package client.net.sf.saxon.ce.regex;
import client.net.sf.saxon.ce.event.Receiver;
import client.net.sf.saxon.ce.expr.XPathContext;
import client.net.sf.saxon.ce.expr.z.IntHashMap;
import client.net.sf.saxon.ce.expr.z.IntToIntHashMap;
import client.net.sf.saxon.ce.om.Item;
import client.net.sf.saxon.ce.om.SequenceIterator;
import client.net.sf.saxon.ce.trans.XPathException;
import client.net.sf.saxon.ce.tree.iter.ArrayIterator;
import client.net.sf.saxon.ce.tree.iter.EmptyIterator;
import client.net.sf.saxon.ce.tree.util.FastStringBuffer;
import client.net.sf.saxon.ce.value.StringValue;
import java.util.ArrayList;
import java.util.List;
/**
* Class ARegexIterator - provides an iterator over matched and unmatched substrings.
* This implementation of RegexIterator uses the modified Jakarta regular expression engine.
*/
public class ARegexIterator implements RegexIterator {
private UnicodeString theString; // the input string being matched
private UnicodeString regex;
private REMatcher matcher; // the Matcher object that does the matching, and holds the state
private UnicodeString current; // the string most recently returned by the iterator
private UnicodeString 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 matcher a matcher for the regular expression
*/
public ARegexIterator(UnicodeString string, UnicodeString regex, REMatcher matcher) {
theString = string;
this.regex = regex;
this.matcher = matcher;
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.match(theString, prevEnd)) {
int start = matcher.getParenStart(0);
int end = matcher.getParenEnd(0);
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, theString.length());
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.getParenEnd(0);
} else {
current = null;
position = -1;
return null;
}
}
position++;
return currentStringValue();
}
private StringValue currentStringValue() {
if (current instanceof BMPString) {
return StringValue.makeStringValue(((BMPString)current).getCharSequence());
} else {
return StringValue.makeStringValue(current.toString());
}
}
/**
* Get the current item in the sequence
* @return the item most recently returned by next()
*/
public Item current() {
return currentStringValue();
}
/**
* Get the position of the current item in the sequence
* @return the position of the item most recently returned by next(), starting at 1
*/
public int position() {
return position;
}
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 ARegexIterator(theString, regex, new REMatcher(matcher.getProgram()));
}
/**
* Get properties of this iterator, as a bit-significant integer.
*
* @return the properties of this iterator. 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.getParenCount() || number < 0) return "";
UnicodeString us = matcher.getParen(number);
return (us == null ? "" : us.toString());
}
/**
* 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.getParenCount() - 1;
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.getParen(i).toString());
}
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 {@link RegexIterator.OnGroup} methods onGroupStart() and onGroupEnd().
* @param context the dynamic evaluation context
* @param action defines the processing to be performed at the start and end of a group
*/
public void processMatchingSubstring(XPathContext context, OnGroup action) throws XPathException {
Receiver out = context.getReceiver();
int c = matcher.getParenCount()-1;
if (c == 0) {
out.characters(current.toString());
} 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<List<Integer>> actions = new IntHashMap<List<Integer>>(c);
for (int i=1; i<=c; i++) {
int start = matcher.getParenStart(i) - matcher.getParenStart(0);
if (start != -1) {
int end = matcher.getParenEnd(i) - matcher.getParenStart(0);
if (start < end) {
// Add the start action after all other actions on the list for the same position
List<Integer> s = actions.get(start);
if (s == null) {
s = new ArrayList<Integer>(4);
actions.put(start, s);
}
s.add(i);
// Add the end action before all other actions on the list for the same position
List<Integer> e = actions.get(end);
if (e == null) {
e = new ArrayList<Integer>(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<Integer> s = actions.get(start);
if (s == null) {
s = new ArrayList<Integer>(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<Integer> events = actions.get(i);
if (events != null) {
if (buff.length() > 0) {
out.characters(buff);
buff.setLength(0);
}
for (Integer group : events) {
if (group > 0) {
action.onGroupStart(context, group);
} else {
action.onGroupEnd(context, -group);
}
}
}
if (i < current.length()) {
buff.appendWideChar(current.charAt(i));
}
}
if (buff.length() > 0) {
out.characters(buff);
}
}
}
/**
* 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);
UnicodeString s = regex;
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++) {
int 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--;
}
}
}
}
// 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.