Also add helper functions to allocate and free such a struct, and make it
usable by providing a new av_eval_expr2 function for which you can specify a
custom AVExprState.
Signed-off-by: Marton Balint <c...@passwd.hu>
---
doc/APIchanges | 3 +++
libavutil/eval.c | 31 +++++++++++++++++++++++++------
libavutil/eval.h | 27 +++++++++++++++++++++++++++
libavutil/version.h | 2 +-
4 files changed, 56 insertions(+), 7 deletions(-)
diff --git a/doc/APIchanges b/doc/APIchanges
index 3c24dc6fbc..e4ad364ed9 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -15,6 +15,9 @@ libavutil: 2017-10-21
API changes, most recent first:
+2020-01-xx - xxxxxxxxxx - lavu 56.39.100 - eval.h
+ Add av_expr_eval2, av_expr_state_alloc, av_expr_state_free
+
2019-12-27 - xxxxxxxxxx - lavu 56.38.100 - eval.h
Add av_expr_count_func().
diff --git a/libavutil/eval.c b/libavutil/eval.c
index d527f6a9d0..86fb634fd8 100644
--- a/libavutil/eval.c
+++ b/libavutil/eval.c
@@ -173,7 +173,11 @@ struct AVExpr {
double (*func2)(void *, double, double);
} a;
struct AVExpr *param[3];
- double *var;
+ AVExprState *state;
+};
+
+struct AVExprState {
+ double vars[VARS];
};
static double etime(double v)
@@ -333,13 +337,23 @@ static double eval_expr(Parser *p, AVExpr *e)
static int parse_expr(AVExpr **e, Parser *p);
+AVExprState *av_expr_state_alloc(void)
+{
+ return av_mallocz(sizeof(AVExprState));
+}
+
+void av_expr_state_free(AVExprState **ps)
+{
+ av_freep(ps);
+}
+
void av_expr_free(AVExpr *e)
{
if (!e) return;
av_expr_free(e->param[0]);
av_expr_free(e->param[1]);
av_expr_free(e->param[2]);
- av_freep(&e->var);
+ av_expr_state_free(&e->state);
av_freep(&e);
}
@@ -724,8 +738,8 @@ int av_expr_parse(AVExpr **expr, const char *s,
ret = AVERROR(EINVAL);
goto end;
}
- e->var= av_mallocz(sizeof(double) *VARS);
- if (!e->var) {
+ e->state = av_expr_state_alloc();
+ if (!e->state) {
ret = AVERROR(ENOMEM);
goto end;
}
@@ -763,16 +777,21 @@ 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)
+double av_expr_eval2(AVExpr *e, AVExprState *s, const double *const_values,
void *opaque)
{
Parser p = { 0 };
- p.var= e->var;
+ p.var = s ? s->vars : e->state->vars;
p.const_values = const_values;
p.opaque = opaque;
return eval_expr(&p, e);
}
+double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
+{
+ return av_expr_eval2(e, NULL, const_values, opaque);
+}
+
int av_expr_parse_and_eval(double *d, const char *s,
const char * const *const_names, const double
*const_values,
const char * const *func1_names, double (* const
*funcs1)(void *, double),
diff --git a/libavutil/eval.h b/libavutil/eval.h
index 068c62cdab..8bd1592f6c 100644
--- a/libavutil/eval.h
+++ b/libavutil/eval.h
@@ -29,6 +29,7 @@
#include "avutil.h"
typedef struct AVExpr AVExpr;
+typedef struct AVExprState AVExprState;
/**
* Parse and evaluate an expression.
@@ -86,6 +87,22 @@ int av_expr_parse(AVExpr **expr, const char *s,
*/
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
+/**
+ * Evaluate a previously parsed expression using a custom state.
+ *
+ * Some expressions can use stateful functions, like random(), st() and ld().
+ * With this function you can provide your own state to the evaluator instead
+ * of using the internal state of the AVExpr. This makes it possible to use the
+ * same AVExpr in multiple threads each with their own AVExprState avoiding
+ * unprotected concurrent access of the internal AVExpr state.
+ *
+ * @param s the state of the expression, if NULL, the internal state of AVExpr
will be used
+ * @param const_values a zero terminated array of values for the identifiers
from av_expr_parse() const_names
+ * @param opaque a pointer which will be passed to all functions from funcs1
and funcs2
+ * @return the value of the expression
+ */
+double av_expr_eval2(AVExpr *e, AVExprState *s, const double *const_values,
void *opaque);
+
/**
* Track the presence of variables and their number of occurrences in a parsed
expression
*
@@ -134,4 +151,14 @@ void av_expr_free(AVExpr *e);
*/
double av_strtod(const char *numstr, char **tail);
+/**
+ * Allocate a new AVExprState struct
+ */
+AVExprState *av_expr_state_alloc(void);
