options: simplify somewhat by introducing a union for option values

The m_option_value union is supposed to contain a field for each
possible option type (as long as it actually stores data). This helps
avoiding silly temporary memory alocations. Using a pointer to an union
and to a field of the union interchangeably should be allowed by
standard C.

1 files changed, 19 insertions, 0 deletions

diff --git a/m_option.h b/m_option.h
index f05fe17bd4..2bd9054ac2 100644
--- a/m_option.h
+++ b/m_option.h
@@ -178,6 +178,25 @@ struct m_sub_options {
 #define CONF_TYPE_TIME          (&m_option_type_time)
 #define CONF_TYPE_TIME_SIZE     (&m_option_type_time_size)
 
+// Possible option values. Code is allowed to access option data without going
+// through this union. It serves for self-documentation and to get minimal
+// size/alignment requirements for option values in general.
+union m_option_value {
+    int flag; // not the C type "bool"!
+    int int_;
+    int64_t int64;
+    float float_;
+    double double_;
+    char *string;
+    char **string_list;
+    int imgfmt;
+    int afmt;
+    m_span_t span;
+    m_obj_settings_t *obj_settings_list;
+    double time;
+    m_time_size_t time_size;
+};
+
 ////////////////////////////////////////////////////////////////////////////
 
 // Option type description