[PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Mark Walters]

Add newlines between complete threads to make asynchronous parsing
of the JSON easier.
---

notmuch-pick uses the JSON output of notmuch show but, in many cases,
for many threads. This can take quite a long time when displaying a
large number of messages (say 20 seconds for the 10,000 messages in
the notmuch archive). Thus it is desirable to display results
incrementally in the same way that search currently does.

To make this easier this patch adds newlines between each toplevel
thread. So the ouput becomes

[
thread1
, thread2
, thread3
...
, last_thread
]

Thus the parser can easily tell if it has enough data to do some more
parsing.

Obviously, this changes the JSON output. This should not break any
consumer as the JSON parsers should not mind. However, it does break
several tests. Obviously, I will fix these but I wanted to check if
people were basically happy with the change first.

Also, should devel/schemata be updated? It seems a little unclear as
this is not really a "JSON" change as the JSON does not care about the
newlines.

Best wishes

Mark


 notmuch-show.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/notmuch-show.c b/notmuch-show.c
index 195e318..4a1d699 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -942,6 +942,8 @@ do_show (void *ctx,
 
     if (format->message_set_start)
 	fputs (format->message_set_start, stdout);
+    if (format == &format_json)
+	fputs ("\n", stdout);
 
     for (threads = notmuch_query_search_threads (query);
 	 notmuch_threads_valid (threads);
@@ -963,6 +965,9 @@ do_show (void *ctx,
 	if (status && !res)
 	    res = status;
 
+	if (format == &format_json)
+	    fputs ("\n", stdout);
+
 	notmuch_thread_destroy (thread);
 
     }
-- 
1.7.9.1

Re: [PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Dmitry Kurochkin]

Hi Mark.

Mark Walters <markwalters1009@gmail.com> writes:

> Add newlines between complete threads to make asynchronous parsing
> of the JSON easier.
> ---
>
> notmuch-pick uses the JSON output of notmuch show but, in many cases,
> for many threads. This can take quite a long time when displaying a
> large number of messages (say 20 seconds for the 10,000 messages in
> the notmuch archive). Thus it is desirable to display results
> incrementally in the same way that search currently does.
>
> To make this easier this patch adds newlines between each toplevel
> thread. So the ouput becomes
>
> [
> thread1
> , thread2
> , thread3
> ...
> , last_thread
> ]
>
> Thus the parser can easily tell if it has enough data to do some more
> parsing.
>
> Obviously, this changes the JSON output. This should not break any
> consumer as the JSON parsers should not mind. However, it does break
> several tests.

I think this should be part of the commit message since it explains the
rationale behind the change.

Regards,
  Dmitry

> Obviously, I will fix these but I wanted to check if
> people were basically happy with the change first.
>
> Also, should devel/schemata be updated? It seems a little unclear as
> this is not really a "JSON" change as the JSON does not care about the
> newlines.
>
> Best wishes
>
> Mark
>
>
>  notmuch-show.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/notmuch-show.c b/notmuch-show.c
> index 195e318..4a1d699 100644
> --- a/notmuch-show.c
> +++ b/notmuch-show.c
> @@ -942,6 +942,8 @@ do_show (void *ctx,
>  
>      if (format->message_set_start)
>  	fputs (format->message_set_start, stdout);
> +    if (format == &format_json)
> +	fputs ("\n", stdout);
>  
>      for (threads = notmuch_query_search_threads (query);
>  	 notmuch_threads_valid (threads);
> @@ -963,6 +965,9 @@ do_show (void *ctx,
>  	if (status && !res)
>  	    res = status;
>  
> +	if (format == &format_json)
> +	    fputs ("\n", stdout);
> +
>  	notmuch_thread_destroy (thread);
>  
>      }
> -- 
> 1.7.9.1
>
> _______________________________________________
> notmuch mailing list
> notmuch@notmuchmail.org
> http://notmuchmail.org/mailman/listinfo/notmuch

Re: [PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Tomi Ollila]

On Sat, Jun 30 2012, Mark Walters <markwalters1009@gmail.com> wrote:

