Add token reader

00_Common/dotnet/Games.Common/IO/TokenReader.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+
+namespace Games.Common.IO
+{
+    internal class TokenReader
+    {
+        private readonly TextIO _io;
+        private readonly Func<Token, bool> _isTokenValid;
+
+        public TokenReader(TextIO io, Func<Token, bool>? isTokenValid = null)
+        {
+            _io = io;
+            _isTokenValid = isTokenValid ?? (t => true);
+        }
+
+        public IEnumerable<Token> ReadTokens(string prompt, uint quantityNeeded)
+        {
+            if (quantityNeeded == 0)
+            {
+                throw new ArgumentOutOfRangeException(
+                    nameof(quantityNeeded),
+                    $"'{nameof(quantityNeeded)}' must be greater than zero.");
+            }
+
+            var tokens = new List<Token>();
+
+            while(tokens.Count < quantityNeeded)
+            {
+                tokens.AddRange(ReadValidTokens(prompt, quantityNeeded - (uint)tokens.Count));
+                prompt = "?";
+            }
+
+            return tokens;
+        }
+
+        private IEnumerable<Token> ReadValidTokens(string prompt, uint maxCount)
+        {
+            while (true)
+            {
+                var tokensValid = true;
+                var tokens = new List<Token>();
+                foreach (var token in ReadLineOfTokens(prompt, maxCount))
+                {
+                    if (!_isTokenValid(token))
+                    {
+                        tokensValid = false;
+                        prompt = "?";
+                        break;
+                    }
+
+                    tokens.Add(token);
+                }
+
+                if (tokensValid) { return tokens; }
+            }
+        }
+
+        private IEnumerable<Token> ReadLineOfTokens(string prompt, uint maxCount)
+        {
+            var tokenCount = 0;
+
+            foreach (var token in Tokenizer.ParseTokens(_io.ReadLine(prompt)))
+            {
+                if (++tokenCount > maxCount)
+                {
+                    _io.WriteLine("!Extra input ingored");
+                    break;
+                }
+
+                yield return token;
+            }
+        }
+    }
+}