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//------------------------------------------------------------------------------
// <copyright file="RegexInterpreter.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
// This RegexInterpreter class is internal to the RegularExpression package.
// It executes a block of regular expression codes while consuming
// input.
namespace System.Text.RegularExpressions
{
using System.Collections;
using System.Diagnostics;
using System.Globalization;
internal sealed class RegexInterpreter : RegexRunner {
internal int runoperator;
internal int [] runcodes;
internal int runcodepos;
internal String [] runstrings;
internal RegexCode runcode;
internal RegexPrefix runfcPrefix;
internal RegexBoyerMoore runbmPrefix;
internal int runanchors;
internal bool runrtl;
internal bool runci;
internal CultureInfo runculture;
#if !SILVERLIGHT
private const int LoopTimeoutCheckCount = 2000; // A conservative value to guarantee the correct timeout handling.
private static readonly bool UseLegacyTimeoutCheck = LocalAppContextSwitches.UseLegacyTimeoutCheck;
#endif
internal RegexInterpreter(RegexCode code, CultureInfo culture) {
runcode = code;
runcodes = code._codes;
runstrings = code._strings;
runfcPrefix = code._fcPrefix;
runbmPrefix = code._bmPrefix;
runanchors = code._anchors;
runculture = culture;
}
protected override void InitTrackCount() {
runtrackcount = runcode._trackcount;
}
private void Advance() {
Advance(0);
}
private void Advance(int i) {
runcodepos += (i + 1);
SetOperator(runcodes[runcodepos]);
}
private void Goto(int newpos) {
// when branching backward, ensure storage
if (newpos < runcodepos)
EnsureStorage();
SetOperator(runcodes[newpos]);
runcodepos = newpos;
}
private void Textto(int newpos) {
runtextpos = newpos;
}
private void Trackto(int newpos) {
runtrackpos = runtrack.Length - newpos;
}
private int Textstart() {
return runtextstart;
}
private int Textpos() {
return runtextpos;
}
// push onto the backtracking stack
private int Trackpos() {
return runtrack.Length - runtrackpos;
}
private void TrackPush() {
runtrack[--runtrackpos] = runcodepos;
}
private void TrackPush(int I1) {
runtrack[--runtrackpos] = I1;
runtrack[--runtrackpos] = runcodepos;
}
private void TrackPush(int I1, int I2) {
runtrack[--runtrackpos] = I1;
runtrack[--runtrackpos] = I2;
runtrack[--runtrackpos] = runcodepos;
}
private void TrackPush(int I1, int I2, int I3) {
runtrack[--runtrackpos] = I1;
runtrack[--runtrackpos] = I2;
runtrack[--runtrackpos] = I3;
runtrack[--runtrackpos] = runcodepos;
}
private void TrackPush2(int I1) {
runtrack[--runtrackpos] = I1;
runtrack[--runtrackpos] = -runcodepos;
}
private void TrackPush2(int I1, int I2) {
runtrack[--runtrackpos] = I1;
runtrack[--runtrackpos] = I2;
runtrack[--runtrackpos] = -runcodepos;
}
private void Backtrack() {
int newpos = runtrack[runtrackpos++];
#if DBG
if (runmatch.Debug) {
if (newpos < 0)
Debug.WriteLine(" Backtracking (back2) to code position " + (-newpos));
else
Debug.WriteLine(" Backtracking to code position " + newpos);
}
#endif
if (newpos < 0) {
newpos = -newpos;
SetOperator(runcodes[newpos] | RegexCode.Back2);
}
else {
SetOperator(runcodes[newpos] | RegexCode.Back);
}
// When branching backward, ensure storage
if (newpos < runcodepos)
EnsureStorage();
runcodepos = newpos;
}
private void SetOperator(int op) {
runci = (0 != (op & RegexCode.Ci));
runrtl = (0 != (op & RegexCode.Rtl));
runoperator = op & ~(RegexCode.Rtl | RegexCode.Ci);
}
private void TrackPop() {
runtrackpos++;
}
// pop framesize items from the backtracking stack
private void TrackPop(int framesize) {
runtrackpos += framesize;
}
// Technically we are actually peeking at items already popped. So if you want to
