rewrite of SearchExpression

ParadoxSaveParser.Lib/SaveParserEU4.cs

@@ -12,17 +12,16 @@ public class SaveParserEU4
 {
     protected Stream _saveFile;
     private BufferedEnumerator<Token> _tokens;
-    private SearchExpression _query;
+    private ISearchExpression? _searchExprCurrent;
-    private int _currentDepth;
     
     /// <param name="savefile">Uncompressed stream of <c>gamestate</c> file which can be extracted from save archive</param>
     /// <param name="query">Parsing whole save takes 10 seconds on mid pc and takes 1GB of RAM,
     /// so you should specify what exactly you want to get from save file</param>
-    public SaveParserEU4(Stream savefile, SearchExpression query)
+    public SaveParserEU4(Stream savefile, ISearchExpression? query)
     {
         _tokens = new BufferedEnumerator<Token>(LexTextSave(), 5);
         _saveFile = savefile;
-        _query = query;
+        _searchExprCurrent = query;
     }
 
     protected enum TokenType : byte
@@ -199,9 +198,7 @@ public class SaveParserEU4
                     return l;
                 return tok.value;
             case TokenType.BracketOpen:
-                _currentDepth++;
                 var obj = ParseListOrDict();
-                _currentDepth--;
                 return obj;
             case TokenType.BracketClose:
                 return null;
@@ -308,15 +305,20 @@ public class SaveParserEU4
             else if (tok.type != TokenType.BracketOpen)
                 throw new UnexpectedTokenException(tok);
 
-            if (!_query.DoesMatch(new SearchArgs(key, _currentDepth, localIndex)))
+            ISearchExpression? searchExprNext = null;
+            if (_searchExprCurrent != null 
+                && !_searchExprCurrent.DoesMatch(new SearchArgs(key, localIndex), out searchExprNext))
             {
                 SkipValue();
                 continue;
             }
 
+            var searExpressionPrevious = _searchExprCurrent;
+            _searchExprCurrent = searchExprNext;
             object? value = ParseValue();
             if (value is null)
                 throw new UnexpectedTokenException(_tokens.Current.Value);
+            _searchExprCurrent = searExpressionPrevious;
             
             if(!dict.TryGetValue(key, out List<object>? list))
             {

ParadoxSaveParser.Lib/SearchExpression.cs

@@ -1,139 +1,141 @@
-using System.Diagnostics;
+namespace ParadoxSaveParser.Lib;
-using System.Linq;
 
-namespace ParadoxSaveParser.Lib;
+public record SearchArgs(string key, int localIndex);
-
-public record SearchArgs(string key, int currentDepth, int localIndex);
 
 public interface ISearchExpression
 {
-    bool DoesMatch(SearchArgs args);
+    bool DoesMatch(SearchArgs args, out ISearchExpression? nextSearchExpression);
 }
 
-public class SearchExpression : ISearchExpression
+public static class SearchExpressionCompiler
 {
-    private List<ISearchExpression> _compiledExpression;
-    private int _expressionDepth;
-
-    private SearchExpression(List<ISearchExpression> compiledExpression, int expressionDepth)
-    {
-        _compiledExpression = compiledExpression;
-        _expressionDepth = expressionDepth;
-    }
-
-    
-    public bool DoesMatch(SearchArgs args)
-    {
-        int index = args.currentDepth - _expressionDepth;
-        if (index < 0 || index >= _compiledExpression.Count)
-            return true;
-
-        return _compiledExpression[index].DoesMatch(args);
-    }
-
-    
     private static bool CharEqualsAndNotEscaped(char c, ReadOnlySpan<char> chars, int i) => 
         chars[i] == c && (i < 1 || chars[i - 1] != '\\') && (i < 2 || chars[i - 2] != '\\');
     
-    public static SearchExpression Parse(string query) => ParseInternal(query, 0);
+    public static ISearchExpression Compile(ReadOnlySpan<char> query)
-    
-    private static SearchExpression ParseInternal(ReadOnlySpan<char> query, int expressionDepth)
     {
-        var compiledExpression = new List<ISearchExpression>();
+        if(query.IsEmpty)
-        ISearchExpression exprPart;
+            throw new ArgumentNullException(nameof(query));
-        int partBegin = 0;
-        int bracketBalance = 0;
-        int expressionDepthIncrement = 0;
         
