Improve error message

goccy · goccy · commit 08c2e1abefa7 · 2021-08-13T17:05:07.000+09:00
diff --git a/decode_test.go b/decode_test.go
@@ -1270,7 +1270,7 @@ var unmarshalTests = []unmarshalTest{
 		in:  `invalid`, // 143
 		ptr: new(json.Number),
 		err: json.NewSyntaxError(
-			`json: json.Number unexpected end of JSON input`,
+			`invalid character 'i' looking for beginning of value`,
 			1,
 		),
 	},
@@ -1998,8 +1998,8 @@ type wrongStringTest struct {
 }
 
 var wrongStringTests = []wrongStringTest{
-	{`{"result":"x"}`, `not at beginning of value`},
-	{`{"result":"foo"}`, `not at beginning of value`},
+	{`{"result":"x"}`, `invalid character 'x' looking for beginning of value`},
+	{`{"result":"foo"}`, `invalid character 'f' looking for beginning of value`},
 	{`{"result":"123"}`, `json: cannot unmarshal number into Go struct field WrongString.Message of type string`},
 	{`{"result":123}`, `json: cannot unmarshal number into Go struct field WrongString.Message of type string`},
 	{`{"result":"\""}`, `json: string unexpected end of JSON input`},
@@ -2691,10 +2691,10 @@ func TestUnmarshalErrorAfterMultipleJSON(t *testing.T) {
 		err error
 	}{{
 		in:  `1 false null :`,
-		err: json.NewSyntaxError("not at beginning of value", 14),
+		err: json.NewSyntaxError("invalid character '\x00' looking for beginning of value", 14),
 	}, {
 		in:  `1 [] [,]`,
-		err: json.NewSyntaxError("not at beginning of value", 6),
+		err: json.NewSyntaxError("invalid character ',' looking for beginning of value", 6),
 	}, {
 		in:  `1 [] [true:]`,
 		err: json.NewSyntaxError("json: slice unexpected end of JSON input", 10),
diff --git a/internal/decoder/func.go b/internal/decoder/func.go
@@ -76,7 +76,7 @@ func (d *funcDecoder) DecodeStream(s *Stream, depth int64, p unsafe.Pointer) err
 			}
 		}
 	}
-	return errors.ErrNotAtBeginningOfValue(start)
+	return errors.ErrInvalidBeginningOfValue(s.buf[s.cursor], s.totalOffset())
 }
 
 func (d *funcDecoder) Decode(ctx *RuntimeContext, cursor, depth int64, p unsafe.Pointer) (int64, error) {
@@ -137,5 +137,5 @@ func (d *funcDecoder) Decode(ctx *RuntimeContext, cursor, depth int64, p unsafe.
 			}
 		}
 	}
-	return 0, errors.ErrNotAtBeginningOfValue(start)
+	return cursor, errors.ErrInvalidBeginningOfValue(buf[cursor], cursor)
 }
diff --git a/internal/decoder/interface.go b/internal/decoder/interface.go
@@ -277,7 +277,7 @@ func (d *interfaceDecoder) decodeStreamEmptyInterface(s *Stream, depth int64, p
 		}
 		break
 	}
-	return errors.ErrNotAtBeginningOfValue(s.totalOffset())
+	return errors.ErrInvalidBeginningOfValue(c, s.totalOffset())
 }
 
 type emptyInterface struct {
@@ -454,5 +454,5 @@ func (d *interfaceDecoder) decodeEmptyInterface(ctx *RuntimeContext, cursor, dep
 		**(**interface{})(unsafe.Pointer(&p)) = nil
 		return cursor, nil
 	}
-	return cursor, errors.ErrNotAtBeginningOfValue(cursor)
+	return cursor, errors.ErrInvalidBeginningOfValue(buf[cursor], cursor)
 }
diff --git a/internal/decoder/number.go b/internal/decoder/number.go
@@ -52,6 +52,7 @@ func (d *numberDecoder) Decode(ctx *RuntimeContext, cursor, depth int64, p unsaf
 }
 
 func (d *numberDecoder) decodeStreamByte(s *Stream) ([]byte, error) {
+	start := s.cursor
 	for {
 		switch s.char() {
 		case ' ', '\n', '\t', '\r':
@@ -76,6 +77,9 @@ func (d *numberDecoder) decodeStreamByte(s *Stream) ([]byte, error) {
 		}
 	}
 ERROR:
+	if s.cursor == start {
+		return nil, errors.ErrInvalidBeginningOfValue(s.char(), s.totalOffset())
+	}
 	return nil, errors.ErrUnexpectedEndOfJSON("json.Number", s.totalOffset())
 }
 