> Add newlines between complete threads to make asynchronous parsing
> of the JSON easier.
> ---
>
> notmuch-pick uses the JSON output of notmuch show but, in many cases,
> for many threads. This can take quite a long time when displaying a
> large number of messages (say 20 seconds for the 10,000 messages in
> the notmuch archive). Thus it is desirable to display results
> incrementally in the same way that search currently does.
>
> To make this easier this patch adds newlines between each toplevel
> thread. So the ouput becomes
>
> [
> thread1
> , thread2
> , thread3
> ...
> , last_thread
> ]
>
> Thus the parser can easily tell if it has enough data to do some more
> parsing.
>
> Obviously, this changes the JSON output. This should not break any
> consumer as the JSON parsers should not mind. However, it does break
> several tests. Obviously, I will fix these but I wanted to check if
> people were basically happy with the change first.

To provide this feature rather than relying on newlines the parser should
use it's state to notice when one thread ends. 

Such a change could be used (privately) for human consumption -- allowing 
free change of whitespace during inspection (in a debugging session or so).
Computer software should not rely (or suffer) from any additional
(or lack thereof) whitespace there is...

... or at least a really convicing argument for the chance needs to
be presented (before "restricting" the json output notmuch spits out).

Btw: AFAIC (json-read) parses the whole json object (ignoring whitespace,
including newlines outside strings). So I quess notmuch-pick uses something
slightly different (probably using json.el subroutines)..

Btw2: I'm very interested to see notmuch-pick in action -- I just don't
see this a way to do this particular support properly.

Btw3: is search is ever going to use json we'll face the same problem -- 
unless writing each line as a separate json object (and starting to use 
s-expressions for speed)

> Also, should devel/schemata be updated? It seems a little unclear as
> this is not really a "JSON" change as the JSON does not care about the
> newlines.
>
> Best wishes

and best luck with your notmuch-pick work.

>
> Mark

Tomi

>
>
>  notmuch-show.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/notmuch-show.c b/notmuch-show.c
> index 195e318..4a1d699 100644
> --- a/notmuch-show.c
> +++ b/notmuch-show.c
> @@ -942,6 +942,8 @@ do_show (void *ctx,
>  
>      if (format->message_set_start)
>  	fputs (format->message_set_start, stdout);
> +    if (format == &format_json)
> +	fputs ("\n", stdout);
>  
>      for (threads = notmuch_query_search_threads (query);
>  	 notmuch_threads_valid (threads);
> @@ -963,6 +965,9 @@ do_show (void *ctx,
>  	if (status && !res)
>  	    res = status;
>  
> +	if (format == &format_json)
> +	    fputs ("\n", stdout);
> +
>  	notmuch_thread_destroy (thread);
>  
>      }
> -- 
> 1.7.9.1
>
> _______________________________________________
> notmuch mailing list
> notmuch@notmuchmail.org
> http://notmuchmail.org/mailman/listinfo/notmuch

Re: [PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Mark Walters]

On Sun, 01 Jul 2012, Tomi Ollila <tomi.ollila@iki.fi> wrote:
> On Sat, Jun 30 2012, Mark Walters <markwalters1009@gmail.com> wrote:
>
>> Add newlines between complete threads to make asynchronous parsing
>> of the JSON easier.
>> ---
>>
>> notmuch-pick uses the JSON output of notmuch show but, in many cases,
>> for many threads. This can take quite a long time when displaying a
>> large number of messages (say 20 seconds for the 10,000 messages in
>> the notmuch archive). Thus it is desirable to display results
>> incrementally in the same way that search currently does.
>>
>> To make this easier this patch adds newlines between each toplevel
>> thread. So the ouput becomes
>>
>> [
>> thread1
>> , thread2
>> , thread3
>> ...
>> , last_thread
>> ]
>>
>> Thus the parser can easily tell if it has enough data to do some more
>> parsing.
>>
>> Obviously, this changes the JSON output. This should not break any
>> consumer as the JSON parsers should not mind. However, it does break
>> several tests. Obviously, I will fix these but I wanted to check if
>> people were basically happy with the change first.
>
> To provide this feature rather than relying on newlines the parser should
> use it's state to notice when one thread ends. 
>
> Such a change could be used (privately) for human consumption -- allowing 
> free change of whitespace during inspection (in a debugging session or so).
> Computer software should not rely (or suffer) from any additional
> (or lack thereof) whitespace there is...
>
> ... or at least a really convicing argument for the chance needs to
> be presented (before "restricting" the json output notmuch spits out).
>
> Btw: AFAIC (json-read) parses the whole json object (ignoring whitespace,
> including newlines outside strings). So I quess notmuch-pick uses something
> slightly different (probably using json.el subroutines)..

