initial commit

.gitignore

@@ -0,0 +1 @@
+.env

converters.go

@@ -0,0 +1,89 @@
+package envvars
+
+import (
+	"errors"
+	"strconv"
+	"unicode/utf8"
+)
+
+func ConvertString(s string) (string, error) {
+	return s, nil
+}
+
+func ConvertRune(s string) (rune, error) {
+	rn, _ := utf8.DecodeRuneInString(s)
+	if rn == utf8.RuneError {
+		return 0, errors.New("rune decoding failed")
+	}
+	return rn, nil
+}
+
+func ConvertInt64(s string) (int64, error) {
+	return strconv.ParseInt(s, 10, 64)
+}
+
+func ConvertInt32(s string) (int32, error) {
+	v, err := strconv.ParseInt(s, 10, 32)
+	return int32(v), err
+}
+
+func ConvertInt16(s string) (int16, error) {
+	v, err := strconv.ParseInt(s, 10, 16)
+	return int16(v), err
+}
+
+func ConvertInt8(s string) (int8, error) {
+	v, err := strconv.ParseInt(s, 10, 8)
+	return int8(v), err
+}
+
+func ConvertInt(s string) (int, error) {
+	v, err := strconv.ParseInt(s, 10, 64)
+	return int(v), err
+}
+
+func ConvertUint64(s string) (uint64, error) {
+	return strconv.ParseUint(s, 10, 64)
+}
+
+func ConvertUint32(s string) (uint32, error) {
+	v, err := strconv.ParseUint(s, 10, 32)
+	return uint32(v), err
+}
+
+func ConvertUint16(s string) (uint16, error) {
+	v, err := strconv.ParseUint(s, 10, 16)
+	return uint16(v), err
+}
+
+func ConvertUint8(s string) (uint8, error) {
+	v, err := strconv.ParseUint(s, 10, 8)
+	return uint8(v), err
+}
+
+func ConvertUint(s string) (uint, error) {
+	v, err := strconv.ParseUint(s, 10, 64)
+	return uint(v), err
+}
+
+func ConvertFloat64(s string) (float64, error) {
+	return strconv.ParseFloat(s, 64)
+}
+
+func ConvertFloat32(s string) (float32, error) {
+	v, err := strconv.ParseFloat(s, 32)
+	return float32(v), err
+}
+
+func ConvertComplex128(s string) (complex128, error) {
+	return strconv.ParseComplex(s, 128)
+}
+
+func ConvertComplex64(s string) (complex64, error) {
+	v, err := strconv.ParseComplex(s, 64)
+	return complex64(v), err
+}
+
+func ConvertBool(s string) (bool, error) {
+	return strconv.ParseBool(s)
+}

go.mod

@@ -0,0 +1,3 @@
+module git.tordarus.net/tordarus/envvars
+
+go 1.18

object.go

@@ -0,0 +1,34 @@
+package envvars
+
+import (
+	"os"
+	"strings"
+)
+
+func Object[T any](key string, defaultValue T, converter func(string) (T, error)) T {
+	if v, ok := os.LookupEnv(key); ok {
+		if v2, err := converter(v); err == nil {
+			return v2
+		}
+	}
+	return defaultValue
+}
+
+func ObjectSlice[T any](key, sep string, defaultValue []T, converter func(string) (T, error)) []T {
+	return Object(key, defaultValue, func(s string) ([]T, error) {
+		if s == "" {
+			return []T{}, nil
+		}
+
+		splits := strings.Split(s, sep)
+		values := make([]T, 0, len(splits))
+		for _, s := range splits {
+			v, err := converter(s)
+			if err != nil {
+				return values, err
+			}
+			values = append(values, v)
+		}
+		return values, nil
+	})
+}

