Date: Sun, 22 Jul 2012 12:08:43 -0400
From: Austin Clements <amdragon@MIT.EDU>
To: craven@gmx.net
Subject: Re: [PATCH v7 2/3] Add structured output formatter for JSON and
	plain text (but don't use them yet).
Message-ID: <20120722160843.GC31834@mit.edu>
References: <20120718194819.GP31670@mit.edu>
	<1342766173-1344-1-git-send-email-craven@gmx.net>
	<1342766173-1344-3-git-send-email-craven@gmx.net>
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Quoth craven@gmx.net on Jul 20 at  8:36 am:
> From: <craven@gmx.net>
> 
> Using the new structured printer support in sprinter.h, implement
> sprinter_json_create, which returns a new JSON structured output
> formatter. The formatter prints output similar to the existing JSON, but
> with differences in whitespace (mostly newlines, --output=summary prints
> the entire message summary on one line, not split across multiple lines).
> 
> Also implement a "structured" formatter for plain text that prints
> prefixed strings, to be used with notmuch-search.c plain text output.
> ---
>  Makefile.local  |   2 +
>  sprinter-json.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  sprinter-text.c | 126 ++++++++++++++++++++++++++++++++++++++
>  sprinter.h      |  10 +++
>  4 files changed, 323 insertions(+)
>  create mode 100644 sprinter-json.c
>  create mode 100644 sprinter-text.c
> 
> diff --git a/Makefile.local b/Makefile.local
> index a890df2..296995d 100644
> --- a/Makefile.local
> +++ b/Makefile.local
> @@ -290,6 +290,8 @@ notmuch_client_srcs =		\
>  	notmuch-show.c		\
>  	notmuch-tag.c		\
>  	notmuch-time.c		\
> +	sprinter-json.c		\
> +	sprinter-text.c		\
>  	query-string.c		\
>  	mime-node.c		\
>  	crypto.c		\
> diff --git a/sprinter-json.c b/sprinter-json.c
> new file mode 100644
> index 0000000..32daa5a
> --- /dev/null
> +++ b/sprinter-json.c
> @@ -0,0 +1,185 @@
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <talloc.h>
> +#include "sprinter.h"
> +
> +struct sprinter_json {
> +    struct sprinter vtable;
> +    FILE *stream;
> +    /* Top of the state stack, or NULL if the printer is not currently
> +     * inside any aggregate types. */
> +    struct json_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 json_state {
> +    struct json_state *parent;
> +    /* True if nothing has been printed in this aggregate yet.
> +     * Suppresses the comma before a value. */
> +    notmuch_bool_t first;
> +    /* 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 comma. */
> +static struct sprinter_json *
> +json_begin_value (struct sprinter *sp)
> +{
> +    struct sprinter_json *spj = (struct sprinter_json *) sp;
> +
> +    if (spj->state) {
> +	if (! spj->state->first) {
> +	    fputc (',', spj->stream);
> +	    if (spj->insert_separator) {
> +		fputc ('\n', spj->stream);
> +		spj->insert_separator = FALSE;
> +	    } else
> +		fputc (' ', spj->stream);
> +	} else
> +	    spj->state->first = FALSE;

Just a nit: if you roll a v8, it would be nice to have braces around
both of these else parts to match the braces on the then parts.
Obviously this doesn't warrant a v8 on its own, though.

