public RegexFindOptimizations(RegexTree tree, CultureInfo culture)
{
_rightToLeft = (tree.Options & RegexOptions.RightToLeft) != 0;
_minRequiredLength = tree.MinRequiredLength;
_textInfo = culture.TextInfo;
// Compute any anchor starting the expression. If there is one, we won't need to search for anything,
// as we can just match at that single location.
LeadingAnchor = RegexPrefixAnalyzer.FindLeadingAnchor(tree.Root);
if (_rightToLeft && LeadingAnchor == RegexNodeKind.Bol)
{
// Filter out Bol for RightToLeft, as we don't currently optimize for it.
LeadingAnchor = RegexNodeKind.Unknown;
}
if (LeadingAnchor is RegexNodeKind.Beginning or RegexNodeKind.Start or RegexNodeKind.EndZ or RegexNodeKind.End)
{
FindMode = (LeadingAnchor, _rightToLeft) switch
{
(RegexNodeKind.Beginning, false) => FindNextStartingPositionMode.LeadingAnchor_LeftToRight_Beginning,
(RegexNodeKind.Beginning, true) => FindNextStartingPositionMode.LeadingAnchor_RightToLeft_Beginning,
(RegexNodeKind.Start, false) => FindNextStartingPositionMode.LeadingAnchor_LeftToRight_Start,
(RegexNodeKind.Start, true) => FindNextStartingPositionMode.LeadingAnchor_RightToLeft_Start,
(RegexNodeKind.End, false) => FindNextStartingPositionMode.LeadingAnchor_LeftToRight_End,
(RegexNodeKind.End, true) => FindNextStartingPositionMode.LeadingAnchor_RightToLeft_End,
(_, false) => FindNextStartingPositionMode.LeadingAnchor_LeftToRight_EndZ,
(_, true) => FindNextStartingPositionMode.LeadingAnchor_RightToLeft_EndZ,
};
return;
}
public override string ToString()
{
var sb = new StringBuilder();
sb.AppendLine($"Direction: {(RightToLeft ? "right-to-left" : "left-to-right")}");
sb.AppendLine($"Anchor: {RegexPrefixAnalyzer.AnchorDescription(FindOptimizations.LeadingAnchor)}");
sb.AppendLine();
for (int i = 0; i < Codes.Length; i += OpcodeSize(Codes[i]))
{
sb.AppendLine(OpcodeDescription(i));
}
sb.AppendLine();
return(sb.ToString());
}