slices.go

@@ -0,0 +1,79 @@
+package envvars
+
+import "time"
+
+func StringSlice(key, sep string, defaultValue []string) []string {
+	return ObjectSlice(key, sep, defaultValue, ConvertString)
+}
+
+func ByteSlice(key, sep string, defaultValue []byte) []byte {
+	return Uint8Slice(key, sep, defaultValue)
+}
+
+func RuneSlice(key, sep string, defaultValue []rune) []rune {
+	return ObjectSlice(key, sep, defaultValue, ConvertRune)
+}
+
+func IntSlice(key, sep string, defaultValue []int) []int {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt)
+}
+
+func Int8Slice(key, sep string, defaultValue []int8) []int8 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt8)
+}
+
+func Int16Slice(key, sep string, defaultValue []int16) []int16 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt16)
+}
+
+func Int32Slice(key, sep string, defaultValue []int32) []int32 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt32)
+}
+
+func Int64Slice(key, sep string, defaultValue []int64) []int64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt64)
+}
+
+func Uint8Slice(key, sep string, defaultValue []uint8) []uint8 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint8)
+}
+
+func Uint16Slice(key, sep string, defaultValue []uint16) []uint16 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint16)
+}
+
+func Uint32Slice(key, sep string, defaultValue []uint32) []uint32 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint32)
+}
+
+func Uint64Slice(key, sep string, defaultValue []uint64) []uint64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint64)
+}
+
+func Float32Slice(key, sep string, defaultValue []float32) []float32 {
+	return ObjectSlice(key, sep, defaultValue, ConvertFloat32)
+}
+
+func Float64Slice(key, sep string, defaultValue []float64) []float64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertFloat64)
+}
+
+func Complex64Slice(key, sep string, defaultValue []complex64) []complex64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertComplex64)
+}
+
+func Complex128Slice(key, sep string, defaultValue []complex128) []complex128 {
+	return ObjectSlice(key, sep, defaultValue, ConvertComplex128)
+}
+
+func BoolSlice(key, sep string, defaultValue []bool) []bool {
+	return ObjectSlice(key, sep, defaultValue, ConvertBool)
+}
+
+func TimeSlice(key, sep string, defaultValue []time.Time, layout string) []time.Time {
+	return ObjectSlice(key, sep, defaultValue, func(s string) (time.Time, error) { return time.Parse(layout, s) })
+}
+
+func DurationSlice(key, sep string, defaultValue []time.Duration) []time.Duration {
+	return ObjectSlice(key, sep, defaultValue, time.ParseDuration)
+}

vars.go

@@ -0,0 +1,83 @@
+package envvars
+
+import "time"
+
+func String(key, defaultValue string) string {
+	return Object(key, defaultValue, ConvertString)
+}
+
+func Byte(key string, defaultValue byte) byte {
+	return Uint8(key, defaultValue)
+}
+
+func Rune(key string, defaultValue rune) rune {
+	return Object(key, defaultValue, ConvertRune)
+}
+
+func Int64(key string, defaultValue int64) int64 {
+	return Object(key, defaultValue, ConvertInt64)
+}
+
+func Int32(key string, defaultValue int32) int32 {
+	return Object(key, defaultValue, ConvertInt32)
+}
+
+func Int16(key string, defaultValue int16) int16 {
+	return Object(key, defaultValue, ConvertInt16)
+}
+
+func Int8(key string, defaultValue int8) int8 {
+	return Object(key, defaultValue, ConvertInt8)
+}
+
+func Int(key string, defaultValue int) int {
+	return Object(key, defaultValue, ConvertInt)
+}
+
+func Uint64(key string, defaultValue uint64) uint64 {
+	return Object(key, defaultValue, ConvertUint64)
+}
+
+func Uint32(key string, defaultValue uint32) uint32 {
+	return Object(key, defaultValue, ConvertUint32)
+}
+
+func Uint16(key string, defaultValue uint16) uint16 {
+	return Object(key, defaultValue, ConvertUint16)
+}
+
+func Uint8(key string, defaultValue uint8) uint8 {
+	return Object(key, defaultValue, ConvertUint8)
+}
+
+func Uint(key string, defaultValue uint) uint {
+	return Object(key, defaultValue, ConvertUint)
+}
+
+func Float64(key string, defaultValue float64) float64 {
+	return Object(key, defaultValue, ConvertFloat64)
+}
+
+func Float32(key string, defaultValue float32) float32 {
+	return Object(key, defaultValue, ConvertFloat32)
+}
+
+func Complex128(key string, defaultValue complex128) complex128 {
+	return Object(key, defaultValue, ConvertComplex128)
+}
+
+func Complex64(key string, defaultValue complex64) complex64 {
+	return Object(key, defaultValue, ConvertComplex64)
+}
+
+func Bool(key string, defaultValue bool) bool {
+	return Object(key, defaultValue, ConvertBool)
+}
+
+func Time(key string, defaultValue time.Time, layout string) time.Time {
+	return Object(key, defaultValue, func(s string) (time.Time, error) { return time.Parse(layout, s) })
+}
+
+func Duration(key string, defaultValue time.Duration) time.Duration {
+	return Object(key, defaultValue, time.ParseDuration)
+}