JsonFoldingStrategy

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

namespace LuYao.Toolkit.Controls.AvalonEdit;

/// <summary>
/// Allows producing foldings from a document based on braces.
/// </summary>
public class JsonFoldingStrategy
{
    /// <summary>
    /// Gets/Sets the opening brace. The default value is '{'.
    /// </summary>
    public char[] OpeningBrace { get; set; }

    /// <summary>
    /// Gets/Sets the closing brace. The default value is '}'.
    /// </summary>
    public char[] ClosingBrace { get; set; }

    /// <summary>
    /// Creates a new BraceFoldingStrategy.
    /// </summary>
    public JsonFoldingStrategy()
    {
        this.OpeningBrace = new char[] { '{', '[' };
        this.ClosingBrace = new char[] { '}', ']' };
    }

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

    /// <summary>
    /// Create <see cref="NewFolding"/>s for the specified document.
    /// </summary>
    public IEnumerable<NewFolding> CreateNewFoldings(TextDocument document, out int firstErrorOffset)
    {
        firstErrorOffset = -1;
        return CreateNewFoldings(document);
    }

    /// <summary>
    /// Create <see cref="NewFolding"/>s for the specified document.
    /// </summary>
    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)
            if (OpeningBrace.Contains(c))
            {
                startOffsets.Push(i);
            }
            else if (ClosingBrace.Contains(c) && startOffsets.Count > 0)
            {
                int startOffset = startOffsets.Pop();
                // don't fold if opening and closing brace are on the same line
                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;
    }
}