Import YamlDotNet.

Assets/YamlDotNet/Core/ParserExtensions.cs

@@ -0,0 +1,151 @@
+// This file is part of YamlDotNet - A .NET library for YAML.
+// Copyright (c) Antoine Aubry and contributors
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+// of the Software, and to permit persons to whom the Software is furnished to do
+// so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using YamlDotNet.Core.Events;
+
+namespace YamlDotNet.Core
+{
+    /// <summary>
+    /// Extension methods that provide useful abstractions over <see cref="IParser"/>.
+    /// </summary>
+    public static class ParserExtensions
+    {
+        /// <summary>
+        /// Ensures that the current event is of the specified type, returns it and moves to the next event.
+        /// </summary>
+        /// <typeparam name="T">Type of the <see cref="ParsingEvent"/>.</typeparam>
+        /// <returns>Returns the current event.</returns>
+        /// <exception cref="YamlException">If the current event is not of the specified type.</exception>
+        public static T Consume<T>(this IParser parser) where T : ParsingEvent
+        {
+            var required = parser.Require<T>();
+            parser.MoveNext();
+            return required;
+        }
+
+        /// <summary>
+        /// Checks whether the current event is of the specified type.
+        /// If the event is of the specified type, returns it and moves to the next event.
+        /// Otherwise returns null.
+        /// </summary>
+        /// <typeparam name="T">Type of the <see cref="ParsingEvent"/>.</typeparam>
+        /// <returns>Returns true if the current event is of type T; otherwise returns null.</returns>
+        public static bool TryConsume<T>(this IParser parser, [MaybeNullWhen(false)] out T @event) where T : ParsingEvent
+        {
+            if (parser.Accept(out @event!))
+            {
+                parser.MoveNext();
+                return true;
+            }
+            return false;
+        }
+
+        /// <summary>
+        /// Enforces that the current event is of the specified type.
+        /// </summary>
+        /// <typeparam name="T">Type of the <see cref="ParsingEvent"/>.</typeparam>
+        /// <returns>Returns the current event.</returns>
+        /// <exception cref="YamlException">If the current event is not of the specified type.</exception>
+        public static T Require<T>(this IParser parser) where T : ParsingEvent
+        {
+            if (!parser.Accept<T>(out var required))
+            {
+                var @event = parser.Current;
+                if (@event == null)
+                {
+                    throw new YamlException($"Expected '{typeof(T).Name}', got nothing.");
+                }
+                throw new YamlException(@event.Start, @event.End, $"Expected '{typeof(T).Name}', got '{@event.GetType().Name}' (at {@event.Start}).");
+            }
+            return required;
+        }
+
+        /// <summary>
+        /// Checks whether the current event is of the specified type.
+        /// </summary>
+        /// <typeparam name="T">Type of the event.</typeparam>
+        /// <returns>Returns true if the current event is of type <typeparamref name="T"/>. Otherwise returns false.</returns>
+        public static bool Accept<T>(this IParser parser, [MaybeNullWhen(false)] out T @event) where T : ParsingEvent
+        {
+            if (parser.Current == null)
+            {
+                if (!parser.MoveNext())
+                {
+                    throw new EndOfStreamException();
+                }
+            }
+
+            if (parser.Current is T evt)
+            {
+                @event = evt;
+                return true;
+            }
+            else
+            {
+                @event = default!;
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Skips the current event and any nested event.
+        /// </summary>
+        public static void SkipThisAndNestedEvents(this IParser parser)
+        {
+            var depth = 0;
+            do
+            {
+                var next = parser.Consume<ParsingEvent>();
+                depth += next.NestingIncrease;
+            }
+            while (depth > 0);
+        }
+
+        [Obsolete("Please use Consume<T>() instead")]
+        public static T Expect<T>(this IParser parser) where T : ParsingEvent
+        {
+            return parser.Consume<T>();
+        }
+
+        [Obsolete("Please use TryConsume<T>(out var evt) instead")]
+        [return: MaybeNull]
+        public static T Allow<T>(this IParser parser) where T : ParsingEvent
+        {
+            return parser.TryConsume<T>(out var @event) ? @event : default;
+        }
+
+        [Obsolete("Please use Accept<T>(out var evt) instead")]
+        [return: MaybeNull]
+        public static T Peek<T>(this IParser parser) where T : ParsingEvent
+        {
+            return parser.Accept<T>(out var @event) ? @event : default;
+        }
+
+        [Obsolete("Please use TryConsume<T>(out var evt) or Accept<T>(out var evt) instead")]
+        public static bool Accept<T>(this IParser parser) where T : ParsingEvent
+        {
+            return Accept<T>(parser, out var _);
+        }
+    }
+}