check: use encoding interfaces

This turned out not to require specific treatment, so the shared interfaces are cleaner.

Signed-off-by: Ophestra <cat@gensokyo.uk>

check/absolute.go

@@ -2,7 +2,7 @@
 package check
 
 import (
-	"encoding/json"
+	"encoding"
 	"errors"
 	"fmt"
 	"path/filepath"
@@ -30,6 +30,16 @@ func (e AbsoluteError) Is(target error) bool {
 // Absolute holds a pathname checked to be absolute.
 type Absolute struct{ pathname unique.Handle[string] }
 
+var (
+	_ encoding.TextAppender    = new(Absolute)
+	_ encoding.TextMarshaler   = new(Absolute)
+	_ encoding.TextUnmarshaler = new(Absolute)
+
+	_ encoding.BinaryAppender    = new(Absolute)
+	_ encoding.BinaryMarshaler   = new(Absolute)
+	_ encoding.BinaryUnmarshaler = new(Absolute)
+)
+
 // ok returns whether [Absolute] is not the zero value.
 func (a *Absolute) ok() bool { return a != nil && *a != (Absolute{}) }
 
@@ -84,13 +94,16 @@ func (a *Absolute) Append(elem ...string) *Absolute {
 // Dir calls [filepath.Dir] with [Absolute] as its argument.
 func (a *Absolute) Dir() *Absolute { return unsafeAbs(filepath.Dir(a.String())) }
 
-// GobEncode returns the checked pathname.
-func (a *Absolute) GobEncode() ([]byte, error) {
-	return []byte(a.String()), nil
+// AppendText appends the checked pathname.
+func (a *Absolute) AppendText(data []byte) ([]byte, error) {
+	return append(data, a.String()...), nil
 }
 
-// GobDecode stores data if it represents an absolute pathname.
-func (a *Absolute) GobDecode(data []byte) error {
+// MarshalText returns the checked pathname.
+func (a *Absolute) MarshalText() ([]byte, error) { return a.AppendText(nil) }
+
+// UnmarshalText stores data if it represents an absolute pathname.
+func (a *Absolute) UnmarshalText(data []byte) error {
 	pathname := string(data)
 	if !filepath.IsAbs(pathname) {
 		return AbsoluteError(pathname)
@@ -99,23 +112,9 @@ func (a *Absolute) GobDecode(data []byte) error {
 	return nil
 }
 
-// MarshalJSON returns a JSON representation of the checked pathname.
-func (a *Absolute) MarshalJSON() ([]byte, error) {
-	return json.Marshal(a.String())
-}
-
-// UnmarshalJSON stores data if it represents an absolute pathname.
-func (a *Absolute) UnmarshalJSON(data []byte) error {
-	var pathname string
-	if err := json.Unmarshal(data, &pathname); err != nil {
-		return err
-	}
-	if !filepath.IsAbs(pathname) {
-		return AbsoluteError(pathname)
-	}
-	a.pathname = unique.Make(pathname)
-	return nil
-}
+func (a *Absolute) AppendBinary(data []byte) ([]byte, error) { return a.AppendText(data) }
+func (a *Absolute) MarshalBinary() ([]byte, error)           { return a.MarshalText() }
+func (a *Absolute) UnmarshalBinary(data []byte) error        { return a.UnmarshalText(data) }
 
 // SortAbs calls [slices.SortFunc] for a slice of [Absolute].
 func SortAbs(x []*Absolute) {