chore: import upstream snapshot with attribution

server/functions/age.go

@@ -0,0 +1,122 @@
+// Copyright 2024 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package functions
+
+import (
+	"time"
+
+	"github.com/dolthub/go-mysql-server/sql"
+
+	"github.com/dolthub/doltgresql/postgres/parser/duration"
+	"github.com/dolthub/doltgresql/server/functions/framework"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// initAge registers the functions to the catalog.
+func initAge() {
+	framework.RegisterFunction(age_timestamp_timestamp)
+	framework.RegisterFunction(age_timestamp)
+}
+
+// age_timestamp_timestamp represents the PostgreSQL date/time function.
+var age_timestamp_timestamp = framework.Function2{
+	Name:               "age",
+	Return:             pgtypes.Interval,
+	Parameters:         [2]*pgtypes.DoltgresType{pgtypes.Timestamp, pgtypes.Timestamp},
+	IsNonDeterministic: true,
+	Strict:             true,
+	Callable: func(ctx *sql.Context, _ [3]*pgtypes.DoltgresType, val1, val2 any) (any, error) {
+		t1 := val1.(time.Time)
+		t2 := val2.(time.Time)
+		return diffTimes(t1, t2), nil
+	},
+}
+
+// age_timestamp_timestamp represents the PostgreSQL date/time function.
+var age_timestamp = framework.Function1{
+	Name:               "age",
+	Return:             pgtypes.Interval,
+	Parameters:         [1]*pgtypes.DoltgresType{pgtypes.Timestamp},
+	IsNonDeterministic: true,
+	Strict:             true,
+	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val any) (any, error) {
+		t := val.(time.Time)
+		// current_date (at midnight)
+		cur, err := time.Parse("2006-01-02", time.Now().Format("2006-01-02"))
+		if err != nil {
+			return nil, err
+		}
+		return diffTimes(cur, t), nil
+	},
+}
+
+// diffTimes returns the duration t1-t2. It subtracts each time component separately,
+// unlike time.Sub() function.
+func diffTimes(t1, t2 time.Time) duration.Duration {
+	// if t1 is before t2, then negate the result.
+	negate := t1.Before(t2)
+	if negate {
+		t1, t2 = t2, t1
+	}
+
+	// Calculate difference in each unit
+	years := int64(t1.Year() - t2.Year())
+	months := int64(t1.Month() - t2.Month())
+	days := int64(t1.Day() - t2.Day())
+	hours := int64(t1.Hour() - t2.Hour())
+	minutes := int64(t1.Minute() - t2.Minute())
+	seconds := int64(t1.Second() - t2.Second())
+	nanoseconds := int64(t1.Nanosecond() - t2.Nanosecond())
+
+	// Adjust for any negative values
+	if nanoseconds < 0 {
+		nanoseconds += 1e9
+		seconds--
+	}
+	if seconds < 0 {
+		seconds += 60
+		minutes--
+	}
+	if minutes < 0 {
+		minutes += 60
+		hours--
+	}
+	if hours < 0 {
+		hours += 24
+		days--
+	}
+	if days < 0 {
+		days += 30
+		months--
+	}
+	if months < 0 {
+		months += 12
+		years--
+	}
+
+	dur := GetIntervalDurationFromTimeComponents(years, months, days, hours, minutes, seconds, nanoseconds)
+	if negate {
+		return dur.Mul(-1)
+	}
+	return dur
+}
+
+func GetIntervalDurationFromTimeComponents(years, months, days, hours, minutes, seconds, nanos int64) duration.Duration {
+	durNanos := nanos + seconds*NanosPerSec + minutes*NanosPerSec*duration.SecsPerMinute + hours*NanosPerSec*duration.SecsPerHour
+	durDays := days
+	durMonths := months + years*duration.MonthsPerYear
+
+	return duration.MakeDuration(durNanos, durDays, durMonths)
+}