From 57c31ec43565cb39d796bbf3592afcd6ef08fb0f Mon Sep 17 00:00:00 2001
From: jackfiled <xcrenchangjun@outlook.com>
Date: Tue, 30 Jul 2024 14:35:03 +0800
Subject: [PATCH] fix: strip unused information and some operator override

---
 .../DeterministicFiniteAutomation.cs          | 21 ++++++-
 .../LexicalAnalyzer/LexicalScannerBuilder.cs  | 55 ++++++++++++++++++-
 .../LexicalAnalyzer/LexicalToken.cs           | 10 ++--
 .../LexicalAnalyzer/RegularExpression.cs      |  6 ++
 4 files changed, 81 insertions(+), 11 deletions(-)

diff --git a/CanonSharp.Common/LexicalAnalyzer/DeterministicFiniteAutomation.cs b/CanonSharp.Common/LexicalAnalyzer/DeterministicFiniteAutomation.cs
index eaf844f..bd789ff 100644
--- a/CanonSharp.Common/LexicalAnalyzer/DeterministicFiniteAutomation.cs
+++ b/CanonSharp.Common/LexicalAnalyzer/DeterministicFiniteAutomation.cs
@@ -1,12 +1,27 @@
 namespace CanonSharp.Common.LexicalAnalyzer;
 
-public class DeterministicState(HashSet<NondeterministicState> closure) : IEquatable<DeterministicState>
+public class DeterministicState : IEquatable<DeterministicState>
 {
-    public Guid Id { get; } = Guid.NewGuid();
+    public Guid Id { get; }
 
     public Dictionary<char, DeterministicState> Transaction { get; } = [];
 
-    public HashSet<NondeterministicState> Closure { get; } = closure;
+    public HashSet<NondeterministicState> Closure { get; }
+
+    public DeterministicState(HashSet<NondeterministicState> closure)
+    {
+        Id = Guid.NewGuid();
+        Closure = closure;
+    }
+
+    private DeterministicState(DeterministicState state)
+    {
+        Id = state.Id;
+        Transaction = state.Transaction;
+        Closure = [];
+    }
+
+    public DeterministicState StripClosure() => new(this);
 
     public bool Equals(DeterministicState? other) => other is not null && Id.Equals(other.Id);
 
diff --git a/CanonSharp.Common/LexicalAnalyzer/LexicalScannerBuilder.cs b/CanonSharp.Common/LexicalAnalyzer/LexicalScannerBuilder.cs
index 5cdf402..c04c872 100644
--- a/CanonSharp.Common/LexicalAnalyzer/LexicalScannerBuilder.cs
+++ b/CanonSharp.Common/LexicalAnalyzer/LexicalScannerBuilder.cs
@@ -24,6 +24,30 @@ public class LexicalScannerBuilder
         }
     }
 
+    /// <summary>
+    /// 定义词法令牌
+    /// </summary>
+    /// <param name="expression">该令牌的正则表达式</param>
+    /// <param name="priority">识别该令牌的优先级</param>
+    /// <returns>定义好的词法令牌</returns>
+    public LexicalToken DefineToken(RegularExpression expression, int priority)
+    {
+        LexicalToken token = new(expression, priority);
+        DefineToken(token);
+        return token;
+    }
+
+    /// <summary>
+    /// 定义输出时需要跳过的词法令牌
+    /// </summary>
+    /// <param name="expression">该令牌的正则表达式</param>
+    /// <param name="priority">该令牌的优先级</param>
+    public void DefineSkippedToken(RegularExpression expression, int priority)
+    {
+        LexicalToken token = DefineToken(expression, priority);
+        AddSkippedToken(token);
+    }
+
     public void AddSkippedToken(LexicalToken token) => _skippedTokens.Add(token);
 
     public LexicalScanner Build(ISourceReader reader)
@@ -36,14 +60,41 @@ public class LexicalScannerBuilder
 
         foreach (DeterministicState state in deterministicFiniteAutomation.FinalStates)
         {
-            finalTokenMap.Add(state, state.Closure
+            finalTokenMap.Add(state.StripClosure(), state.Closure
                 .Where(s => _finalStateMap.ContainsKey(s))
                 .Select(s => _finalStateMap[s])
                 .OrderByDescending(t => t.Priority)
                 .First());
         }
 
