Range types Set method supports its own type, string, and nil

Previously Set would always return an error when called on a range type.
Now it will accept an instance of itself, a pointer to an instance of
itself, a string, or nil. Strings are parsed with the same logic as
DecodeText.

daterange.go

@@ -16,7 +16,24 @@ type Daterange struct {
 }
 
 func (dst *Daterange) Set(src interface{}) error {
-	return errors.Errorf("cannot convert %v to Daterange", src)
+	// untyped nil and typed nil interfaces are different
+	if src == nil {
+		*dst = Daterange{Status: Null}
+		return nil
+	}
+
+	switch value := src.(type) {
+	case Daterange:
+		*dst = value
+	case *Daterange:
+		*dst = *value
+	case string:
+		return dst.DecodeText(nil, []byte(value))
+	default:
+		return errors.Errorf("cannot convert %v to Daterange", src)
+	}
+
+	return nil
 }
 
 func (dst Daterange) Get() interface{} {

daterange_test.go

@@ -65,3 +65,69 @@ func TestDaterangeNormalize(t *testing.T) {
 			a.Upper.InfinityModifier == b.Upper.InfinityModifier
 	})
 }
+
+func TestDaterangeSet(t *testing.T) {
+	successfulTests := []struct {
+		source interface{}
+		result pgtype.Daterange
+	}{
+		{
+			source: nil,
+			result: pgtype.Daterange{Status: pgtype.Null},
+		},
+		{
+			source: &pgtype.Daterange{
+				Lower:     pgtype.Date{Time: time.Date(1990, 12, 31, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				Upper:     pgtype.Date{Time: time.Date(2028, 1, 1, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				LowerType: pgtype.Inclusive,
+				UpperType: pgtype.Exclusive,
+				Status:    pgtype.Present,
+			},
+			result: pgtype.Daterange{
+				Lower:     pgtype.Date{Time: time.Date(1990, 12, 31, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				Upper:     pgtype.Date{Time: time.Date(2028, 1, 1, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				LowerType: pgtype.Inclusive,
+				UpperType: pgtype.Exclusive,
+				Status:    pgtype.Present,
+			},
+		},
+		{
+			source: pgtype.Daterange{
+				Lower:     pgtype.Date{Time: time.Date(1990, 12, 31, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				Upper:     pgtype.Date{Time: time.Date(2028, 1, 1, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				LowerType: pgtype.Inclusive,
+				UpperType: pgtype.Exclusive,
+				Status:    pgtype.Present,
+			},
+			result: pgtype.Daterange{
+				Lower:     pgtype.Date{Time: time.Date(1990, 12, 31, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				Upper:     pgtype.Date{Time: time.Date(2028, 1, 1, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				LowerType: pgtype.Inclusive,
+				UpperType: pgtype.Exclusive,
+				Status:    pgtype.Present,
+			},
+		},
+		{
+			source: "[1990-12-31,2028-01-01)",
+			result: pgtype.Daterange{
+				Lower:     pgtype.Date{Time: time.Date(1990, 12, 31, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				Upper:     pgtype.Date{Time: time.Date(2028, 1, 1, 0, 0, 0, 0, time.UTC), Status: pgtype.Present},
+				LowerType: pgtype.Inclusive,
+				UpperType: pgtype.Exclusive,
+				Status:    pgtype.Present,
+			},
+		},
+	}
+
+	for i, tt := range successfulTests {
+		var r pgtype.Daterange
+		err := r.Set(tt.source)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+
+		if r != tt.result {
+			t.Errorf("%d: expected %v to convert to %v, but it was %v", i, tt.source, tt.result, r)
+		}
+	}
+}

int4range.go

@@ -16,7 +16,24 @@ type Int4range struct {
 }
 
 func (dst *Int4range) Set(src interface{}) error {
-	return errors.Errorf("cannot convert %v to Int4range", src)
+	// untyped nil and typed nil interfaces are different
+	if src == nil {
+		*dst = Int4range{Status: Null}
+		return nil
+	}
+
+	switch value := src.(type) {
+	case Int4range:
+		*dst = value
+	case *Int4range:
+		*dst = *value
+	case string:
+		return dst.DecodeText(nil, []byte(value))
+	default:
+		return errors.Errorf("cannot convert %v to Int4range", src)
+	}
+
+	return nil
 }
 
