/// <summary>
/// The main list matching logic.
/// </summary>
/// <returns>Returns whether the list match was successful.
/// If the method returns true, it adds the capture groups (if any) to the match.
/// If the method returns false, the match object remains in a partially-updated state and needs to be restored
/// before it can be reused.</returns>
internal static bool DoMatch(IReadOnlyList <ILInstruction> patterns, IReadOnlyList <ILInstruction> syntaxList, ref Match match)
{
ListMatch listMatch = new ListMatch(syntaxList);
do
{
if (PerformMatchSequence(patterns, ref listMatch, ref match))
{
// If we have a successful match and it matches the whole list,
// we are done.
if (listMatch.SyntaxIndex == syntaxList.Count)
{
return(true);
}
}
// Otherwise, restore a savepoint created by PerformMatch() and resume the matching logic at that savepoint.
} while (listMatch.RestoreSavePoint(ref match));
return(false);
}
/// <summary>
/// PerformMatch() for a sequence of patterns.
/// </summary>
/// <param name="patterns">List of patterns to match.</param>
/// <param name="listMatch">Stores state about the current list match.</param>
/// <param name="match">The match object, used to store global state during the match (such as the results of capture groups).</param>
/// <returns>Returns whether all patterns were matched successfully against a part of the list.
/// If the method returns true, it updates listMatch.SyntaxIndex to point to the next node that was not part of the match,
/// and adds the capture groups (if any) to the match.
/// If the method returns false, the listMatch and match objects remain in a partially-updated state and need to be restored
/// before they can be reused.</returns>
internal static bool PerformMatchSequence(IReadOnlyList <ILInstruction> patterns, ref ListMatch listMatch, ref Match match)
{
// The patterns may create savepoints, so we need to save the 'i' variable
// as part of those checkpoints.
for (int i = listMatch.PopFromSavePoint() ?? 0; i < patterns.Count; i++)
{
int startMarker = listMatch.GetSavePointStartMarker();
bool success = patterns[i].PerformMatch(ref listMatch, ref match);
listMatch.PushToSavePoints(startMarker, i);
if (!success)
{
return(false);
}
}
return(true);
}