-        return new LexicalScanner(deterministicFiniteAutomation.Start, finalTokenMap, _skippedTokens, reader);
+        // 清除在分析中不需要的Closure引用
+        // 释放内存占用
+        Queue<DeterministicState> queue = [];
+        HashSet<DeterministicState> visited = [deterministicFiniteAutomation.Start];
+        DeterministicState strippedStartState = deterministicFiniteAutomation.Start.StripClosure();
+        queue.Enqueue(strippedStartState);
+
+        while (queue.TryDequeue(out DeterministicState? state))
+        {
+            Dictionary<char, DeterministicState> transactions = [];
+
+            foreach (KeyValuePair<char,DeterministicState> pair in state.Transaction)
+            {
+                transactions.Add(pair.Key, pair.Value.StripClosure());
+            }
+
+            state.Transaction.Clear();
+            foreach (KeyValuePair<char,DeterministicState> pair in transactions)
+            {
+                state.Transaction.Add(pair.Key, pair.Value);
+                if (visited.Add(pair.Value))
+                {
+                    queue.Enqueue(pair.Value);
+                }
+            }
+        }
+
+        return new LexicalScanner(strippedStartState, finalTokenMap, _skippedTokens, reader);
     }
 
     private NondeterministicFiniteAutomation Combine()
diff --git a/CanonSharp.Common/LexicalAnalyzer/LexicalToken.cs b/CanonSharp.Common/LexicalAnalyzer/LexicalToken.cs
index e6be9eb..71d97d9 100644
--- a/CanonSharp.Common/LexicalAnalyzer/LexicalToken.cs
+++ b/CanonSharp.Common/LexicalAnalyzer/LexicalToken.cs
@@ -42,15 +42,13 @@ public class LexicalToken : IEquatable<LexicalToken>
     /// 匹配所有的空白字符
     /// </summary>
     public static readonly LexicalToken WhiteSpace = new(
-        RegularExpression.Alternate(
-            RegularExpression.CharSetOf(c => char.GetUnicodeCategory(c) == UnicodeCategory.SpaceSeparator),
-            RegularExpression.CharSetOf("\u0009\u000B\u000C")), int.MinValue);
+        RegularExpression.CharSetOf(c => char.GetUnicodeCategory(c) == UnicodeCategory.SpaceSeparator) |
+        RegularExpression.CharSetOf("\u0009\u000B\u000C"), int.MinValue);
 
     /// <summary>
     /// 匹配所有的换行符
     /// </summary>
     public static readonly LexicalToken LineBreaker = new(
-        RegularExpression.Alternate(
-            RegularExpression.CharSetOf("\u000D\u000A\u0085\u2028\u2029"),
-            RegularExpression.String("\r\n")), int.MinValue);
+            RegularExpression.CharSetOf("\u000D\u000A\u0085\u2028\u2029") |
+            RegularExpression.String("\r\n"), int.MinValue);
 }
diff --git a/CanonSharp.Common/LexicalAnalyzer/RegularExpression.cs b/CanonSharp.Common/LexicalAnalyzer/RegularExpression.cs
index 79a98d8..80e2b3c 100644
--- a/CanonSharp.Common/LexicalAnalyzer/RegularExpression.cs
+++ b/CanonSharp.Common/LexicalAnalyzer/RegularExpression.cs
@@ -26,6 +26,9 @@ public abstract class RegularExpression
     public static RegularExpression Alternate(RegularExpression left, RegularExpression right) =>
         new AlternationExpression(left, right);
 
+    public static RegularExpression operator |(RegularExpression left, RegularExpression right) =>
+        new AlternationExpression(left, right);
+
     /// <summary>
     /// left-right
     /// </summary>
@@ -35,6 +38,9 @@ public abstract class RegularExpression
     public static RegularExpression Concatenate(RegularExpression first, RegularExpression second) =>
         new ConcatenationExpression(first, second);
 
+    public static RegularExpression operator +(RegularExpression left, RegularExpression right) =>
+        new ConcatenationExpression(left, right);
+
     /// <summary>
     /// inner*
     /// </summary>