refactor: Use generic parser for integers (#105)

* refactor: Implement generic parser for integers

* chore: Remove redundant default

Author: obalunenko

internal/iface.go

@@ -225,7 +225,7 @@ func (s stringSliceParser) ParseEnv(key string, defaltVal any, options Parameter
 type intParser int
 
 func (i intParser) ParseEnv(key string, defaltVal any, _ Parameters) any {
-	val := intOrDefault(key, defaltVal.(int))
+	val := intOrDefaultGen(key, defaltVal.(int))
 
 	return val
 }
@@ -263,31 +263,31 @@ func (i float64SliceParser) ParseEnv(key string, defaltVal any, options Paramete
 type int64Parser int64
 
 func (i int64Parser) ParseEnv(key string, defaltVal any, _ Parameters) any {
-	val := int64OrDefault(key, defaltVal.(int64))
+	val := intOrDefaultGen(key, defaltVal.(int64))
 
 	return val
 }
 
 type int8Parser int8
 
 func (i int8Parser) ParseEnv(key string, defaltVal any, _ Parameters) any {
-	val := int8OrDefault(key, defaltVal.(int8))
+	val := intOrDefaultGen(key, defaltVal.(int8))
 
 	return val
 }
 
 type int16Parser int16
 
 func (i int16Parser) ParseEnv(key string, defaltVal any, _ Parameters) any {
-	val := int16OrDefault(key, defaltVal.(int16))
+	val := intOrDefaultGen(key, defaltVal.(int16))
 
 	return val
 }
 
 type int32Parser int32
 
 func (i int32Parser) ParseEnv(key string, defaltVal any, _ Parameters) any {
-	val := int32OrDefault(key, defaltVal.(int32))
+	val := intOrDefaultGen(key, defaltVal.(int32))
 
 	return val
 }

internal/parsers.go

@@ -229,6 +229,57 @@ func int8SliceOrDefault(key string, defaultVal []int8, sep string) []int8 {
 	return val
 }
 
+func intOrDefaultGen[T int | int8 | int16 | int32 | int64](key string, defaultVal T) T {
+	env := stringOrDefault(key, "")
+	if env == "" {
+		return defaultVal
+	}
+
+	const (
+		base = 10
+	)
+
+	var (
+		bitsize int
+		castFn  func(val int64) T
+	)
+
+	switch any(defaultVal).(type) {
+	case int:
+		bitsize = 0
+		castFn = func(val int64) T {
+			return any(int(val)).(T)
+		}
+	case int8:
+		bitsize = 8
+		castFn = func(val int64) T {
+			return any(int8(val)).(T)
+		}
+	case int16:
+		bitsize = 16
+		castFn = func(val int64) T {
+			return any(int16(val)).(T)
+		}
+	case int32:
+		bitsize = 32
+		castFn = func(val int64) T {
+			return any(int32(val)).(T)
+		}
+	case int64:
+		bitsize = 64
+		castFn = func(val int64) T {
+			return any(val).(T)
+		}
+	}
+
+	val, err := strconv.ParseInt(env, base, bitsize)
+	if err != nil {
+		return defaultVal
+	}
+
+	return castFn(val)
+}
+
 // int32SliceOrDefault retrieves the int32 slice value of the environment variable named
 // by the key and separated by sep.
 // If variable not set or value is empty - defaultVal will be returned.
@@ -365,94 +416,6 @@ func durationSliceOrDefault(key string, defaultVal []time.Duration, separator st
 	return val
 }
 