diff --git a/internal/decoder/string.go b/internal/decoder/string.go
@@ -281,7 +281,7 @@ func (d *stringDecoder) decodeStreamByte(s *Stream) ([]byte, error) {
 		}
 		break
 	}
-	return nil, errors.ErrNotAtBeginningOfValue(s.totalOffset())
+	return nil, errors.ErrInvalidBeginningOfValue(s.char(), s.totalOffset())
 }
 
 func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
@@ -356,7 +356,7 @@ func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, err
 			cursor += 4
 			return nil, cursor, nil
 		default:
-			return nil, 0, errors.ErrNotAtBeginningOfValue(cursor)
+			return nil, 0, errors.ErrInvalidBeginningOfValue(buf[cursor], cursor)
 		}
 	}
 }
diff --git a/internal/decoder/struct.go b/internal/decoder/struct.go
@@ -261,7 +261,7 @@ func decodeKeyByBitmapUint8(d *structDecoder, buf []byte, cursor int64) (int64,
 				cursor++
 			}
 		default:
-			return cursor, nil, errors.ErrNotAtBeginningOfValue(cursor)
+			return cursor, nil, errors.ErrInvalidBeginningOfValue(char(b, cursor), cursor)
 		}
 	}
 }
@@ -324,7 +324,7 @@ func decodeKeyByBitmapUint16(d *structDecoder, buf []byte, cursor int64) (int64,
 				cursor++
 			}
 		default:
-			return cursor, nil, errors.ErrNotAtBeginningOfValue(cursor)
+			return cursor, nil, errors.ErrInvalidBeginningOfValue(char(b, cursor), cursor)
 		}
 	}
 }
@@ -376,7 +376,7 @@ func decodeKeyByBitmapUint8Stream(d *structDecoder, s *Stream) (*structFieldSet,
 				_, cursor, p = s.stat()
 				continue
 			}
-			return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())
+			return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())
 		case '"':
 			cursor++
 		FIRST_CHAR:
@@ -443,7 +443,7 @@ func decodeKeyByBitmapUint8Stream(d *structDecoder, s *Stream) (*structFieldSet,
 				cursor++
 			}
 		default:
-			return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())
+			return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())
 		}
 	}
 }
@@ -463,7 +463,7 @@ func decodeKeyByBitmapUint16Stream(d *structDecoder, s *Stream) (*structFieldSet
 				_, cursor, p = s.stat()
 				continue
 			}
-			return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())
+			return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())
 		case '"':
 			cursor++
 		FIRST_CHAR:
@@ -530,7 +530,7 @@ func decodeKeyByBitmapUint16Stream(d *structDecoder, s *Stream) (*structFieldSet
 				cursor++
 			}
 		default:
-			return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())
+			return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())
 		}
 	}
 }
@@ -653,7 +653,7 @@ func (d *structDecoder) DecodeStream(s *Stream, depth int64, p unsafe.Pointer) e
 		return nil
 	default:
 		if s.char() != '{' {
-			return errors.ErrNotAtBeginningOfValue(s.totalOffset())
+			return errors.ErrInvalidBeginningOfValue(s.char(), s.totalOffset())
 		}
 	}
 	s.cursor++
@@ -740,7 +740,7 @@ func (d *structDecoder) Decode(ctx *RuntimeContext, cursor, depth int64, p unsaf
 		return cursor, nil
 	case '{':
 	default:
-		return 0, errors.ErrNotAtBeginningOfValue(cursor)
+		return 0, errors.ErrInvalidBeginningOfValue(char(b, cursor), cursor)
 	}
 	cursor++
 	cursor = skipWhiteSpace(buf, cursor)
diff --git a/internal/errors/error.go b/internal/errors/error.go
@@ -155,3 +155,10 @@ func ErrInvalidCharacter(c byte, context string, cursor int64) *SyntaxError {
 		Offset: cursor,
 	}
 }
+
+func ErrInvalidBeginningOfValue(c byte, cursor int64) *SyntaxError {
+	return &SyntaxError{
+		msg:    fmt.Sprintf("invalid character '%c' looking for beginning of value", c),
+		Offset: cursor,
+	}
+}

