Flee

2025-10-08 09:49:37 +08:00
commit 284e764345
99 changed files with 21742 additions and 0 deletions
--- a/Parsing/Automaton.cs
+++ b/Parsing/Automaton.cs
@@ -0,0 +1,111 @@
+namespace Flee.Parsing
+{
+    internal class Automaton
+    {
+        private object _value;
+        private readonly AutomatonTree _tree = new AutomatonTree();
+
+        public Automaton()
+        {
+        }
+
+        public void AddMatch(string str, bool caseInsensitive, object value)
+        {
+            if (str.Length == 0)
+            {
+                this._value = value;
+            }
+            else
+            {
+                var state = _tree.Find(str[0], caseInsensitive);
+                if (state == null)
+                {
+                    state = new Automaton();
+                    state.AddMatch(str.Substring(1), caseInsensitive, value);
+                    _tree.Add(str[0], caseInsensitive, state);
+                }
+                else
+                {
+                    state.AddMatch(str.Substring(1), caseInsensitive, value);
+                }
+            }
+        }
+
+        public object MatchFrom(LookAheadReader input, int pos, bool caseInsensitive)
+        {
+
+            object result = null;
+            Automaton state = null;
+            int c = 0;
+
+            c = input.Peek(pos);
+            if (_tree != null && c >= 0)
+            {
+                state = _tree.Find(Convert.ToChar(c), caseInsensitive);
+                if (state != null)
+                {
+                    result = state.MatchFrom(input, pos + 1, caseInsensitive);
+                }
+            }
+            return result ?? _value;
+        }
+    }
+
+    // * An automaton state transition tree. This class contains a 
+    // * binary search tree for the automaton transitions from one state 
+    // * to another. All transitions are linked to a single character. 
+    internal class AutomatonTree
+    {
+        private char _value;
+        private Automaton _state;
+        private AutomatonTree _left;
+        private AutomatonTree _right;
+
+        public AutomatonTree()
+        {
+        }
+
+        public Automaton Find(char c, bool lowerCase)
+        {
+            if (lowerCase)
+            {
+                c = Char.ToLower(c);
+            }
+            if (_value == (char)0 || _value == c)
+            {
+                return _state;
+            }
+            else if (_value > c)
+            {
+                return _left.Find(c, false);
+            }
+            else
+            {
+                return _right.Find(c, false);
+            }
+        }
+
+        public void Add(char c, bool lowerCase, Automaton state)
+        {
+            if (lowerCase)
+            {
+                c = Char.ToLower(c);
+            }
+            if (_value == (char)0)
+            {
+                this._value = c;
+                this._state = state;
+                this._left = new AutomatonTree();
+                this._right = new AutomatonTree();
+            }
+            else if (_value > c)
+            {
+                _left.Add(c, false, state);
+            }
+            else
+            {
+                _right.Add(c, false, state);
+            }
+        }
+    }
+}