[PATCH v4 1/5] Adding an S-expression structured output printer.
Peter Feigl
craven at gmx.net
Thu Dec 6 03:44:55 PST 2012
This commit adds a structured output printer for Lisp
S-Expressions. Later commits will use this printer in notmuch search,
show and reply.
The structure is the same as json, but:
- arrays are written as lists: ("foo" "bar" "baaz" 1 2 3)
- maps are written as p-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 | 238 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
sprinter.h | 4 +
3 files changed, 243 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..8f84eed
--- /dev/null
+++ b/sprinter-sexp.c
@@ -0,0 +1,238 @@
+/* notmuch - Not much of an email program, (just index and search)
+ *
+ * Copyright © 2012 Peter Feigl
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see http://www.gnu.org/licenses/ .
+ *
+ * Author: Peter Feigl <peter.feigl at gmx.at>
+ */
+
+#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;
+};
+
+/* 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 {
+ 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)
+{
+ struct sprinter_sexp *sps = sexp_begin_value (sp);
+ struct sexp_state *state = talloc (sps, struct sexp_state);
+ fputc ('(', sps->stream);
+ state->parent = sps->state;
+ state->first = TRUE;
+ sps->state = state;
+}
+
+static void
+sexp_begin_map (struct sprinter *sp)
+{
+ sexp_begin_aggregate (sp);
+}
+
+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;
+
+ fputc (')', sps->stream);
+ sps->state = state->parent;
+ talloc_free (state);
+ if (sps->state == NULL)
+ fputc ('\n', sps->stream);
+}
+
+static void
+sexp_string_len (struct sprinter *sp, const char *val, size_t len)
+{
+ /* Some characters need escaping. " and \ work fine in all Lisps,
+ * \n is not supported in CL, but all others work fine.
+ * Characters below 32 are printed as \123o (three-digit
+ * octals), which work fine in most Schemes and Emacs. */
+ static const char *const escapes[] = {
+ ['\"'] = "\\\"", ['\\'] = "\\\\", ['\n'] = "\\n"
+ };
+ struct sprinter_sexp *sps = sexp_begin_value (sp);
+
+ 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, "\\%03oo", ch);
+ }
+ fputc ('"', sps->stream);
+}
+
+static void
+sexp_string (struct sprinter *sp, const char *val)
+{
+ if (val == NULL)
+ val = "";
+ sexp_string_len (sp, val, strlen (val));
+}
+
+/* Prints a symbol, i.e. the name preceded by a colon. This should work
+ * in all Lisps, at least as a symbol, if not as a proper keyword */
+static void
+sexp_symbol (struct sprinter *sp, const char *val)
+{
+ static const char illegal_characters[] = {
+ ' ', '\t', '\n'
+ };
+ unsigned int i = 0;
+ struct sprinter_sexp *sps = (struct sprinter_sexp *) sp;
+
+ if (val == NULL)
+ INTERNAL_ERROR ("illegal symbol NULL");
+
+ for(i = 0; i < ARRAY_SIZE (illegal_characters); i++) {
+ if(strchr(val, illegal_characters[i]) != NULL) {
+ INTERNAL_ERROR ("illegal character in symbol %s", val);
+ }
+ }
+ fputc (':', sps->stream);
+ fputs (val, sps->stream);
+}
+
+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 && ! sps->state->first)
+ fputc (' ', sps->stream);
+
+ sps->state->first = FALSE;
+ sexp_symbol (sp, key);
+}
+
+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;
+}
diff --git a/sprinter.h b/sprinter.h
index 912a526..59776a9 100644
--- a/sprinter.h
+++ b/sprinter.h
@@ -70,4 +70,8 @@ sprinter_text_create (const void *ctx, FILE *stream);
struct sprinter *
sprinter_json_create (const void *ctx, FILE *stream);
+/* Create a new structure printer that emits S-Expressions. */
+struct sprinter *
+sprinter_sexp_create (const void *ctx, FILE *stream);
+
#endif // NOTMUCH_SPRINTER_H
--
1.8.0
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