[PATCH 1/3] Adding an S-expression structured output printer.
Tomi Ollila
tomi.ollila at iki.fi
Sat Dec 1 05:29:36 PST 2012
On Sat, Dec 01 2012, Mark Walters <markwalters1009 at gmail.com> wrote:
> On Sat, 01 Dec 2012, Tomi Ollila <tomi.ollila at iki.fi> wrote:
>> On Sat, Dec 01 2012, Mark Walters wrote:
>>
>>> Hi
>>>
>>> Overall I like the series: I think I agree with all of Jani's
>>> comments.
>>>
>>> My one extra comment is that I think we should decide on whether we also
>>> want a sexp plist version. I think we might want one for the emacs
>>> front-end as that currently uses plists for everything.
>>>
>>> If we do we might want to change the names a little, both for functions
>>> and options (eg sexp_a and sexp_p or something). Probably a lot of
>>> sprinter-sexp would be common to both versions.
>>
>> This is an important question that needs to be addressed fast: options
>> are:
>>
>> 1) have options to spit both alist & plist formats
>> 2) when converting emacs to use s-expressions, convert it to use alists
>> 3) start using plists instead of alists in Peter's android client
>
> Ok I have looked at this and the changes needed to output plist (or
> both) are pretty small: the only functions from sprinter-sexp.c that
> need to be changed are sexp_end and sexp_map_key. The total diff from
> alist to plist is about 10 lines. I have a version which allows both
> (the same sprinter file creates both possibilities) and have hooked it
> into emacs/notmuch-show.el and it all seems to work.
>
> (Search is more difficult as that uses the async parser; indeed even for
> show I used sexp-at-point as suggested by Tomi which seems rather
> underdocumented but does seem to work)
>
> Given the ease with which we can allow both I think that would be my
> preference: the biggest problem is that slightly more cluttered option
> list (i.e., we have to allow both --format=sexpa and --format=sexpp or
> similar).
>
> (I can post the patch doing the above but almost all of it is modifying the
> commands to choose alist or plist rather than modifying the
> sprinter-sexp itself)
As the diff is so small I agree that supporting 2 formats is good
option.
In case this is done I suggest that we proceed the following way:
1) Agree how we call these formats (sexpa & sexpp or something else)
2) Peter does his updates, including to call the format as will be decided
3) Mark posts his patches after Peter's work is pushed
>
> Best wishes
>
> Mark
Tomi
>
>
>
>
>
>>
>>
>> In case (1) is chosen then we just need to support one more format.
>>
>> How much work would it involve to convert emacs to receive content in
>> alists (and how feasible would that be)?
>>
>> How much work would it require in Peter's client to use plists (and how
>> feasible would that be)?
>>
>>>
>>> Best wishes
>>>
>>> Mark
>>
>> Tomi
>>
>>
>>>
>>>
>>> On Fri, 30 Nov 2012, Peter Feigl <craven at gmx.net> wrote:
>>>> This commit adds an sprinter for Lisp S-Expressions. Later commits will
>>>> use this printer.
>>>>
>>>> The structure is the same as json, but:
>>>> - arrays are written as lists: ("foo" "bar" "baaz" 1 2 3)
>>>> - maps are written as a-lists: ((key "value") (other-key "other-value"))
>>>> - true is written as t
>>>> - false is written as nil
>>>> - null is written as nil
>>>> ---
>>>> Makefile.local | 1 +
>>>> sprinter-sexp.c | 235 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>> 2 files changed, 236 insertions(+)
>>>> create mode 100644 sprinter-sexp.c
>>>>
>>>> diff --git a/Makefile.local b/Makefile.local
>>>> index 2b91946..0db1713 100644
>>>> --- a/Makefile.local
>>>> +++ b/Makefile.local
>>>> @@ -270,6 +270,7 @@ notmuch_client_srcs = \
>>>> notmuch-tag.c \
>>>> notmuch-time.c \
>>>> sprinter-json.c \
>>>> + sprinter-sexp.c \
>>>> sprinter-text.c \
>>>> query-string.c \
>>>> mime-node.c \
>>>> diff --git a/sprinter-sexp.c b/sprinter-sexp.c
>>>> new file mode 100644
>>>> index 0000000..8401c52
>>>> --- /dev/null
>>>> +++ b/sprinter-sexp.c
>>>> @@ -0,0 +1,235 @@
>>>> +#include <stdbool.h>
>>>> +#include <stdio.h>
>>>> +#include <talloc.h>
>>>> +#include "sprinter.h"
>>>> +
>>>> +struct sprinter_sexp {
>>>> + struct sprinter vtable;
>>>> + FILE *stream;
>>>> + /* Top of the state stack, or NULL if the printer is not currently
>>>> + * inside any aggregate types. */
>>>> + struct sexp_state *state;
>>>> +
>>>> + /* A flag to signify that a separator should be inserted in the
>>>> + * output as soon as possible.