> +    }
> +    return spj;
> +}
> +
> +/* Helper function to begin an aggregate type.  Prints the open
> + * character and pushes a new state frame. */
> +static void
> +json_begin_aggregate (struct sprinter *sp, char open, char close)
> +{
> +    struct sprinter_json *spj = json_begin_value (sp);
> +    struct json_state *state = talloc (spj, struct json_state);
> +
> +    fputc (open, spj->stream);
> +    state->parent = spj->state;
> +    state->first = TRUE;
> +    state->close = close;
> +    spj->state = state;
> +}
> +
> +static void
> +json_begin_map (struct sprinter *sp)
> +{
> +    json_begin_aggregate (sp, '{', '}');
> +}
> +
> +static void
> +json_begin_list (struct sprinter *sp)
> +{
> +    json_begin_aggregate (sp, '[', ']');
> +}
> +
> +static void
> +json_end (struct sprinter *sp)
> +{
> +    struct sprinter_json *spj = (struct sprinter_json *) sp;
> +    struct json_state *state = spj->state;
> +
> +    fputc (spj->state->close, spj->stream);
> +    spj->state = state->parent;
> +    talloc_free (state);
> +    if (spj->state == NULL)
> +	fputc ('\n', spj->stream);
> +}
> +
> +static void
> +json_string (struct sprinter *sp, const char *val)
> +{
> +    static const char *const escapes[] = {
> +	['\"'] = "\\\"", ['\\'] = "\\\\", ['\b'] = "\\b",
> +	['\f'] = "\\f",  ['\n'] = "\\n",  ['\t'] = "\\t"
> +    };
> +    struct sprinter_json *spj = json_begin_value (sp);
> +
> +    fputc ('"', spj->stream);
> +    for (; *val; ++val) {
> +	unsigned char ch = *val;
> +	if (ch < ARRAY_SIZE (escapes) && escapes[ch])
> +	    fputs (escapes[ch], spj->stream);
> +	else if (ch >= 32)
> +	    fputc (ch, spj->stream);
> +	else
> +	    fprintf (spj->stream, "\\u%04x", ch);
> +    }
> +    fputc ('"', spj->stream);
> +}
> +
> +static void
> +json_integer (struct sprinter *sp, int val)
> +{
> +    struct sprinter_json *spj = json_begin_value (sp);
> +
> +    fprintf (spj->stream, "%d", val);
> +}
> +
> +static void
> +json_boolean (struct sprinter *sp, notmuch_bool_t val)
> +{
> +    struct sprinter_json *spj = json_begin_value (sp);
> +
> +    fputs (val ? "true" : "false", spj->stream);
> +}
> +
> +static void
> +json_null (struct sprinter *sp)
> +{
> +    struct sprinter_json *spj = json_begin_value (sp);
> +
> +    fputs ("null", spj->stream);
> +}
> +
> +static void
> +json_map_key (struct sprinter *sp, const char *key)
> +{
> +    struct sprinter_json *spj = (struct sprinter_json *) sp;
> +
> +    json_string (sp, key);
> +    fputs (": ", spj->stream);
> +    spj->state->first = TRUE;
> +}
> +
> +static void
> +json_set_prefix (unused (struct sprinter *sp), unused (const char *name))
> +{
> +}
> +
> +static void
> +json_separator (struct sprinter *sp)
> +{
> +    struct sprinter_json *spj = (struct sprinter_json *) sp;
> +
> +    spj->insert_separator = TRUE;
> +}
> +
> +struct sprinter *
> +sprinter_json_create (const void *ctx, FILE *stream)
> +{
> +    static const struct sprinter_json template = {
> +	.vtable = {
> +	    .begin_map = json_begin_map,
> +	    .begin_list = json_begin_list,
> +	    .end = json_end,
> +	    .string = json_string,
> +	    .integer = json_integer,
> +	    .boolean = json_boolean,
> +	    .null = json_null,
> +	    .map_key = json_map_key,
> +	    .separator = json_separator,
> +	    .set_prefix = json_set_prefix,
> +	    .is_text_printer = FALSE,
> +	}
> +    };
> +    struct sprinter_json *res;
> +
> +    res = talloc (ctx, struct sprinter_json);
> +    if (! res)
> +	return NULL;
> +
> +    *res = template;
> +    res->stream = stream;
> +    return &res->vtable;
> +}
> diff --git a/sprinter-text.c b/sprinter-text.c
> new file mode 100644
> index 0000000..b208840
> --- /dev/null
> +++ b/sprinter-text.c
> @@ -0,0 +1,126 @@
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <talloc.h>
> +#include "sprinter.h"
> +
> +/* "Structured printer" interface for unstructured text printing.
