net.sf.saxon.expr.UnionConstructorFunction Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of Saxon-HE Show documentation
Show all versions of Saxon-HE Show documentation
The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.functions.AbstractFunction;
import net.sf.saxon.lib.ConversionRules;
import net.sf.saxon.om.*;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.*;
import net.sf.saxon.value.AnyURIValue;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.value.StringValue;
/**
* Function to perform a cast to a union type
*/
public class UnionConstructorFunction extends AbstractFunction {
protected UnionType targetType;
protected NamespaceResolver resolver;
protected boolean allowEmpty;
/**
* Create a cast expression to a union type
* @param targetType the union type that is the result of the cast
* @param resolver used for resolving namespace prefixes if the type is namespace-sensitive
* @param allowEmpty true if an empty sequence may be supplied as input, converting to an empty sequence on output
*/
public UnionConstructorFunction(UnionType targetType, NamespaceResolver resolver, boolean allowEmpty) {
this.targetType = targetType;
this.resolver = resolver;
this.allowEmpty = allowEmpty;
}
/**
* Get the usage (in terms of streamability analysis) of the single operand
* @return the operand usage
*/
protected OperandRole getOperandRole() {
return OperandRole.SINGLE_ATOMIC;
}
/**
* Ask whether the value of the operand is allowed to be empty
* @return true if an empty sequence may be supplied as input, converting to an empty sequence on output
*/
public boolean isAllowEmpty() {
return allowEmpty;
}
/**
* Get the union type that is the target of this cast operation
* @return the target type of the cast
*/
public UnionType getTargetType() {
return targetType;
}
/**
* Get the namespace resolver that will be used to resolve any namespace-sensitive values (such as QNames) when casting
* @return the namespace resolver, or null if there is none.
*/
public NamespaceResolver getNamespaceResolver() {
return resolver;
}
/**
* Get the item type of the function item
*
* @return the function item's type
*/
@Override
public FunctionItemType getFunctionItemType() {
SequenceType resultType = targetType.getResultTypeOfCast();
SequenceType argType = allowEmpty ? SequenceType.OPTIONAL_ATOMIC : SequenceType.SINGLE_ATOMIC;
return new SpecificFunctionType(
new SequenceType[]{argType}, resultType);
}
/**
* Get the name of the function, or null if it is anonymous
*
* @return the function name, or null for an anonymous inline function
*/
@Override
public StructuredQName getFunctionName() {
return targetType.getTypeName();
}
/**
* Get a description of this function for use in error messages. For named functions, the description
* is the function name (as a lexical QName). For others, it might be, for example, "inline function",
* or "partially-applied ends-with function".
*
* @return a description of the function for use in error messages
*/
@Override
public String getDescription() {
return getFunctionName().getDisplayName();
}
/**
* Get the arity of the function
*
* @return the number of arguments in the function signature
*/
@Override
public int getArity() {
return 1;
}
/**
* Method to perform the cast of an atomic value to a union type
*
* @param value the input value to be converted. Must not be null.
* @param context the evaluation context
* @return the result of the conversion (may be a sequence if the union includes list types in its membership)
* @throws net.sf.saxon.trans.XPathException if the conversion fails
*/
public AtomicSequence cast(AtomicValue value, XPathContext context)
throws XPathException {
ConversionRules rules = context.getConfiguration().getConversionRules();
if (value == null) {
throw new NullPointerException();
}
// 1. If the value is a string or untypedAtomic, try casting to each of the member types
if (value instanceof StringValue && !(value instanceof AnyURIValue)) {
try {
return targetType.getTypedValue(value.getUnicodeStringValue(), resolver, rules);
} catch (ValidationException e) {
e.setErrorCode("FORG0001");
throw e;
}
}
// 2. If the value is an instance of a type in the transitive membership of the union, return it unchanged
AtomicType label = value.getItemType();
Iterable memberTypes = ((UnionType)targetType).getPlainMemberTypes();
// 2a. Is the type annotation itself a member type of the union, and of the union type itself?
