avutil/eval: add function to track variable use

[ffmpeg] / libavutil / eval.h

diff --git a/libavutil/eval.h b/libavutil/eval.h
index dacd22b96e66cec8818f1b2f5c806df166eb9d86..9bdb10cca2b02a41245c2a0482ea76e344cce3dc 100644 (file)
--- a/libavutil/eval.h
+++ b/libavutil/eval.h
@@ -86,6 +86,16 @@ int av_expr_parse(AVExpr **expr, const char *s,
  */
 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
 
+/**
+ * Track the presence of variables and their number of occurrences in a parsed expression
+ *
+ * @param counter a zero-initialized array where the count of each variable will be stored
+ * @param size size of array
+ * @return 0 on success, a negative value indicates that no expression or array was passed
+ * or size was zero
+ */
+int av_expr_count_vars(AVExpr *e, unsigned *counter, int size);
+
 /**
  * Free a parsed expression previously created with av_expr_parse().
  */