1 files changed, 120 insertions, 0 deletions
diff --git a/src/runtime/dotNet/Bracket.cs b/src/runtime/dotNet/Bracket.cs
new file mode 100644
index 000000000..fa9c77d74
--- /dev/null
+++ b/src/runtime/dotNet/Bracket.cs
@@ -0,0 +1,120 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace PGFSharp
+{
+	// Brackets should only be constructed from the Concrete class.
+	// These classes just store the data, they do not own or use
+	// unmanaged memory (except in the builder class).
+	
+	public interface IBracketChild {
+		bool IsString {get;}
+		string AsStringChild {get;}
+		Bracket AsBracketChild {get;}
+	}
+
+
+	public class Bracket : IBracketChild
+    {
+		public class StringChildBracket : IBracketChild {
+
+			string str;
+			internal StringChildBracket(string str) {
+				this.str = str;
+			}
+
+			public bool IsString => true;
+			public string AsStringChild => str;
+			public Bracket AsBracketChild {
+				get {
+					throw new NotImplementedException ();
+				}
+			}
+
+			public override string ToString () => AsStringChild;
+		}
+
+		internal class BracketBuilder {
+			internal Native.PgfLinFuncs LinFuncs { get; private set; }
+
+			private Stack<Bracket> stack = new Stack<Bracket> ();
+			private Bracket final = null;
+			internal BracketBuilder() {
+				LinFuncs = new Native.PgfLinFuncs {
+					symbol_token = SymbolToken,
+					begin_prase = BeginPhrase,
+					end_phrase = EndPhrase,
+					symbol_ne = null,
+					symbol_bind = null,
+					symbol_capit = null
+				};
+			}
+
+			// TODO: the Python wrapper discards begin/end phrase pairs
+			// which don't have any tokens. Is this correct and/or necessary?
+			private void SymbolToken(IntPtr self, IntPtr token) {
+				var str = Native.NativeString.StringFromNativeUtf8 (token);
+				stack.Peek ().AddChild (new StringChildBracket (str));
+			}
+
+			private void BeginPhrase(IntPtr self, IntPtr cat, int fid, int lindex, IntPtr fun) {
+				stack.Push (new Bracket ());
+			}
+
+			private void EndPhrase(IntPtr self, IntPtr cat, int fid, int lindex, IntPtr fun) {
+				var b = stack.Pop ();
+
+				b.CatName = Native.NativeString.StringFromNativeUtf8 (cat);
+				b.FunName = Native.NativeString.StringFromNativeUtf8 (fun);
+				b.FId = fid;
+				b.LIndex = lindex;
+
+				if (stack.Count == 0)
+					final = b;
+				else 
+					stack.Peek ().AddChild (b);
+			}
+
+			public Bracket Build() {
+				return final;
+			}
+		}
+
+		private List<IBracketChild> _children = new List<IBracketChild> ();
+		private Bracket() {
+		}
+
+		private void AddChild(IBracketChild c) {
+			_children.Add(c);
+		}
+
+		public bool IsString => false;
+		public Bracket AsBracketChild => this;
+		public string AsStringChild {
+			get {
+				throw new NotImplementedException ();
+			}
+		}
+
+		public IEnumerable<IBracketChild> Children { get { return _children; } }
+
+		public string CatName { get; private set; }
+		public string FunName { get; private set; }
+		public int FId { get; private set; }
+		public int LIndex { get; private set; }
+
+		public override string ToString ()
+		{
+			return "(" + CatName + ":" + FId + " " + String.Join (" ", Children) + ")";
+		}
+
+		public string ToBracketsString =>  "{" + String.Join(" ", 
+			Children.Select(c => (c is Bracket) ? ((Bracket)c).ToBracketsString : c.ToString() )
+		 ) + "}";
+    }
+
+
+}