Original file line number	Diff line number	Diff line change
`@@ -76,7 +76,7 @@ func (d funcDecoder) DecodeStream(s Stream, depth int64, p unsafe.Pointer) err`
`76`	`76`	`}`
`77`	`77`	`}`
`78`	`78`	`}`
`79`		`- return errors.ErrNotAtBeginningOfValue(start)`
	`79`	`+ return errors.ErrInvalidBeginningOfValue(s.buf[s.cursor], s.totalOffset())`
`80`	`80`	`}`
`81`	`81`
`82`	`82`	`func (d funcDecoder) Decode(ctx RuntimeContext, cursor, depth int64, p unsafe.Pointer) (int64, error) {`
`@@ -137,5 +137,5 @@ func (d funcDecoder) Decode(ctx RuntimeContext, cursor, depth int64, p unsafe.`
`137`	`137`	`}`
`138`	`138`	`}`
`139`	`139`	`}`
`140`		`- return 0, errors.ErrNotAtBeginningOfValue(start)`
	`140`	`+ return cursor, errors.ErrInvalidBeginningOfValue(buf[cursor], cursor)`
`141`	`141`	`}`
Original file line number	Diff line number	Diff line change
`@@ -277,7 +277,7 @@ func (d interfaceDecoder) decodeStreamEmptyInterface(s Stream, depth int64, p`
`277`	`277`	`}`
`278`	`278`	`break`
`279`	`279`	`}`
`280`		`- return errors.ErrNotAtBeginningOfValue(s.totalOffset())`
	`280`	`+ return errors.ErrInvalidBeginningOfValue(c, s.totalOffset())`
`281`	`281`	`}`
`282`	`282`
`283`	`283`	`type emptyInterface struct {`
`@@ -454,5 +454,5 @@ func (d interfaceDecoder) decodeEmptyInterface(ctx RuntimeContext, cursor, dep`
`454`	`454`	`(interface{})(unsafe.Pointer(&p)) = nil`
`455`	`455`	`return cursor, nil`
`456`	`456`	`}`
`457`		`- return cursor, errors.ErrNotAtBeginningOfValue(cursor)`
	`457`	`+ return cursor, errors.ErrInvalidBeginningOfValue(buf[cursor], cursor)`
`458`	`458`	`}`
Original file line number	Diff line number	Diff line change
`@@ -52,6 +52,7 @@ func (d numberDecoder) Decode(ctx RuntimeContext, cursor, depth int64, p unsaf`
`52`	`52`	`}`
`53`	`53`
`54`	`54`	`func (d numberDecoder) decodeStreamByte(s Stream) ([]byte, error) {`
	`55`	`+ start := s.cursor`
`55`	`56`	`for {`
`56`	`57`	`switch s.char() {`
`57`	`58`	`case ' ', '\n', '\t', '\r':`
`@@ -76,6 +77,9 @@ func (d numberDecoder) decodeStreamByte(s Stream) ([]byte, error) {`
`76`	`77`	`}`
`77`	`78`	`}`
`78`	`79`	`ERROR:`
	`80`	`+ if s.cursor == start {`
	`81`	`+ return nil, errors.ErrInvalidBeginningOfValue(s.char(), s.totalOffset())`
	`82`	`+ }`
`79`	`83`	`return nil, errors.ErrUnexpectedEndOfJSON("json.Number", s.totalOffset())`
`80`	`84`	`}`
`81`	`85`
Original file line number	Diff line number	Diff line change
`@@ -281,7 +281,7 @@ func (d stringDecoder) decodeStreamByte(s Stream) ([]byte, error) {`
`281`	`281`	`}`
`282`	`282`	`break`
`283`	`283`	`}`
`284`		`- return nil, errors.ErrNotAtBeginningOfValue(s.totalOffset())`
	`284`	`+ return nil, errors.ErrInvalidBeginningOfValue(s.char(), s.totalOffset())`
`285`	`285`	`}`
`286`	`286`
`287`	`287`	`func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {`
`@@ -356,7 +356,7 @@ func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, err`
`356`	`356`	`cursor += 4`
`357`	`357`	`return nil, cursor, nil`
`358`	`358`	`default:`
`359`		`- return nil, 0, errors.ErrNotAtBeginningOfValue(cursor)`
	`359`	`+ return nil, 0, errors.ErrInvalidBeginningOfValue(buf[cursor], cursor)`
`360`	`360`	`}`
`361`	`361`	`}`
`362`	`362`	`}`
Original file line number	Diff line number	Diff line change
`@@ -261,7 +261,7 @@ func decodeKeyByBitmapUint8(d *structDecoder, buf []byte, cursor int64) (int64,`
`261`	`261`	`cursor++`
`262`	`262`	`}`
`263`	`263`	`default:`