-// int64OrDefault retrieves the int64 value of the environment variable named
-// by the key.
-// If variable not set or value is empty - defaultVal will be returned.
-func int64OrDefault(key string, defaultVal int64) int64 {
-	env := stringOrDefault(key, "")
-	if env == "" {
-		return defaultVal
-	}
-
-	const (
-		base    = 10
-		bitsize = 64
-	)
-
-	val, err := strconv.ParseInt(env, base, bitsize)
-	if err != nil {
-		return defaultVal
-	}
-
-	return val
-}
-
-// int8OrDefault retrieves the int8 value of the environment variable named
-// by the key.
-// If variable not set or value is empty - defaultVal will be returned.
-func int8OrDefault(key string, defaultVal int8) int8 {
-	env := stringOrDefault(key, "")
-	if env == "" {
-		return defaultVal
-	}
-
-	const (
-		base    = 10
-		bitsize = 8
-	)
-
-	val, err := strconv.ParseInt(env, base, bitsize)
-	if err != nil {
-		return defaultVal
-	}
-
-	return int8(val)
-}
-
-// int16OrDefault retrieves the int16 value of the environment variable named
-// by the key.
-// If variable not set or value is empty - defaultVal will be returned.
-func int16OrDefault(key string, defaultVal int16) int16 {
-	env := stringOrDefault(key, "")
-	if env == "" {
-		return defaultVal
-	}
-
-	const (
-		base    = 10
-		bitsize = 16
-	)
-
-	val, err := strconv.ParseInt(env, base, bitsize)
-	if err != nil {
-		return defaultVal
-	}
-
-	return int16(val)
-}
-
-// int32OrDefault retrieves the int32 value of the environment variable named
-// by the key.
-// If variable not set or value is empty - defaultVal will be returned.
-func int32OrDefault(key string, defaultVal int32) int32 {
-	env := stringOrDefault(key, "")
-	if env == "" {
-		return defaultVal
-	}
-
-	const (
-		base    = 10
-		bitsize = 32
-	)
-
-	val, err := strconv.ParseInt(env, base, bitsize)
-	if err != nil {
-		return defaultVal
-	}
-
-	return int32(val)
-}
-
 // float32OrDefault retrieves the float32 value of the environment variable named
 // by the key.
 // If variable not set or value is empty - defaultVal will be returned.
@@ -946,7 +909,7 @@ func complex128OrDefault(key string, defaultVal complex128) complex128 {
 
 // complex128SliceOrDefault retrieves the complex128 slice value of the environment variable named
 // by the key and separated by sep.
-// If variable not set or value is empty - defaultVal will be returned.
+// If the variable is not set or the value is empty - defaultVal will be returned.
 func complex128SliceOrDefault(key string, defaultVal []complex128, sep string) []complex128 {
 	valraw := stringSliceOrDefault(key, nil, sep)
 	if valraw == nil {

internal/parsers_test.go

@@ -233,7 +233,7 @@ func Test_int64OrDefault(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			tt.precond.maybeSetEnv(t, tt.args.key)
 
-			got := int64OrDefault(tt.args.key, tt.args.defaultVal)
+			got := intOrDefaultGen(tt.args.key, tt.args.defaultVal)
 			assert.Equal(t, tt.expected.val, got)
 		})
 	}
@@ -309,7 +309,7 @@ func Test_int8OrDefault(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			tt.precond.maybeSetEnv(t, tt.args.key)
 
-			got := int8OrDefault(tt.args.key, tt.args.defaultVal)
+			got := intOrDefaultGen(tt.args.key, tt.args.defaultVal)
 			assert.Equal(t, tt.expected.val, got)
 		})
 	}
@@ -385,7 +385,7 @@ func Test_int16OrDefault(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			tt.precond.maybeSetEnv(t, tt.args.key)
 
-			got := int16OrDefault(tt.args.key, tt.args.defaultVal)
+			got := intOrDefaultGen(tt.args.key, tt.args.defaultVal)
 			assert.Equal(t, tt.expected.val, got)
 		})
 	}
@@ -461,7 +461,7 @@ func Test_int32OrDefault(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			tt.precond.maybeSetEnv(t, tt.args.key)
 
-			got := int32OrDefault(tt.args.key, tt.args.defaultVal)
+			got := intOrDefaultGen(tt.args.key, tt.args.defaultVal)
 			assert.Equal(t, tt.expected.val, got)
 		})
 	}