From c2e63f92904286095d74b3d76a2cccaacecdbb26 Mon Sep 17 00:00:00 2001
From: Tomasz Sowa <t.sowa@ttmath.org>
Date: Thu, 31 Jan 2019 20:56:40 +0000
Subject: [PATCH] added: to Date: support for parsing timezone offsets

git-svn-id: svn://ttmath.org/publicrep/pikotools/trunk@1168 e52654a7-88a9-db11-a3e9-0013d4bc506e
---
 date/date.cpp |  2 +-
 date/date.h   | 84 +++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 79 insertions(+), 7 deletions(-)

diff --git a/date/date.cpp b/date/date.cpp
index 75277a2..1e79c39 100644
--- a/date/date.cpp
+++ b/date/date.cpp
@@ -5,7 +5,7 @@
  */
 
 /* 
- * Copyright (c) 2012, Tomasz Sowa
+ * Copyright (c) 2012-2018, Tomasz Sowa
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
diff --git a/date/date.h b/date/date.h
index b891413..f17b7ab 100644
--- a/date/date.h
+++ b/date/date.h
@@ -415,6 +415,11 @@ public:
 	template<class StringType>
 	bool ParseHourMin(const StringType & str);
 
+	template<class CStringType>
+	bool ParseZoneOffset(const CStringType * str, const CStringType ** str_after = 0);
+
+	template<class StringType>
+	bool ParseZoneOffset(const StringType & str);
 
 	/*
 		parsing hour and minutes (if exists) and seconds (if exists)
@@ -507,7 +512,7 @@ private:
 	void SkipWhite(const CStringType * & str);
 
 	template<class CStringType>
-	bool ReadInt(const CStringType * & str, int & result);
+	bool ReadInt(const CStringType * & str, int & result, size_t max_digits = 0);
 
 	template<class CStringType>
 	bool SkipSeparator(const CStringType * & str, int separator, int separator2 = -1, int separator3 = -1);
@@ -720,6 +725,67 @@ bool Date::ParseHourMin(const StringType & str)
 }
 
 
+template<class CStringType>
+bool Date::ParseZoneOffset(const CStringType * str, const CStringType ** str_after)
+{
+	bool result = false;
+	bool is_sign = false;
+	int offset_hour = 0;
+	int offset_min = 0;
+
+	SkipWhite(str);
+
+	if( *str == '-' || *str == '+' )
+	{
+		if( *str == '-' )
+			is_sign = true;
+
+		str += 1;
+
+		if( ReadInt(str, offset_hour, 2) && offset_hour >= -12 && offset_hour <= 14 )
+		{
+			SkipWhite(str);
+			SetAfter(str, str_after);
+
+			if( *str == ':' )
+			{
+				str += 1;
+				SkipWhite(str);
+				SetAfter(str, str_after);
+			}
+
+			if( ReadInt(str, offset_min, 2) && offset_min > -60 && offset_min < 60 )
+			{
+				SetAfter(str, str_after);
+			}
+			else
+			{
+				offset_min = 0;
+			}
+
+			time_t offset = (time_t)offset_hour * 60 * 60 + (time_t)offset_min * 60;
+			result = true;
+
+			if( is_sign )
+				offset = -offset;
+
+			FromTime(ToTime() - offset);
+		}
+	}
+
+return result;
+}
+
+
+template<class StringType>
+bool Date::ParseZoneOffset(const StringType & str)
+{
+	return ParseZoneOffset(str.c_str());
+}
+
+
+
+
 
 template<class CStringType>
 bool Date::ParseTime(const CStringType * str, const CStringType ** str_after)
@@ -801,7 +867,6 @@ bool Date::Parse(const CStringType * str, const CStringType ** str_after)
 {
 const CStringType * after;
 bool result = false;
-bool is_iso = false;
 
 	if( ParseYearMonthDay(str, &after) )
 	{
@@ -813,17 +878,22 @@ bool is_iso = false;
 			// https://en.wikipedia.org/wiki/ISO_8601
 			// at the moment skip the 'T' character only
 			after += 1;
-			is_iso = true;
 		}
 
 		if( ParseHourMinSec(after, &after) )
 		{
+			SkipWhite(after);
 			result = true;
 
-			if( is_iso && *after == 'Z' )
+			if( *after == 'Z' )
 			{
 				after += 1;
 			}
+			else
+			{
+				// we dont have to check errors here
+				ParseZoneOffset(after, &after);
+			}
 		}
 	}
 
@@ -864,17 +934,19 @@ void Date::SkipWhite(const CStringType * & str)
 
 
 template<class CStringType>
-bool Date::ReadInt(const CStringType * & str, int & result)
+bool Date::ReadInt(const CStringType * & str, int & result, size_t max_digits)
 {
 bool something_read = false;
 
 	SkipWhite(str);
 	result = 0;
+	size_t len = 0;
 
-	while( *str >= '0' && *str <= '9' )
+	while( *str >= '0' && *str <= '9' && (max_digits == 0 || len < max_digits))
 	{
 		result = result * 10 + (*str - '0');
 		str += 1;
+		len += 1;
 		something_read = true;
 
 		if( result > 10000 )