`264`		`- return cursor, nil, errors.ErrNotAtBeginningOfValue(cursor)`
	`264`	`+ return cursor, nil, errors.ErrInvalidBeginningOfValue(char(b, cursor), cursor)`
`265`	`265`	`}`
`266`	`266`	`}`
`267`	`267`	`}`
`@@ -324,7 +324,7 @@ func decodeKeyByBitmapUint16(d *structDecoder, buf []byte, cursor int64) (int64,`
`324`	`324`	`cursor++`
`325`	`325`	`}`
`326`	`326`	`default:`
`327`		`- return cursor, nil, errors.ErrNotAtBeginningOfValue(cursor)`
	`327`	`+ return cursor, nil, errors.ErrInvalidBeginningOfValue(char(b, cursor), cursor)`
`328`	`328`	`}`
`329`	`329`	`}`
`330`	`330`	`}`
`@@ -376,7 +376,7 @@ func decodeKeyByBitmapUint8Stream(d structDecoder, s Stream) (*structFieldSet,`
`376`	`376`	`_, cursor, p = s.stat()`
`377`	`377`	`continue`
`378`	`378`	`}`
`379`		`- return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())`
	`379`	`+ return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())`
`380`	`380`	`case '"':`
`381`	`381`	`cursor++`
`382`	`382`	`FIRST_CHAR:`
`@@ -443,7 +443,7 @@ func decodeKeyByBitmapUint8Stream(d structDecoder, s Stream) (*structFieldSet,`
`443`	`443`	`cursor++`
`444`	`444`	`}`
`445`	`445`	`default:`
`446`		`- return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())`
	`446`	`+ return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())`
`447`	`447`	`}`
`448`	`448`	`}`
`449`	`449`	`}`
`@@ -463,7 +463,7 @@ func decodeKeyByBitmapUint16Stream(d structDecoder, s Stream) (*structFieldSet`
`463`	`463`	`_, cursor, p = s.stat()`
`464`	`464`	`continue`
`465`	`465`	`}`
`466`		`- return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())`
	`466`	`+ return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())`
`467`	`467`	`case '"':`
`468`	`468`	`cursor++`
`469`	`469`	`FIRST_CHAR:`
`@@ -530,7 +530,7 @@ func decodeKeyByBitmapUint16Stream(d structDecoder, s Stream) (*structFieldSet`
`530`	`530`	`cursor++`
`531`	`531`	`}`
`532`	`532`	`default:`
`533`		`- return nil, "", errors.ErrNotAtBeginningOfValue(s.totalOffset())`
	`533`	`+ return nil, "", errors.ErrInvalidBeginningOfValue(char(p, cursor), s.totalOffset())`
`534`	`534`	`}`
`535`	`535`	`}`
`536`	`536`	`}`
`@@ -653,7 +653,7 @@ func (d structDecoder) DecodeStream(s Stream, depth int64, p unsafe.Pointer) e`
`653`	`653`	`return nil`
`654`	`654`	`default:`
`655`	`655`	`if s.char() != '{' {`
`656`		`- return errors.ErrNotAtBeginningOfValue(s.totalOffset())`
	`656`	`+ return errors.ErrInvalidBeginningOfValue(s.char(), s.totalOffset())`
`657`	`657`	`}`
`658`	`658`	`}`
`659`	`659`	`s.cursor++`
`@@ -740,7 +740,7 @@ func (d structDecoder) Decode(ctx RuntimeContext, cursor, depth int64, p unsaf`
`740`	`740`	`return cursor, nil`
`741`	`741`	`case '{':`
`742`	`742`	`default:`
`743`		`- return 0, errors.ErrNotAtBeginningOfValue(cursor)`
	`743`	`+ return 0, errors.ErrInvalidBeginningOfValue(char(b, cursor), cursor)`
`744`	`744`	`}`
`745`	`745`	`cursor++`
`746`	`746`	`cursor = skipWhiteSpace(buf, cursor)`
Original file line number	Diff line number	Diff line change
`@@ -155,3 +155,10 @@ func ErrInvalidCharacter(c byte, context string, cursor int64) *SyntaxError {`
`155`	`155`	`Offset: cursor,`
`156`	`156`	`}`
`157`	`157`	`}`
	`158`	`+`
	`159`	`+func ErrInvalidBeginningOfValue(c byte, cursor int64) *SyntaxError {`
	`160`	`+ return &SyntaxError{`
	`161`	`+ msg: fmt.Sprintf("invalid character '%c' looking for beginning of value", c),`
	`162`	`+ Offset: cursor,`
	`163`	`+ }`
	`164`	`+}`