>>>> + */
>>>> + notmuch_bool_t insert_separator;
>>>> +};
>>>> +
>>>> +struct sexp_state {
>>>> + struct sexp_state *parent;
>>>> +
>>>> + /* True if nothing has been printed in this aggregate yet.
>>>> + * Suppresses the space before a value. */
>>>> + notmuch_bool_t first;
>>>> +
>>>> + /* True if the state is a map state.
>>>> + Used to add a space between key/value pairs. */
>>>> + notmuch_bool_t in_map;
>>>> +
>>>> + /* The character that closes the current aggregate. */
>>>> + char close;
>>>> +};
>>>> +
>>>> +/* Helper function to set up the stream to print a value. If this
>>>> + * value follows another value, prints a space. */
>>>> +static struct sprinter_sexp *
>>>> +sexp_begin_value (struct sprinter *sp)
>>>> +{
>>>> + struct sprinter_sexp *sps = (struct sprinter_sexp *) sp;
>>>> +
>>>> + if (sps->state) {
>>>> + if (! sps->state->first) {
>>>> + if (sps->insert_separator) {
>>>> + fputc ('\n', sps->stream);
>>>> + sps->insert_separator = FALSE;
>>>> + } else {
>>>> + if( ! sps->state->in_map)
>>>> + fputc (' ', sps->stream);
>>>> + }
>>>> + } else {
>>>> + sps->state->first = FALSE;
>>>> + }
>>>> + }
>>>> + return sps;
>>>> +}
>>>> +
>>>> +/* Helper function to begin an aggregate type. Prints the open
>>>> + * character and pushes a new state frame. */
>>>> +static void
>>>> +sexp_begin_aggregate (struct sprinter *sp, char open, char close)
>>>> +{
>>>> + struct sprinter_sexp *sps = sexp_begin_value (sp);
>>>> + struct sexp_state *state = talloc (sps, struct sexp_state);
>>>> + fputc (open, sps->stream);
>>>> + state->parent = sps->state;
>>>> + state->first = TRUE;
>>>> + state->in_map = FALSE;
>>>> + state->close = close;
>>>> + sps->state = state;
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_begin_map (struct sprinter *sp)
>>>> +{
>>>> + struct sprinter_sexp *sps = (struct sprinter_sexp *) sp;
>>>> + sexp_begin_aggregate (sp, '(', ')');
>>>> + sps->state->in_map = TRUE;
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_begin_list (struct sprinter *sp)
>>>> +{
>>>> + sexp_begin_aggregate (sp, '(', ')');
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_end (struct sprinter *sp)
>>>> +{
>>>> + struct sprinter_sexp *sps = (struct sprinter_sexp *) sp;
>>>> + struct sexp_state *state = sps->state;
>>>> +
>>>> + if (sps->state->in_map)
>>>> + fputc (')', sps->stream);
>>>> + fputc (sps->state->close, sps->stream);
>>>> + sps->state = state->parent;
>>>> + talloc_free (state);
>>>> + if (sps->state == NULL)
>>>> + fputc ('\n', sps->stream);
>>>> +}
>>>> +
>>>> +/* This implementation supports embedded NULs as allowed by the JSON
>>>> + * specification and Unicode. Support for *parsing* embedded NULs
>>>> + * varies, but is generally not a problem outside of C-based parsers
>>>> + * (Python's json module and Emacs' json.el take embedded NULs in
>>>> + * stride). */
>>>> +static void
>>>> +sexp_string_len_internal (struct sprinter *sp, const char *val, size_t len, notmuch_bool_t quote)
>>>> +{
>>>> + static const char *const escapes[] = {
>>>> + ['\"'] = "\\\"", ['\\'] = "\\\\", ['\b'] = "\\b",
>>>> + ['\f'] = "\\f", ['\n'] = "\\n", ['\t'] = "\\t"
>>>> + };
>>>> + struct sprinter_sexp *sps = sexp_begin_value (sp);
>>>> +
>>>> + if(quote)
>>>> + fputc ('"', sps->stream);
>>>> + for (; len; ++val, --len) {
