Be more careful about importing encoding/json

5 files changed, 62 insertions, 36 deletions

diff --git a/ReleaseNotes.md b/ReleaseNotes.md
index d1b5693..9974f0e 100644
--- a/ReleaseNotes.md
+++ b/ReleaseNotes.md
@@ -1,3 +1,13 @@
+# v0.3.6 (TBD)
+
+  Theme: TBD
+
+  User-facing changes:
+
+   - `Number` and `RawMessage` type aliases are now available, so that
+     a user of lowmemjson's native APIs does not need to import
+     `encoding/json` or compat/json in order to use them.
+
 # v0.3.5 (2023-02-10)
 
   Theme: Compatibility bugfixes
diff --git a/common.go b/common.go
deleted file mode 100644
index 90156b9..0000000
--- a/common.go
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
-//
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-package lowmemjson
-
-import (
-	"encoding/json"
-	"reflect"
-)
-
-var (
-	numberType    = reflect.TypeOf(json.Number(""))
-	byteType      = reflect.TypeOf(byte(0))
-	byteSliceType = reflect.TypeOf(([]byte)(nil))
-)
diff --git a/decode.go b/decode.go
index 1b6bdf2..645f8de 100644
--- a/decode.go
+++ b/decode.go
@@ -14,7 +14,6 @@ package lowmemjson
 import (
 	"bytes"
 	"encoding"
-	"encoding/json"
 	"fmt"
 	"io"
 	"reflect"
@@ -357,14 +356,6 @@ func (dec *Decoder) limitingScanner() io.RuneScanner {
 
 // decoder main ////////////////////////////////////////////////////////////////////////////////////
 
-var (
-	rawMessagePtrType   = reflect.TypeOf((*json.RawMessage)(nil))
-	decodableType       = reflect.TypeOf((*Decodable)(nil)).Elem()
-	jsonUnmarshalerType = reflect.TypeOf((*json.Unmarshaler)(nil)).Elem()
-	textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
-	float64Type         = reflect.TypeOf(float64(0))
-)
-
 var kind2bits = map[reflect.Kind]int{
 	reflect.Int:   int(32 << (^uint(0) >> 63)),
 	reflect.Int8:  8,
@@ -393,7 +384,7 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) {
 		t := dec.peekRuneType()
 		var buf bytes.Buffer
 		dec.scan(&buf)
-		if err := val.Addr().Interface().(*json.RawMessage).UnmarshalJSON(buf.Bytes()); err != nil {
+		if err := val.Addr().Interface().(*RawMessage).UnmarshalJSON(buf.Bytes()); err != nil {
 			dec.panicType(t.JSONType(), reflect.PointerTo(typ), err)
 		}
 	case val.CanAddr() && reflect.PointerTo(typ).Implements(decodableType):
@@ -410,7 +401,7 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) {
 		t := dec.peekRuneType()
 		var buf bytes.Buffer
 		dec.scan(&buf)
-		obj := val.Addr().Interface().(json.Unmarshaler)
+		obj := val.Addr().Interface().(jsonUnmarshaler)
 		if err := obj.UnmarshalJSON(buf.Bytes()); err != nil {
 			dec.panicType(t.JSONType(), reflect.PointerTo(typ), err)
 		}
@@ -826,7 +817,7 @@ func (dec *Decoder) decodeAny() any {
 	case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
 		var buf strings.Builder
 		dec.scan(&buf)
-		num := json.Number(buf.String())
+		num := Number(buf.String())
 		if dec.useNumber {
 			return num
 		}
diff --git a/encode.go b/encode.go
index 492b40f..b6541cd 100644
--- a/encode.go
+++ b/encode.go
@@ -8,7 +8,6 @@ import (
 	"bytes"
 	"encoding"
 	"encoding/base64"
-	"encoding/json"
 	"fmt"
 	"io"
 	"reflect"
@@ -96,12 +95,6 @@ func discardInt(_ int, err error) error {
 	return err
 }
 
-var (
-	encodableType     = reflect.TypeOf((*Encodable)(nil)).Elem()
-	jsonMarshalerType = reflect.TypeOf((*json.Marshaler)(nil)).Elem()
-	textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
-)
-
 const startDetectingCyclesAfter = 1000
 
 func encode(w *ReEncoder, val reflect.Value, escaper BackslashEscaper, quote bool, cycleDepth uint, cycleSeen map[any]struct{}) error {
@@ -145,7 +138,7 @@ func encode(w *ReEncoder, val reflect.Value, escaper BackslashEscaper, quote boo
 		if val.Kind() == reflect.Pointer && val.IsNil() {
 			return discardInt(w.WriteString("null"))
 		}
-		obj, ok := val.Interface().(json.Marshaler)
+		obj, ok := val.Interface().(jsonMarshaler)
 		if !ok {
 			return discardInt(w.WriteString("null"))
 		}
diff --git a/external.go b/external.go
new file mode 100644
index 0000000..c8a1f68
--- /dev/null
+++ b/external.go
@@ -0,0 +1,48 @@
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package lowmemjson
+
+import (
+	"encoding"
+	"encoding/json"
+	"reflect"
+)
+
+// A Number represents a JSON number value.  It is represented as a
+// string containing the raw JSON text; it is useful for preserving
+// number values with perfect fidelity, but isn't so useful for use as
+// a number value in a Go program.
+type Number = json.Number
+
+// A RawMessage is a raw encoded JSON value.  This saves time when
+// encoding or decoding, but does mean that the full text must be
+// buffered when decoding.
+type RawMessage = json.RawMessage
+
+type (
+	jsonMarshaler   = json.Marshaler
+	jsonUnmarshaler = json.Unmarshaler
+)
+
+var (
+	// common types.
+	numberType    = reflect.TypeOf(Number(""))
+	byteType      = reflect.TypeOf(byte(0))
+	byteSliceType = reflect.TypeOf(([]byte)(nil))
+
+	// encodable/marshaler types.
+	encodableType     = reflect.TypeOf((*Encodable)(nil)).Elem()
+	jsonMarshalerType = reflect.TypeOf((*json.Marshaler)(nil)).Elem()
+	textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
+
+	// decodable/unmarshaler types.
+	decodableType       = reflect.TypeOf((*Decodable)(nil)).Elem()
+	jsonUnmarshalerType = reflect.TypeOf((*json.Unmarshaler)(nil)).Elem()
+	textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+
+	// other types used by Decoder.
+	rawMessagePtrType = reflect.TypeOf((*json.RawMessage)(nil))
+	float64Type       = reflect.TypeOf(float64(0))
+)