m_property: add a way to switch on property values in property expansion

Allows for example: --status-msg='${?pause==yes:(Paused) } ...' to
emulate the normal terminal status line. It's useful in other situations
too.

I'm a bit worried about extending this mini-DSL, and sure hope nobody
will implement a generic formula evaluator at some point in the future.
But for now we're probably safe.

1 files changed, 9 insertions, 3 deletions

diff --git a/mpvcore/m_property.c b/mpvcore/m_property.c
index 83c6ea1018..6e25bf4e43 100644
--- a/mpvcore/m_property.c
+++ b/mpvcore/m_property.c
@@ -219,14 +219,20 @@ static int expand_property(const m_option_t *prop_list, char **ret, int *ret_len
 {
     bool cond_yes = bstr_eatstart0(&prop, "?");
     bool cond_no = !cond_yes && bstr_eatstart0(&prop, "!");
+    bool test = cond_yes || cond_no;
     bool raw = bstr_eatstart0(&prop, "=");
-    int method =
-        (raw || cond_yes || cond_no) ? M_PROPERTY_GET_STRING : M_PROPERTY_PRINT;
+    bstr comp_with = {0};
+    bool comp = test && bstr_split_tok(prop, "==", &prop, &comp_with);
+    if (test && !comp)
+        raw = true;
+    int method = raw ? M_PROPERTY_GET_STRING : M_PROPERTY_PRINT;
 
     char *s = NULL;
     int r = m_property_do_bstr(prop_list, prop, method, &s, ctx);
     bool skip;
-    if (cond_yes || cond_no) {
+    if (comp) {
+        skip = ((s && bstr_equals0(comp_with, s)) != cond_yes);
+    } else if (test) {
         skip = (!!s != cond_yes);
     } else {
         skip = !!s;