feat: exotic cells support, fix issue #9

Author: justdmitry

TonLibDotNet.Tests/Cells/ExoticCellTests.cs

@@ -0,0 +1,24 @@
+namespace TonLibDotNet.Cells
+{
+    public class ExoticCellTests
+    {
+        private readonly Xunit.Abstractions.ITestOutputHelper outputHelper;
+
+        public ExoticCellTests(Xunit.Abstractions.ITestOutputHelper testOutputHelper)
+        {
+            this.outputHelper = testOutputHelper;
+        }
+
+        [Fact]
+        public void Issue9()
+        {
+            var source = "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";
+
+            var boc = Boc.ParseFromBase64(source);
+            outputHelper.WriteLine(boc.DumpCells());
+
+            var result = boc.SerializeToBase64(false);
+            Assert.Equal(source, result);
+        }
+    }
+}

TonLibDotNet/Cells/Boc.cs

@@ -165,8 +165,9 @@ static void AppendRefs(Cell cell, List<Cell> list)
 
             foreach(var cell in list)
             {
-                ms.WriteByte((byte)cell.Refs.Count);
-                ms.WriteByte((byte)(Math.Ceiling(cell.BitsCount / 8f) + Math.Floor(cell.BitsCount / 8f)));
+                var (d1, d2) = cell.GetDescriptors();
+                ms.WriteByte(d1);
+                ms.WriteByte(d2);
                 ms.Write(cell.Content);
                 foreach(var r in cell.Refs)
                 {
@@ -282,39 +283,31 @@ protected static (Boc?, string? error) TryParseImpl(ReadOnlySpan<byte> bytes)
                 }
             }
 
-            var data = new (bool isOrdinary, int start, int length, bool isAugmented, int[] links)[numberOfCells];
+            var data = new (bool isExotic, byte level, int start, int length, bool isAugmented, int[] links)[numberOfCells];
             for (var i = 0; i < numberOfCells; i++)
             {
                 var d1 = bytes[pos++];
-                var numberOfLinks = d1 & 0b111;
-                var isOrdinary = (d1 & 0b1000) == 0;
                 var d2 = bytes[pos++];
-                var isAugmented = (d2 % 2) != 0;
-                var bytesOfData = d2 / 2 + (isAugmented ? 1 : 0);
+                var (refCount, isExotic, level, dataLength, isAugmented) = Cell.ParseDescriptors(d1, d2);
                 var dataStart = pos;
-                pos += bytesOfData;
+                pos += dataLength;
 
-                var refs = new int[numberOfLinks];
-                for (var j = 0; j < numberOfLinks; j++)
+                var refs = new int[refCount];
+                for (var j = 0; j < refCount; j++)
                 {
                     refs[j] = ReadValue(bytes, ref pos, bytesForNumberOfCells);
                 }
 
-                data[i] = (isOrdinary, dataStart, bytesOfData, isAugmented, refs);
+                data[i] = (isExotic, level, dataStart, dataLength, isAugmented, refs);
             }
 
             var cells = new Cell[numberOfCells];
             for (var i = numberOfCells - 1; i >= 0; i--)
             {
-                var item = data[i];
-                if (!item.isOrdinary)
-                {
-                    continue;
-                }
-
-                var content = bytes.Slice(item.start, item.length);
-                var refs = item.links.Select(x => cells[x]).ToArray();
-                cells[i] = new Cell(content, item.isAugmented, refs);
+                var (isExotic, level, start, length, isAugmented, links) = data[i];
+                var content = bytes.Slice(start, length);
+                var refs = links.Select(x => cells[x]).ToArray();
+                cells[i] = new Cell(isExotic, level, content, isAugmented, refs);
             }
 
             var rootCells = rootCellIndexes.Select(x => cells[x]).ToArray();

TonLibDotNet/Cells/Cell.cs

@@ -7,6 +7,12 @@ public class Cell
         public const int MaxRefs = 4;
 
         public Cell(ReadOnlySpan<byte> content, bool isAugmented, ICollection<Cell>? refs = null)
+            : this (false, 0, content, isAugmented, refs)
+        {
+            // Nothing.
+        }
+
+        public Cell(bool isExotic, byte level, ReadOnlySpan<byte> content, bool isAugmented, ICollection<Cell>? refs = null)
         {
             if (content.Length > MaxContentLength)
             {
@@ -23,6 +29,8 @@ public Cell(ReadOnlySpan<byte> content, bool isAugmented, ICollection<Cell>? ref
                 throw new ArgumentOutOfRangeException(nameof(refs), $"Too many refs ({refs.Count}), only {MaxRefs} are allowed.");
             }
 
+            this.IsExotic = isExotic;
+            this.Level = level;
             this.Content = content.ToArray();
             BitsCount = this.Content.Length * 8;
             if (isAugmented)
@@ -48,6 +56,10 @@ public Cell(ReadOnlySpan<byte> content, bool isAugmented, ICollection<Cell>? ref
             this.Refs = refs?.ToList().AsReadOnly() ?? new List<Cell>().AsReadOnly();
         }
 
+        public bool IsExotic { get; set; }
+
+        public byte Level { get; set; }
+
         public byte[] Content { get; init; }
 
         public bool IsAugmented { get; init; }
@@ -56,6 +68,35 @@ public Cell(ReadOnlySpan<byte> content, bool isAugmented, ICollection<Cell>? ref
 
         public int BitsCount { get; protected set; }
 
+        public static (byte refCount, bool isExotic, byte level, int dataLength, bool isAugmented) ParseDescriptors(byte d1, byte d2)
+        {
+            var refCount = d1 & 0b111;
+            var isExotic = (d1 & 0b1000) != 0;
+            var level = d1 / 32;
+            var isAugmented = (d2 % 2) != 0;
+            var dataLength = d2 / 2 + (isAugmented ? 1 : 0);
+            return ((byte)refCount, isExotic, (byte)level, dataLength, isAugmented);
+        }
+
+        /// <summary>
+        /// Builds cell d1 and d2 descriptors.
+        /// </summary>
+        /// <remarks>
+        /// <para>tvm.pdf, 3.1.4. Standard cell representation:</para>
+        /// <para>
+        /// Byte d1 equals r + 8s + 32l, where 0 ≤ r ≤ 4 is the quantity of cell references contained
+        ///   in the cell, 0 ≤ l ≤ 3 is the level of the cell, and 0 ≤ s ≤ 1 is 1 for
+        ///   exotic cells and 0 for ordinary cells.
+        /// </para>
+        /// <para>Byte d2 equals ⌊b / 8⌋+⌈b / 8⌉, where 0 ≤ b ≤ 1023 is the quantity of data bits in c.</para>
+        /// </remarks>
+        public (byte d1, byte d2) GetDescriptors()
+        {
+            var d1 = 32 * Level + (IsExotic ? 8 : 0) + Refs.Count;
+            var d2 = Math.Ceiling(BitsCount / 8f) + Math.Floor(BitsCount / 8f);
+            return ((byte)d1, (byte)d2);
+        }
+
         public Slice BeginRead()
         {
             var bits = new bool[BitsCount];