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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 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.regex;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.iter.ArrayIterator;
import net.sf.saxon.tree.iter.EmptyIterator;
import net.sf.saxon.tree.util.FastStringBuffer;
import net.sf.saxon.value.StringValue;
import net.sf.saxon.z.IntHashMap;
import net.sf.saxon.z.IntToIntHashMap;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
//import java.util.regex.Matcher;
//import java.util.regex.Pattern;
/**
* Class JRegexIterator - provides an iterator over matched and unmatched substrings.
* This implementation of RegexIterator uses the JDK regular expression engine.
*/
public class JRegexIterator implements RegexIterator {
private String theString; // the input string being matched
private Pattern pattern; // the regex against which the string is matched
private Matcher matcher; // the Matcher object that does the matching, and holds the state
/*@Nullable*/ private String current; // the string most recently returned by the iterator
private String next; // if the last string was a matching string, null; otherwise the next substring
// matched by the regex
private int position = 0; // the value of XPath position()
private int prevEnd = 0; // the position in the input string of the end of the last match or non-match
private IntToIntHashMap nestingTable = null;
// evaluated on demand: a table that indicates for each captured group,
// what its immediately-containing captured group is.
/**
* Construct a RegexIterator. Note that the underlying matcher.find() method is called once
* to obtain each matching substring. But the iterator also returns non-matching substrings
* if these appear between the matching substrings.
*
* @param string the string to be analysed
* @param pattern the regular expression
*/
public JRegexIterator(String string, Pattern pattern) {
theString = string;
this.pattern = pattern;
matcher = pattern.matcher(string);
next = null;
}
/**
* Get the next item in the sequence
*
* @return the next item in the sequence
*/
public Item next() {
if (next == null && prevEnd >= 0) {
// we've returned a match (or we're at the start), so find the next match
if (matcher.find()) {
int start = matcher.start();
int end = matcher.end();
if (prevEnd == start) {
// there's no intervening non-matching string to return
next = null;
current = theString.substring(start, end);
prevEnd = end;
} else {
// return the non-matching substring first
current = theString.substring(prevEnd, start);
next = theString.substring(start, end);
}
} else {
// there are no more regex matches, we must return the final non-matching text if any
if (prevEnd < theString.length()) {
current = theString.substring(prevEnd);
next = null;
} else {
// this really is the end...
current = null;
position = -1;
prevEnd = -1;
return null;
}
prevEnd = -1;
}
} else {
// we've returned a non-match, so now return the match that follows it, if there is one
if (prevEnd >= 0) {
current = next;
next = null;
prevEnd = matcher.end();
} else {
current = null;
position = -1;
return null;
}
}
position++;
return StringValue.makeStringValue(current);
}
public void close() {
}
/**
* Get another iterator over the same items
*
* @return a new iterator, positioned before the first item
*/
/*@NotNull*/
public SequenceIterator getAnother() {
return new JRegexIterator(theString, pattern);
}
/**
* Get properties of this iterator, as a bit-significant integer.
*
* @return the properties of this iterator. This will be some combination of
* properties such as {@link #GROUNDED}, {@link #LAST_POSITION_FINDER},
* and {@link #LOOKAHEAD}. It is always
* acceptable to return the value zero, indicating that there are no known special properties.
* It is acceptable for the properties of the iterator to change depending on its state.
*/
public int getProperties() {
return 0;
}
/**
* Determine whether the current item is a matching item or a non-matching item
*
* @return true if the current item (the one most recently returned by next()) is
* an item that matches the regular expression, or false if it is an item that
* does not match
*/
public boolean isMatching() {
return next == null && prevEnd >= 0;
}
/**
* Get a substring that matches a parenthesised group within the regular expression
*
* @param number the number of the group to be obtained
* @return the substring of the current item that matches the n'th parenthesized group
* within the regular expression
*/
public String getRegexGroup(int number) {
if (!isMatching()) return null;
if (number > matcher.groupCount() || number < 0) return "";
String s = matcher.group(number);
if (s == null) return "";
return s;
}
/**
* Get a sequence containing all the regex groups (except group 0, because we want to use indexing from 1).
* This is used by the saxon:analyze-string() higher-order extension function.
