From 726f4f2425ddee6b04926c8f19b0eda41fa91e72 Mon Sep 17 00:00:00 2001
From: Timerix22 <timerix11@gmail.com>
Date: Fri, 22 Dec 2023 23:10:48 +0600
Subject: [PATCH] really implemented negative numbers

---
 src/Lexer.fu  | 13 +++++++------
 src/Parser.fu |  8 --------
 2 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/src/Lexer.fu b/src/Lexer.fu
index 065c6d4..929e499 100644
--- a/src/Lexer.fu
+++ b/src/Lexer.fu
@@ -37,7 +37,7 @@ class Lexer {
     internal List<Token()> Lex!(string exprStr){
         ExprStr = exprStr;
 
-        while (i < ExprStr.Length) {
+        for(i=0; i < ExprStr.Length; i++) {
             switch (ExprStr[i]) {
                 // end token, add new predifined token and move next
                 case '(': AddStaticToken(TokBracketOpen); break;
@@ -47,21 +47,22 @@ class Lexer {
                 case '%': AddStaticToken(TokMod); break;
                 case '/': AddStaticToken(TokDiv); break;
                 case '+': AddStaticToken(TokAdd); break;
-                case '-': AddStaticToken(TokSub); break;
+                case '-': 
+                    if(i != 0 && ExprStr[i-1] != '(')
+                        AddStaticToken(TokSub);
+                    // else '-' is a part of numeric expression
+                    break;
                 // try end token and skip current char
                 case ' ': case '\t': case '\n': case '\r':
                     TryEndToken();
-                    i++;
                     break;
                 // move next
                 case '0': case '1': case '2': case '3': case '4':
                 case '5': case '6': case '7': case '8': case '9':
-                    i++;
                     break;
                 // set type from Numeric to Literal
                 default:
                     tokType = Token.Type_Literal;
-                    i++;
                     break;
             }
         }
@@ -86,6 +87,6 @@ class Lexer {
         TokenStorage.Add();
         TokenStorage[TokenStorage.Count-1] = tok;
         tokType = Token.Type_Number;
-        tokBegin = ++i;
+        tokBegin = i+1;
     }
 }
diff --git a/src/Parser.fu b/src/Parser.fu
index bbbd0a3..3e10c6b 100644
--- a/src/Parser.fu
+++ b/src/Parser.fu
@@ -2,11 +2,9 @@ class Parser {
     List<Token()> TokenStorage;
     IExpression# RootExpression;
     TokenLinkedList() TokensInRPN;
-    Token() TokZero;
 
     internal Parser(){
         RootExpression = new NumericExpression(); // NaN
-        TokZero = Token.Create("0", 0, 1, Token.Type_Number);
     }
 
     internal IExpression# Parse!(List<Token()> tokens){
@@ -26,8 +24,6 @@ class Parser {
     // Implementation of https://en.wikipedia.org/wiki/Shunting_yard_algorithm
     void SortTokensInRPN!(){
         Stack<Token>() RPNStack;
-        // is needed for negative numbers recognition
-        int prevTokType = Token.Type_BracketOpen;
 
         for(int i = 0; i < TokenStorage.Count; i++){
             Token tok = TokenStorage[i];
@@ -43,8 +39,6 @@ class Parser {
                 case Token.Type_OperatorMod:
                 case Token.Type_OperatorAdd:
                 case Token.Type_OperatorSub:
-                    if(type == Token.Type_OperatorSub && prevTokType == Token.Type_BracketOpen)
-                        TokensInRPN.AddToEnd(TokZero);
                     while(RPNStack.Count != 0 && RPNStack.Peek().GetTokType() >= type){
                         Token op2 = RPNStack.Pop();
                         TokensInRPN.AddToEnd(op2);
@@ -69,8 +63,6 @@ class Parser {
                     ThrowError($"unexpected token type '{type}'");
                     break;
             }
-
-            prevTokType = type;
         }
         
         // add remaining operators