[FFmpeg-devel] [PATCH 1/3] avutil/eval: Add av_expr_count_func() similar to av_expr_count_vars()
Michael Niedermayer
michael at niedermayer.cc
Tue Dec 17 12:18:51 EET 2019
On Tue, Dec 17, 2019 at 01:50:37AM +0100, Marton Balint wrote:
>
>
> On Tue, 17 Dec 2019, Michael Niedermayer wrote:
>
> >On Sun, Dec 15, 2019 at 01:59:23PM +0100, Marton Balint wrote:
> >>
> >>
> >>On Fri, 6 Dec 2019, Michael Niedermayer wrote:
> >>
> >>>Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> >>>---
> >>>libavutil/eval.c | 28 ++++++++++++++++++++--------
> >>>libavutil/eval.h | 11 +++++++++++
> >>>2 files changed, 31 insertions(+), 8 deletions(-)
> >>>
> >>>diff --git a/libavutil/eval.c b/libavutil/eval.c
> >>>index 62d2ae938b..d527f6a9d0 100644
> >>>--- a/libavutil/eval.c
> >>>+++ b/libavutil/eval.c
> >>>@@ -166,8 +166,8 @@ struct AVExpr {
> >>> e_sgn,
> >>> } type;
> >>> double value; // is sign in other types
> >>>+ int const_index;
> >>> union {
> >>>- int const_index;
> >>> double (*func0)(double);
> >>> double (*func1)(void *, double);
> >>> double (*func2)(void *, double, double);
> >>>@@ -185,7 +185,7 @@ static double eval_expr(Parser *p, AVExpr *e)
> >>>{
> >>> switch (e->type) {
> >>> case e_value: return e->value;
> >>>- case e_const: return e->value * p->const_values[e->a.const_index];
> >>>+ case e_const: return e->value * p->const_values[e->const_index];
> >>> case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
> >>> case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
> >>> case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
> >>>@@ -367,7 +367,7 @@ static int parse_primary(AVExpr **e, Parser *p)
> >>> if (strmatch(p->s, p->const_names[i])) {
> >>> p->s+= strlen(p->const_names[i]);
> >>> d->type = e_const;
> >>>- d->a.const_index = i;
> >>>+ d->const_index = i;
> >>> *e = d;
> >>> return 0;
> >>> }
> >>>@@ -478,6 +478,7 @@ static int parse_primary(AVExpr **e, Parser *p)
> >>> if (strmatch(next, p->func1_names[i])) {
> >>> d->a.func1 = p->funcs1[i];
> >>> d->type = e_func1;
> >>>+ d->const_index = i;
> >>> *e = d;
> >>> return 0;
> >>> }
> >>>@@ -487,6 +488,7 @@ static int parse_primary(AVExpr **e, Parser *p)
> >>> if (strmatch(next, p->func2_names[i])) {
> >>> d->a.func2 = p->funcs2[i];
> >>> d->type = e_func2;
> >>>+ d->const_index = i;
> >>> *e = d;
> >>> return 0;
> >>> }
> >>>@@ -735,22 +737,32 @@ end:
> >>> return ret;
> >>>}
> >>>
> >>>-int av_expr_count_vars(AVExpr *e, unsigned *counter, int size)
> >>>+static int expr_count(AVExpr *e, unsigned *counter, int size, int type)
> >>>{
> >>> int i;
> >>>
> >>> if (!e || !counter || !size)
> >>> return AVERROR(EINVAL);
> >>>
> >>>- for (i = 0; e->type != e_const && i < 3 && e->param[i]; i++)
> >>>- av_expr_count_vars(e->param[i], counter, size);
> >>>+ for (i = 0; e->type != type && i < 3 && e->param[i]; i++)
> >>>+ expr_count(e->param[i], counter, size, type);
> >>>
> >>>- if (e->type == e_const && e->a.const_index < size)
> >>>- counter[e->a.const_index]++;
> >>>+ if (e->type == type && e->const_index < size)
> >>>+ counter[e->const_index]++;
> >>>
> >>> return 0;
> >>>}
> >>>
> >>>+int av_expr_count_vars(AVExpr *e, unsigned *counter, int size)
> >>>+{
> >>>+ return expr_count(e, counter, size, e_const);
> >>>+}
> >>>+
> >>>+int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg)
> >>>+{
> >>>+ return expr_count(e, counter, size, ((int[]){e_const, e_func1, e_func2})[arg]);
> >>>+}
> >>>+
> >>>double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
> >>>{
> >>> Parser p = { 0 };
> >>>diff --git a/libavutil/eval.h b/libavutil/eval.h
> >>>index 9bdb10cca2..688c523fbe 100644
> >>>--- a/libavutil/eval.h
> >>>+++ b/libavutil/eval.h
> >>>@@ -96,6 +96,17 @@ double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
> >>>*/
> >>>int av_expr_count_vars(AVExpr *e, unsigned *counter, int size);
> >>>
> >>>+/**
> >>>+ * Track the presence of functions and their number of occurrences in a parsed expression
> >>>+ *
> >>>+ * @param counter a zero-initialized array where the count of each function will be stored
> >>>+ * @param size size of array
> >>>+ * @param arg number of arguments the counted functions have
> >>>+ * @return 0 on success, a negative value indicates that no expression or array was passed
> >>>+ * or size was zero
> >>>+ */
> >>>+int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg);
> >>>+
> >>
> >>In order to define a function like this in public API you should change the
> >>functions list enum in eval.c to become public API as well. Otherwise the
> >>user would not know which function has which identifier. Also the number of
> >>functions should also become public API.
> >
> >The user would know which function is the i-th function in the array which
> >the user passed to the expression evaluator.
> >It indeed would not work with built in functions, thats the same though with
> >the constants counted by av_expr_count_vars()
>
> I missed that only the user functions are counted. I guess it is fine then
> from an API perspective, but please emphasize this in the docs.
will chnage the docs as in:
@@ -97,9 +97,12 @@ double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
int av_expr_count_vars(AVExpr *e, unsigned *counter, int size);
/**
- * Track the presence of functions and their number of occurrences in a parsed expression
+ * Track the presence of user provided functions and their number of occurrences
+ * in a parsed expression.
*
* @param counter a zero-initialized array where the count of each function will be stored
+ * if you passed 5 functions with 2 arguments to av_expr_parse()
+ * then for arg=2 this will use upto 5 entries.
* @param size size of array
* @param arg number of arguments the counted functions have
* @return 0 on success, a negative value indicates that no expression or array was passed
thx
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Democracy is the form of government in which you can choose your dictator
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