/// <summary> /// Folds a negated set node. /// </summary> /// <param name="negatedSet"></param> /// <param name="argument">The argument to be passed to the visitor method.</param> /// <returns> /// <list type="number"> /// <item>The original node if it's to be kept</item> /// <item>A different node to replace the original node with</item> /// <item>Null if the node is to be removed</item> /// </list> /// </returns> protected override GrammarNode <Char>?VisitNegatedSet(NegatedSet negatedSet, TArgument argument) => negatedSet;
protected override String?VisitNegatedSet(NegatedSet negatedSet, Unit argument) => null;
/// <summary> /// Visits a negated set node. /// </summary> /// <param name="negatedSet"></param> /// <param name="argument">The argument data passed by the caller.</param> /// <returns>The result of visiting this node.</returns> protected abstract TReturn VisitNegatedSet(NegatedSet negatedSet, TArgument argument);
protected override GrammarNode <Char>?VisitNegatedSet(NegatedSet negatedSet, OptimizeArgs argument)
{
var characters = negatedSet.Characters.ToList();
var ranges = negatedSet.Ranges.ToList();
var categories = negatedSet.UnicodeCategories.ToList();
// We don't want inner sets to be optimized since we'll flatten them.
OptimizeArgs childrenArgument = argument.WithIsParentASet(true);
List <GrammarNode <Char> > nodes =
negatedSet.Nodes.Select(node => this.Visit(node, childrenArgument))
.Where(node => node is not null)
.ToList() !;
var nodeIdx = 0;
while (true)
{
loopStart:
if (nodeIdx >= nodes.Count)
{
break;
}
GrammarNode <Char> node = nodes[nodeIdx] !;
switch (node.Kind)
{
case GrammarNodeKind.CharacterTerminal:
{
var characterTerminal = (CharacterTerminal)node;
nodes.RemoveAt(nodeIdx);
characters.Add(characterTerminal.Value);
goto loopStart;
}
case GrammarNodeKind.CharacterRange:
{
var characterRange = (CharacterRange)node;
nodes.RemoveAt(nodeIdx);
ranges.Add(characterRange.Range);
goto loopStart;
}
case GrammarNodeKind.CharacterUnicodeCategoryTerminal:
{
var unicodeCategoryTerminal = (UnicodeCategoryTerminal)node;
nodes.RemoveAt(nodeIdx);
categories.Add(unicodeCategoryTerminal.Category);
goto loopStart;
}
case GrammarNodeKind.CharacterSet:
{
var subSet = (Set)node;
nodes.RemoveAt(nodeIdx);
characters.AddRange(subSet.Characters);
ranges.AddRange(subSet.Ranges);
categories.AddRange(subSet.UnicodeCategories);
nodes.AddRange(subSet.Nodes);
goto loopStart;
}
}
nodeIdx++;
}
characters.Sort();
OptimizationAlgorithms.ExpandRanges(characters, ranges, true);
OptimizationAlgorithms.RangifyCharacters(characters, ranges, true);
OptimizationAlgorithms.MergeRanges(ranges);
ImmutableArray <Char> flattenedRanges = CharUtils.FlattenRanges(ranges);
var categoriesFlagSet = CharUtils.CreateCategoryFlagSet(categories);
OptimizationAlgorithms.RemoveMatchedCharacters(characters, flattenedRanges, categoriesFlagSet);
// Characters are still sorted at this point
CharacterBitVector?characterBitVector = null;
if (characters.Any())
{
var charactersDistance = characters[characters.Count - 1] - characters[0];
if (charactersDistance is > 1 and <= 256)
{
characterBitVector = new CharacterBitVector(characters);
}
}
return(new OptimizedNegatedSet(
characters.ToImmutableHashSet(),
flattenedRanges,
categoriesFlagSet,
nodes.ToImmutableArray(),
characterBitVector));
}
/// <summary>
/// Initializes a new set element.
/// </summary>
/// <param name="negatedSet"></param>
public SetElement(NegatedSet negatedSet) : this((GrammarNode <Char>)negatedSet)
{
}