C# 编辑器项目 括号折叠策略

using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Folding;
using ICSharpCode.NRefactory.Editor;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AvalonEditor
{
    /// <summary>
    /// 大括号折叠策略
    /// </summary>
    public class BraceFoldingStrategy
    {
        public char OpeningBrace { get; set; }

        public char ClosingBrace { get; set; }

        public BraceFoldingStrategy()
        {
            this.OpeningBrace = '{';
            this.ClosingBrace = '}';
        }

        public void UpdateFoldings(FoldingManager manager, TextDocument document)
        {
            int firstErrorOffset;
            IEnumerable<NewFolding> newFoldings = CreateNewFoldings(document, out firstErrorOffset);
            manager.UpdateFoldings(newFoldings, firstErrorOffset);
        }

        public IEnumerable<NewFolding> CreateNewFoldings(TextDocument document, out int firstErrorOffset)
        {
            firstErrorOffset = -1;
            return CreateNewFoldings(document);
        }

        public IEnumerable<NewFolding> CreateNewFoldings(ITextSource document)
        {
            List<NewFolding> newFoldings = new List<NewFolding>();

            Stack<int> startOffsets = new Stack<int>();
            int lastNewLineOffset = 0;
            char openingBrace = this.OpeningBrace;
            char closingBrace = this.ClosingBrace;
            for (int i = 0; i < document.TextLength; i++)
            {
                char c = document.GetCharAt(i);
                if (c == openingBrace)
                {
                    startOffsets.Push(i);
                }
                else if (c == closingBrace && startOffsets.Count > 0)
                {
                    int startOffset = startOffsets.Pop();
                    if (startOffset < lastNewLineOffset)
                    {
                        newFoldings.Add(new NewFolding(startOffset, i + 1));
                    }
                }
                else if (c == '\n' || c == '\r')
                {
                    lastNewLineOffset = i + 1;
                }
            }
            newFoldings.Sort((a, b) => a.StartOffset.CompareTo(b.StartOffset));
            return newFoldings;
        }

    }
}