> + * Note that --output=summary is dispatched and formatted in
> + * notmuch-search.c, the code in this file is only used for all other
> + * output types.
> + */
> +
> +struct sprinter_text {
> +    struct sprinter vtable;
> +    FILE *stream;
> +
> +    /* The current prefix to be printed with string/integer/boolean
> +     * data.
> +     */
> +    const char *current_prefix;
> +
> +    /* A flag to indicate if this is the first tag. Used in list of tags
> +     * for summary.
> +     */
> +    notmuch_bool_t first_tag;
> +};
> +
> +static void
> +text_string (struct sprinter *sp, const char *val)
> +{
> +    struct sprinter_text *sptxt = (struct sprinter_text *) sp;
> +
> +    if (sptxt->current_prefix != NULL)
> +	fprintf (sptxt->stream, "%s:", sptxt->current_prefix);
> +
> +    fputs(val, sptxt->stream);
> +}
> +
> +static void
> +text_integer (struct sprinter *sp, int val)
> +{
> +    struct sprinter_text *sptxt = (struct sprinter_text *) sp;
> +
> +    fprintf (sptxt->stream, "%d", val);
> +}
> +
> +static void
> +text_boolean (struct sprinter *sp, notmuch_bool_t val)
> +{
> +    struct sprinter_text *sptxt = (struct sprinter_text *) sp;
> +
> +    fputs (val ? "true" : "false", sptxt->stream);
> +}
> +
> +static void
> +text_separator (struct sprinter *sp)
> +{
> +    struct sprinter_text *sptxt = (struct sprinter_text *) sp;
> +
> +    fputc ('\n', sptxt->stream);
> +}
> +
> +static void
> +text_set_prefix (struct sprinter *sp, const char *prefix)
> +{
> +    struct sprinter_text *sptxt = (struct sprinter_text *) sp;
> +
> +    sptxt->current_prefix = prefix;
> +}
> +
> +/* The structure functions begin_map, begin_list, end and map_key
> + * don't do anything in the text formatter.
> + */
> +
> +static void
> +text_begin_map (unused (struct sprinter *sp))
> +{
> +}
> +
> +static void
> +text_begin_list (unused (struct sprinter *sp))
> +{
> +}
> +
> +static void
> +text_end (unused (struct sprinter *sp))
> +{
> +}
> +
> +static void
> +text_null (unused (struct sprinter *sp))
> +{
> +}
> +
> +static void
> +text_map_key (unused (struct sprinter *sp), unused (const char *key))
> +{
> +}
> +
> +struct sprinter *
> +sprinter_text_create (const void *ctx, FILE *stream)
> +{
> +    static const struct sprinter_text template = {
> +	.vtable = {
> +	    .begin_map = text_begin_map,
> +	    .begin_list = text_begin_list,
> +	    .end = text_end,
> +	    .string = text_string,
> +	    .integer = text_integer,
> +	    .boolean = text_boolean,
> +	    .null = text_null,
> +	    .map_key = text_map_key,
> +	    .separator = text_separator,
> +	    .set_prefix = text_set_prefix,
> +	    .is_text_printer = TRUE,
> +	},
> +    };
> +    struct sprinter_text *res;
> +
> +    res = talloc (ctx, struct sprinter_text);
> +    if (! res)
> +	return NULL;
> +
> +    *res = template;
> +    res->stream = stream;
> +    return &res->vtable;
> +}
> diff --git a/sprinter.h b/sprinter.h
> index 77dc26f..6680d41 100644
> --- a/sprinter.h
> +++ b/sprinter.h
> @@ -55,4 +55,14 @@ typedef struct sprinter {
>      notmuch_bool_t is_text_printer;
>  } sprinter_t;
>  
> +
> +/* Create a new unstructured printer that emits the default text format
> + * for "notmuch search". */
> +struct sprinter *
> +sprinter_text_create (const void *ctx, FILE *stream);
> +
> +/* Create a new structure printer that emits JSON. */
> +struct sprinter *
> +sprinter_json_create (const void *ctx, FILE *stream);
> +
>  #endif // NOTMUCH_SPRINTER_H