decode: Have .readRune() and .expectRune() return *DecodeError

1 files changed, 111 insertions, 36 deletions

diff --git a/decode.go b/decode.go
index 15ab766..9ec706f 100644
--- a/decode.go
+++ b/decode.go
@@ -268,17 +268,17 @@ func (dec *Decoder) newTypeError(jTyp string, gTyp reflect.Type, err error) *Dec
 	}
 }
 
-func (dec *Decoder) readRune() (rune, jsonparse.RuneType) {
+func (dec *Decoder) readRune() (rune, jsonparse.RuneType, *DecodeError) {
 	c, _, t, e := dec.io.ReadRuneType()
 	if e != nil {
-		panic(decodeError{
+		return 0, 0, &DecodeError{
 			Field:       dec.structStackStr(),
 			FieldParent: dec.structStackParent(),
 			FieldName:   dec.structStackName(),
 			Err:         e,
-		})
+		}
 	}
-	return c, t
+	return c, t, nil
 }
 
 func (dec *Decoder) unreadRune() {
@@ -289,22 +289,31 @@ func (dec *Decoder) unreadRune() {
 	}
 }
 
-//nolint:unparam // It will start returning errors soon.
 func (dec *Decoder) peekRuneType() (jsonparse.RuneType, *DecodeError) {
-	_, t := dec.readRune()
+	_, t, err := dec.readRune()
+	if err != nil {
+		return 0, err
+	}
 	dec.unreadRune()
 	return t, nil
 }
 
-func (dec *Decoder) expectRune(ec rune, et jsonparse.RuneType) {
-	ac, at := dec.readRune()
+func (dec *Decoder) expectRune(ec rune, et jsonparse.RuneType) *DecodeError {
+	ac, at, err := dec.readRune()
+	if err != nil {
+		return err
+	}
 	if ac != ec || at != et {
 		panic("should not happen")
 	}
+	return nil
 }
 
 func (dec *Decoder) expectRuneType(ec rune, et jsonparse.RuneType, gt reflect.Type) *DecodeError {
-	ac, at := dec.readRune()
+	ac, at, err := dec.readRune()
+	if err != nil {
+		return err
+	}
 	if ac != ec || at != et {
 		return dec.newTypeError(at.JSONType(), gt, nil)
 	}
@@ -869,7 +878,10 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 func (dec *Decoder) scan(out fastio.RuneWriter) *DecodeError {
 	dec.io.PushReadBarrier()
 	for {
-		c, t := dec.readRune()
+		c, t, err := dec.readRune()
+		if err != nil {
+			return err
+		}
 		if t == jsonparse.RuneTypeEOF {
 			break
 		}
@@ -891,7 +903,10 @@ func (dec *Decoder) scanNumber(gTyp reflect.Type, out fastio.RuneWriter) *Decode
 }
 
 func (dec *Decoder) decodeAny() (any, *DecodeError) {
-	c, _ := dec.readRune()
+	c, _, err := dec.readRune()
+	if err != nil {
+		return nil, err
+	}
 	dec.unreadRune()
 	switch c {
 	case '{':
@@ -1037,7 +1052,10 @@ func (dec *Decoder) decodeObject(gTyp reflect.Type, decodeKey, decodeVal func()
 	if err := dec.expectRuneType('{', jsonparse.RuneTypeObjectBeg, gTyp); err != nil {
 		return err
 	}
-	_, t := dec.readRune()
+	_, t, err := dec.readRune()
+	if err != nil {
+		return err
+	}
 	switch t {
 	case jsonparse.RuneTypeObjectEnd:
 		return nil
@@ -1047,14 +1065,21 @@ func (dec *Decoder) decodeObject(gTyp reflect.Type, decodeKey, decodeVal func()
 		if err := decodeKey(); err != nil {
 			return err
 		}
-		dec.expectRune(':', jsonparse.RuneTypeObjectColon)
+		if err := dec.expectRune(':', jsonparse.RuneTypeObjectColon); err != nil {
+			return err
+		}
 		if err := decodeVal(); err != nil {
 			return err
 		}
-		_, t := dec.readRune()
+		_, t, err := dec.readRune()
+		if err != nil {
+			return err
+		}
 		switch t {
 		case jsonparse.RuneTypeObjectComma:
-			dec.expectRune('"', jsonparse.RuneTypeStringBeg)
+			if err := dec.expectRune('"', jsonparse.RuneTypeStringBeg); err != nil {
+				return err
+			}
 			goto decodeMember
 		case jsonparse.RuneTypeObjectEnd:
 			return nil
@@ -1121,7 +1146,10 @@ func (dec *Decoder) decodeArray(gTyp reflect.Type, decodeMember func() *DecodeEr
 	if err := dec.expectRuneType('[', jsonparse.RuneTypeArrayBeg, gTyp); err != nil {
 		return err
 	}
-	_, t := dec.readRune()
+	_, t, err := dec.readRune()
+	if err != nil {
+		return err
+	}
 	switch t {
 	case jsonparse.RuneTypeArrayEnd:
 		return nil
@@ -1131,7 +1159,10 @@ func (dec *Decoder) decodeArray(gTyp reflect.Type, decodeMember func() *DecodeEr
 		if err := decodeMember(); err != nil {
 			return err
 		}
-		_, t := dec.readRune()
+		_, t, err := dec.readRune()
+		if err != nil {
+			return err
+		}
 		switch t {
 		case jsonparse.RuneTypeArrayComma:
 			goto decodeNextMember
@@ -1149,7 +1180,10 @@ func (dec *Decoder) decodeString(gTyp reflect.Type, out fastio.RuneWriter) *Deco
 	}
 	var uhex [4]byte
 	for {
-		c, t := dec.readRune()
+		c, t, err := dec.readRune()
+		if err != nil {
+			return err
+		}
 		switch t {
 		case jsonparse.RuneTypeStringChar:
 			_, _ = out.WriteRune(c)
@@ -1199,7 +1233,9 @@ func (dec *Decoder) decodeString(gTyp reflect.Type, out fastio.RuneWriter) *Deco
 					_, _ = out.WriteRune(utf8.RuneError)
 					break
 				}
-				dec.expectRune('\\', jsonparse.RuneTypeStringEsc)
+				if err := dec.expectRune('\\', jsonparse.RuneTypeStringEsc); err != nil {
+					return err
+				}
 				t, err = dec.peekRuneType()
 				if err != nil {
 					return err
@@ -1208,15 +1244,29 @@ func (dec *Decoder) decodeString(gTyp reflect.Type, out fastio.RuneWriter) *Deco
 					_, _ = out.WriteRune(utf8.RuneError)
 					break
 				}
-				dec.expectRune('u', jsonparse.RuneTypeStringEscU)
+				if err := dec.expectRune('u', jsonparse.RuneTypeStringEscU); err != nil {
+					return err
+				}
 
