package net.sf.saxon.functions;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.ExpressionVisitor;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.Item;
import net.sf.saxon.regex.JRegularExpression;
import net.sf.saxon.regex.RegularExpression;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.StringValue;
import java.util.regex.PatternSyntaxException;
/**
* This class implements the replace() function for replacing
* substrings that match a regular expression
*/
public class Replace extends SystemFunction {
private RegularExpression regexp;
/**
* Simplify and validate.
* This is a pure function so it can be simplified in advance if the arguments are known
* @param visitor an expression visitor
*/
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
Expression e = simplifyArguments(visitor);
if (e == this) {
maybePrecompile(visitor);
}
return e;
}
private void maybePrecompile(ExpressionVisitor visitor) throws XPathException {
// compile the regular expression once if possible
if (regexp == null) {
try {
regexp = Matches.tryToCompile(argument, 1, 3, visitor.getStaticContext());
} catch (XPathException err) {
err.setLocator(this);
throw err;
}
// check that it's not a pattern that matches ""
if (regexp != null && regexp.matches("")) {
XPathException err = new XPathException("The regular expression in replace() must not be one that matches a zero-length string");
err.setErrorCode("FORX0003");
err.setLocator(this);
throw err;
}
}
}
/**
* Perform optimisation of an expression and its subexpressions.
* <p/>
* <p>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.</p>
*
* @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 net.sf.saxon.trans.XPathException
* if an error is discovered during this phase
* (typically a type error)
*/
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
Expression e = super.optimize(visitor, contextItemType);
// try once again to compile the regular expression once if possible
// (used when the regex has been identified as a constant as a result of earlier rewrites)
if (e == this) {
maybePrecompile(visitor);
}
return e;
}
/**
* Get the compiled regular expression if available, otherwise return null
* @return the compiled regex, or null
*/
public RegularExpression getCompiledRegularExpression() {
return regexp;
}
/**
* Evaluate the function in a string context
*/
public Item evaluateItem(XPathContext c) throws XPathException {
AtomicValue arg0 = (AtomicValue)argument[0].evaluateItem(c);
if (arg0==null) {
arg0 = StringValue.EMPTY_STRING;
}
AtomicValue arg2 = (AtomicValue)argument[2].evaluateItem(c);
CharSequence replacement = arg2.getStringValueCS();
String msg = checkReplacement(replacement);
if (msg != null) {
dynamicError(msg, "FORX0004", c);
}
RegularExpression re = regexp;
if (re == null) {
AtomicValue arg1 = (AtomicValue)argument[1].evaluateItem(c);
CharSequence flags;
if (argument.length == 3) {
flags = "";
} else {
AtomicValue arg3 = (AtomicValue)argument[3].evaluateItem(c);
flags = arg3.getStringValueCS();
}
try {
final int xmlVersion = c.getConfiguration().getXMLVersion();
int flagBits = JRegularExpression.setFlags(flags);
re = new JRegularExpression(arg1.getStringValueCS(), xmlVersion, RegularExpression.XPATH_SYNTAX, flagBits);
} catch (XPathException err) {
XPathException de = new XPathException(err);
de.setErrorCode("FORX0002");
de.setXPathContext(c);
de.setLocator(this);
throw de;
} catch (PatternSyntaxException err) {
XPathException de = new XPathException(err);
de.setErrorCode("FORX0002");
de.setXPathContext(c);
de.setLocator(this);
throw de;
}
// check that it's not a pattern that matches ""
if (re.matches("")) {
dynamicError(
"The regular expression in replace() must not be one that matches a zero-length string",
"FORX0003", c);
}
}
String input = arg0.getStringValue();
CharSequence res = re.replace(input, replacement);
return StringValue.makeStringValue(res);
}
/**
* 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(CharSequence rep) {
for (int i=0; i<rep.length(); i++) {
char c = rep.charAt(i);
if (c == '$') {
if (i+1 < rep.length()) {
char next = rep.charAt(++i);
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()) {
char next = rep.charAt(++i);
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;
}
}
//
// 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.
//