[RFC 1/2] lib/config: introduce notmuch_config_values_from_string function

[andreas@rammhold.de]

From: Andreas Rammhold <andreas@rammhold.de>

This factors out the code required to initialize a
notmuch_config_values_t from a string into a dedicated function. By
exposing this function we can allow consumers (such as notmuch-new(1))
to customize certain configuration values via command line flags.
---
 lib/config.cc          | 12 +++++++++++-
 lib/notmuch.h          | 14 ++++++++++++++
 test/T590-libconfig.sh | 22 ++++++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/lib/config.cc b/lib/config.cc
index 8775b00a..195483a6 100644
--- a/lib/config.cc
+++ b/lib/config.cc
@@ -280,6 +280,16 @@ notmuch_config_get_values (notmuch_database_t *notmuch, notmuch_config_key_t key
 
 notmuch_config_values_t *
 notmuch_config_get_values_string (notmuch_database_t *notmuch, const char *key_str)
+{
+    const char * val = _notmuch_string_map_get (notmuch->config, key_str);
+    if (! val)
+        return NULL;
+
+    return notmuch_config_values_from_string (notmuch, val);
+}
+
+notmuch_config_values_t *
+notmuch_config_values_from_string (notmuch_database_t *notmuch, const char *val)
 {
     notmuch_config_values_t *values = NULL;
     bool ok = false;
@@ -290,7 +300,7 @@ notmuch_config_get_values_string (notmuch_database_t *notmuch, const char *key_s
 
     values->children = talloc_new (values);
 
-    values->string = _notmuch_string_map_get (notmuch->config, key_str);
+    values->string = val;
     if (! values->string)
 	goto DONE;
 
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 546643e8..59dc9dae 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -2608,6 +2608,20 @@ notmuch_config_get_values (notmuch_database_t *notmuch, notmuch_config_key_t key
 notmuch_config_values_t *
 notmuch_config_get_values_string (notmuch_database_t *notmuch, const char *key);
 
+
+/**
+ * Returns an iterator for a ';'-delimited list of configuration values
+ *
+ * @param[in] notmuch database
+ * @param[in] val configuration value
+ *
+ * @since libnotmuch FIXME (notmuch FIXME)
+ *
+ * @retval NULL in case of error.
+ */
+notmuch_config_values_t *
+notmuch_config_values_from_string (notmuch_database_t *notmuch, const char* val);
+
 /**
  * Is the given 'config_values' iterator pointing at a valid element.
  *
diff --git a/test/T590-libconfig.sh b/test/T590-libconfig.sh
index 59b82a6f..3df2ffec 100755
--- a/test/T590-libconfig.sh
+++ b/test/T590-libconfig.sh
@@ -295,6 +295,28 @@ EOF
 test_expect_equal_file EXPECTED OUTPUT
 restore_database
 
+test_begin_subtest "notmuch_config_values_from_string"
+cat c_head - c_tail <<'EOF' | test_C ${MAIL_DIR} ${NOTMUCH_CONFIG} %NULL%
+{
+    notmuch_config_values_t *values = notmuch_config_values_from_string (db, "x;y;z");
+    for (notmuch_config_values_start (values);
+	 notmuch_config_values_valid (values);
+	 notmuch_config_values_move_to_next (values))
+    {
+	  puts (notmuch_config_values_get (values));
+    }
+}
+EOF
+cat <<'EOF' >EXPECTED
+== stdout ==
+x
+y
+z
+== stderr ==
+EOF
+test_expect_equal_file EXPECTED OUTPUT
+restore_database
+
 test_begin_subtest "notmuch_config_get_values (restart)"
 cat c_head - c_tail <<'EOF' | test_C ${MAIL_DIR} ${NOTMUCH_CONFIG} %NULL%
 {
-- 
2.32.0