Parser.SortTokensInRPN and TokenLinkedList

src/Calculator.fu

@@ -19,8 +19,8 @@ public static class Calculator
             string() tokStr = tok.GetStr();
             Console.WriteLine($"'{tokStr}' {tokType:D1}");
         }
-        Parser() parser = { Tokens = tokens };
+        Parser() parser = { TokenStorage = tokens };
-        IExpression# expr = parser.Parse();
+        IExpression expr = parser.Parse();
         return expr.Calculate();
     }
 }

src/Lexer.fu

@@ -2,7 +2,7 @@ class Lexer
 {
     string ExprStr;
 
-    List<Token()>() tokens;
+    List<Token()>() TokenStorage;
     int tokType = Token.Type_Number;
     int tokBegin = 0;
     int i = 0;
@@ -62,7 +62,7 @@ class Lexer
 
         // end last token
         TryEndToken();
-        return tokens;
+        return TokenStorage;
     }
 
     void TryEndToken!()
@@ -70,8 +70,8 @@ class Lexer
         if (tokBegin != i)
         {
             Token() tok = Token.Create(ExprStr, tokBegin, i - tokBegin, tokType);
-            tokens.Add();
+            TokenStorage.Add();
-            tokens[tokens.Count-1] = tok;
+            TokenStorage[TokenStorage.Count-1] = tok;
             tokType = Token.Type_Number;
             tokBegin = i;
         }
@@ -80,8 +80,8 @@ class Lexer
     void AddStaticToken!(Token() tok)
     {
         TryEndToken();
-        tokens.Add();
+        TokenStorage.Add();
-        tokens[tokens.Count-1] = tok;
+        TokenStorage[TokenStorage.Count-1] = tok;
         tokType = Token.Type_Number;
         tokBegin = ++i;
     }

src/Parser.fu

@@ -1,9 +1,65 @@
 class Parser
 {
-    List<Token()> Tokens;
+    List<Token()> TokenStorage;
+    Stack<Token>() RPNStack;
+    IExpression# RootNode;
+    TokenLinkedList() TokensInRPN;
 
-    internal IExpression# Parse(){
+    internal IExpression# Parse!(){
-        NumericExpression# n = new NumericExpression { N = 1 };
+        SortTokensInRPN();
-        return n;
+        BuildTreeFromRPN();
+        return RootNode;
+    }
+
+    // Implementation of https://en.wikipedia.org/wiki/Shunting_yard_algorithm
+    void SortTokensInRPN!(){
+        for(int i = 0; i < TokenStorage.Count; i++){
+            Token tok = TokenStorage[i];
+            int type = tok.GetType();
+            switch(type){
+                case Token.Type_Number:
+                    TokensInRPN.AddToEnd(tok);
+                    break;
+                case Token.Type_OperatorPow:
+                case Token.Type_OperatorMul:
+                case Token.Type_OperatorDiv:
+                case Token.Type_OperatorMod:
+                case Token.Type_OperatorAdd:
+                case Token.Type_OperatorSub:
+                    while(RPNStack.Count != 0 && RPNStack.Peek().GetType() >= type){
+                        Token op2 = RPNStack.Pop();
+                        TokensInRPN.AddToEnd(op2);
+                    }
+                    RPNStack.Push(tok);
+                    break;
+                case Token.Type_BracketOpen:
+                    RPNStack.Push(tok);
+                    break;
+                case Token.Type_BracketClose:
+                    while(RPNStack.Count != 0){
+                        Token op2 = RPNStack.Pop();
+                        TokensInRPN.AddToEnd(op2);
+                    }
+                    break;
+                case Token.Type_Literal:
+                    // not implemented
+                    assert false;
+                default:
+                    // unexpected token type
+                    assert false;
+            }
+        }
+        
+        // add remaining operators
+        while(RPNStack.Count != 0){
+            Token op2 = RPNStack.Pop();
+            TokensInRPN.AddToEnd(op2);
+        }
+    }
+    
+    void BuildTreeFromRPN!(){
+        RootNode = new NumericExpression { N = 0 };
+        string() graphviz = TokensInRPN.ToGraphVizCode();
+        Console.WriteLine(graphviz);
     }
 }

src/Token.fu

@@ -7,16 +7,16 @@ class Token
     // The Type is also the priority of the token in calculation (see Parser). 
     int Type;
 
