From 1e6aa2975f0f6507a3d64f3dae29fd148b9a6aaf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Wei=C3=9F?= <jan@geheimwerk.de>
Date: Thu, 6 May 2021 14:06:27 +0200
Subject: [PATCH] Add negative zero support.

---
 Formatters/SecondsFormatter.m                 |  8 ++++++--
 SecondsFormatterTests/SecondsFormatterTests.m |  3 ++-
 Window/TimeField.m                            | 11 +++++++----
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/Formatters/SecondsFormatter.m b/Formatters/SecondsFormatter.m
index 7c9036c86..4b7bcf1c6 100644
--- a/Formatters/SecondsFormatter.m
+++ b/Formatters/SecondsFormatter.m
@@ -34,7 +34,7 @@
 	if (isnan(floatValue)) { return @"NaN"; }
 	if (isinf(floatValue)) { return @"Inf"; }
 	
-	BOOL isNegative = floatValue < 0;
+	BOOL isNegative = signbit(floatValue);
 
 	int totalSeconds = (int)(isNegative ? -floatValue : floatValue);
 	
@@ -191,7 +191,11 @@
 	const BOOL result = (malformed == NO);
 	
 	if (result && NULL != object) {
-		*object = [NSNumber numberWithInt:seconds];
+		NSTimeInterval timeInterval = (NSTimeInterval)seconds;
+		// NOTE: The floating point standard has support for negative zero.
+		// We use that to represent the parsing result without information loss.
+		if (isNegative && (timeInterval == 0.0)) { timeInterval = -0.0; }
+		*object = @(timeInterval);
 	}
 	else if(NULL != error) {
 		*error = @"Couldn't convert value to seconds";
diff --git a/SecondsFormatterTests/SecondsFormatterTests.m b/SecondsFormatterTests/SecondsFormatterTests.m
index 56e1b5069..108c54180 100644
--- a/SecondsFormatterTests/SecondsFormatterTests.m
+++ b/SecondsFormatterTests/SecondsFormatterTests.m
@@ -32,7 +32,7 @@
 	NSDictionary *testsDict =
 	@{
 		// key: test name, value: test string
-		//@"Example": @"0:00",
+		@"Zero": @"0:00",
 		@"One Second": @"0:01",
 		@"One Minute": @"1:00",
 		@"One Hour": @"1:00:00",
@@ -62,6 +62,7 @@
 	NSDictionary *testsDict =
 	@{
 		// key: test name, value: test string
+		@"Negative Zero": @"-0:00",
 		@"Negative One Second": @"-0:01",
 		@"Negative One Minute": @"-1:00",
 		@"Negative One Hour": @"-1:00:00",
diff --git a/Window/TimeField.m b/Window/TimeField.m
index 832414376..277ad90cf 100644
--- a/Window/TimeField.m
+++ b/Window/TimeField.m
@@ -10,9 +10,9 @@
 
 static NSString *kTimerModeKey = @"timerShowTimeRemaining";
 
-NSString * timeStringForTimeInterval(NSTimeInterval timeInterval, BOOL enforceMinusSign) {
+NSString * timeStringForTimeInterval(NSTimeInterval timeInterval) {
 	const int64_t signed_total_seconds = (int64_t)timeInterval;
-	const bool need_minus_sign = enforceMinusSign || signed_total_seconds < 0;
+	const bool need_minus_sign = signbit(timeInterval);
 	const int64_t total_seconds = (need_minus_sign ? -1 : 1) * signed_total_seconds;
 	const int64_t seconds = total_seconds % 60;
 	const int64_t total_minutes = (total_seconds - seconds) / 60;
@@ -74,12 +74,15 @@ NSString * timeStringForTimeInterval(NSTimeInterval timeInterval, BOOL enforceMi
     if (showTimeRemaining == NO)
     {
 		NSTimeInterval sec = self.currentTime;
-        text = timeStringForTimeInterval(sec, NO);
+        text = timeStringForTimeInterval(sec);
     }
     else
     {
 		NSTimeInterval sec = self.currentTime - self.duration;
-		text = timeStringForTimeInterval(sec, YES);
+		// NOTE: The floating point standard has support for negative zero.
+		// We use that to enforce the sign prefix.
+		if (sec == 0.0) { sec = -0.0; }
+		text = timeStringForTimeInterval(sec);
     }
     NSAttributedString *string = [[NSAttributedString alloc] initWithString:text
                                                                  attributes:fontAttributes];