/// <summary>
/// Parse the required quantities - we must match at least the minimum.
/// </summary>
private IEnumerable <ParseStep> ParseRequired(IRegexEngine engine, StringBuilder matchedText, State initialState)
{
for (int i = 0; i < Min; i++)
{
foreach (var result in Child.Parse(engine))
{
if (result.Type == ParseStepType.Break && ReferenceEquals(Child, result.Node))
{
break;
}
yield return(result);
if (ReferenceEquals(Child, result.Node))
{
if (result.Type == ParseStepType.Pass)
{
matchedText.Append(result.MatchedText);
}
else if (result.Type == ParseStepType.Fail)
{
yield return(ParseStep.Fail(
this,
initialState,
engine.State,
string.Format("Greedy quantifier was required to match at least {0} times, but matched {1} times", Min, i)));
yield return(ParseStep.Break(this));
}
}
}
}
}
internal override IEnumerable <ParseStep> Parse(IRegexEngine engine)
{
yield return(ParseStep.BeginParse(this, engine.State));
if (engine.State.Index >= engine.Input.Length)
{
yield return(ParseStep.Fail(this, engine.State, engine.State));
yield return(ParseStep.Break(this));
yield break;
}
if (Matches(engine.Input[engine.State.Index]))
{
var match = engine.Input.Substring(engine.State.Index, 1);
var initialState = engine.State;
engine.State = engine.State.Advance();
yield return(ParseStep.Pass(this, match, initialState, engine.State));
yield return(ParseStep.AdvanceIndex(this, engine.State));
yield return(ParseStep.Break(this));
}
else
{
yield return(ParseStep.Fail(this, engine.State, engine.State));
yield return(ParseStep.Break(this));
}
}
internal override IEnumerable <ParseStep> Parse(IRegexEngine engine)
{
yield return(ParseStep.BeginParse(this, engine.State));
var initialState = engine.State;
var capture = engine.GetCaptures(Number).FirstOrDefault();
if (capture == null || string.IsNullOrEmpty(capture.Value))
{
yield return(ParseStep.Fail(this, initialState, engine.State, "No backreference value found"));
yield return(ParseStep.Break(this));
}
else
{
var literals = capture.Value.Select((c, i) => new CharacterLiteral(c, _ignoreCase, capture.Index + i, new string(new[] { c })));
foreach (var literal in literals)
{
var success = false;
foreach (var result in literal.Parse(engine))
{
if (result.Type == ParseStepType.Break)
{
break;
}
if (result.Type == ParseStepType.Pass)
{
success = true;
}
}
if (!success)
{
yield return(ParseStep.Fail(this, initialState, engine.State));
yield return(ParseStep.Break(this));
yield break;
}
}
yield return(ParseStep.Pass(this, capture.Value, initialState, engine.State));
yield return(ParseStep.Break(this));
}
}
internal override sealed IEnumerable <ParseStep> Parse(IRegexEngine engine)
{
yield return(ParseStep.BeginParse(this, engine.State));
if (Matches(engine.State))
{
yield return(ParseStep.Pass(this, "", engine.State, engine.State));
}
else
{
yield return(ParseStep.Fail(this, engine.State, engine.State));
}
yield return(ParseStep.Break(this));
}
protected override IEnumerable <ParseStep> ParseSpecific(IRegexEngine engine, State initialState, StringBuilder matchedText)
{
for (int i = Min; Max == null || i <= Max; i++)
{
// We're lazy - we've already matched what was required of us, so declare that we're done.
yield return(ParseStep.StateSaved(this, initialState, string.Format("Saving state - index {0}", engine.State.Index)));
yield return(ParseStep.Pass(this, matchedText.ToString(), initialState, engine.State));
yield return(ParseStep.Break(this));
// However, if we make it to here, it indicates that we need to match more, in order to (attempt to) get the overall regex to match.
