/// <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());
}
/// <summary>
/// Does a split. In the right-to-left case we reorder the
/// array to be forwards.
/// </summary>
private static string[] Split(Regex regex, string input, int count, int startat)
{
if (count < 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.count, ExceptionResource.CountTooSmall);
}
if ((uint)startat > (uint)input.Length)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.startat, ExceptionResource.BeginIndexNotNegative);
}
if (count == 1)
{
return(new[] { input });
}
count--;
var state = (results : new List <string>(), prevat : 0, input, count);
if (!regex.RightToLeft)
{
regex.RunAllMatchesWithCallback(input, startat, ref state, static (ref (List <string> results, int prevat, string input, int count)state, Match match) =>
{
state.results.Add(state.input.Substring(state.prevat, match.Index - state.prevat));
state.prevat = match.Index + match.Length;
// add all matched capture groups to the list.
for (int i = 1; i < match.Groups.Count; i++)
{
if (match.IsMatched(i))
{
state.results.Add(match.Groups[i].Value);
}
}
return(--state.count != 0);
}, RegexRunnerMode.FullMatchRequired, reuseMatchObject: true);
private readonly int[] _rules; // negative -> group #, positive -> string #
/// <summary>
/// Since RegexReplacement shares the same parser as Regex,
/// the constructor takes a RegexNode which is a concatenation
/// of constant strings and backreferences.
/// </summary>
public RegexReplacement(string rep, RegexNode concat, Hashtable _caps)
{
if (concat.Kind != RegexNodeKind.Concatenate)
{
throw ThrowHelper.CreateArgumentException(ExceptionResource.ReplacementError);
}
Span <char> vsbStack = stackalloc char[256];
var vsb = new ValueStringBuilder(vsbStack);
FourStackStrings stackStrings = default;
var strings = new ValueListBuilder <string>(MemoryMarshal.CreateSpan(ref stackStrings.Item1 !, 4));
var rules = new ValueListBuilder <int>(stackalloc int[64]);
int childCount = concat.ChildCount();
for (int i = 0; i < childCount; i++)
{
RegexNode child = concat.Child(i);
switch (child.Kind)
{
case RegexNodeKind.Multi:
vsb.Append(child.Str !);
break;
case RegexNodeKind.One:
vsb.Append(child.Ch);
break;
case RegexNodeKind.Backreference:
if (vsb.Length > 0)
{
rules.Append(strings.Length);
strings.Append(vsb.ToString());
vsb = new ValueStringBuilder(vsbStack);
}
int slot = child.M;
if (_caps != null && slot >= 0)
{
slot = (int)_caps[slot] !;
}
rules.Append(-Specials - 1 - slot);
break;
default:
throw ThrowHelper.CreateArgumentException(ExceptionResource.ReplacementError);
}
}
if (vsb.Length > 0)
{
rules.Append(strings.Length);
strings.Append(vsb.ToString());
}
Pattern = rep;
_strings = strings.AsSpan().ToArray();
_rules = rules.AsSpan().ToArray();
rules.Dispose();
}
