[PATCH 1/3] Adding an S-expression structured output printer.
Mark Walters
markwalters1009 at gmail.com
Sat Dec 1 04:24:41 PST 2012
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)
Best wishes
Mark
>
>
> 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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