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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2023 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.functions;
import net.sf.saxon.expr.elab.ItemEvaluator;
import net.sf.saxon.expr.elab.Elaborator;
import net.sf.saxon.expr.elab.ItemElaborator;
import net.sf.saxon.expr.*;
import net.sf.saxon.expr.parser.ContextItemStaticInfo;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.type.TypeHierarchy;
import net.sf.saxon.value.Cardinality;
import net.sf.saxon.value.Int64Value;
import net.sf.saxon.value.NumericValue;
import net.sf.saxon.value.StringValue;
/**
* This class implements the XPath substring() function
*/
public class Substring extends SystemFunction implements Callable {
/**
* 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 typeCheckCaller(FunctionCall caller, ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
Expression e2 = super.typeCheckCaller(caller, visitor, contextInfo);
if (e2 != caller) {
return e2;
}
TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
if (caller.getArg(1).isCallOn(Number_1.class)) {
Expression a1 = ((StaticFunctionCall)caller.getArg(1)).getArg(0);
if (th.isSubType(a1.getItemType(), BuiltInAtomicType.INTEGER)) {
caller.setArg(1, a1);
}
}
if (getArity() > 2 && caller.getArg(2).isCallOn(Number_1.class)) {
Expression a2 = ((StaticFunctionCall) caller.getArg(2)).getArg(0);
if (th.isSubType(a2.getItemType(), BuiltInAtomicType.INTEGER)) {
caller.setArg(2, a2);
}
}
return caller;
}
/**
* Implement the substring function with two arguments.
*
* @param sv the string value
* @param start the numeric offset (1-based) of the first character to be included in the result
* (if not an integer, the XPath rules apply)
* @return the substring starting at this position.
*/
public static StringValue substring(StringValue sv, NumericValue start) {
long slength = sv.length();
long lstart;
if (start instanceof Int64Value) {
//noinspection RedundantCast
lstart = ((Int64Value) start).longValue();
if (lstart > slength) {
return StringValue.EMPTY_STRING;
} else if (lstart <= 0) {
lstart = 1;
}
} else {
//NumericValue rstart = start.round();
// We need to be careful to handle cases such as plus/minus infinity
if (start.isNaN()) {
return StringValue.EMPTY_STRING;
} else if (start.signum() <= 0) {
return sv;
} else if (start.compareTo(slength) > 0) {
return StringValue.EMPTY_STRING;
} else {
lstart = Math.round(start.getDoubleValue());
}
}
if (lstart > slength) {
return StringValue.EMPTY_STRING;
}
return new StringValue(sv.getContent().substring((int) lstart - 1, slength));
}
/**
* Implement the substring function with three arguments.
*
*
* @param sv the string value
* @param start the numeric offset (1-based) of the first character to be included in the result
* (if not an integer, the XPath rules apply)
* @param len the length of the required substring (again, XPath rules apply)
* @return the substring starting at this position.
*/
public static StringValue substring(StringValue sv, NumericValue start, /*@NotNull*/ NumericValue len) {
long slength = sv.length();
long lstart;
if (start instanceof Int64Value) {
//noinspection RedundantCast
lstart = ((Int64Value) start).longValue();
if (lstart > slength) {
return StringValue.EMPTY_STRING;
}
} else {
// We need to be careful to handle cases such as plus/minus infinity and NaN
if (start.isNaN()) {
return StringValue.EMPTY_STRING;
} else if (start.compareTo(slength) > 0) {
// this works even where the string contains surrogate pairs,
// because the Java length is always >= the XPath length
return StringValue.EMPTY_STRING;
} else {
double dstart = start.getDoubleValue();
lstart = Double.isInfinite(dstart) ? -Integer.MAX_VALUE : Math.round(dstart);
}
}
long llen;
if (len instanceof Int64Value) {
llen = ((Int64Value) len).longValue();
if (llen <= 0) {
return StringValue.EMPTY_STRING;
}
} else {
if (len.isNaN()) {
return StringValue.EMPTY_STRING;
}
if (len.signum() <= 0) {
return StringValue.EMPTY_STRING;
}
double dlen = len.getDoubleValue();
if (Double.isInfinite(dlen)) {
llen = Integer.MAX_VALUE;
} else {
llen = Math.round(len.getDoubleValue());
}
}
long lend = lstart + llen;
if (lend < lstart) {
return StringValue.EMPTY_STRING;
}
int a1 = (int) lstart - 1;
if (a1 >= slength) {
return StringValue.EMPTY_STRING;
}
long a2 = Math.min(slength, (int) lend - 1);
if (a1 < 0) {
if (a2 < 0) {
return StringValue.EMPTY_STRING;
} else {
a1 = 0;
}
}
return new StringValue(sv.getContent().substring(a1, a2));
}
/**
* Evaluate the expression
*
* @param context the dynamic evaluation context
* @param arguments the values of the arguments, supplied as Sequences
* @return the result of the evaluation, in the form of a Sequence
* @throws net.sf.saxon.trans.XPathException
* if a dynamic error occurs during the evaluation of the expression
*/
@Override
public StringValue call(XPathContext context, Sequence[] arguments) throws XPathException {
StringValue arg0 = (StringValue) arguments[0].head();
if (arg0 == null) {
return StringValue.EMPTY_STRING;
}
NumericValue arg1 = (NumericValue) arguments[1].head();
if (arguments.length == 2) {
return substring(arg0, arg1);
} else {
NumericValue arg2 = (NumericValue) arguments[2].head();
return substring(arg0, arg1, arg2);
}
}
@Override
public String getCompilerName() {
return "SubstringCompiler";
}
/**
* Make an elaborator for a system function call on this function
*
* @return a suitable elaborator; or null if no custom elaborator is available
*/
@Override
public Elaborator getElaborator() {
return new SubstringFnElaborator();
}
public static class SubstringFnElaborator extends ItemElaborator {
public ItemEvaluator elaborateForItem() {
final SystemFunctionCall fnc = (SystemFunctionCall) getExpression();
final ItemEvaluator arg0Eval = fnc.getArg(0).makeElaborator().elaborateForItem();
final ItemEvaluator arg1Eval = fnc.getArg(1).makeElaborator().elaborateForItem();
final boolean nullable = Cardinality.allowsZero(fnc.getArg(0).getCardinality());
if (fnc.getArity() == 2) {
return context -> {
StringValue sv = (StringValue)arg0Eval.eval(context);
if (nullable && sv == null) {
return StringValue.EMPTY_STRING;
}
NumericValue start = (NumericValue)arg1Eval.eval(context);
return substring(sv, start);
};
} else {
final ItemEvaluator arg2Eval = fnc.getArg(2).makeElaborator().elaborateForItem();
return context -> {
StringValue sv = (StringValue) arg0Eval.eval(context);
if (nullable && sv == null) {
return StringValue.EMPTY_STRING;
}
NumericValue start = (NumericValue) arg1Eval.eval(context);
NumericValue len = (NumericValue) arg2Eval.eval(context);
return substring(sv, start, len);
};
}
}
}
}