SIFOSC、配列から値を取得する。

Author: Takym

FastChatProtocolInterface/SimpleFormulaScript/SifoscArray.cs

@@ -79,5 +79,16 @@ protected override bool PrintMembers(StringBuilder builder)
 
 			return null;
 		}
+
+		public override SifoscObject? Get(SifoscObject? other)
+		{
+			if (other is SifoscInteger index &&
+				0 <= index.Value             &&
+				     index.Value < this.Values.Length) {
+				return this.Values.Span[unchecked((int)(index.Value))];
+			}
+
+			return null;
+		}
 	}
 }

FastChatProtocolInterface/SimpleFormulaScript/SifoscObject.cs

@@ -8,6 +8,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Net.Http.Headers;
 using System.Threading;
 
 namespace FastChatProtocolInterface.SimpleFormulaScript
@@ -49,6 +50,9 @@ private ulong CreateIdentifier()
 		public static IEnumerable<SifoscObject> EnumerateAllObjects()
 			=> _objects.Values;
 
+		public static SifoscObject? GetObject(ulong id)
+			=> _objects.TryGetValue(id, out var result) ? result : null;
+
 		public virtual SifoscObject? Plus    ()                    => null;
 		public virtual SifoscObject? Minus   ()                    => null;
 		public virtual SifoscObject? Negate  ()                    => null;
@@ -60,6 +64,7 @@ public static IEnumerable<SifoscObject> EnumerateAllObjects()
 		public virtual SifoscObject? And     (SifoscObject? other) => null;
 		public virtual SifoscObject? Or      (SifoscObject? other) => null;
 		public virtual SifoscObject? Xor     (SifoscObject? other) => null;
+		public virtual SifoscObject? Get     (SifoscObject? other) => null;
 	}
 
 	public sealed record SifoscNull : SifoscObject

FastChatProtocolInterface/SimpleFormulaScript/SifoscParser.cs

@@ -178,6 +178,7 @@ public static bool TryParseValueExpression(this SourceCode sc, [NotNullWhen(true
 			sc.SkipSpaces();
 
 			return sc.TryParseParenthesisExpression(out result)
+				|| sc.TryParseGetExpression        (out result)
 				|| sc.TryParseSignExpression       (out result)
 				|| sc.TryParseNotExpression        (out result)
 				|| sc.TryParseValueLiteral         (out result);
@@ -200,6 +201,34 @@ public static bool TryParseParenthesisExpression(this SourceCode sc, [NotNullWhe
 			return false;
 		}
 
+		public static bool TryParseGetExpression(this SourceCode sc, [NotNullWhen(true)][MaybeNullWhen(false)] out SifoscObject? result)
+		{
+			sc.BeginScope();
+
+			if (sc.TryParseValueExpression(out var left)) {
+				sc.SkipSpaces();
+				if (sc.AdvanceIf('.') && sc.TryParseValueExpression(out var right)) {
+					result = left.Get(right);
+
+					if (result is null) {
+						goto fail;
+					} else {
+						goto succeed;
+					}
+				}
+			}
+
+			result = null;
+
+		fail:
+			sc.EndScope(true);
+			return false;
+
+		succeed:
+			sc.EndScope(false);
+			return true;
+		}
+
 		public static bool TryParseSignExpression(this SourceCode sc, [NotNullWhen(true)][MaybeNullWhen(false)] out SifoscObject? result)
 		{
 			sc.BeginScope();

FastChatProtocolInterface/SimpleFormulaScript/SifoscViewForAllObjects.cs

@@ -51,5 +51,14 @@ public void PrintMembersSimply(StringBuilder builder)
 
 			builder.Append('}');
 		}
+
+		public override SifoscObject? Get(SifoscObject? other)
+		{
+			if (other is SifoscInteger id) {
+				return GetObject(unchecked((ulong)(id.Value)));
+			}
+
+			return null;
+		}
 	}
 }