copied some google-cloud-go/civil Time methods into iso8601 package

iso8601/time.go

@@ -4,6 +4,7 @@ import (
 	"encoding"
 	"fmt"
 	"math"
+	"time"
 
 	"github.com/Code-Hex/synchro/internal/constraints"
 )
@@ -24,6 +25,15 @@ var _ interface {
 	encoding.TextUnmarshaler
 } = (*Time)(nil)
 
+// TimeOf returns the Time representing the time of day in which a time occurs
+// in that time's location. It ignores the date.
+func TimeOf(t time.Time) Time {
+	var tm Time
+	tm.Hour, tm.Minute, tm.Second = t.Clock()
+	tm.Nanosecond = t.Nanosecond()
+	return tm
+}
+
 // String returns the ISO8601 string representation of the format "hh:mm:dd".
 // For example: "12:59:59.123456789".
 func (t Time) String() string {
@@ -39,6 +49,25 @@ func (t Time) IsZero() bool {
 	return (t.Hour == 0) && (t.Minute == 0) && (t.Second == 0) && (t.Nanosecond == 0)
 }
 
+// Before reports whether t occurs before t2.
+func (t Time) Before(t2 Time) bool {
+	if t.Hour != t2.Hour {
+		return t.Hour < t2.Hour
+	}
+	if t.Minute != t2.Minute {
+		return t.Minute < t2.Minute
+	}
+	if t.Second != t2.Second {
+		return t.Second < t2.Second
+	}
+	return t.Nanosecond < t2.Nanosecond
+}
+
+// After reports whether t occurs after t2.
+func (t Time) After(t2 Time) bool {
+	return t2.Before(t)
+}
+
 // MarshalText implements the encoding.TextMarshaler interface.
 // The output is the result of t.String().
 func (t Time) MarshalText() ([]byte, error) {

iso8601/time_test.go

@@ -854,3 +854,51 @@ func TestTimeJSON(t *testing.T) {
 		})
 	}
 }
+
+func TestTimeOf(t *testing.T) {
+	for _, test := range []struct {
+		time time.Time
+		want Time
+	}{
+		{time.Date(2014, 8, 20, 15, 8, 43, 1, time.Local), Time{15, 8, 43, 1}},
+		{time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC), Time{0, 0, 0, 0}},
+	} {
+		if got := TimeOf(test.time); got != test.want {
+			t.Errorf("TimeOf(%v) = %+v, want %+v", test.time, got, test.want)
+		}
+	}
+}
+
+func TestTimeBefore(t *testing.T) {
+	for _, test := range []struct {
+		t1, t2 Time
+		want   bool
+	}{
+		{Time{12, 0, 0, 0}, Time{14, 0, 0, 0}, true},
+		{Time{12, 20, 0, 0}, Time{12, 30, 0, 0}, true},
+		{Time{12, 20, 10, 0}, Time{12, 20, 20, 0}, true},
+		{Time{12, 20, 10, 5}, Time{12, 20, 10, 10}, true},
+		{Time{12, 20, 10, 5}, Time{12, 20, 10, 5}, false},
+	} {
+		if got := test.t1.Before(test.t2); got != test.want {
+			t.Errorf("%v.Before(%v): got %t, want %t", test.t1, test.t2, got, test.want)
+		}
+	}
+}
+
+func TestTimeAfter(t *testing.T) {
+	for _, test := range []struct {
+		t1, t2 Time
+		want   bool
+	}{
+		{Time{12, 0, 0, 0}, Time{14, 0, 0, 0}, false},
+		{Time{12, 20, 0, 0}, Time{12, 30, 0, 0}, false},
+		{Time{12, 20, 10, 0}, Time{12, 20, 20, 0}, false},
+		{Time{12, 20, 10, 5}, Time{12, 20, 10, 10}, false},
+		{Time{12, 20, 10, 5}, Time{12, 20, 10, 5}, false},
+	} {
+		if got := test.t1.After(test.t2); got != test.want {
+			t.Errorf("%v.After(%v): got %t, want %t", test.t1, test.t2, got, test.want)
+		}
+	}
+}