[PATCH v3 2/5] config: split do_event() into start and flush operations

[Josh Steadmon <steadmon@google.com>]

When handling config-parsing events, the current do_event() handler is a
bit confusing; calling it with a specific event type records the initial
offset where the event occurred, and runs the supplied callback against
the previous event (whose end offset is now known).

Split this operation into "start_event" and "flush_event" functions.
Then reimplement "do_event" (preserving the original behavior) using the
newly split functions.

In a later change, we can use these building blocks to also handle
"immediate" events, where we want to run the callback without having to
calculate an end offset for the event.

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 config.c | 50 ++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 36 insertions(+), 14 deletions(-)

diff --git a/config.c b/config.c
index 1518f70fc2..ff138500a2 100644
--- a/config.c
+++ b/config.c
@@ -985,19 +985,11 @@ struct parse_event_data {
 	const struct config_parse_options *opts;
 };
 
-static int do_event(struct config_source *cs, enum config_event_t type,
-		    struct parse_event_data *data)
+static size_t get_corrected_offset(struct config_source *cs,
+				   enum config_event_t type)
 {
-	size_t offset;
-
-	if (!data->opts || !data->opts->event_fn)
-		return 0;
-
-	if (type == CONFIG_EVENT_WHITESPACE &&
-	    data->previous_type == type)
-		return 0;
+	size_t offset = cs->do_ftell(cs);
 
-	offset = cs->do_ftell(cs);
 	/*
 	 * At EOF, the parser always "inserts" an extra '\n', therefore
 	 * the end offset of the event is the current file position, otherwise
@@ -1005,14 +997,44 @@ static int do_event(struct config_source *cs, enum config_event_t type,
 	 */
 	if (type != CONFIG_EVENT_EOF)
 		offset--;
+	return offset;
+}
+
+static void start_event(struct config_source *cs, enum config_event_t type,
+		       struct parse_event_data *data)
+{
+	data->previous_type = type;
+	data->previous_offset = get_corrected_offset(cs, type);
+}
+
+static int flush_event(struct config_source *cs, enum config_event_t type,
+		       struct parse_event_data *data)
+{
+	if (!data->opts || !data->opts->event_fn)
+		return 0;
+
+	if (type == CONFIG_EVENT_WHITESPACE &&
+	    data->previous_type == type)
+		return 0;
 
 	if (data->previous_type != CONFIG_EVENT_EOF &&
 	    data->opts->event_fn(data->previous_type, data->previous_offset,
-				 offset, cs, data->opts->event_fn_data) < 0)
+				 get_corrected_offset(cs, type), cs,
+				 data->opts->event_fn_data) < 0)
 		return -1;
 
-	data->previous_type = type;
-	data->previous_offset = offset;
+	return 1;
+}
+
+static int do_event(struct config_source *cs, enum config_event_t type,
+		    struct parse_event_data *data)
+{
+	int maybe_ret;
+
+	if ((maybe_ret = flush_event(cs, type, data)) < 1)
+		return maybe_ret;
+
+	start_event(cs, type, data);
 
 	return 0;
 }
-- 
2.42.0.515.g380fc7ccd1-goog