 func (dst Int4range) Get() interface{} {

int8range.go

@@ -16,7 +16,24 @@ type Int8range struct {
 }
 
 func (dst *Int8range) Set(src interface{}) error {
-	return errors.Errorf("cannot convert %v to Int8range", src)
+	// untyped nil and typed nil interfaces are different
+	if src == nil {
+		*dst = Int8range{Status: Null}
+		return nil
+	}
+
+	switch value := src.(type) {
+	case Int8range:
+		*dst = value
+	case *Int8range:
+		*dst = *value
+	case string:
+		return dst.DecodeText(nil, []byte(value))
+	default:
+		return errors.Errorf("cannot convert %v to Int8range", src)
+	}
+
+	return nil
 }
 
 func (dst Int8range) Get() interface{} {

numrange.go

@@ -16,7 +16,24 @@ type Numrange struct {
 }
 
 func (dst *Numrange) Set(src interface{}) error {
-	return errors.Errorf("cannot convert %v to Numrange", src)
+	// untyped nil and typed nil interfaces are different
+	if src == nil {
+		*dst = Numrange{Status: Null}
+		return nil
+	}
+
+	switch value := src.(type) {
+	case Numrange:
+		*dst = value
+	case *Numrange:
+		*dst = *value
+	case string:
+		return dst.DecodeText(nil, []byte(value))
+	default:
+		return errors.Errorf("cannot convert %v to Numrange", src)
+	}
+
+	return nil
 }
 
 func (dst Numrange) Get() interface{} {

tsrange.go

@@ -16,7 +16,24 @@ type Tsrange struct {
 }
 
 func (dst *Tsrange) Set(src interface{}) error {
-	return errors.Errorf("cannot convert %v to Tsrange", src)
+	// untyped nil and typed nil interfaces are different
+	if src == nil {
+		*dst = Tsrange{Status: Null}
+		return nil
+	}
+
+	switch value := src.(type) {
+	case Tsrange:
+		*dst = value
+	case *Tsrange:
+		*dst = *value
+	case string:
+		return dst.DecodeText(nil, []byte(value))
+	default:
+		return errors.Errorf("cannot convert %v to Tsrange", src)
+	}
+
+	return nil
 }
 
 func (dst Tsrange) Get() interface{} {

tstzrange.go

@@ -16,7 +16,24 @@ type Tstzrange struct {
 }
 
 func (dst *Tstzrange) Set(src interface{}) error {
-	return errors.Errorf("cannot convert %v to Tstzrange", src)
+	// untyped nil and typed nil interfaces are different
+	if src == nil {
+		*dst = Tstzrange{Status: Null}
+		return nil
+	}
+
+	switch value := src.(type) {
+	case Tstzrange:
+		*dst = value
+	case *Tstzrange:
+		*dst = *value
+	case string:
+		return dst.DecodeText(nil, []byte(value))
+	default:
+		return errors.Errorf("cannot convert %v to Tstzrange", src)
+	}
+
+	return nil
 }
 
 func (dst Tstzrange) Get() interface{} {

typed_range.go.erb

@@ -18,7 +18,24 @@ type <%= range_type %> struct {
 }
 
 func (dst *<%= range_type %>) Set(src interface{}) error {
-	return errors.Errorf("cannot convert %v to <%= range_type %>", src)
+	// untyped nil and typed nil interfaces are different
+	if src == nil {
+		*dst = <%= range_type %>{Status: Null}
+		return nil
+	}
+
+	switch value := src.(type) {
+	case <%= range_type %>:
+		*dst = value
+	case *<%= range_type %>:
+		*dst = *value
+	case string:
+		return dst.DecodeText(nil, []byte(value))
+	default:
+		return errors.Errorf("cannot convert %v to <%= range_type %>", src)
+	}
+
+	return nil
 }
 
 func (dst <%= range_type %>) Get() interface{} {