dart:convert: support indented output w/ JsonEncoder

dart:convert: support indented output w/ JsonEncoder

BUG= https://code.google.com/p/dart/issues/detail?id=7846
R=lrn@google.com

Committed: https://code.google.com/p/dart/source/detail?r=34758

[Lasse Reichstein Nielsen, 2014-04-03 18:18:17]

https://codereview.chromium.org/224093007/diff/1/sdk/lib/convert/json.dart
File sdk/lib/convert/json.dart (right):

https://codereview.chromium.org/224093007/diff/1/sdk/lib/convert/json.dart#ne...
sdk/lib/convert/json.dart:165: final int indent;
Consider letting "indent" be a string which will be repeated. Then you can pick
either space or tab indentation as you please.

[kevmoo, 2014-04-03 18:27:57]

On 2014/04/03 18:18:17, Lasse Reichstein Nielsen wrote:
> https://codereview.chromium.org/224093007/diff/1/sdk/lib/convert/json.dart
> File sdk/lib/convert/json.dart (right):
> 
>
https://codereview.chromium.org/224093007/diff/1/sdk/lib/convert/json.dart#ne...
> sdk/lib/convert/json.dart:165: final int indent;
> Consider letting "indent" be a string which will be repeated. Then you can
pick
> either space or tab indentation as you please.

I pondered that -- allowing an arbitrary sting -- but then folks can insert junk
and not create valid json.

I also pondered an optional named bool 'useTab' defaulting to false - space -
but that seemed a bit heavy.

Open to discussion, certainly.

I'm a big for for "encouraging" the use of space for indention. :-)

[Anders Johnsen, 2014-04-04 07:05:59]

What if the indent String was validated like

  if (indent.trim().isNotEmpty()) throw new FormatException('bad indent
string');

?

[Lasse Reichstein Nielsen, 2014-04-04 13:40:56]

I don't particularly mind giving people more power to shoot themselves in the
foot.

The "trim" test isn't simple enough - there are characters removed by trim that
aren't JSON whitespace characters - and it feels arbitrary. 

Maybe the point isn't to create valid JSON, but to create something JSON-shaped
and human readable (I sometimes use JSON.encode when debugging, to get a more
readable output).

[kevmoo, 2014-04-05 18:41:56]

Updated to use a String for the input.

PTAL

[Lasse Reichstein Nielsen, 2014-04-05 19:34:42]

lgtm

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dart
File sdk/lib/convert/json.dart (right):

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:161: * The value appended for each level the JSON
output is indented.
The string used for indentation.

When generating multi-line output, this string is inserted once at the beginning
of each indented line for each level of indentation.

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:163: * If `null`, the output is encoded in a single
line.
in -> as

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:186: * Creates a JSON encoder with each output level
having a specified [indent].
"output level" is not defined anywhere.
How about:

Creates a JSON encoder that creates multi-line JSON.

The encoding of elements of lists and maps are indented and put on separate
lines. The [indent] string is prepended to these elements, once for each level
of indentation.

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:225: * Json Objects should not change during
serialization.
Not your text, but ...
 Json -> JSON 
(Or make a TODO that I should fix it, there is no such thing as a "JSON
object").

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:553: class _JsonStringifierPretty extends
_JsonStringifier {
Add a class comment.

https://codereview.chromium.org/224093007/diff/20001/tests/lib/convert/json_p...
File tests/lib/convert/json_pretty_test.dart (right):

https://codereview.chromium.org/224093007/diff/20001/tests/lib/convert/json_p...
tests/lib/convert/json_pretty_test.dart:73: 

Test with "\x00" as indentation.
Test [[],[[]]] for me, please :)

[kevmoo, 2014-04-05 20:08:58]

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dart
File sdk/lib/convert/json.dart (right):

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:161: * The value appended for each level the JSON
output is indented.
On 2014/04/05 19:34:43, Lasse Reichstein Nielsen wrote:
> The string used for indentation.
> 
> When generating multi-line output, this string is inserted once at the
beginning
> of each indented line for each level of indentation.

Done.

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:163: * If `null`, the output is encoded in a single
line.
On 2014/04/05 19:34:43, Lasse Reichstein Nielsen wrote:
> in -> as

Done.

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:186: * Creates a JSON encoder with each output level
having a specified [indent].
On 2014/04/05 19:34:43, Lasse Reichstein Nielsen wrote:
> "output level" is not defined anywhere.
> How about:
> 
> Creates a JSON encoder that creates multi-line JSON.
> 
> The encoding of elements of lists and maps are indented and put on separate
> lines. The [indent] string is prepended to these elements, once for each level
> of indentation.

Done.

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:225: * Json Objects should not change during
serialization.
On 2014/04/05 19:34:43, Lasse Reichstein Nielsen wrote:
> Not your text, but ...
>  Json -> JSON 
> (Or make a TODO that I should fix it, there is no such thing as a "JSON
> object").

Done. Cleaned this up a bit.

https://codereview.chromium.org/224093007/diff/20001/sdk/lib/convert/json.dar...
sdk/lib/convert/json.dart:553: class _JsonStringifierPretty extends
_JsonStringifier {
On 2014/04/05 19:34:43, Lasse Reichstein Nielsen wrote:
> Add a class comment.

Done.

https://codereview.chromium.org/224093007/diff/20001/tests/lib/convert/json_p...
File tests/lib/convert/json_pretty_test.dart (right):

https://codereview.chromium.org/224093007/diff/20001/tests/lib/convert/json_p...
tests/lib/convert/json_pretty_test.dart:73: 
On 2014/04/05 19:34:43, Lasse Reichstein Nielsen wrote:
> 
> Test with "\x00" as indentation.
> Test [[],[[]]] for me, please :)

Done.

The output from the null character seems to be what's expected...although a bit
weird when you print it.

[kevmoo, 2014-04-05 20:09:26]

Committed patchset #3 manually as r34758 (presubmit successful).