// According to the parlance of regex people smarter than me, this is a backtrack, even though it's forward.
yield return(ParseStep.Backtrack(this, initialState, engine.State));
var childSuccess = false;
foreach (var result in Child.Parse(engine))
{
if (result.Type == ParseStepType.Break && ReferenceEquals(Child, result.Node))
{
break;
}
yield return(result);
if (ReferenceEquals(Child, result.Node))
{
if (result.Type == ParseStepType.Pass)
{
matchedText.Append(result.MatchedText);
childSuccess = true;
}
}
}
if (!childSuccess)
{
break;
}
}
// If we ever make it outside the loop, it means either we were asked to backtrack and our child didn't pass,
// or, we were asked to backtrack more than the Max allowed matches
yield return(ParseStep.Fail(this, initialState, engine.State, "Exceeded max allowled quantities"));
yield return(ParseStep.Break(this));
}
protected override IEnumerable <ParseStep> GetFailParseSteps(IRegexEngine engine, State initialState, State currentState, bool skipAdvance)
{
yield return(ParseStep.Fail(this, initialState, currentState));
yield return(ParseStep.Break(this));
}
protected override IEnumerable <ParseStep> ParseSpecific(IRegexEngine engine, State initialState, StringBuilder matchedText)
{
// At this point, we know we'll match. Attempt to match everything else, until we hit max, a non-match, or the end of the string.
// We need to save states as we go, in case we're asked to backtrack.
var savedStates = new Stack <SavedState>();
int matchedQuantity = Min;
for (; Max == null || matchedQuantity < Max; matchedQuantity++)
{
// If the last state we saved was at the end of the string, there's no point in going any further...
if (savedStates.Count > 0 && savedStates.Peek().State.Index >= engine.Input.Length)
{
// Should we ever get here???
savedStates.Pop();
break;
}
if (engine.State.Index < engine.Input.Length)
{
// We're not at the end of the string, so save state before attempting a match - since we're greedy, we leave breadcrumbs before doing anything.
savedStates.Push(new SavedState(engine.State, matchedText.ToString()));
yield return(ParseStep.StateSaved(this, engine.State, string.Format("Saving state - index {0}", engine.State.Index)));
}
else
{
// It looks like we're at the end of the string - which means we're done. Time to report as such.
yield return(ParseStep.EndOfString(this, engine.State));
yield return(ParseStep.Pass(this, matchedText.ToString(), initialState, engine.State));
yield return(ParseStep.Break(this));
break;
}
var endOfMatch = false;
// TODO: I think that we're going to need to use an enumerator here so we can initiate backtracking in our child and its descendants.
foreach (var result in Child.Parse(engine))
{
if (result.Type == ParseStepType.Break && ReferenceEquals(Child, result.Node))
{
break;
}
yield return(result);
if (ReferenceEquals(Child, result.Node))
{
if (result.Type == ParseStepType.Pass)
{
matchedText.Append(result.MatchedText);
}
else if (result.Type == ParseStepType.Fail)
{
endOfMatch = true;
foreach (var backtrackStep in Backtrack(engine, initialState, savedStates))
{
yield return(backtrackStep);
}
break;
}
}
}
if (endOfMatch)
{
break;
}
}
if (matchedQuantity >= Max)
{
// We've reached the maximum allowed quantity of repetitions, time to break;
yield return(ParseStep.Pass(this, matchedText.ToString(), initialState, engine.State));
yield return(ParseStep.Break(this));
}
// If we get here, it means that we're backtracking
while (savedStates.Count > 0)
{
foreach (var backtrackStep in Backtrack(engine, initialState, savedStates))
{
yield return(backtrackStep);
}
}
// If we get here, we ran out of saved states to backtrack to - report failure.