-				b, _ := dec.readRune()
+				b, _, err := dec.readRune()
+				if err != nil {
+					return err
+				}
 				uhex[0], _ = jsonparse.HexToInt(b)
-				b, _ = dec.readRune()
+				b, _, err = dec.readRune()
+				if err != nil {
+					return err
+				}
 				uhex[1], _ = jsonparse.HexToInt(b)
-				b, _ = dec.readRune()
+				b, _, err = dec.readRune()
+				if err != nil {
+					return err
+				}
 				uhex[2], _ = jsonparse.HexToInt(b)
-				b, _ = dec.readRune()
+				b, _, err = dec.readRune()
+				if err != nil {
+					return err
+				}
 				uhex[3], _ = jsonparse.HexToInt(b)
 				c2 := 0 |
 					rune(uhex[0])<<12 |
@@ -1242,18 +1292,35 @@ func (dec *Decoder) decodeString(gTyp reflect.Type, out fastio.RuneWriter) *Deco
 }
 
 func (dec *Decoder) decodeBool(gTyp reflect.Type) (bool, *DecodeError) {
-	c, t := dec.readRune()
+	c, t, err := dec.readRune()
+	if err != nil {
+		return false, err
+	}
 	switch c {
 	case 't':
-		dec.expectRune('r', jsonparse.RuneTypeTrueR)
-		dec.expectRune('u', jsonparse.RuneTypeTrueU)
-		dec.expectRune('e', jsonparse.RuneTypeTrueE)
+		if err := dec.expectRune('r', jsonparse.RuneTypeTrueR); err != nil {
+			return false, err
+		}
+		if err := dec.expectRune('u', jsonparse.RuneTypeTrueU); err != nil {
+			return false, err
+		}
+		if err := dec.expectRune('e', jsonparse.RuneTypeTrueE); err != nil {
+			return false, err
+		}
 		return true, nil
 	case 'f':
-		dec.expectRune('a', jsonparse.RuneTypeFalseA)
-		dec.expectRune('l', jsonparse.RuneTypeFalseL)
-		dec.expectRune('s', jsonparse.RuneTypeFalseS)
-		dec.expectRune('e', jsonparse.RuneTypeFalseE)
+		if err := dec.expectRune('a', jsonparse.RuneTypeFalseA); err != nil {
+			return false, err
+		}
+		if err := dec.expectRune('l', jsonparse.RuneTypeFalseL); err != nil {
+			return false, err
+		}
+		if err := dec.expectRune('s', jsonparse.RuneTypeFalseS); err != nil {
+			return false, err
+		}
+		if err := dec.expectRune('e', jsonparse.RuneTypeFalseE); err != nil {
+			return false, err
+		}
 		return false, nil
 	default:
 		return false, dec.newTypeError(t.JSONType(), gTyp, nil)
@@ -1261,10 +1328,18 @@ func (dec *Decoder) decodeBool(gTyp reflect.Type) (bool, *DecodeError) {
 }
 
 func (dec *Decoder) decodeNull() *DecodeError {
-	dec.expectRune('n', jsonparse.RuneTypeNullN)
-	dec.expectRune('u', jsonparse.RuneTypeNullU)
-	dec.expectRune('l', jsonparse.RuneTypeNullL1)
-	dec.expectRune('l', jsonparse.RuneTypeNullL2)
+	if err := dec.expectRune('n', jsonparse.RuneTypeNullN); err != nil {
+		return err
+	}
+	if err := dec.expectRune('u', jsonparse.RuneTypeNullU); err != nil {
+		return err
+	}
+	if err := dec.expectRune('l', jsonparse.RuneTypeNullL1); err != nil {
+		return err
+	}
+	if err := dec.expectRune('l', jsonparse.RuneTypeNullL2); err != nil {
+		return err
+	}
 	return nil
 }