// get and pop the top item from the stack, you do
// TrackPop();
// TrackPeek();
private int TrackPeek() {
return runtrack[runtrackpos - 1];
}
// get the ith element down on the backtracking stack
private int TrackPeek(int i) {
return runtrack[runtrackpos - i - 1];
}
// Push onto the grouping stack
private void StackPush(int I1) {
runstack[--runstackpos] = I1;
}
private void StackPush(int I1, int I2) {
runstack[--runstackpos] = I1;
runstack[--runstackpos] = I2;
}
private void StackPop() {
runstackpos++;
}
// pop framesize items from the grouping stack
private void StackPop(int framesize) {
runstackpos += framesize;
}
// Technically we are actually peeking at items already popped. So if you want to
// get and pop the top item from the stack, you do
// StackPop();
// StackPeek();
private int StackPeek() {
return runstack[runstackpos - 1];
}
// get the ith element down on the grouping stack
private int StackPeek(int i) {
return runstack[runstackpos - i - 1];
}
private int Operator() {
return runoperator;
}
private int Operand(int i) {
return runcodes[runcodepos + i + 1];
}
private int Leftchars() {
return runtextpos - runtextbeg;
}
private int Rightchars() {
return runtextend - runtextpos;
}
private int Bump() {
return runrtl ? -1 : 1;
}
private int Forwardchars() {
return runrtl ? runtextpos - runtextbeg : runtextend - runtextpos;
}
private char Forwardcharnext() {
char ch = (runrtl ? runtext[--runtextpos] : runtext[runtextpos++]);
return(runci ? Char.ToLower(ch, runculture) : ch);
}
private bool Stringmatch(String str) {
int c;
int pos;
if (!runrtl) {
if (runtextend - runtextpos < (c = str.Length))
return false;
pos = runtextpos + c;
}
else {
if (runtextpos - runtextbeg < (c = str.Length))
return false;
pos = runtextpos;
}
if (!runci) {
while (c != 0)
if (str[--c] != runtext[--pos])
return false;
}
else {
while (c != 0)
if (str[--c] != Char.ToLower(runtext[--pos], runculture))
return false;
}
if (!runrtl) {
pos += str.Length;
}
runtextpos = pos;
return true;
}
private bool Refmatch(int index, int len) {
int c;
int pos;
int cmpos;
if (!runrtl) {
if (runtextend - runtextpos < len)
return false;
pos = runtextpos + len;
}
else {
if (runtextpos - runtextbeg < len)
return false;
pos = runtextpos;
}
cmpos = index + len;
c = len;
if (!runci) {
while (c-- != 0)
if (runtext[--cmpos] != runtext[--pos])
return false;
}
else {
while (c-- != 0)
if (Char.ToLower(runtext[--cmpos], runculture) != Char.ToLower(runtext[--pos], runculture))
return false;
}
if (!runrtl) {
pos += len;
}
runtextpos = pos;
return true;
}
private void Backwardnext() {
runtextpos += runrtl ? 1 : -1;
}
private char CharAt(int j) {
return runtext[j];
}
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// !!!! This function must be kept synchronized with GenerateFindFirstChar !!!!
// !!!! in RegexCompiler.cs !!!!
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
protected override bool FindFirstChar() {
int i;
String set;
if (0 != (runanchors & (RegexFCD.Beginning | RegexFCD.Start | RegexFCD.EndZ | RegexFCD.End))) {
if (!runcode._rightToLeft) {
if ((0 != (runanchors & RegexFCD.Beginning) && runtextpos > runtextbeg) ||
(0 != (runanchors & RegexFCD.Start) && runtextpos > runtextstart)) {
runtextpos = runtextend;
return false;
}
if (0 != (runanchors & RegexFCD.EndZ) && runtextpos < runtextend - 1) {
runtextpos = runtextend - 1;
}
else if (0 != (runanchors & RegexFCD.End) && runtextpos < runtextend) {
runtextpos = runtextend;
}
}
else {
if ((0 != (runanchors & RegexFCD.End) && runtextpos < runtextend) ||
(0 != (runanchors & RegexFCD.EndZ) && (runtextpos < runtextend - 1 ||
(runtextpos == runtextend - 1 && CharAt(runtextpos) != '\n'))) ||
(0 != (runanchors & RegexFCD.Start) && runtextpos < runtextstart)) {
