Release v5.3.0

src/RCParsing/Building/ParserRules/BuildableSequenceParserRule.cs

@@ -16,6 +16,12 @@ public class BuildableSequenceParserRule : BuildableParserRule
 		/// The elements of the sequence parser rule.
 		/// </summary>
 		public List<Or<string, BuildableParserRule>> Elements { get; } = new List<Or<string, BuildableParserRule>>();
+
+		/// <summary>
+		/// Labels for the elements of the sequence parser rule.
+		/// </summary>
+		public Dictionary<string, int> Labels { get; set; } = new Dictionary<string, int>();
+
 		public override IEnumerable<Or<string, BuildableParserRule>>? RuleChildren => Elements;
 		public override IEnumerable<Or<string, BuildableTokenPattern>>? TokenChildren => null;
 
@@ -26,20 +32,22 @@ public BuildableSequenceParserRule()
 
 		protected override ParserRule BuildRule(List<int>? ruleChildren, List<int>? tokenChildren)
 		{
-			return new SequenceParserRule(ruleChildren);
+			return new SequenceParserRule(ruleChildren, Labels);
 		}
 
 		public override bool Equals(object? obj)
 		{
 			return base.Equals(obj) &&
 				   obj is BuildableSequenceParserRule other &&
-				   Elements.SequenceEqual(other.Elements);
+				   Elements.SequenceEqual(other.Elements) &&
+				   Labels.SequenceEqual(other.Labels);
 		}
 
 		public override int GetHashCode()
 		{
 			int hashCode = base.GetHashCode();
-			hashCode = hashCode * 397 + Elements.GetSequenceHashCode() * 23;
+			hashCode = hashCode * 397 + Elements.GetSequenceHashCode() * 17;
+			hashCode = hashCode * 397 + Labels.GetSequenceHashCode() * 17;
 			return hashCode;
 		}
 	}

src/RCParsing/Building/RuleBuilder.cs

@@ -100,6 +100,37 @@ public RuleBuilder Rule(Or<string, BuildableParserRule> childRule)
 			return this;
 		}
 
+		/// <summary>
+		/// Sets a label for last rule in the sequence. Converts current rule to sequence if it is not already one.
+		/// </summary>
+		/// <param name="label">Label to assign to the last rule in the sequence.</param>
+		/// <returns>Current instance for method chaining.</returns>
+		public RuleBuilder Label(string label)
+		{
+			if (!BuildingRule.HasValue)
+			{
+				throw new ParserBuildingException("Cannot label an empty sequence.");
+			}
+			else if (BuildingRule.Value.VariantIndex == 1 &&
+					BuildingRule.Value.AsT2() is BuildableSequenceParserRule sequenceRule)
+			{
+				int lastIndex = sequenceRule.Elements.Count - 1;
+				if (sequenceRule.Labels.ContainsValue(lastIndex))
+					sequenceRule.Labels.Remove(sequenceRule.Labels.First(v => v.Value == lastIndex).Key);
+				if (sequenceRule.Labels.ContainsKey(label))
+					throw new ParserBuildingException("Label already exists in this sequence element.");
+				sequenceRule.Labels[label] = lastIndex;
+			}
+			else
+			{
+				var newSequence = new BuildableSequenceParserRule();
+				newSequence.Elements.Add(BuildingRule.Value);
+				newSequence.Labels[label] = 0;
+				BuildingRule = newSequence;
+			}
+			return this;
+		}
+
 		/// <summary>
 		/// Adds a rule to the current sequence.
 		/// </summary>

src/RCParsing/ParsedRuleResult.cs

@@ -11,7 +11,7 @@ namespace RCParsing
 	/// </summary>
 	public sealed class ParsedRuleResult : ParsedRuleResultBase
 	{
-		public override ParsedRuleResultBase this[int index] =>
+		public override ParsedRuleResultBase GetChild(int index) =>
 			new ParsedRuleResult(this, ContextReference, Result.children[index]);
 		public override int Count => Result.children?.Count ?? 0;
 		public override IEnumerator<ParsedRuleResultBase> GetEnumerator()
@@ -77,8 +77,8 @@ public sealed class ParsedRuleResultOptimized : ParsedRuleResultBase, IOptimized
 	{
 		public ParseTreeOptimization Optimization { get; }
 
-		public override ParsedRuleResultBase this[int index] =>
-			new ParsedRuleResultOptimized(Optimization, this, ContextReference, Result.children[index]);
+		public override ParsedRuleResultBase GetChild(int index)
+			=> new ParsedRuleResultOptimized(Optimization, this, ContextReference, Result.children[index]);
 		public override int Count => Result.children?.Count ?? 0;
 		public override IEnumerator<ParsedRuleResultBase> GetEnumerator()
 		{