-    public const int Type_BracketOpen=1;
+    public const int Type_BracketOpen=10;
-    public const int Type_BracketClose=2;
+    public const int Type_BracketClose=9;
-    public const int Type_OperatorPow=3;
+    public const int Type_OperatorPow=8;
-    public const int Type_OperatorMul=4;
+    public const int Type_OperatorMul=7;
-    public const int Type_OperatorMod=5;
+    public const int Type_OperatorMod=6;
-    public const int Type_OperatorDiv=6;
+    public const int Type_OperatorDiv=5;
-    public const int Type_OperatorAdd=7;
+    public const int Type_OperatorAdd=4;
-    public const int Type_OperatorSub=8;
+    public const int Type_OperatorSub=3;
-    public const int Type_Number=9;
+    public const int Type_Number=2;
-    public const int Type_Literal=10;
+    public const int Type_Literal=1;
 
     internal static Token() Create(string str, int startIndex, int length, int type){
         Token() tok = {

src/TokenLinkedList.fu

@@ -0,0 +1,74 @@
+class TokenLinkedList {
+    TokenLinkedListNode!? FirstNode = null;
+    TokenLinkedListNode!? LastNode = null;
+    List<TokenLinkedListNode()>() Storage;
+
+    internal TokenLinkedListNode! GetFirstNode() => FirstNode;
+    internal TokenLinkedListNode! GetLastNode() => LastNode;
+
+    internal void AddToStart!(Token tok) {
+        TokenLinkedListNode! node = CreateOrphanedNode(tok);
+        if(FirstNode == null){
+            assert LastNode == null; 
+            FirstNode = node;
+            LastNode = node;
+        }
+        else {
+            assert FirstNode.GetPrev() == null;
+            FirstNode.SetPrev(node);
+            FirstNode = node;
+        }
+    }
+
+    internal void AddToEnd!(Token tok) {
+        TokenLinkedListNode! node = CreateOrphanedNode(tok);
+        if(LastNode == null){
+            assert FirstNode == null;
+            FirstNode = node;
+            LastNode = node;
+        }
+        else {
+            assert LastNode.GetNext() == null;
+            LastNode.SetNext(node);
+            LastNode = node;
+        }
+    }
+
+    internal TokenLinkedListNode# CreateOrphanedNode!(Token tok) {
+        TokenLinkedListNode# sharedPtr = new TokenLinkedListNode { 
+            Value = tok, 
+            Prev = null, 
+            Next = null 
+        };
+        return sharedPtr;
+    }
+
+    // Can be used by GraphViz to create node graph.
+    // GraphViz online: https://dreampuf.github.io/GraphvizOnline/  
+    internal string() ToGraphVizCode() {
+        string() s = "strict digraph {\n" +  /* directed graph with no multi-edges */
+            "    start [shape=Mdiamond];\n" + /* 'start' node style */
+            "    end [shape=Msquare];\n" + /* 'end' node style */
+            "    node [style=filled,color=white];\n";  /* regular node style */
+        
+        TokenLinkedListNode? currentNode = null;
+        TokenLinkedListNode? nextNode = FirstNode;
+        string() currentNodeName = "start";
+        // enumerating the tree from FirstNode
+        while(nextNode != null){
+            string() nextTokStr = nextNode.GetValue().GetStr();
+            string() nextNodeName =  "\"";
+            nextNodeName += nextTokStr;
+            nextNodeName += "\"";
+            s += $"    {currentNodeName} -> {nextNodeName};\n";
+
+            currentNodeName = nextNodeName;
+            currentNode = nextNode;
+            nextNode = currentNode.GetNext();
+        }
+        if(currentNode == LastNode)
+            s += $"    {currentNodeName} -> end;\n";
+        s += "}";
+        return s;
+    }
+}

src/TokenLinkedListNode.fu

@@ -0,0 +1,26 @@
+class TokenLinkedListNode {
+    Token Value;
+    TokenLinkedListNode!? Prev = null;
+    TokenLinkedListNode!? Next = null;
+
+    internal Token GetValue() => Value;
+    internal void SetValue!(Token value) { Value = value; }
+
+    internal TokenLinkedListNode!? GetPrev() => Prev;
+    internal void SetPrev!(TokenLinkedListNode! prev) { Prev = prev; }
+
+    internal TokenLinkedListNode!? GetNext() => Next;
+    internal void SetNext!(TokenLinkedListNode! next) { Next = next; }
+
+    internal void InsertAfter!(TokenLinkedListNode! prev){
+        Next = prev.GetNext();
+        Prev = prev;
+        prev.SetNext(this);
+    }
+    
+    internal void InsertBefore!(TokenLinkedListNode! next){
+        Next = next;
+        Prev = next.GetPrev();
+        next.SetPrev(this);
+    }
+}