runtextpos = runtextbeg;
return false;
}
if (0 != (runanchors & RegexFCD.Beginning) && runtextpos > runtextbeg) {
runtextpos = runtextbeg;
}
}
if (runbmPrefix != null) {
return runbmPrefix.IsMatch(runtext, runtextpos, runtextbeg, runtextend);
}
return true; // found a valid start or end anchor
}
else if (runbmPrefix != null) {
runtextpos = runbmPrefix.Scan(runtext, runtextpos, runtextbeg, runtextend);
if (runtextpos == -1) {
runtextpos = (runcode._rightToLeft ? runtextbeg : runtextend);
return false;
}
return true;
}
else if (runfcPrefix == null) {
return true;
}
runrtl = runcode._rightToLeft;
runci = runfcPrefix.CaseInsensitive;
set = runfcPrefix.Prefix;
if (RegexCharClass.IsSingleton(set)) {
char ch = RegexCharClass.SingletonChar(set);
for (i = Forwardchars(); i > 0; i--) {
if (ch == Forwardcharnext()) {
Backwardnext();
return true;
}
}
}
else {
for (i = Forwardchars(); i > 0; i--) {
if (RegexCharClass.CharInClass(Forwardcharnext(), set)) {
Backwardnext();
return true;
}
}
}
return false;
}
protected override void Go() {
Goto(0);
for (;;) {
#if DBG
if (runmatch.Debug) {
DumpState();
}
#endif
CheckTimeout();
switch (Operator()) {
case RegexCode.Stop:
return;
case RegexCode.Nothing:
break;
case RegexCode.Goto:
Goto(Operand(0));
continue;
case RegexCode.Testref:
if (!IsMatched(Operand(0)))
break;
Advance(1);
continue;
case RegexCode.Lazybranch:
TrackPush(Textpos());
Advance(1);
continue;
case RegexCode.Lazybranch | RegexCode.Back:
TrackPop();
Textto(TrackPeek());
Goto(Operand(0));
continue;
case RegexCode.Setmark:
StackPush(Textpos());
TrackPush();
Advance();
continue;
case RegexCode.Nullmark:
StackPush(-1);
TrackPush();
Advance();
continue;
case RegexCode.Setmark | RegexCode.Back:
case RegexCode.Nullmark | RegexCode.Back:
StackPop();
break;
case RegexCode.Getmark:
StackPop();
TrackPush(StackPeek());
Textto(StackPeek());
Advance();
continue;
case RegexCode.Getmark | RegexCode.Back:
TrackPop();
StackPush(TrackPeek());
break;
case RegexCode.Capturemark:
if (Operand(1) != -1 && !IsMatched(Operand(1)))
break;
StackPop();
if (Operand(1) != -1)
TransferCapture(Operand(0), Operand(1), StackPeek(), Textpos());
else
Capture(Operand(0), StackPeek(), Textpos());
TrackPush(StackPeek());
Advance(2);
continue;
case RegexCode.Capturemark | RegexCode.Back:
TrackPop();
StackPush(TrackPeek());
Uncapture();
if (Operand(0) != -1 && Operand(1) != -1)
Uncapture();
break;
case RegexCode.Branchmark:
{
int matched;
StackPop();
matched = Textpos() - StackPeek();
if (matched != 0) { // Nonempty match -> loop now
TrackPush(StackPeek(), Textpos()); // Save old mark, textpos
StackPush(Textpos()); // Make new mark
Goto(Operand(0)); // Loop
}
else { // Empty match -> straight now
TrackPush2(StackPeek()); // Save old mark
Advance(1); // Straight
}
continue;
}
case RegexCode.Branchmark | RegexCode.Back:
TrackPop(2);
StackPop();
Textto(TrackPeek(1)); // Recall position
TrackPush2(TrackPeek()); // Save old mark
Advance(1); // Straight
continue;
case RegexCode.Branchmark | RegexCode.Back2:
TrackPop();
StackPush(TrackPeek()); // Recall old mark
break; // Backtrack
case RegexCode.Lazybranchmark:
{
// We hit this the first time through a lazy loop and after each
// successful match of the inner expression. It simply continues
// on and doesn't loop.
StackPop();
int oldMarkPos = StackPeek();
if (Textpos() != oldMarkPos) { // Nonempty match -> try to loop again by going to 'back' state
if (oldMarkPos != -1)
TrackPush(oldMarkPos, Textpos()); // Save old mark, textpos
else
TrackPush(Textpos(), Textpos());
}
else {
// The inner expression found an empty match, so we'll go directly to 'back2' if we
// backtrack. In this case, we need to push something on the stack, since back2 pops.