I was following Austin's suggestion (on irc and
id:"20120214152114.GQ27039@mit.edu"). The idea is that each thread in
the JSON output is an entire JSON object. Thus pick skips the first [
and the waits until there are two \n's in the incoming stream. Then it
knows that the complete first thread has been received and it parses
that with json-read as normal. The important thing is that it is trivial
to tell when a complete (and so parsable) JSON object has arrived.

It seems to work, but I am definitely open to other approaches.

> Btw2: I'm very interested to see notmuch-pick in action -- I just don't
> see this a way to do this particular support properly.
>
> Btw3: is search is ever going to use json we'll face the same problem -- 
> unless writing each line as a separate json object (and starting to use 
> s-expressions for speed)
>
>> Also, should devel/schemata be updated? It seems a little unclear as
>> this is not really a "JSON" change as the JSON does not care about the
>> newlines.
>>
>> Best wishes


> and best luck with your notmuch-pick work.

Thanks!

Mark

>>
>>  notmuch-show.c |    5 +++++
>>  1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/notmuch-show.c b/notmuch-show.c
>> index 195e318..4a1d699 100644
>> --- a/notmuch-show.c
>> +++ b/notmuch-show.c
>> @@ -942,6 +942,8 @@ do_show (void *ctx,
>>  
>>      if (format->message_set_start)
>>  	fputs (format->message_set_start, stdout);
>> +    if (format == &format_json)
>> +	fputs ("\n", stdout);
>>  
>>      for (threads = notmuch_query_search_threads (query);
>>  	 notmuch_threads_valid (threads);
>> @@ -963,6 +965,9 @@ do_show (void *ctx,
>>  	if (status && !res)
>>  	    res = status;
>>  
>> +	if (format == &format_json)
>> +	    fputs ("\n", stdout);
>> +
>>  	notmuch_thread_destroy (thread);
>>  
>>      }
>> -- 
>> 1.7.9.1
>>
>> _______________________________________________
>> notmuch mailing list
>> notmuch@notmuchmail.org
>> http://notmuchmail.org/mailman/listinfo/notmuch

Re: [PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Austin Clements]

Quoth Tomi Ollila on Jul 02 at  1:13 am:
> On Sat, Jun 30 2012, Mark Walters <markwalters1009@gmail.com> wrote:
> 
> > Add newlines between complete threads to make asynchronous parsing
> > of the JSON easier.
> > ---
> >
> > notmuch-pick uses the JSON output of notmuch show but, in many cases,
> > for many threads. This can take quite a long time when displaying a
> > large number of messages (say 20 seconds for the 10,000 messages in
> > the notmuch archive). Thus it is desirable to display results
> > incrementally in the same way that search currently does.
> >
> > To make this easier this patch adds newlines between each toplevel
> > thread. So the ouput becomes
> >
> > [
> > thread1
> > , thread2
> > , thread3
> > ...
> > , last_thread
> > ]
> >
> > Thus the parser can easily tell if it has enough data to do some more
> > parsing.
> >
> > Obviously, this changes the JSON output. This should not break any
> > consumer as the JSON parsers should not mind. However, it does break
> > several tests. Obviously, I will fix these but I wanted to check if
> > people were basically happy with the change first.
> 
> To provide this feature rather than relying on newlines the parser should
> use it's state to notice when one thread ends. 
> 
> Such a change could be used (privately) for human consumption -- allowing 
> free change of whitespace during inspection (in a debugging session or so).
> Computer software should not rely (or suffer) from any additional
> (or lack thereof) whitespace there is...
> 
> ... or at least a really convicing argument for the chance needs to
> be presented (before "restricting" the json output notmuch spits out).

Given a JSON parser that only knows how to parse complete JSON
expressions, it's potentially very inefficient to keep attempting to
parse something when you don't know if it's complete.  The newlines
provide an in-band framing so the consumer knows when there's a
complete object to be parsed.

