cmdutils: add a commandline pre-parser.

It splits the commandline into a more convenient internal representation
for further parsing.

This will allow e.g.
- processing global options first independently of their location on the
  commandline, eliminating ugly hacks for processing e.g. cpuflags
  first
- better options validation and error reporting. It is now possible for
  the parser to know that it's applying an input option to an output
  file or vice versa and act accordingly.

1 files changed, 88 insertions, 0 deletions

diff --git a/cmdutils.h b/cmdutils.h
index 8485a8ba61..1af30d7676 100644
--- a/cmdutils.h
+++ b/cmdutils.h
@@ -206,6 +206,94 @@ int parse_option(void *optctx, const char *opt, const char *arg,
                  const OptionDef *options);
 
 /**
+ * An option extracted from the commandline.
+ * Cannot use AVDictionary because of options like -map which can be
+ * used multiple times.
+ */
+typedef struct Option {
+    const OptionDef  *opt;
+    const char       *key;
+    const char       *val;
+} Option;
+
+typedef struct OptionGroupDef {
+    /**< group name */
+    const char *name;
+    /**
+     * Option to be used as group separator. Can be NULL for groups which
+     * are terminated by a non-option argument (e.g. avconv output files)
+     */
+    const char *sep;
+} OptionGroupDef;
+
+typedef struct OptionGroup {
+    const OptionGroupDef *group_def;
+    const char *arg;
+
+    Option *opts;
+    int  nb_opts;
+
+    AVDictionary *codec_opts;
+    AVDictionary *format_opts;
+    struct SwsContext *sws_opts;
+} OptionGroup;
+
+/**
+ * A list of option groups that all have the same group type
+ * (e.g. input files or output files)
+ */
+typedef struct OptionGroupList {
+    const OptionGroupDef *group_def;
+
+    OptionGroup *groups;
+    int       nb_groups;
+} OptionGroupList;
+
+typedef struct OptionParseContext {
+    OptionGroup global_opts;
+
+    OptionGroupList *groups;
+    int           nb_groups;
+
+    /* parsing state */
+    OptionGroup cur_group;
+} OptionParseContext;
+
+/**
+ * Parse an options group and write results into optctx.
+ *
+ * @param optctx an app-specific options context. NULL for global options group
+ */
+int parse_optgroup(void *optctx, OptionGroup *g);
+
+/**
+ * Split the commandline into an intermediate form convenient for further
+ * processing.
+ *
+ * The commandline is assumed to be composed of options which either belong to a
+ * group (those with OPT_SPEC, OPT_OFFSET or OPT_PERFILE) or are global
+ * (everything else).
+ *
+ * A group (defined by an OptionGroupDef struct) is a sequence of options
+ * terminated by either a group separator option (e.g. -i) or a parameter that
+ * is not an option (doesn't start with -). A group without a separator option
+ * must always be first in the supplied groups list.
+ *
+ * All options within the same group are stored in one OptionGroup struct in an
+ * OptionGroupList, all groups with the same group definition are stored in one
+ * OptionGroupList in OptionParseContext.groups. The order of group lists is the
+ * same as the order of group definitions.
+ */
+int split_commandline(OptionParseContext *octx, int argc, char *argv[],
+                      const OptionDef *options,
+                      const OptionGroupDef *groups);
+
+/**
+ * Free all allocated memory in an OptionParseContext.
+ */
+void uninit_parse_context(OptionParseContext *octx);
+
+/**
  * Find the '-loglevel' option in the command line args and apply it.
  */
 void parse_loglevel(int argc, char **argv, const OptionDef *options);