Add common deconstruct procedure to PABCSystem

Patterns/Desugaring-v2.pas

@@ -0,0 +1,21 @@
+// Source
+match e with
+    Person(var value): <ACTION>
+end;
+
+// Desugared code
+
+var <>genVar: Person;
+if IsTest(e, <>genVar) then
+begin
+  // always the same code
+  var value: ?; // should be filled during semantic analysis
+  <>genVar.Deconstruct(value);
+  
+  <ACTION>
+end;
+
+{
+info we need to fill the tree:
+1. Syntactic nodes of parameters' types    
+} 

Patterns/Desugaring.pas

@@ -0,0 +1,45 @@
+// Source
+match e with
+    Person(var value): <ACTION>
+end;
+
+// Desugared code
+
+var <>genVar: Person;
+if IsTest(e, <>genVar) then
+begin
+  // one of 3 cases
+  
+  // *********************************************************
+  
+  // 1 - instance deconstruct
+  var value: ?; // should be filled during semantic analysis
+  <>genVar.Deconstruct(value);
+  
+  // 2 - extension deconstruct
+  var value: ?; // should be filled during semantic analysis
+  PersonExt.Deconstruct(<>genVar, value);
+  
+  // 3 - typecast - when there's only one deconstruction parameter and no Deconstruct methods were found
+  var value := <>genVar;
+  
+  // *********************************************************
+  
+  <ACTION>
+end;
+
+{
+info we need to fill the tree:
+1. Method type (instance or static) and a qualifier if static
+2. Syntactic nodes of parameters' types
+
+General: how to get the type of expression
+
+case 1:
+How to check if a certain type has instance method with given name - option 1
+Save information about all Deconstruct methods during creation of a semantic tree - option 2
+
+case 2:
+
+    
+} 

SyntaxTree/tree/TreeHelper.cs

@@ -88,9 +88,9 @@ namespace PascalABCCompiler.SyntaxTree
         /// </summary>
         /// <param name="from">Исходное значение</param>
         /// <param name="to">Новое значение</param>
-        public void RenameIdentifierInDescendants(string from, string to)
+        public void RenameIdentifierInDescendants(string from, string to, bool includingThis = true)
         {
-            foreach (var identifier in DescendantNodes().OfType<ident>().Where(x => x.name == from))
+            foreach (var identifier in DescendantNodes(TraversalType.PostOrder, null, includingThis).OfType<ident>().Where(x => x.name == from))
                 identifier.name = to;
         }
 

TreeConverter/TreeConversion/syntax_tree_visitor.cs

@@ -19318,4 +19318,4 @@ namespace PascalABCCompiler.TreeConverter
 
         
     }
-}
+}

bin/Lib/PABCSystem.pas

@@ -1843,6 +1843,7 @@ function KV<TKey, TVal>(key: TKey; value: TVal): KeyValuePair<TKey, TVal>;
 // -----------------------------------------------------
 //>>     Вспомогательные функции для pattern matching
 // -----------------------------------------------------
+
 function IsTest<T>(obj: object; var res: T): boolean;
 
 //{{{--doc: Конец секции интерфейса для документации }}} 
@@ -4205,7 +4206,6 @@ begin
   Result := new KeyValuePair<TKey, TVal>(key, value);
 end;
 
-
 function IsTest<T>(obj: object; var res: T): boolean;
 begin
   if obj is T then
@@ -4220,6 +4220,11 @@ begin
   end;
 end;
 
+procedure Deconstruct<T>(self: T; var res: T); extensionmethod;
+begin
+  res := self;
+end;
+
 {function read_lexem: string; 
 var
   c: char;