In effect, this defines a super-protocol of JSON that's compatible
with standard JSON, but easy to incrementally parse.

That said, just this weekend I implemented JSON-based search with
incremental JSON parsing and I took a slightly different approach.  I
still put framing into the newlines of the search results, but rather
than rely on it for correctness, the consumer uses it as an
optimization that only hints that a complete JSON expression is
probably available.  If the expression turns out to be incomplete,
that's okay.

I considered building a fully-incremental JSON parser that never
backtracks by more than a token, which would eliminate even the cost
of reparsing, but if we do move to S-expressions (which I think we
should), we want to let Emacs' C implementation do as much of the
parsing as possible, and the only thing we can do with that is read a
complete expression.

> Btw: AFAIC (json-read) parses the whole json object (ignoring whitespace,
> including newlines outside strings). So I quess notmuch-pick uses something
> slightly different (probably using json.el subroutines)..
> 
> Btw2: I'm very interested to see notmuch-pick in action -- I just don't
> see this a way to do this particular support properly.
> 
> Btw3: is search is ever going to use json we'll face the same problem -- 
> unless writing each line as a separate json object (and starting to use 
> s-expressions for speed)

Done.  I'll post the patches after a little more cleanup.

> > Also, should devel/schemata be updated? It seems a little unclear as
> > this is not really a "JSON" change as the JSON does not care about the
> > newlines.
> >
> > Best wishes
> 
> and best luck with your notmuch-pick work.
> 
> >
> > Mark
> 
> Tomi

Re: [PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Austin Clements]

Quoth myself on Jul 01 at  8:12 pm:
> Quoth Tomi Ollila on Jul 02 at  1:13 am:
> > On Sat, Jun 30 2012, Mark Walters <markwalters1009@gmail.com> wrote:
> > 
> > > Add newlines between complete threads to make asynchronous parsing
> > > of the JSON easier.
> > > ---
> > >
> > > notmuch-pick uses the JSON output of notmuch show but, in many cases,
> > > for many threads. This can take quite a long time when displaying a
> > > large number of messages (say 20 seconds for the 10,000 messages in
> > > the notmuch archive). Thus it is desirable to display results
> > > incrementally in the same way that search currently does.
> > >
> > > To make this easier this patch adds newlines between each toplevel
> > > thread. So the ouput becomes
> > >
> > > [
> > > thread1
> > > , thread2
> > > , thread3
> > > ...
> > > , last_thread
> > > ]
> > >
> > > Thus the parser can easily tell if it has enough data to do some more
> > > parsing.
> > >
> > > Obviously, this changes the JSON output. This should not break any
> > > consumer as the JSON parsers should not mind. However, it does break
> > > several tests. Obviously, I will fix these but I wanted to check if
> > > people were basically happy with the change first.
> > 
> > To provide this feature rather than relying on newlines the parser should
> > use it's state to notice when one thread ends. 
> > 
> > Such a change could be used (privately) for human consumption -- allowing 
> > free change of whitespace during inspection (in a debugging session or so).
> > Computer software should not rely (or suffer) from any additional
> > (or lack thereof) whitespace there is...
> > 
> > ... or at least a really convicing argument for the chance needs to
> > be presented (before "restricting" the json output notmuch spits out).
> 
> Given a JSON parser that only knows how to parse complete JSON
> expressions, it's potentially very inefficient to keep attempting to
> parse something when you don't know if it's complete.  The newlines
> provide an in-band framing so the consumer knows when there's a
> complete object to be parsed.
> 
> In effect, this defines a super-protocol of JSON that's compatible
> with standard JSON, but easy to incrementally parse.
> 
> That said, just this weekend I implemented JSON-based search with
> incremental JSON parsing and I took a slightly different approach.  I
> still put framing into the newlines of the search results, but rather
> than rely on it for correctness, the consumer uses it as an
> optimization that only hints that a complete JSON expression is
> probably available.  If the expression turns out to be incomplete,
> that's okay.
> 
> I considered building a fully-incremental JSON parser that never
> backtracks by more than a token, which would eliminate even the cost
> of reparsing, but if we do move to S-expressions (which I think we
> should), we want to let Emacs' C implementation do as much of the
> parsing as possible, and the only thing we can do with that is read a
> complete expression.