// However, in the case of ()+? or similar, this empty match may be legitimate, so push the text
// position associated with that empty match.
StackPush(oldMarkPos);
TrackPush2(StackPeek()); // Save old mark
}
Advance(1);
continue;
}
case RegexCode.Lazybranchmark | RegexCode.Back:
{
// After the first time, Lazybranchmark | RegexCode.Back occurs
// with each iteration of the loop, and therefore with every attempted
// match of the inner expression. We'll try to match the inner expression,
// then go back to Lazybranchmark if successful. If the inner expression
// failes, we go to Lazybranchmark | RegexCode.Back2
int pos;
TrackPop(2);
pos = TrackPeek(1);
TrackPush2(TrackPeek()); // Save old mark
StackPush(pos); // Make new mark
Textto(pos); // Recall position
Goto(Operand(0)); // Loop
continue;
}
case RegexCode.Lazybranchmark | RegexCode.Back2:
// The lazy loop has failed. We'll do a true backtrack and
// start over before the lazy loop.
StackPop();
TrackPop();
StackPush(TrackPeek()); // Recall old mark
break;
case RegexCode.Setcount:
StackPush(Textpos(), Operand(0));
TrackPush();
Advance(1);
continue;
case RegexCode.Nullcount:
StackPush(-1, Operand(0));
TrackPush();
Advance(1);
continue;
case RegexCode.Setcount | RegexCode.Back:
StackPop(2);
break;
case RegexCode.Nullcount | RegexCode.Back:
StackPop(2);
break;
case RegexCode.Branchcount:
// StackPush:
// 0: Mark
// 1: Count
{
StackPop(2);
int mark = StackPeek();
int count = StackPeek(1);
int matched = Textpos() - mark;
if (count >= Operand(1) || (matched == 0 && count >= 0)) { // Max loops or empty match -> straight now
TrackPush2(mark, count); // Save old mark, count
Advance(2); // Straight
}
else { // Nonempty match -> count+loop now
TrackPush(mark); // remember mark
StackPush(Textpos(), count + 1); // Make new mark, incr count
Goto(Operand(0)); // Loop
}
continue;
}
case RegexCode.Branchcount | RegexCode.Back:
// TrackPush:
// 0: Previous mark
// StackPush:
// 0: Mark (= current pos, discarded)
// 1: Count
TrackPop();
StackPop(2);
if (StackPeek(1) > 0) { // Positive -> can go straight
Textto(StackPeek()); // Zap to mark
TrackPush2(TrackPeek(), StackPeek(1) - 1); // Save old mark, old count
Advance(2); // Straight
continue;
}
StackPush(TrackPeek(), StackPeek(1) - 1); // recall old mark, old count
break;
case RegexCode.Branchcount | RegexCode.Back2:
// TrackPush:
// 0: Previous mark
// 1: Previous count
TrackPop(2);
StackPush(TrackPeek(), TrackPeek(1)); // Recall old mark, old count
break; // Backtrack
case RegexCode.Lazybranchcount:
// StackPush:
// 0: Mark
// 1: Count
{
StackPop(2);
int mark = StackPeek();
int count = StackPeek(1);
if (count < 0) { // Negative count -> loop now
TrackPush2(mark); // Save old mark
StackPush(Textpos(), count + 1); // Make new mark, incr count
Goto(Operand(0)); // Loop
}
else { // Nonneg count -> straight now
TrackPush(mark, count, Textpos()); // Save mark, count, position
Advance(2); // Straight
}
continue;
}
case RegexCode.Lazybranchcount | RegexCode.Back:
// TrackPush:
// 0: Mark
// 1: Count
// 2: Textpos
{
TrackPop(3);
int mark = TrackPeek();
int textpos = TrackPeek(2);
if (TrackPeek(1) < Operand(1) && textpos != mark) { // Under limit and not empty match -> loop
Textto(textpos); // Recall position
StackPush(textpos, TrackPeek(1) + 1); // Make new mark, incr count
TrackPush2(mark); // Save old mark
Goto(Operand(0)); // Loop
continue;
}
