[PATCH v7 1/3] Add support for structured output formatters.
craven at gmx.net
craven at gmx.net
Thu Jul 19 23:36:11 PDT 2012
From: <craven at gmx.net>
This patch adds a new struct type sprinter_t, which is used for
structured formatting, e.g. JSON or S-Expressions. The structure printer
is heavily based on code from Austin Clements
(id:87d34hsdx8.fsf at awakening.csail.mit.edu).
It includes the following functions:
/* Start a new map/dictionary structure. This should be followed by
* a sequence of alternating calls to map_key and one of the
* value-printing functions until the map is ended by end.
*/
void (*begin_map) (struct sprinter *);
/* Start a new list/array structure.
*/
void (*begin_list) (struct sprinter *);
/* End the last opened list or map structure.
*/
void (*end) (struct sprinter *);
/* Print one string/integer/boolean/null element (possibly inside a
* list or map, followed or preceded by separators).
* For string, the char * must be UTF-8 encoded.
*/
void (*string) (struct sprinter *, const char *);
void (*integer) (struct sprinter *, int);
void (*boolean) (struct sprinter *, notmuch_bool_t);
void (*null) (struct sprinter *);
/* Print the key of a map's key/value pair. The char * must be UTF-8
* encoded.
*/
void (*map_key) (struct sprinter *, const char *);
/* Insert a separator (usually extra whitespace) for improved
* readability without affecting the abstract syntax of the
* structure being printed.
* For JSON, this could simply be a line break.
*/
void (*separator) (struct sprinter *);
/* Set the current string prefix. This only affects the text
* printer, which will print this string, followed by a colon,
* before any string. For other printers, this does nothing.
*/
void (*set_prefix) (struct sprinter *, const char *);
To support the plain text format properly, the following additional
function must also be implemented:
/* Set the current string prefix. This only affects the text
* printer, which will print this string, followed by a colon,
* before any string. For other printers, this does nothing.
*/
void (*set_prefix) (struct sprinter *, const char *);
The structure also contains a flag that should be set to FALSE in all
custom printers and to TRUE in the plain text formatter.
/* True if this is the special-cased plain text printer.
*/
notmuch_bool_t is_text_printer;
The printer can (and should) use internal state to insert delimiters
and syntax at the correct places.
Example:
format->begin_map(format);
format->map_key(format, "foo");
format->begin_list(format);
format->integer(format, 1);
format->integer(format, 2);
format->integer(format, 3);
format->end(format);
format->map_key(format, "bar");
format->begin_map(format);
format->map_key(format, "baaz");
format->string(format, "hello world");
format->end(format);
format->end(format);
would output JSON as follows:
{"foo": [1, 2, 3], "bar": { "baaz": "hello world"}}
---
sprinter.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 58 insertions(+)
create mode 100644 sprinter.h
diff --git a/sprinter.h b/sprinter.h
new file mode 100644
index 0000000..77dc26f
--- /dev/null
+++ b/sprinter.h
@@ -0,0 +1,58 @@
+#ifndef NOTMUCH_SPRINTER_H
+#define NOTMUCH_SPRINTER_H
+
+/* Necessary for notmuch_bool_t */
+#include "notmuch-client.h"
+
+/* Structure printer interface. This is used to create output
+ * structured as maps (with key/value pairs), lists and primitives
+ * (strings, integers and booleans).
+ */
+typedef struct sprinter {
+ /* Start a new map/dictionary structure. This should be followed by
+ * a sequence of alternating calls to map_key and one of the
+ * value-printing functions until the map is ended by end.
+ */
+ void (*begin_map) (struct sprinter *);
+
+ /* Start a new list/array structure.
+ */
+ void (*begin_list) (struct sprinter *);
+
+ /* End the last opened list or map structure.
+ */
+ void (*end) (struct sprinter *);
+
+ /* Print one string/integer/boolean/null element (possibly inside a
+ * list or map, followed or preceded by separators).
+ * For string, the char * must be UTF-8 encoded.
+ */
+ void (*string) (struct sprinter *, const char *);
+ void (*integer) (struct sprinter *, int);
+ void (*boolean) (struct sprinter *, notmuch_bool_t);
+ void (*null) (struct sprinter *);
+
+ /* Print the key of a map's key/value pair. The char * must be UTF-8
+ * encoded.
+ */
+ void (*map_key) (struct sprinter *, const char *);
+
+ /* Insert a separator (usually extra whitespace) for improved
+ * readability without affecting the abstract syntax of the
+ * structure being printed.
+ * For JSON, this could simply be a line break.
+ */
+ void (*separator) (struct sprinter *);
+
+ /* Set the current string prefix. This only affects the text
+ * printer, which will print this string, followed by a colon,
+ * before any string. For other printers, this does nothing.
+ */
+ void (*set_prefix) (struct sprinter *, const char *);
+
+ /* True if this is the special-cased plain text printer.
+ */
+ notmuch_bool_t is_text_printer;
+} sprinter_t;
+
+#endif // NOTMUCH_SPRINTER_H
--
1.7.11.2
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