code review 4430043: json: keep track of error offset in SyntaxError

json: keep track of error offset in SyntaxError

[bradfitz, 2011-04-15 04:41:43]

Hello rsc (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://go.googlecode.com/hg/

[rsc, 2011-04-15 05:03:49]

http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/decode_test.go
File src/pkg/json/decode_test.go (right):

http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/decode_test.go#n...
src/pkg/json/decode_test.go:74: {`{"X": "foo", "Y"}`, nil, nil,
&SyntaxError{"invalid character '}' after object key", 0}},
presumably should be s/0/16/ or so

http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/scanner.go
File src/pkg/json/scanner.go (right):

http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/scanner.go#newco...
src/pkg/json/scanner.go:60: msg   string
More typical for errors to just export the fields
and do without the getters

Msg string   // description of error
Offset int64  // error occurred after reading Offset bytes

http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/stream.go
File src/pkg/json/stream.go (right):

http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/stream.go#newcode27
src/pkg/json/stream.go:27: // Reader and stores it in the value pointed to by v.
s/Reader/input/

http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/stream.go#newcode65
src/pkg/json/stream.go:65: dec.scan.bytes++
A line like this needs to be in checkValid in scanner.go,
so that Unmarshal's syntax errors have offsets.

[bradfitz, 2011-04-15 06:34:54]

Hello rsc (cc: golang-dev@googlegroups.com),

Please take another look.

[bradfitz, 2011-04-15 06:37:19]

All done.

With checkValid also incrementing the test now fails without offset 17, as
expected.  (I knew I was probably missing something before when it was
zero...)

PTAL

On Thu, Apr 14, 2011 at 10:03 PM, <rsc@golang.org> wrote:

>
> http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/decode_test.go
> File src/pkg/json/decode_test.go (right):
>
>
>
http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/decode_test.go#n...
> src/pkg/json/decode_test.go:74: {`{"X": "foo", "Y"}`, nil, nil,
>
> &SyntaxError{"invalid character '}' after object key", 0}},
> presumably should be s/0/16/ or so
>
> http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/scanner.go
> File src/pkg/json/scanner.go (right):
>
>
>
http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/scanner.go#newco...
> src/pkg/json/scanner.go:60: msg   string
> More typical for errors to just export the fields
> and do without the getters
>
> Msg string   // description of error
> Offset int64  // error occurred after reading Offset bytes
>
> http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/stream.go
> File src/pkg/json/stream.go (right):
>
>
>
http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/stream.go#newcode27
> src/pkg/json/stream.go:27: // Reader and stores it in the value pointed
> to by v.
> s/Reader/input/
>
>
>
http://codereview.appspot.com/4430043/diff/4001/src/pkg/json/stream.go#newcode65
> src/pkg/json/stream.go:65: dec.scan.bytes++
> A line like this needs to be in checkValid in scanner.go,
> so that Unmarshal's syntax errors have offsets.
>
>
> http://codereview.appspot.com/4430043/
>

[rsc, 2011-04-15 12:13:43]

LGTM

[bradfitz, 2011-04-15 15:14:37]

*** Submitted as http://code.google.com/p/go/source/detail?r=22beb9c71c9c ***

json: keep track of error offset in SyntaxError

R=rsc
CC=golang-dev
http://codereview.appspot.com/4430043