/// <summary>
/// Replaces all occurrences of the regex in the string with the
/// replacement evaluator.
///
/// Note that the special case of no matches is handled on its own:
/// with no matches, the input string is returned unchanged.
/// The right-to-left case is split out because StringBuilder
/// doesn't handle right-to-left string building directly very well.
/// </summary>
private static string Replace(MatchEvaluator evaluator, Regex regex, string input, int count, int startat)
{
if (evaluator is null)
{
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.evaluator);
}
if (count < -1)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.count, ExceptionResource.CountTooSmall);
}
if ((uint)startat > (uint)input.Length)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.startat, ExceptionResource.BeginIndexNotNegative);
}
if (count == 0)
{
return(input);
}
var state = (segments : SegmentStringBuilder.Create(), evaluator, prevat : 0, input, count);
if (!regex.RightToLeft)
{
regex.Run(input, startat, ref state, static (ref (SegmentStringBuilder segments, MatchEvaluator evaluator, int prevat, string input, int count)state, Match match) =>
{
state.segments.Add(state.input.AsMemory(state.prevat, match.Index - state.prevat));
state.prevat = match.Index + match.Length;
state.segments.Add(state.evaluator(match).AsMemory());
return(--state.count != 0);
}, reuseMatchObject: false);
/// <summary>
/// Replaces all occurrences of the regex in the string with the
/// replacement pattern.
///
/// Note that the special case of no matches is handled on its own:
/// with no matches, the input string is returned unchanged.
/// The right-to-left case is split out because StringBuilder
/// doesn't handle right-to-left string building directly very well.
/// </summary>
public string Replace(Regex regex, string input, int count, int startat)
{
if (count < -1)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.count, ExceptionResource.CountTooSmall);
}
if ((uint)startat > (uint)input.Length)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.startat, ExceptionResource.BeginIndexNotNegative);
}
if (count == 0)
{
return(input);
}
var state = (replacement : this, segments : SegmentStringBuilder.Create(), inputMemory : input.AsMemory(), prevat : 0, count);
if (!regex.RightToLeft)
{
regex.Run(input, startat, ref state, (ref (RegexReplacement thisRef, SegmentStringBuilder segments, ReadOnlyMemory <char> inputMemory, int prevat, int count)state, Match match) =>
{
state.segments.Add(state.inputMemory.Slice(state.prevat, match.Index - state.prevat));
state.prevat = match.Index + match.Length;
state.thisRef.ReplacementImpl(ref state.segments, match);
return(--state.count != 0);
}, reuseMatchObject: true);
/// <summary>
/// Returns the expansion of the passed replacement pattern. For
/// example, if the replacement pattern is ?$1$2?, Result returns the concatenation
/// of Group(1).ToString() and Group(2).ToString().
/// </summary>
public virtual string Result(string replacement)
{
if (replacement is null)
{
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.replacement);
}
Regex?regex = _regex;
if (regex is null)
{
throw new NotSupportedException(SR.NoResultOnFailed);
}
// Gets the weakly cached replacement helper or creates one if there isn't one already.
RegexReplacement repl = RegexReplacement.GetOrCreate(regex.RegexReplacementWeakReference, replacement, regex.caps !, regex.capsize, regex.capnames !, regex.roptions);
SegmentStringBuilder segments = SegmentStringBuilder.Create();
repl.ReplacementImpl(ref segments, this);
return(segments.ToString());
}