yield return(ParseStep.Fail(this, initialState, engine.State, "No backtrack is available"));
if (engine.State.Index != initialState.Index)
{
yield return(ParseStep.ResetIndex(this, initialState, engine.State));
engine.State = initialState;
}
yield return(ParseStep.Break(this));
}
internal override IEnumerable <ParseStep> Parse(IRegexEngine outerEngine)
{
var engine = new RegexEngine.RegexEngineInternal(GetEngineInput(outerEngine));
foreach (var capture in outerEngine.GetAllDefinedCaptures().SelectMany(kvp => kvp.Value))
{
engine.AddCapture(capture.Number, capture.Index, capture.Value);
}
var modifier = GetModifier(outerEngine);
bool match = false;
yield return(ParseStep.StartLookaround(this, engine.State.Plus(modifier)).WithSkipAdvanceOnFail(ShouldSkipAdvance));
foreach (var result in _regex.Parse(engine))
{
// Don't report the results of the non-reporting start of string element.
if (ReferenceEquals(result.Node, _nonReportingNode))
{
continue;
}
if (ReferenceEquals(result.Node, _regex))
{
if (result.Type == ParseStepType.Match)
{
match = true;
break;
}
if (result.Type == ParseStepType.Fail)
{
continue;
}
if (result.Type == ParseStepType.Break)
{
break;
}
}
if (result.Type != ParseStepType.Break && engine.State.Index <= engine.Input.Length)
{
yield return(result
.ConvertToOuterContext(outerEngine.Input, modifier, this, n => ReferenceEquals(n, _regex), message => message.Replace(_regex.NodeType, NodeType))
.AsLookaround()
.WithSkipAdvanceOnFail(ShouldSkipAdvance));
}
}
if (match)
{
if (!Negative)
{
// TODO: we need to forward any captures from the look-around to the outer engine.
yield return(ParseStep.Pass(this, "", outerEngine.State, engine.State.Plus(modifier)).WithSkipAdvanceOnFail(ShouldSkipAdvance));
}
else
{
yield return(ParseStep.Fail(this, outerEngine.State, engine.State.Plus(modifier)).WithSkipAdvanceOnFail(ShouldSkipAdvance));
}
}
else
{
if (!Negative)
{
yield return(ParseStep.Fail(this, outerEngine.State, engine.State.Plus(modifier)).WithSkipAdvanceOnFail(ShouldSkipAdvance));
}
else
{
// TODO: we need to forward any captures from the look-around to the outer engine.
yield return(ParseStep.Pass(this, "", outerEngine.State, engine.State.Plus(modifier)).WithSkipAdvanceOnFail(ShouldSkipAdvance));
}
}
yield return(ParseStep.EndLookaround(this).WithSkipAdvanceOnFail(ShouldSkipAdvance));
yield return(ParseStep.Break(this).WithSkipAdvanceOnFail(ShouldSkipAdvance));
}
internal override IEnumerable <ParseStep> Parse(IRegexEngine engine)
{
yield return(ParseStep.BeginParse(this, engine.State));
var initialState = engine.State;
var choiceIndex = 0;
foreach (var choice in Choices)
{
var matchedText = "";
var choicePassed = false;
foreach (var result in choice.Parse(engine))
{
if (ReferenceEquals(choice, result.Node) && result.Type == ParseStepType.Break)
{
break;
}
yield return(result);
if (ReferenceEquals(choice, result.Node))
{
if (result.Type == ParseStepType.Pass)
{
matchedText = result.MatchedText;
choicePassed = true;
if (choiceIndex < Choices.Count - 1)
{
// Only save state if we're not the last choice...
yield return(ParseStep.StateSaved(this, initialState, string.Format("Saving state - index {0}", engine.State.Index)));
}
}
}
}
if (choicePassed)
{
yield return(ParseStep.Pass(this, matchedText, initialState, engine.State));
yield return(ParseStep.Break(this)); // TODO: lazy quantifiers might act in a similar manner as alternation here...
yield return(ParseStep.Backtrack(this, initialState, engine.State));
}
else
{
if (engine.State.Index != initialState.Index)
{
yield return(ParseStep.ResetIndex(this, initialState, engine.State));
engine.State = initialState;
}
}
choiceIndex++;
}
yield return(ParseStep.Fail(this, initialState, engine.State));
yield return(ParseStep.Break(this));
}
