From d1c86c84cfe21260cf622cdb3c1ef3cf6673ca78 Mon Sep 17 00:00:00 2001
From: Tomasz Sowa <t.sowa@ttmath.org>
Date: Wed, 11 Jan 2023 23:06:27 +0100
Subject: [PATCH] fix: allow to use a minus sign in strings with FT::numeric
 flag

---
 src/baseexpression.h | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/baseexpression.h b/src/baseexpression.h
index 3952dce..b8043da 100644
--- a/src/baseexpression.h
+++ b/src/baseexpression.h
@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018-2022, Tomasz Sowa
+ * Copyright (c) 2018-2023, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -795,6 +795,7 @@ protected:
 	{
 		bool was_comma = false;
 		bool was_something_printed = false;
+		bool was_digit_printed = false;
 
 		for(size_t i = 0 ; has_known_length ? (i < len) : val[i] != 0 ; ++i)
 		{
@@ -803,17 +804,30 @@ protected:
 			if( c == ',' )
 				c = '.';
 
-			if( (c=='.' && !was_comma) || (c>='0' && c<='9') )
+			if( (c=='.' && !was_comma) || (c>='0' && c<='9') || (c=='-' && !was_something_printed) )
 			{
+				if( c=='.' )
+				{
+					if( !was_digit_printed )
+					{
+						esc(static_cast<CharType>('0'), stream, field_type, model_env);
+						was_digit_printed = true;
+					}
+
+					was_comma = true;
+				}
+
 				esc(c, stream, field_type, model_env);
 				was_something_printed = true;
 
-				if( c == '.' )
-					was_comma = true;
+				if( c>='0' && c<='9' )
+				{
+					was_digit_printed = true;
+				}
 			}
 		}
 
-		if( !was_something_printed )
+		if( !was_digit_printed )
 		{
 			esc(static_cast<CharType>('0'), stream, field_type, model_env);
 		}