-        for (int i = 0; i < query.Length; i++)
+        if(query[0] is '(')
+        {
+            var subExprs = new List<ISearchExpression>();
+            int supExprBegin = 1;
+            int bracketBalance = 1;
+            for (int i = supExprBegin; i < query.Length && bracketBalance != 0; i++)
             {
                 if (CharEqualsAndNotEscaped('(', query, i))
                     bracketBalance++;
                 else if (CharEqualsAndNotEscaped(')', query, i))
                     bracketBalance--;
-            else if (bracketBalance == 0 && CharEqualsAndNotEscaped('.', query, i))
+                else if (bracketBalance == 1 && CharEqualsAndNotEscaped('|', query, i))
                 {
-                var part = query.Slice(partBegin, i - partBegin);
+                    var subPart = query.Slice(supExprBegin, i - supExprBegin);
-                expressionDepthIncrement++;
+                    var subExpr = Compile(subPart);
-                exprPart = ParsePart(part, query, partBegin, 
-                    expressionDepth + expressionDepthIncrement);
-                compiledExpression.Add(exprPart);
-                partBegin = i + 1;
-            }
-        }
-
-        exprPart = ParsePart(query.Slice(partBegin), query, partBegin, 
-            expressionDepth + expressionDepthIncrement);
-        compiledExpression.Add(exprPart);
-        
-        return new SearchExpression(compiledExpression, expressionDepth);
-    }
-
-    private static ISearchExpression ParsePart(ReadOnlySpan<char> part, 
-        ReadOnlySpan<char> query, int partBegin, int expressionDepth)
-    {
-        if (part is "*")
-        {
-            return new AnyMatchExpression();
-        }
-        
-        if (CharEqualsAndNotEscaped('[', query, partBegin))
-        {
-            part = part.Slice(1, part.Length - 2);
-            return new IndexMatchExpression(int.Parse(part));
-        }
-        
-        if(part[0] is '(')
-        {
-            var subExprs = new List<ISearchExpression>();
-            ISearchExpression subExpr;
-            part = part.Slice(1, part.Length - 2);
-            int supExprBegin = 0;
-            for (int j = 0; j < part.Length; j++)
-            {
-                if (CharEqualsAndNotEscaped('|', part, j))
-                {
-                    subExpr = ParseInternal(part.Slice(supExprBegin, j - supExprBegin), 
-                        expressionDepth);
                     subExprs.Add(subExpr);
-                    supExprBegin = j + 1;
+                    supExprBegin = i + 1;
                 }
             }
 
-            subExpr = ParseInternal(part.Slice(supExprBegin), expressionDepth);
+            if(query[^1] != ')')
-            subExprs.Add(subExpr);
+                throw new NotImplementedException("Expressions after ')' are not supported");
+            
+            if (bracketBalance > 0)
+                throw new Exception("Too many opening brackets");
+            if (bracketBalance < 0)
+                    throw new Exception("Too many closing brackets");
+            
+            var subPartLast = query.Slice(supExprBegin, query.Length - supExprBegin - 1);
+            var subExprLast = Compile(subPartLast);
+            subExprs.Add(subExprLast);
             return new MultipleMatchExpression(subExprs);
         }
 
-        return new ExactMatchExpression(part.ToString());
+        int partBeforePointLength = 0;
+        while (partBeforePointLength < query.Length)
+        {
+            if(CharEqualsAndNotEscaped('.', query, partBeforePointLength))
+                break;
+            partBeforePointLength++;
+        }
+        var part = query.Slice(0, partBeforePointLength);
+        ReadOnlySpan<char> remaining = default;
+        if (partBeforePointLength < query.Length)
+            remaining = query.Slice(partBeforePointLength + 1);
+        if (part is "*")
+        {
+            return new AnyMatchExpression(remaining.IsEmpty ? null : Compile(remaining));
         }
 
