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ucm: add ${eval:EXPR} substitution (Syntax 5)

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It is useful to do simple integer math in UCM configurations, too.
Use snd_config_evaluate_string() string for this job.

Example:

    ${eval:1+1}
    ${eval:100*$var1}
    ${eval:$[$var2+1]/5}

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2021-11-30 14:19:58 +01:00
parent bf528b9066
commit 7b6da9ee6d
3 changed files with 42 additions and 5 deletions
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2
src/ucm/ucm_local.h
View file

@ -40,7 +40,7 @@
#include <pthread.h>
#include "use-case.h"
#define SYNTAX_VERSION_MAX 4
#define SYNTAX_VERSION_MAX 5
#define MAX_CARD_SHORT_NAME 32
#define MAX_CARD_LONG_NAME 80

37
src/ucm/ucm_subs.c
View file

@ -585,6 +585,42 @@ static char *rval_var(snd_use_case_mgr_t *uc_mgr, const char *id)
return NULL;
}
int _snd_eval_string(snd_config_t **dst, const char *s,
snd_config_expand_fcn_t fcn, void *private_data);
static int rval_eval_var_cb(snd_config_t **dst, const char *s, void *private_data)
{
snd_use_case_mgr_t *uc_mgr = private_data;
const char *v;
v = uc_mgr_get_variable(uc_mgr, s);
if (v == NULL)
return -ENOENT;
return snd_config_imake_string(dst, NULL, v);
}
static char *rval_eval(snd_use_case_mgr_t *uc_mgr, const char *e)
{
snd_config_t *dst;
char *r;
int err;
if (uc_mgr->conf_format < 5) {
uc_error("variable substitution is supported in v5+ syntax");
return NULL;
}
err = _snd_eval_string(&dst, e, rval_eval_var_cb, uc_mgr);
if (err < 0) {
uc_error("unable to evaluate '%s'", e);
return NULL;
}
err = snd_config_get_ascii(dst, &r);
snd_config_delete(dst);
if (err < 0)
return NULL;
return r;
}
#define MATCH_VARIABLE(name, id, fcn, empty_ok) \
if (strncmp((name), (id), sizeof(id) - 1) == 0) { \
rval = fcn(uc_mgr); \
@ -688,6 +724,7 @@ __std:
MATCH_VARIABLE2(value, "${env:", rval_env, false);
MATCH_VARIABLE2(value, "${sys:", rval_sysfs, false);
MATCH_VARIABLE2(value, "${var:", rval_var, true);
MATCH_VARIABLE2(value, "${eval:", rval_eval, false);
MATCH_VARIABLE2(value, "${find-card:", rval_card_lookup, false);
MATCH_VARIABLE2(value, "${find-device:", rval_device_lookup, false);
MATCH_VARIABLE2(value, "${CardNumberByName:", rval_card_number_by_name, false);