decode: Lean in to io.RuneScanner

So that it's easier to compose your own .DecodeJSON methods, since
.DecodeJSON takes an io.RuneScanner.

1 files changed, 6 insertions, 13 deletions

diff --git a/decode.go b/decode.go
index 51402e7..98a0e5b 100644
--- a/decode.go
+++ b/decode.go
@@ -5,7 +5,6 @@
 package lowmemjson
 
 import (
-	"bufio"
 	"bytes"
 	"encoding"
 	"encoding/json"
@@ -47,15 +46,11 @@ type Decoder struct {
 
 const maxNestingDepth = 10000
 
-func NewDecoder(r io.Reader) *Decoder {
-	rr, ok := r.(io.RuneReader)
-	if !ok {
-		rr = bufio.NewReader(r)
-	}
+func NewDecoder(r io.RuneScanner) *Decoder {
 	return &Decoder{
 		io: &noWSRuneTypeScanner{
 			inner: &runeTypeScannerImpl{
-				inner: rr,
+				inner: r,
 				parser: Parser{
 					MaxDepth: maxNestingDepth,
 				},
@@ -114,18 +109,16 @@ func (dec *Decoder) stackName() string {
 	return strings.Join(fields, ".")
 }
 
-func Decode(r interface {
-	io.Reader
-	io.RuneScanner // enforce that the reader have .UnreadRune() so that we don't risk reading too far when decoding a number
-}, ptr any) error {
+func Decode(r io.RuneScanner, ptr any) error {
 	return NewDecoder(r).Decode(ptr)
 }
 
-// DecodeThenEOF is like decode, but emits an error if there is extra data after the JSON.
-func DecodeThenEOF(r io.Reader, ptr any) error {
+func DecodeThenEOF(r io.RuneScanner, ptr any) error {
 	return NewDecoder(r).DecodeThenEOF(ptr)
 }
 
+// DecodeThenEOF is like decode, but emits an error if there is extra
+// data after the JSON.
 func (dec *Decoder) DecodeThenEOF(ptr any) (err error) {
 	if err := dec.Decode(ptr); err != nil {
 		return err