-    private record AnyMatchExpression : ISearchExpression
+        for (int j = 0; j < part.Length; j++)
         {
-        public bool DoesMatch(SearchArgs args) => true;
+            if(CharEqualsAndNotEscaped('*', part, j))
+                throw new NotImplementedException("pattern matching other than '*' is not implemented yet");
+        }
+        
+        if (part[0] is '[')
+        {
+            part = part.Slice(1, part.Length - 2);
+            return new IndexMatchExpression(int.Parse(part), remaining.IsEmpty ? null : Compile(remaining));
+        }
+        
+        return new ExactMatchExpression(part.ToString(), remaining.IsEmpty ? null : Compile(remaining));
+    }
+
+    
+    private record AnyMatchExpression(ISearchExpression? next) : ISearchExpression
+    {
+        public bool DoesMatch(SearchArgs args, out ISearchExpression? nextSearchExpression)
+        {
+            nextSearchExpression = next;
+            return true;
+        }
     }
     
     private record MultipleMatchExpression(List<ISearchExpression> subExprs) : ISearchExpression
     {
-        public bool DoesMatch(SearchArgs args)
+        public bool DoesMatch(SearchArgs args, out ISearchExpression? nextSearchExpression)
         {
             foreach (var e in subExprs)
             {
-                if(e.DoesMatch(args))
+                if(e.DoesMatch(args, out nextSearchExpression))
+                {
                     return true;
                 }
+            }
+            
+            nextSearchExpression = null;
             return false;
         }
     }
 
-    private record IndexMatchExpression(int index) : ISearchExpression
+    private record IndexMatchExpression(int index, ISearchExpression? next) : ISearchExpression
     {
-        public bool DoesMatch(SearchArgs args) => args.localIndex == index;
+        public bool DoesMatch(SearchArgs args, out ISearchExpression? nextSearchExpression)
+        {
+            if (args.localIndex == index)
+            {
+                nextSearchExpression = next;
+                return true;
             }
             
-    private record ExactMatchExpression(string key) : ISearchExpression
+            nextSearchExpression = null;
-    {
+            return false;
-        public bool DoesMatch(SearchArgs args) => args.key == key;
+        }
     }
     
+    private record ExactMatchExpression(string key, ISearchExpression? next) : ISearchExpression
+    {
+        public bool DoesMatch(SearchArgs args, out ISearchExpression? nextSearchExpression)
+        {
+            if (args.key == key)
+            {
+                nextSearchExpression = next;
+                return true;
+            }
+            
+            nextSearchExpression = null;
+            return false;
+        }
+    }
 }

ParadoxSaveParser.WebAPI/Program.Responses.cs

@@ -101,7 +101,7 @@ public partial class Program
             var gamestateStream = File.OpenRead(extractedGamestatePath);
 
             meta.status = SaveFileProcessingStatus.Parsing;
-            var se = SearchExpression.Parse(searchQuery);
+            var se = SearchExpressionCompiler.Compile(searchQuery);
             var parser = new SaveParserEU4(gamestateStream, se);
             var result = parser.Parse();
 

ParadoxSaveParser.WebAPI/Program.cs

@@ -42,8 +42,11 @@ public partial class Program
 
     static void TestSearchExpression(Stream saveStream, TestCase tc)
     {
+        try
+        {
+
             saveStream.Seek(0, SeekOrigin.Begin);
-        var se = SearchExpression.Parse(tc.q);
+            var se = SearchExpressionCompiler.Compile(tc.q);
             var parser = new SaveParserEU4(saveStream, se);
             var rootNode = parser.Parse();
             string json = JsonSerializer.Serialize(rootNode, _saveSerializerOptions);
@@ -56,7 +59,12 @@ public partial class Program
             }
             else
             {
-            Console.WriteLine($"[Error] q:'{tc.q}' a:'{tc.a}' r:'{pdx}'");
+                Console.WriteLine($"[Invalid] q:'{tc.q}' a:'{tc.a}' r:'{pdx}'");
+            }
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine($"[Error] q:'{tc.q}' a:'{tc.a}' e:\n" + ex.ToStringDemystified());
         }
     }