net.sf.saxon.sort.GenericAtomicComparer Maven / Gradle / Ivy
package net.sf.saxon.sort;
import net.sf.saxon.Configuration;
import net.sf.saxon.Platform;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.StandardNames;
import net.sf.saxon.trans.NoDynamicContextException;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.type.Type;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.CalendarValue;
import net.sf.saxon.value.StringValue;
import java.io.Serializable;
/**
* An AtomicComparer used for comparing atomic values of arbitrary item types. It encapsulates
* a Collator that is used when the values to be compared are strings. It also supports
* a separate method for testing equality of items, which can be used for data types that
* are not ordered.
*
* @author Michael H. Kay
*
*/
public class GenericAtomicComparer implements AtomicComparer, Serializable {
private StringCollator collator;
private transient XPathContext context;
/**
* Create an GenericAtomicComparer
* @param collator the collation to be used
* @param conversion a context, used when converting untyped atomic values to the target type.
*/
public GenericAtomicComparer(StringCollator collator, XPathContext conversion) {
this.collator = collator;
if (collator == null) {
this.collator = CodepointCollator.getInstance();
}
context = conversion;
}
/**
* Factory method to make a GenericAtomicComparer for values of known types
* @param type0 primitive type of the first operand
* @param type1 primitive type of the second operand
* @param collator the collation to be used, if any. This is supplied as a NamedCollation object
* which encapsulated both the collation URI and the collation itself.
* @param context the dynamic context
* @return a GenericAtomicComparer for values of known types
*/
public static AtomicComparer makeAtomicComparer(
BuiltInAtomicType type0, BuiltInAtomicType type1, StringCollator collator, XPathContext context) {
int fp0 = type0.getFingerprint();
int fp1 = type1.getFingerprint();
if (fp0 == fp1) {
switch (fp0) {
case StandardNames.XS_DATE_TIME:
case StandardNames.XS_DATE:
case StandardNames.XS_TIME:
case StandardNames.XS_G_DAY:
case StandardNames.XS_G_MONTH:
case StandardNames.XS_G_YEAR:
case StandardNames.XS_G_MONTH_DAY:
case StandardNames.XS_G_YEAR_MONTH:
return new CalendarValueComparer(context);
case StandardNames.XS_BOOLEAN:
case StandardNames.XS_DAY_TIME_DURATION:
case StandardNames.XS_YEAR_MONTH_DURATION:
return ComparableAtomicValueComparer.getInstance();
case StandardNames.XS_BASE64_BINARY:
case StandardNames.XS_HEX_BINARY:
case StandardNames.XS_QNAME:
case StandardNames.XS_NOTATION:
return EqualityComparer.getInstance();
}
}
if (type0.isPrimitiveNumeric() && type1.isPrimitiveNumeric()) {
return ComparableAtomicValueComparer.getInstance();
}
if ((fp0 == StandardNames.XS_STRING ||
fp0 == StandardNames.XS_UNTYPED_ATOMIC ||
fp0 == StandardNames.XS_ANY_URI) &&
(fp1 == StandardNames.XS_STRING ||
fp1 == StandardNames.XS_UNTYPED_ATOMIC ||
fp1 == StandardNames.XS_ANY_URI)) {
if (collator instanceof CodepointCollator) {
return CodepointCollatingComparer.getInstance();
} else {
return new CollatingAtomicComparer(collator, Configuration.getPlatform());
}
}
return new GenericAtomicComparer(collator, context);
}
/**
* Supply the dynamic context in case this is needed for the comparison
*
* @param context the dynamic evaluation context
* @return either the original AtomicComparer, or a new AtomicComparer in which the context
* is known. The original AtomicComparer is not modified
*/
public AtomicComparer provideContext(XPathContext context) {
return new GenericAtomicComparer(collator, context);
}
/**
* Get the underlying string collator
* @return the string collator
*/
public StringCollator getStringCollator() {
return collator;
}
/**
* Compare two AtomicValue objects according to the rules for their data type. UntypedAtomic
* values are compared as if they were strings; if different semantics are wanted, the conversion
* must be done by the caller.
* @param a the first object to be compared. It is intended that this should be an instance
* of AtomicValue, though this restriction is not enforced. If it is a StringValue, the
* collator is used to compare the values, otherwise the value must implement the java.util.Comparable
* interface.
* @param b the second object to be compared. This must be comparable with the first object: for
* example, if one is a string, they must both be strings.
* @return <0 if a < b, 0 if a = b, >0 if a > b
* @throws ClassCastException if the objects are not comparable
* @throws NoDynamicContextException if this comparer required access to dynamic context information,
* notably the implicit timezone, and this information is not available. In general this happens if a
* context-dependent comparison is attempted at compile-time, and it signals the compiler to generate
* code that tries again at run-time.
*/
public int compareAtomicValues(AtomicValue a, AtomicValue b) throws NoDynamicContextException {
// System.err.println("Comparing " + a.getClass() + "(" + a + ") with " + b.getClass() + "(" + b + ") using " + collator);
if (a == null) {
return (b == null ? 0 : -1);
} else if (b == null) {
return +1;
}
if (a instanceof StringValue && b instanceof StringValue) {
if (collator instanceof CodepointCollator) {
return ((CodepointCollator)collator).compareCS(a.getStringValueCS(), b.getStringValueCS());
} else {
return collator.compareStrings(a.getStringValue(), b.getStringValue());
}
} else {
Comparable ac = (Comparable)a.getXPathComparable(true, collator, context);
Comparable bc = (Comparable)b.getXPathComparable(true, collator, context);
if (ac == null || bc == null) {
throw new ClassCastException("Objects are not comparable (" +
Type.displayTypeName(a) + ", " + Type.displayTypeName(b) + ')');
} else {
return ac.compareTo(bc);
}
}
}
/**
* Compare two AtomicValue objects for equality according to the rules for their data type. UntypedAtomic
* values are compared as if they were strings; if different semantics are wanted, the conversion
* must be done by the caller.
* @param a the first object to be compared. If it is a StringValue, the
* collator is used to compare the values, otherwise the value must implement the equals() method.
* @param b the second object to be compared. This must be comparable with the first object: for
* example, if one is a string, they must both be strings.
* @return <0 if a0 if a>b
* @throws ClassCastException if the objects are not comparable
*/
public boolean comparesEqual(AtomicValue a, AtomicValue b) throws NoDynamicContextException {
// System.err.println("Comparing " + a.getClass() + ": " + a + " with " + b.getClass() + ": " + b);
if (a instanceof StringValue && b instanceof StringValue) {
return collator.compareStrings(a.getStringValue(), b.getStringValue()) == 0;
} else if (a instanceof CalendarValue && b instanceof CalendarValue) {
return ((CalendarValue)a).compareTo((CalendarValue)b, context) == 0;
} else {
Object ac = a.getXPathComparable(false, collator, context);
Object bc = b.getXPathComparable(false, collator, context);
return ac.equals(bc);
}
}
/**
* Get a comparison key for an object. This must satisfy the rule that if two objects are equal,
* then their comparison keys are equal, and vice versa. There is no requirement that the
* comparison keys should reflect the ordering of the underlying objects.
*/
public ComparisonKey getComparisonKey(AtomicValue a) {
if (a instanceof StringValue) {
Platform platform = Configuration.getPlatform();
if (platform.canReturnCollationKeys(collator)) {
return new ComparisonKey(StandardNames.XS_STRING,
collator.getCollationKey(a.getStringValue()));
} else {
return new ComparisonKey(StandardNames.XS_STRING, a.getStringValue());
}
} else {
return new ComparisonKey(StandardNames.XS_STRING, a);
}
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none
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