if (targetType.isPlainType()) {
for (PlainType member : memberTypes) {
if (label.equals(member)) {
return value;
}
}
// 2b. Failing that, is some supertype of the type annotation a member type of the union?
for (PlainType member : memberTypes) {
AtomicType t = label;
while (t != null) {
if (t.equals(member)) {
return value;
} else {
t = t.getBaseType() instanceof AtomicType ? (AtomicType) t.getBaseType() : null;
}
}
}
}
// 3. if the value can be cast to any of the member types, return the result of that cast
for (PlainType type : memberTypes) {
if (type instanceof AtomicType) {
Converter c = rules.getConverter(value.getItemType(), (AtomicType) type);
if (c != null) {
ConversionResult result = c.convert(value);
if (result instanceof AtomicValue) {
// 3b. if the union type has constraining facets then the value must satisfy these
if (!targetType.isPlainType()) {
ValidationFailure vf = targetType.checkAgainstFacets((AtomicValue)result, rules);
if (vf == null) {
return (AtomicValue) result;
}
} else {
return (AtomicValue) result;
}
}
}
}
}
throw new XPathException("Cannot convert the supplied value to " + targetType.getDescription(), "FORG0001");
}
/**
* Invoke the function
*
* @param context the XPath dynamic evaluation context
* @param args the actual arguments to be supplied
* @return the result of invoking the function
* @throws net.sf.saxon.trans.XPathException if a dynamic error occurs within the function
*/
@Override
public AtomicSequence call(XPathContext context, Sequence[] args) throws XPathException {
AtomicValue val = (AtomicValue) args[0].head();
if (val == null) {
if (allowEmpty) {
return EmptyAtomicSequence.getInstance();
} else {
XPathException e = new XPathException("Cast expression does not allow an empty sequence to be supplied", "XPTY0004");
e.setIsTypeError(true);
throw e;
}
}
return cast(val, context);
}
/**
* Static method to perform the cast of an atomic value to a union type
*
* @param value the input value to be converted. Must not be null.
* @param targetType the union type to which the value is to be converted
* @param nsResolver the namespace context, required if the type is namespace-sensitive
* @param rules the conversion rules
* @return the result of the conversion (may be a sequence if the union includes list types in its membership)
* @throws XPathException if the conversion fails
*/
public static AtomicSequence cast(AtomicValue value, UnionType targetType,
NamespaceResolver nsResolver, ConversionRules rules)
throws XPathException {
//ConversionRules rules = context.getConfiguration().getConversionRules();
if (value == null) {
throw new NullPointerException();
}
// 1. If the value is a string or untypedAtomic, try casting to each of the member types
if (value instanceof StringValue && !(value instanceof AnyURIValue)) {
try {
return targetType.getTypedValue(value.getUnicodeStringValue(), nsResolver, rules);
} catch (ValidationException e) {
e.setErrorCode("FORG0001");
throw e;
}
}
// 2. If the value is an instance of a type in the transitive membership of the union, return it unchanged
AtomicType label = value.getItemType();
Iterable memberTypes = targetType.getPlainMemberTypes();
// 2a. Is the type annotation itself a member type of the union?
for (PlainType member : memberTypes) {
if (label.equals(member)) {
return value;
}
}
// 2b. Failing that, is some supertype of the type annotation a member type of the union?
for (PlainType member : memberTypes) {
AtomicType t = label;
while (t != null) {
if (t.equals(member)) {
return value;
} else {
t = t.getBaseType() instanceof AtomicType ? (AtomicType) t.getBaseType() : null;
}
}
}
// 3. if the value can be cast to any of the member types, return the result of that cast
for (PlainType type : memberTypes) {
if (type instanceof AtomicType) {
Converter c = rules.getConverter(value.getItemType(), (AtomicType) type);
if (c != null) {
ConversionResult result = c.convert(value);
if (result instanceof AtomicValue) {
return (AtomicValue) result;
}
}
}
}
throw new XPathException("Cannot convert the supplied value to " + targetType.getDescription(), "FORG0001");
}
}
// Copyright (c) 2018-2022 Saxonica Limited