Refactor pattern matching to be static & stand alone

src/DocoptNet/Argument.cs

@@ -1,7 +1,6 @@
 namespace DocoptNet
 {
     using System.Collections;
-    using System.Collections.Generic;
 
     class Argument: LeafPattern
     {
@@ -24,16 +23,6 @@ public Argument(string name, int value)
         {
         }
 
-        public override (int Index, LeafPattern Match) SingleMatch(IList<LeafPattern> left)
-        {
-            for (var i = 0; i < left.Count; i++)
-            {
-                if (left[i] is Argument arg)
-                    return (i, new Argument(Name, arg.Value));
-            }
-            return default;
-        }
-
         public override Node ToNode()
         {
             return new ArgumentNode(this.Name, (this.Value != null && this.Value.IsList) ? ValueType.List : ValueType.String);

src/DocoptNet/BranchPattern.cs → src/DocoptNet/BranchPatterns.cs

@@ -9,7 +9,6 @@ namespace DocoptNet
     /// </summary>
     class BranchPattern : Pattern
     {
-
         public BranchPattern(params Pattern[] children)
         {
             if (children == null) throw new ArgumentNullException(nameof(children));
@@ -38,4 +37,27 @@ public override string ToString()
             return string.Format("{0}({1})", GetType().Name, string.Join(", ", Children.Select(c => c == null ? "None" : c.ToString())));
         }
     }
+
+    class Required : BranchPattern
+    {
+        public Required(params Pattern[] patterns) : base(patterns) { }
+    }
+
+    class Optional : BranchPattern
+    {
+        public Optional(params Pattern[] patterns) : base(patterns) { }
+    }
+
+    // Marker/placeholder for [options] shortcut.
+    class OptionsShortcut : Optional { }
+
+    class Either : BranchPattern
+    {
+        public Either(params Pattern[] patterns) : base(patterns) { }
+    }
+
+    class OneOrMore : BranchPattern
+    {
+        public OneOrMore(params Pattern[] patterns) : base(patterns) { }
+    }
 }

src/DocoptNet/Command.cs

@@ -1,27 +1,11 @@
 namespace DocoptNet
 {
-    using System.Collections.Generic;
-
     class Command : Argument
     {
         public Command(string name, ValueObject value = null) : base(name, value ?? new ValueObject(false))
         {
         }
 
-        public override (int Index, LeafPattern Match) SingleMatch(IList<LeafPattern> left)
-        {
-            for (var i = 0; i < left.Count; i++)
-            {
-                if (left[i] is Argument arg)
-                {
-                    if (arg.Value.ToString() == Name)
-                        return (i, new Command(Name, new ValueObject(true)));
-                    break;
-                }
-            }
-            return default;
-        }
-
         public override Node ToNode() { return new CommandNode(this.Name); }
 
         public override string GenerateCode()

src/DocoptNet/Docopt.cs

@@ -52,7 +52,7 @@ protected IDictionary<string, ValueObject> Apply(string doc, Tokens tokens,
                     optionsShortcut.Children = docOptions.Distinct().Except(patternOptions).ToList();
                 }
                 Extras(help, version, arguments, doc);
-                if (pattern.Fix().Match(arguments) is (true, { Count: 0 }, _) res)
+                if (pattern.Fix().Match(arguments, null) is (true, { Count: 0 }, _) res)
                 {
                     var dict = new Dictionary<string, ValueObject>();
                     foreach (var p in pattern.Flat().OfType<LeafPattern>())

src/DocoptNet/LeafPattern.cs

@@ -38,46 +38,6 @@ public override ICollection<Pattern> Flat(params Type[] types)
             return new Pattern[] {};
         }
 
-        public virtual (int Index, LeafPattern Match) SingleMatch(IList<LeafPattern> patterns)
-        {
-            return default;
-        }
-
-        public override MatchResult Match(IList<LeafPattern> left,
-                                          IEnumerable<LeafPattern> collected = null)
-        {
-            var coll = collected ?? new List<LeafPattern>();
-            var (index, match) = SingleMatch(left);
-            if (match == null)
-            {
-                return new MatchResult(false, left, coll);
-            }
-            var left_ = new List<LeafPattern>();
-            left_.AddRange(left.Take(index));
-            left_.AddRange(left.Skip(index + 1));
-            var sameName = coll.Where(a => a.Name == Name).ToList();
-            if (Value != null && (Value.IsList || Value.IsOfTypeInt))
-            {
-                var increment = new ValueObject(1);
-                if (!Value.IsOfTypeInt)
-                {
-                    increment = match.Value.IsString ? new ValueObject(new [] {match.Value})  : match.Value;
-                }
-                if (sameName.Count == 0)
-                {
-                    match.Value = increment;
-                    var res = new List<LeafPattern>(coll) {match};
-                    return new MatchResult(true, left_, res);
-                }
-                sameName[0].Value.Add(increment);
-                return new MatchResult(true, left_, coll);
-            }
-            var resColl = new List<LeafPattern>();
-            resColl.AddRange(coll);
-            resColl.Add(match);
-            return new MatchResult(true, left_, resColl);
-        }
-
         public override string ToString()
         {
             return string.Format("{0}({1}, {2})", GetType().Name, Name, Value);

src/DocoptNet/Option.cs

@@ -1,7 +1,6 @@
 namespace DocoptNet
 {
     using System;
-    using System.Collections.Generic;
     using System.Text.RegularExpressions;
 
     class Option : LeafPattern
@@ -48,16 +47,6 @@ public override string GenerateCode()
             return string.Format("public string {0} {{ get {{ return null == _args[\"{1}\"] ? {2} : _args[\"{1}\"].ToString(); }} }}", s, Name, defaultValue);
         }
 
-        public override (int Index, LeafPattern Match) SingleMatch(IList<LeafPattern> left)
-        {
-            for (var i = 0; i < left.Count; i++)
-            {
-                if (left[i].Name == Name)
-                    return (i, left[i]);
-            }
-            return default;
-        }
-
         public override string ToString()
         {
             return string.Format("Option({0},{1},{2},{3})", ShortName, LongName, ArgCount, Value);

src/DocoptNet/Pattern.cs

@@ -173,12 +173,6 @@ public static Either Transform(Pattern pattern)
             return new Either(result.Select(r => new Required(r.ToArray()) as Pattern).ToArray());
         }
 
-        public virtual MatchResult Match(IList<LeafPattern> left,
-                                         IEnumerable<LeafPattern> collected = null)
-        {
-            return new MatchResult();
-        }
-
         public abstract ICollection<Pattern> Flat(params Type[] types);
 
         /// <summary>