else { // Max loops or empty match -> backtrack
StackPush(TrackPeek(), TrackPeek(1)); // Recall old mark, count
break; // backtrack
}
}
case RegexCode.Lazybranchcount | RegexCode.Back2:
// TrackPush:
// 0: Previous mark
// StackPush:
// 0: Mark (== current pos, discarded)
// 1: Count
TrackPop();
StackPop(2);
StackPush(TrackPeek(), StackPeek(1) - 1); // Recall old mark, count
break; // Backtrack
case RegexCode.Setjump:
StackPush(Trackpos(), Crawlpos());
TrackPush();
Advance();
continue;
case RegexCode.Setjump | RegexCode.Back:
StackPop(2);
break;
case RegexCode.Backjump:
// StackPush:
// 0: Saved trackpos
// 1: Crawlpos
StackPop(2);
Trackto(StackPeek());
while (Crawlpos() != StackPeek(1))
Uncapture();
break;
case RegexCode.Forejump:
// StackPush:
// 0: Saved trackpos
// 1: Crawlpos
StackPop(2);
Trackto(StackPeek());
TrackPush(StackPeek(1));
Advance();
continue;
case RegexCode.Forejump | RegexCode.Back:
// TrackPush:
// 0: Crawlpos
TrackPop();
while (Crawlpos() != TrackPeek())
Uncapture();
break;
case RegexCode.Bol:
if (Leftchars() > 0 && CharAt(Textpos() - 1) != '\n')
break;
Advance();
continue;
case RegexCode.Eol:
if (Rightchars() > 0 && CharAt(Textpos()) != '\n')
break;
Advance();
continue;
case RegexCode.Boundary:
if (!IsBoundary(Textpos(), runtextbeg, runtextend))
break;
Advance();
continue;
case RegexCode.Nonboundary:
if (IsBoundary(Textpos(), runtextbeg, runtextend))
break;
Advance();
continue;
case RegexCode.ECMABoundary:
if (!IsECMABoundary(Textpos(), runtextbeg, runtextend))
break;
Advance();
continue;
case RegexCode.NonECMABoundary:
if (IsECMABoundary(Textpos(), runtextbeg, runtextend))
break;
Advance();
continue;
case RegexCode.Beginning:
if (Leftchars() > 0)
break;
Advance();
continue;
case RegexCode.Start:
if (Textpos() != Textstart())
break;
Advance();
continue;
case RegexCode.EndZ:
if (Rightchars() > 1 || Rightchars() == 1 && CharAt(Textpos()) != '\n')
break;
Advance();
continue;
case RegexCode.End:
if (Rightchars() > 0)
break;
Advance();
continue;
case RegexCode.One:
if (Forwardchars() < 1 || Forwardcharnext() != (char)Operand(0))
break;
Advance(1);
continue;
case RegexCode.Notone:
if (Forwardchars() < 1 || Forwardcharnext() == (char)Operand(0))
break;
Advance(1);
continue;
case RegexCode.Set:
if (Forwardchars() < 1 || !RegexCharClass.CharInClass(Forwardcharnext(), runstrings[Operand(0)]))
break;
Advance(1);
continue;
case RegexCode.Multi:
{
if (!Stringmatch(runstrings[Operand(0)]))
break;
Advance(1);
continue;
}
case RegexCode.Ref:
{
int capnum = Operand(0);
if (IsMatched(capnum)) {
if (!Refmatch(MatchIndex(capnum), MatchLength(capnum)))
break;
} else {
if ((runregex.roptions & RegexOptions.ECMAScript) == 0)
break;
}
Advance(1);
continue;
}
case RegexCode.Onerep:
{
int c = Operand(1);
if (Forwardchars() < c)
break;
char ch = (char)Operand(0);
while (c-- > 0)
if (Forwardcharnext() != ch)
goto BreakBackward;
Advance(2);
continue;
}
case RegexCode.Notonerep:
{
int c = Operand(1);
if (Forwardchars() < c)
break;
char ch = (char)Operand(0);
while (c-- > 0)
if (Forwardcharnext() == ch)
goto BreakBackward;
Advance(2);
continue;
}
case RegexCode.Setrep:
{
int c = Operand(1);
if (Forwardchars() < c)
break;
String set = runstrings[Operand(0)];
while (c-- > 0)
{
#if !SILVERLIGHT
// Check the timeout every 2000th iteration. The aditional if check
// in every iteration can be neglected as the cost of the CharInClass
// check is many times higher.