Actually, I take that back.  While we can't do fast incremental
S-expression parsing, `parse-partial-sexp' can tell us incrementally
(and probably very quickly) *if* there's a complete expression ready
to parse, so we could avoid calling into the parser at all unless it
would succeed.

I'll try this out in my incremental JSON parser and see how well it
works.

Re: [PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Tomi Ollila]

On Mon, Jul 02 2012, Austin Clements <amdragon@MIT.EDU> wrote:

> Quoth myself on Jul 01 at  8:12 pm:
>> Quoth Tomi Ollila on Jul 02 at  1:13 am:
>> > On Sat, Jun 30 2012, Mark Walters <markwalters1009@gmail.com> wrote:
>> > 
>> > > Add newlines between complete threads to make asynchronous parsing
>> > > of the JSON easier.
>> > > ---
>> > >
>> > > notmuch-pick uses the JSON output of notmuch show but, in many cases,
>> > > for many threads. This can take quite a long time when displaying a
>> > > large number of messages (say 20 seconds for the 10,000 messages in
>> > > the notmuch archive). Thus it is desirable to display results
>> > > incrementally in the same way that search currently does.
>> > >
>> > > To make this easier this patch adds newlines between each toplevel
>> > > thread. So the ouput becomes
>> > >
>> > > [
>> > > thread1
>> > > , thread2
>> > > , thread3
>> > > ...
>> > > , last_thread
>> > > ]
>> > >
>> > > Thus the parser can easily tell if it has enough data to do some more
>> > > parsing.
>> > >
>> > > Obviously, this changes the JSON output. This should not break any
>> > > consumer as the JSON parsers should not mind. However, it does break
>> > > several tests. Obviously, I will fix these but I wanted to check if
>> > > people were basically happy with the change first.
>> > 
>> > To provide this feature rather than relying on newlines the parser should
>> > use it's state to notice when one thread ends. 
>> > 
>> > Such a change could be used (privately) for human consumption -- allowing 
>> > free change of whitespace during inspection (in a debugging session or so).
>> > Computer software should not rely (or suffer) from any additional
>> > (or lack thereof) whitespace there is...
>> > 
>> > ... or at least a really convicing argument for the chance needs to
>> > be presented (before "restricting" the json output notmuch spits out).
>> 
>> Given a JSON parser that only knows how to parse complete JSON
>> expressions, it's potentially very inefficient to keep attempting to
>> parse something when you don't know if it's complete.  The newlines
>> provide an in-band framing so the consumer knows when there's a
>> complete object to be parsed.
>> 
>> In effect, this defines a super-protocol of JSON that's compatible
>> with standard JSON, but easy to incrementally parse.
>> 
>> That said, just this weekend I implemented JSON-based search with
>> incremental JSON parsing and I took a slightly different approach.  I
>> still put framing into the newlines of the search results, but rather
>> than rely on it for correctness, the consumer uses it as an
>> optimization that only hints that a complete JSON expression is
>> probably available.  If the expression turns out to be incomplete,
>> that's okay.
>> 
>> I considered building a fully-incremental JSON parser that never
>> backtracks by more than a token, which would eliminate even the cost
>> of reparsing, but if we do move to S-expressions (which I think we
>> should), we want to let Emacs' C implementation do as much of the
>> parsing as possible, and the only thing we can do with that is read a
>> complete expression.
>
> Actually, I take that back.  While we can't do fast incremental
> S-expression parsing, `parse-partial-sexp' can tell us incrementally
> (and probably very quickly) *if* there's a complete expression ready
> to parse, so we could avoid calling into the parser at all unless it
> would succeed.
>
> I'll try this out in my incremental JSON parser and see how well it
> works.

I played a bit with parse-partial-sexp (and sexp-at-point) and it looks
like this really could work. IMO the things to be done could be

1) add --format=sexp support to notmuch cli
2) add tests for that (I can do some tests)
3) review those patches (I will definitely be one reviewer)
4) convert emacs to use --format=sexp everywhere it now uses --format=json,
   (is it then basically s/(json-read)/(sexp-at-point)/ ?) and adjust tests.
5) review those patches (I will definitely be one reviewer)
6) add support to commands lines like 
   'notmuch search --output=sexp --sort=oldest-first tag:unread' ...
   (even I can do that) (of course --output=json would work too as expected)
7) review...
8) convert emacs notmuch search to use that syntax and incrementally
   display progress.
9) review...

