(getLocation());
throw err;
}
return numArgs;
}
/**
* An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
* This method indicates which of these methods is provided directly. The other methods will always be available
* indirectly, using an implementation that relies on one of the other methods.
*
* @return the implementation method, for example {@link #ITERATE_METHOD} or {@link #EVALUATE_METHOD} or
* {@link #PROCESS_METHOD}
*/
@Override
public int getImplementationMethod() {
return ITERATE_METHOD;
}
/**
* Utility routine used in constructing error messages: get the word "argument" or "arguments"
*
* @param num the number of arguments
* @return the singular or plural word
*/
public static String pluralArguments(int num) {
return num == 1 ? "one argument" : (num + " arguments");
}
/**
* Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited
* by an expression in a source tree.
* The default implementation of this method assumes that an expression does no navigation other than
* the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the
* same context as the containing expression. The method must be overridden for any expression
* where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression,
* and RootExpression (because they perform navigation), and for the doc(), document(), and collection()
* functions because they create a new navigation root. Implementations also exist for PathExpression and
* FilterExpression because they have subexpressions that are evaluated in a different context from the
* calling expression.
*
* @param pathMap the PathMap to which the expression should be added
* @param 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, in which case the expression, if it
* is registered in the path map at all, must create a new path map root.
* @return 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. For an expression that does
* navigation, it represents the end of the arc in the path map that describes the navigation route. For other
* expressions, it is the same as the input pathMapNode.
*/
public PathMap.PathMapNodeSet addExternalFunctionCallToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodes) {
// Except in the case of system functions, we have no idea where a function call might
// navigate, so we assume the worst, and register that the path has unknown dependencies
PathMap.PathMapNodeSet result = new PathMap.PathMapNodeSet();
for (Operand o : operands()) {
result.addNodeSet(o.getChildExpression().addToPathMap(pathMap, pathMapNodes));
}
result.setHasUnknownDependencies();
return result;
}
/**
* Get a name identifying the kind of expression, in terms meaningful to a user.
*
* @return a name identifying the kind of expression, in terms meaningful to a user.
* The name will always be in the form of a lexical XML QName, and should match the name used
* in explain() output displaying the expression.
*/
@Override
public String getExpressionName() {
return "functionCall";
}
/**
* Get the name of the function for display in messages
*
* @return the name of the function as a lexical QName
*/
public final String getDisplayName() {
StructuredQName fName = getFunctionName();
return fName == null ? "(anonymous)" : fName.getDisplayName();
}
/**
* The toString() method for an expression attempts to give a representation of the expression
* in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
* In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax
*/
public String toString() {
StringBuilder buff = new StringBuilder(64);
StructuredQName fName = getFunctionName();
String f;
if (fName == null) {
f = "$anonymousFunction";
} else if (fName.hasURI(NamespaceConstant.FN)) {
f = fName.getLocalPart();
} else {
f = fName.getEQName();
}
buff.append(f);
boolean first = true;
for (Operand o : operands()) {
buff.append(first ? "(" : ", ");
buff.append(o.getChildExpression().toString());
first = false;
}
buff.append(first ? "()" : ")");
return buff.toString();
}
/**
* Produce a short string identifying the expression for use in error messages
*
* @return a short string, sufficient to identify the expression
*/
@Override
public String toShortString() {
StructuredQName fName = getFunctionName();
return (fName == null ? "$anonFn" : fName.getDisplayName()) +
"(" + (getArity() == 0 ? "" : "...") + ")";
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
@Override
public void export(ExpressionPresenter out) throws XPathException {
out.startElement("functionCall", this);
if (getFunctionName() == null) {
throw new AssertionError("Exporting call to anonymous function");
} else {
out.emitAttribute("name", getFunctionName().getDisplayName());
}
for (Operand o : operands()) {
o.getChildExpression().export(out);
}
out.endElement();
}
/**
* Determine whether two expressions are equivalent
*/
public boolean equals(Object o) {
if (!(o instanceof FunctionCall)) {
return false;
}
if (getFunctionName() == null) {
return this == o;
}
FunctionCall f = (FunctionCall) o;
if (!getFunctionName().equals(f.getFunctionName())) {
return false;
}
if (getArity() != f.getArity()) {
return false;
}
for (int i = 0; i < getArity(); i++) {
if (!getArg(i).isEqual(f.getArg(i))) {
return false;
}
}
return true;
}
/**
* Get hashCode in support of equals() method
*/
@Override
protected int computeHashCode() {
if (getFunctionName() == null) {
return super.computeHashCode();
}
int h = getFunctionName().hashCode();
for (int i = 0; i < getArity(); i++) {
h ^= getArg(i).hashCode();
}
return h;
}
/**
* Return an Iterator to iterate over the values of a sequence. The value of every
* expression can be regarded as a sequence, so this method is supported for all
* expressions. This default implementation handles iteration for expressions that
* return singleton values: for non-singleton expressions, the subclass must
* provide its own implementation.
*
* @param context supplies the context for evaluation
* @return a SequenceIterator that can be used to iterate over the result
* of the expression
* @throws net.sf.saxon.trans.XPathException if any dynamic error occurs evaluating the
* expression
*/
@Override
public SequenceIterator iterate(XPathContext context) throws XPathException {
Function target = getTargetFunction(context);
Sequence[] actualArgs = evaluateArguments(context);
try {
return target.call(context, actualArgs).iterate();
} catch (XPathException e) {
e.maybeSetLocation(getLocation());
e.maybeSetContext(context);
e.maybeSetFailingExpression(this);
throw e;
}
}
public Sequence[] evaluateArguments(XPathContext context) throws XPathException {
int numArgs = getArity();
Sequence[] actualArgs = new Sequence[numArgs];
for (int i = 0; i < numArgs; i++) {
actualArgs[i] = ExpressionTool.lazyEvaluate(getArg(i), context, false);
}
return actualArgs;
}
/**
* When a call to a Java extension function appears in a context where there the required type
* is a Java external object (typically an xsl:variable with a declared type, or as an argument
* to another Java extension function), notify this required type so that the process of converting
* the result to an XDM value can be short-circuited.
*
* @param requiredType the required type of the result of the function, determined by the context
* in which the function call appears
* @return Ok if the type has been successfully adjusted
* @throws XPathException if the required return type is incompatible with the type actually returned
* by the Java method
*/
public boolean adjustRequiredType(JavaExternalObjectType requiredType) throws XPathException {
return false;
}
}