if (!UseLegacyTimeoutCheck && c % LoopTimeoutCheckCount == 0)
{
CheckTimeout();
}
#endif
if (!RegexCharClass.CharInClass(Forwardcharnext(), set))
goto BreakBackward;
}
Advance(2);
continue;
}
case RegexCode.Oneloop:
{
int c = Operand(1);
if (c > Forwardchars())
c = Forwardchars();
char ch = (char)Operand(0);
int i;
for (i = c; i > 0; i--) {
if (Forwardcharnext() != ch) {
Backwardnext();
break;
}
}
if (c > i)
TrackPush(c - i - 1, Textpos() - Bump());
Advance(2);
continue;
}
case RegexCode.Notoneloop:
{
int c = Operand(1);
if (c > Forwardchars())
c = Forwardchars();
char ch = (char)Operand(0);
int i;
for (i = c; i > 0; i--) {
if (Forwardcharnext() == ch) {
Backwardnext();
break;
}
}
if (c > i)
TrackPush(c - i - 1, Textpos() - Bump());
Advance(2);
continue;
}
case RegexCode.Setloop:
{
int c = Operand(1);
if (c > Forwardchars())
c = Forwardchars();
String set = runstrings[Operand(0)];
int i;
for (i = c; i > 0; i--) {
#if !SILVERLIGHT
// Check the timeout every 2000th iteration. The aditional if check
// in every iteration can be neglected as the cost of the CharInClass
// check is many times higher.
if (!UseLegacyTimeoutCheck && i % LoopTimeoutCheckCount == 0)
{
CheckTimeout();
}
#endif
if (!RegexCharClass.CharInClass(Forwardcharnext(), set)) {
Backwardnext();
break;
}
}
if (c > i)
TrackPush(c - i - 1, Textpos() - Bump());
Advance(2);
continue;
}
case RegexCode.Oneloop | RegexCode.Back:
case RegexCode.Notoneloop | RegexCode.Back:
{
TrackPop(2);
int i = TrackPeek();
int pos = TrackPeek(1);
Textto(pos);
if (i > 0)
TrackPush(i - 1, pos - Bump());
Advance(2);
continue;
}
case RegexCode.Setloop | RegexCode.Back:
{
TrackPop(2);
int i = TrackPeek();
int pos = TrackPeek(1);
Textto(pos);
if (i > 0)
TrackPush(i - 1, pos - Bump());
Advance(2);
continue;
}
case RegexCode.Onelazy:
case RegexCode.Notonelazy:
{
int c = Operand(1);
if (c > Forwardchars())
c = Forwardchars();
if (c > 0)
TrackPush(c - 1, Textpos());
Advance(2);
continue;
}
case RegexCode.Setlazy:
{
int c = Operand(1);
if (c > Forwardchars())
c = Forwardchars();
if (c > 0)
TrackPush(c - 1, Textpos());
Advance(2);
continue;
}
case RegexCode.Onelazy | RegexCode.Back:
{
TrackPop(2);
int pos = TrackPeek(1);
Textto(pos);
if (Forwardcharnext() != (char)Operand(0))
break;
int i = TrackPeek();
if (i > 0)
TrackPush(i - 1, pos + Bump());
Advance(2);
continue;
}
case RegexCode.Notonelazy | RegexCode.Back:
{
TrackPop(2);
int pos = TrackPeek(1);
Textto(pos);
if (Forwardcharnext() == (char)Operand(0))
break;
int i = TrackPeek();
if (i > 0)
TrackPush(i - 1, pos + Bump());
Advance(2);
continue;
}
case RegexCode.Setlazy | RegexCode.Back:
{
TrackPop(2);
int pos = TrackPeek(1);
Textto(pos);
if (!RegexCharClass.CharInClass(Forwardcharnext(), runstrings[Operand(0)]))
break;
int i = TrackPeek();
if (i > 0)
TrackPush(i - 1, pos + Bump());
Advance(2);
continue;
}
default:
throw new NotImplementedException(SR.GetString(SR.UnimplementedState));
}
BreakBackward:
;
// "break Backward" comes here:
Backtrack();
}
}
#if DBG
internal override void DumpState() {
base.DumpState();
Debug.WriteLine(" " + runcode.OpcodeDescription(runcodepos) +
((runoperator & RegexCode.Back) != 0 ? " Back" : "") +
((runoperator & RegexCode.Back2) != 0 ? " Back2" : ""));
Debug.WriteLine("");
}
#endif
}
}
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