This means that we would drop adding new features using json output in
emacs mua and concentrate using sexps wherever applicable.

(during this we should be able to determine whether those framing newlines
 are needed or not)

Tomi

PS: A week ago I also did some experiments how notmuch cli could spit sexp
output using current json formatters -- just naiively copying those and
modifying would result like 99% of copy-paste and 1% of changes. I got some
initial thoughts how thihgs could be done but luckily Peter & Austin are
ahead of me -- I now just eagerly wait for patches to be reviewed :D

Re: [PATCH] cli: notmuch-show with framing newlines between threads in JSON.

[Mark Walters]

On Mon, 02 Jul 2012, Austin Clements <amdragon@MIT.EDU> wrote:
> Quoth myself on Jul 01 at  8:12 pm:
>> Quoth Tomi Ollila on Jul 02 at  1:13 am:
>> > On Sat, Jun 30 2012, Mark Walters <markwalters1009@gmail.com> wrote:
>> > 
>> > > Add newlines between complete threads to make asynchronous parsing
>> > > of the JSON easier.
>> > > ---
>> > >
>> > > notmuch-pick uses the JSON output of notmuch show but, in many cases,
>> > > for many threads. This can take quite a long time when displaying a
>> > > large number of messages (say 20 seconds for the 10,000 messages in
>> > > the notmuch archive). Thus it is desirable to display results
>> > > incrementally in the same way that search currently does.
>> > >
>> > > To make this easier this patch adds newlines between each toplevel
>> > > thread. So the ouput becomes
>> > >
>> > > [
>> > > thread1
>> > > , thread2
>> > > , thread3
>> > > ...
>> > > , last_thread
>> > > ]
>> > >
>> > > Thus the parser can easily tell if it has enough data to do some more
>> > > parsing.
>> > >
>> > > Obviously, this changes the JSON output. This should not break any
>> > > consumer as the JSON parsers should not mind. However, it does break
>> > > several tests. Obviously, I will fix these but I wanted to check if
>> > > people were basically happy with the change first.
>> > 
>> > To provide this feature rather than relying on newlines the parser should
>> > use it's state to notice when one thread ends. 
>> > 
>> > Such a change could be used (privately) for human consumption -- allowing 
>> > free change of whitespace during inspection (in a debugging session or so).
>> > Computer software should not rely (or suffer) from any additional
>> > (or lack thereof) whitespace there is...
>> > 
>> > ... or at least a really convicing argument for the chance needs to
>> > be presented (before "restricting" the json output notmuch spits out).
>> 
>> Given a JSON parser that only knows how to parse complete JSON
>> expressions, it's potentially very inefficient to keep attempting to
>> parse something when you don't know if it's complete.  The newlines
>> provide an in-band framing so the consumer knows when there's a
>> complete object to be parsed.
>> 
>> In effect, this defines a super-protocol of JSON that's compatible
>> with standard JSON, but easy to incrementally parse.
>> 
>> That said, just this weekend I implemented JSON-based search with
>> incremental JSON parsing and I took a slightly different approach.  I
>> still put framing into the newlines of the search results, but rather
>> than rely on it for correctness, the consumer uses it as an
>> optimization that only hints that a complete JSON expression is
>> probably available.  If the expression turns out to be incomplete,
>> that's okay.
>> 
>> I considered building a fully-incremental JSON parser that never
>> backtracks by more than a token, which would eliminate even the cost
>> of reparsing, but if we do move to S-expressions (which I think we
>> should), we want to let Emacs' C implementation do as much of the
>> parsing as possible, and the only thing we can do with that is read a
>> complete expression.
>
> Actually, I take that back.  While we can't do fast incremental
> S-expression parsing, `parse-partial-sexp' can tell us incrementally
> (and probably very quickly) *if* there's a complete expression ready
> to parse, so we could avoid calling into the parser at all unless it
> would succeed.
>
> I'll try this out in my incremental JSON parser and see how well it
> works.

I have converted pick to use Austin's incremental parser and all works
well so this seems the way to go. Hence I have marked my original patch
obsolete.

Best wishes

Mark