*/
public SequenceIterator getRegexGroupIterator() {
int c = matcher.groupCount();
if (c == 0) {
return EmptyIterator.getInstance();
} else {
StringValue[] groups = new StringValue[c];
for (int i = 1; i <= groups.length; i++) {
groups[i - 1] = StringValue.makeStringValue(matcher.group(i));
}
return new ArrayIterator(groups);
}
}
/**
* Process a matching substring, performing specified actions at the start and end of each captured
* subgroup. This method will always be called when operating in "push" mode; it writes its
* result to context.getReceiver(). The matching substring text is all written to the receiver,
* interspersed with calls to the methods onGroupStart() and onGroupEnd().
*
* @param action defines the processing to be performed at the start and end of a group
*/
public void processMatchingSubstring(MatchHandler action) throws XPathException {
int c = matcher.groupCount();
if (c == 0) {
action.characters(current);
} else {
// Create a map from positions in the string to lists of actions.
// The "actions" in each list are: +N: start group N; -N: end group N.
IntHashMap> actions = new IntHashMap>(c);
for (int i = 1; i <= c; i++) {
int start = matcher.start(i) - matcher.start();
if (start != -1) {
int end = matcher.end(i) - matcher.start();
if (start < end) {
// Add the start action after all other actions on the list for the same position
List s = actions.get(start);
if (s == null) {
s = new ArrayList(4);
actions.put(start, s);
}
s.add(i);
// Add the end action before all other actions on the list for the same position
List e = actions.get(end);
if (e == null) {
e = new ArrayList(4);
actions.put(end, e);
}
e.add(0, -i);
} else {
// zero-length group (start==end). The problem here is that the information available
// from Java isn't sufficient to determine the nesting of groups: match("a", "(a(b?))")
// and match("a", "(a)(b?)") will both give the same result for group 2 (start=1, end=1).
// So we need to go back to the original regex to determine the group nesting
if (nestingTable == null) {
computeNestingTable();
}
int parentGroup = nestingTable.get(i);
// insert the start and end events immediately before the end event for the parent group,
// if present; otherwise after all existing events for this position
List s = actions.get(start);
if (s == null) {
s = new ArrayList(4);
actions.put(start, s);
s.add(i);
s.add(-i);
} else {
int pos = s.size();
for (int e = 0; e < s.size(); e++) {
if (s.get(e) == -parentGroup) {
pos = e;
break;
}
}
s.add(pos, -i);
s.add(pos, i);
}
}
}
}
FastStringBuffer buff = new FastStringBuffer(current.length());
for (int i = 0; i < current.length() + 1; i++) {
List events = actions.get(i);
if (events != null) {
if (buff.length() > 0) {
action.characters(buff);
buff.setLength(0);
}
for (Iterator ii = events.iterator(); ii.hasNext(); ) {
int group = ii.next();
if (group > 0) {
action.onGroupStart(group);
} else {
action.onGroupEnd(-group);
}
}
}
if (i < current.length()) {
buff.append(current.charAt(i));
}
}
if (buff.length() > 0) {
action.characters(buff);
}
}
}
public RegexIterator getSnapShot(XPathContext context) throws XPathException {
JRegexIterator regexItr = new JRegexIterator(theString, pattern);
regexItr.position = this.position;
regexItr.current = this.current;
regexItr.nestingTable = this.nestingTable;
regexItr.prevEnd = this.prevEnd;
return regexItr;
}
/**
* Compute a table showing for each captured group number (opening paren in the regex),
* the number of its parent group. This is done by reparsing the source of the regular
* expression. This is needed when the result of a match includes an empty group, to determine
* its position relative to other groups finishing at the same character position.
*/
private void computeNestingTable() {
nestingTable = new IntToIntHashMap(16);
String s = pattern.pattern();
int[] stack = new int[s.length()];
int tos = 0;
int group = 1;
int inBrackets = 0;
stack[tos++] = 0;
for (int i = 0; i < s.length(); i++) {
char ch = s.charAt(i);
if (ch == '\'') {
i++;
} else if (ch == '[') {
inBrackets++;
} else if (ch == ']') {
inBrackets--;
} else if (ch == '(' && s.charAt(i + 1) != '?' && inBrackets == 0) {
nestingTable.put(group, stack[tos - 1]);
stack[tos++] = group++;
} else if (ch == ')' && inBrackets == 0) {
tos--;
}
}
}
}
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