>>>> + unsigned char ch = *val;
>>>> + if (ch < ARRAY_SIZE (escapes) && escapes[ch])
>>>> + fputs (escapes[ch], sps->stream);
>>>> + else if (ch >= 32)
>>>> + fputc (ch, sps->stream);
>>>> + else
>>>> + fprintf (sps->stream, "\\u%04x", ch);
>>>> + }
>>>> + if(quote)
>>>> + fputc ('"', sps->stream);
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_string_len (struct sprinter *sp, const char *val, size_t len)
>>>> +{
>>>> + sexp_string_len_internal (sp, val, len, TRUE); /* print quoted */
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_symbol_len (struct sprinter *sp, const char *val, size_t len)
>>>> +{
>>>> + sexp_string_len_internal (sp, val, len, FALSE); /* print unquoted */
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_string (struct sprinter *sp, const char *val)
>>>> +{
>>>> + if (val == NULL)
>>>> + val = "";
>>>> + sexp_string_len (sp, val, strlen (val));
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_symbol (struct sprinter *sp, const char *val)
>>>> +{
>>>> + if (val == NULL)
>>>> + val = "";
>>>> + sexp_symbol_len (sp, val, strlen (val));
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_integer (struct sprinter *sp, int val)
>>>> +{
>>>> + struct sprinter_sexp *sps = sexp_begin_value (sp);
>>>> +
>>>> + fprintf (sps->stream, "%d", val);
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_boolean (struct sprinter *sp, notmuch_bool_t val)
>>>> +{
>>>> + struct sprinter_sexp *sps = sexp_begin_value (sp);
>>>> +
>>>> + fputs (val ? "t" : "nil", sps->stream);
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_null (struct sprinter *sp)
>>>> +{
>>>> + struct sprinter_sexp *sps = sexp_begin_value (sp);
>>>> +
>>>> + fputs ("nil", sps->stream);
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_map_key (struct sprinter *sp, const char *key)
>>>> +{
>>>> + struct sprinter_sexp *sps = (struct sprinter_sexp *) sp;
>>>> +
>>>> + if( sps->state->in_map && ! sps->state->first)
>>>> + fputs (") ", sps->stream);
>>>> + fputc ('(', sps->stream);
>>>> + sexp_symbol (sp, key);
>>>> + fputc (' ', sps->stream);
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_set_prefix (unused (struct sprinter *sp), unused (const char *name))
>>>> +{
>>>> +}
>>>> +
>>>> +static void
>>>> +sexp_separator (struct sprinter *sp)
>>>> +{
>>>> + struct sprinter_sexp *sps = (struct sprinter_sexp *) sp;
>>>> +
>>>> + sps->insert_separator = TRUE;
>>>> +}
>>>> +
>>>> +struct sprinter *
>>>> +sprinter_sexp_create (const void *ctx, FILE *stream)
>>>> +{
>>>> + static const struct sprinter_sexp template = {
>>>> + .vtable = {
>>>> + .begin_map = sexp_begin_map,
>>>> + .begin_list = sexp_begin_list,
>>>> + .end = sexp_end,
>>>> + .string = sexp_string,
>>>> + .string_len = sexp_string_len,
>>>> + .integer = sexp_integer,
>>>> + .boolean = sexp_boolean,
>>>> + .null = sexp_null,
>>>> + .map_key = sexp_map_key,
>>>> + .separator = sexp_separator,
>>>> + .set_prefix = sexp_set_prefix,
>>>> + .is_text_printer = FALSE,
>>>> + }
>>>> + };
>>>> + struct sprinter_sexp *res;
>>>> +
>>>> + res = talloc (ctx, struct sprinter_sexp);
>>>> + if (! res)
>>>> + return NULL;
>>>> +
>>>> + *res = template;
>>>> + res->stream = stream;
>>>> + return &res->vtable;
>>>> +}
>>>> --
>>>> 1.8.0
>>>>
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