tags: Re-implement tags iterator to avoid having C++ in the interface

We want to be able to iterate over tags stored in various ways, so
the previous TermIterator-based tags object just wasn't general
enough. The new interface is nice and simple, and involves only
C datatypes.

message.cc

@@ -18,7 +18,7 @@
  * Author: Carl Worth <cworth@cworth.org>
  */
 
-#include "notmuch-private-cxx.h"
+#include "notmuch-private.h"
 #include "database-private.h"
 
 #include <xapian.h>
@@ -289,7 +289,40 @@ notmuch_message_get_filename (notmuch_message_t *message)
 notmuch_tags_t *
 notmuch_message_get_tags (notmuch_message_t *message)
 {
-    return _notmuch_tags_create_terms (message, message->doc, "tag");
+    const char *prefix = _find_prefix ("tag");
+    Xapian::TermIterator i, end;
+    notmuch_tags_t *tags;
+    std::string tag;
+
+    /* Currently this iteration is written with the assumption that
+     * "tag" has a single-character prefix. */
+    assert (strlen (prefix) == 1);
+
+    tags = _notmuch_tags_create (message);
+    if (unlikely (tags == NULL))
+	return NULL;
+
+    i = message->doc.termlist_begin ();
+    end = message->doc.termlist_end ();
+
+    i.skip_to (prefix);
+
+    while (1) {
+	tag = *i;
+
+	if (tag.empty () || tag[0] != *prefix)
+	    break;
+
+	_notmuch_tags_add_tag (tags, tag.c_str () + 1);
+
+	i++;
+    }
+
+    _notmuch_tags_sort (tags);
+
+    _notmuch_tags_reset (tags);
+
+    return tags;
 }
 
 void

notmuch-private-cxx.h

@@ -1,42 +0,0 @@
-/* notmuch-private-cxx.h - Internal, C++ interfaces for notmuch.
- *
- * Copyright © 2009 Carl Worth
- *
- * 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: Carl Worth <cworth@cworth.org>
- */
-
-#ifndef NOTMUCH_PRIVATE_CXX_H
-#define NOTMUCH_PRIVATE_CXX_H
-
-/* It's a bit annoying to have a separate C++ private header, but I
- * don't yet have C wrappers for types like Xapian::Document and
- * Xapian::PostingIterator. Maybe I'll write those to be able to fold
- * this stuff back into notmuch-private.h */
-
-#include "notmuch-private.h"
-
-#include <xapian.h>
-
-/***********/
-/* tags.cc */
-/***********/
-
-notmuch_tags_t *
-_notmuch_tags_create_terms (void *ctx,
-			    Xapian::Document doc,
-			    const char *prefix_name);
-
-#endif

notmuch-private.h

@@ -274,6 +274,20 @@ notmuch_sha1_of_string (const char *str);
 char *
 notmuch_sha1_of_file (const char *filename);
 
+/* tags.c */
+
+notmuch_tags_t *
+_notmuch_tags_create (void *ctx);
+
+void
+_notmuch_tags_add_tag (notmuch_tags_t *tags, const char *tag);
+
+void
+_notmuch_tags_sort (notmuch_tags_t *tags);
+
+void
+_notmuch_tags_reset (notmuch_tags_t *tags);
+
 NOTMUCH_END_DECLS
 
 #endif

notmuch.c

@@ -924,11 +924,11 @@ main (int argc, char *argv[])
 	strcmp (argv[1], "--help") == 0)
     {
 	fprintf (stderr, "The notmuch mail system.\n\n");
+	usage ();
+	return 0;
     } else {
 	fprintf (stderr, "Error: Unknown command '%s'\n\n", argv[1]);
+	usage ();
+	return 1;
     }
-    usage ();
-    exit (1);
-
-    return 0;
 }

tags.c

@@ -0,0 +1,104 @@
+/* tags.c - Iterator for tags returned from message or thread
+ *
+ * Copyright © 2009 Carl Worth
+ *
+ * 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: Carl Worth <cworth@cworth.org>
+ */
+
+#include "notmuch-private.h"
+
+#include <glib.h> /* GList */
+
+struct _notmuch_tags {
+    GList *tags;
+    GList *iterator;
+};
+
+/* XXX: Should write some talloc-friendly list to avoid the need for
+ * this. */
+static int
+_notmuch_tags_destructor (notmuch_tags_t *tags)
+{
+    g_list_free (tags->tags);
+
+    return 0;
+}
+
+/* Create a new notmuch_tags_t object, with 'ctx' as its talloc owner.
+ *
+ * This function can return NULL in case of out-of-memory.
+ */
+notmuch_tags_t *
+_notmuch_tags_create (void *ctx)
+{
+    notmuch_tags_t *tags;
+
+    tags = talloc (ctx, notmuch_tags_t);
+    if (unlikely (tags == NULL))
+	return NULL;
+
+    talloc_set_destructor (tags, _notmuch_tags_destructor);
+
+    tags->tags = NULL;
+    tags->iterator = NULL;
+
+    return tags;
+}
+
+void
+_notmuch_tags_add_tag (notmuch_tags_t *tags, const char *tag)
+{
+    tags->tags = g_list_prepend (tags->tags, talloc_strdup (tags, tag));
+}
+
+void
+_notmuch_tags_sort (notmuch_tags_t *tags)
+{
+    tags->tags = g_list_sort (tags->tags, (GCompareFunc) strcmp);
+}
+
+void
+_notmuch_tags_reset (notmuch_tags_t *tags)
+{
+    tags->iterator = tags->tags;
+}
+
+notmuch_bool_t
+notmuch_tags_has_more (notmuch_tags_t *tags)
+{
+    return tags->iterator != NULL;
+}
+
+const char *
+notmuch_tags_get (notmuch_tags_t *tags)
+{
+    if (tags->iterator)
+	return (char *) tags->iterator->data;
+    else
+	return NULL;
+}
+
+void
+notmuch_tags_advance (notmuch_tags_t *tags)
+{
+    tags->iterator = tags->iterator->next;
+}
+
+void
+notmuch_tags_destroy (notmuch_tags_t *tags)
+{
+    talloc_free (tags);
+}

