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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.functions;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StringLiteral;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.regex.RegularExpression;
import net.sf.saxon.str.EmptyUnicodeString;
import net.sf.saxon.str.UnicodeString;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.StringValue;
/**
* This class implements the replace() function for replacing
* substrings that match a regular expression
*/
public class Replace extends RegexFunction {
private boolean replacementChecked = false;
@Override
protected boolean allowRegexMatchingEmptyString() {
return false;
}
/**
* Make an expression that either calls this function, or that is equivalent to a call
* on this function
*
* @param arguments the supplied arguments to the function call
* @return either a function call on this function, or an expression that delivers
* the same result
*/
@Override
public Expression makeFunctionCall(Expression... arguments) {
boolean maybeQ = arguments.length == 4 && (!(arguments[3] instanceof StringLiteral) || ((StringLiteral) arguments[3]).stringify().contains("q"));
if (arguments[2] instanceof StringLiteral && !maybeQ) {
// Do early checking of the replacement expression if known statically
UnicodeString rep = ((StringLiteral) arguments[2]).getString();
if (checkReplacement(rep) == null) {
replacementChecked = true;
}
}
return super.makeFunctionCall(arguments);
}
/**
* Evaluate the expression
*
* @param context the dynamic evaluation context
* @param arguments the values of the arguments, supplied as SequenceIterators
* @return the result of the evaluation, in the form of a SequenceIterator
* @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();
UnicodeString input = arg0 == null ? EmptyUnicodeString.getInstance() : arg0.getUnicodeStringValue();
UnicodeString replacement = arguments[2].head().getUnicodeStringValue();
RegularExpression re = getRegularExpression(arguments);
if (!re.getFlags().contains("q")) {
if (!replacementChecked) {
// if it is a string literal, the check was done at compile time
String msg = checkReplacement(replacement);
if (msg != null) {
throw new XPathException(msg, "FORX0004", context);
}
}
}
return new StringValue(re.replace(input, replacement));
}
/**
* Check the contents of the replacement string
*
* @param rep the replacement string
* @return null if the string is OK, or an error message if not
*/
public static String checkReplacement(UnicodeString rep) {
for (int i = 0; i < rep.length(); i++) {
int c = rep.codePointAt(i);
if (c == '$') {
if (i + 1 < rep.length()) {
int index = ++i;
int next = rep.codePointAt(index);
if (next < '0' || next > '9') {
return "Invalid replacement string in replace(): $ sign must be followed by digit 0-9";
}
} else {
return "Invalid replacement string in replace(): $ sign at end of string";
}
} else if (c == '\\') {
if (i + 1 < rep.length()) {
int index = ++i;
int next = rep.codePointAt(index);
if (next != '\\' && next != '$') {
return "Invalid replacement string in replace(): \\ character must be followed by \\ or $";
}
} else {
return "Invalid replacement string in replace(): \\ character at end of string";
}
}
}
return null;
}
}