tags.cc

@@ -1,157 +0,0 @@
-/* tags.cc - Iterator for tags returned from message or thread
- *
- * Copyright © 2009 Carl Worth
- *
- * 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: Carl Worth <cworth@cworth.org>
- */
-
-#include "notmuch-private-cxx.h"
-#include "database-private.h"
-
-#include <xapian.h>
-
-typedef struct _notmuch_terms {
-    char prefix_char;
-    Xapian::TermIterator iterator;
-    Xapian::TermIterator iterator_end;
-} notmuch_terms_t;
-
-struct _notmuch_tags {
-    notmuch_terms_t terms;
-};
-
-notmuch_terms_t *
-_notmuch_terms_create (void *ctx,
-		       Xapian::Document doc,
-		       const char *prefix_name);
-
-/* The assertion is to ensure that 'type' is a derivative of
- * notmuch_terms_t in that it contains a notmuch_terms_t as its first
- * member. We do this by name of 'terms' as opposed to type, because
- * that's as clever as I've been so far. */
-#define _notmuch_terms_create_type(ctx, doc, prefix_name, type) \
-    (COMPILE_TIME_ASSERT(offsetof(type, terms) == 0),		\
-     (type *) _notmuch_terms_create (ctx, doc, prefix_name))
-
-/* We end up having to call the destructors explicitly because we had
- * to use "placement new" in order to initialize C++ objects within a
- * block that we allocated with talloc. So C++ is making talloc
- * slightly less simple to use, (we wouldn't need
- * talloc_set_destructor at all otherwise).
- */
-static int
-_notmuch_terms_destructor (notmuch_terms_t *terms)
-{
-    terms->iterator.~TermIterator ();
-    terms->iterator_end.~TermIterator ();
-
-    return 0;
-}
-
-notmuch_terms_t *
-_notmuch_terms_create (void *ctx,
-		       Xapian::Document doc,
-		       const char *prefix_name)
-{
-    notmuch_terms_t *terms;
-    const char *prefix = _find_prefix (prefix_name);
-
-    /* Currently, notmuch_terms_t is written with the assumption that
-     * any prefix its derivatives use will be only a single
-     * character. */
-    assert (strlen (prefix) == 1);
-
-    terms = talloc (ctx, notmuch_terms_t);
-    if (unlikely (terms == NULL))
-	return NULL;
-
-    terms->prefix_char = *prefix;
-    new (&terms->iterator) Xapian::TermIterator;
-    new (&terms->iterator_end) Xapian::TermIterator;
-
-    talloc_set_destructor (terms, _notmuch_terms_destructor);
-
-    terms->iterator = doc.termlist_begin ();
-    terms->iterator.skip_to (prefix);
-    terms->iterator_end = doc.termlist_end ();
-
-    return terms;
-}
-
-static notmuch_bool_t
-_notmuch_terms_has_more (notmuch_terms_t *terms)
-{
-    std::string s;
-
-    if (terms->iterator == terms->iterator_end)
-	return FALSE;
-
-    s = *terms->iterator;
-    if (! s.empty () && s[0] == terms->prefix_char)
-	return TRUE;
-    else
-	return FALSE;
-}
-
-static const char *
-_notmuch_terms_get (notmuch_terms_t *terms)
-{
-    return talloc_strdup (terms, (*terms->iterator).c_str () + 1);
-}
-
-static void
-_notmuch_terms_advance (notmuch_terms_t *terms)
-{
-    terms->iterator++;
-}
-
-static void
-_notmuch_terms_destroy (notmuch_terms_t *terms)
-{
-    talloc_free (terms);
-}
-
-notmuch_tags_t *
-_notmuch_tags_create_terms (void *ctx,
-			    Xapian::Document doc,
-			    const char *prefix_name)
-{
-    return _notmuch_terms_create_type (ctx, doc, prefix_name, notmuch_tags_t);
-}
-
-notmuch_bool_t
-notmuch_tags_has_more (notmuch_tags_t *tags)
-{
-    return _notmuch_terms_has_more (&tags->terms);
-}
-
-const char *
-notmuch_tags_get (notmuch_tags_t *tags)
-{
-    return _notmuch_terms_get (&tags->terms);
-}
-
-void
-notmuch_tags_advance (notmuch_tags_t *tags)
-{
-    return _notmuch_terms_advance (&tags->terms);
-}
-
-void
-notmuch_tags_destroy (notmuch_tags_t *tags)
-{
-    return _notmuch_terms_destroy (&tags->terms);
-}