Swap a running app's module: --watch and the swap command

vega tui|web MODULE --watch replaces the running app's module when its
file is written again (aup watch writes it); states keep their values by
name through pure_app_replace and every web page hears of it. The file is
compared by the digest of its bytes, at most five times a second, so a
module of the same size written within the same second is not missed; a
module that does not load leaves the app as it was and is not tried
again. Modules alternate between two slots so a failed load never touches
the running one. Scripts get swap MODULE; whether a module runs frames is
now a property of the screen.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/vega.h b/src/vega.h
index 59a663e..47e7e91 100644
--- a/src/vega.h
+++ b/src/vega.h
@@ -30,6 +30,7 @@ typedef struct {
     const PureModule *module;
     int title;  /* text view, or -1 */
     int prompt; /* the first text input, or -1 */
+    bool ticks; /* it handles frames: a surface runs them, about 60 a second */
     VegaPart parts[VEGA_PARTS];
     unsigned count;
 } VegaScreen;
@@ -82,8 +83,9 @@ void vega_print(FILE *, PureApp *, const VegaScreen *, bool color);
 /* NUI: the screen as sentences (all), or only the focused item of the first list. */
 void vega_say(FILE *, PureApp *, const VegaScreen *, bool all);
 /* GUI: the screen as a web page on listen:port (0: any free port, printed as
- * {"port":N}); runs until SIGINT or SIGTERM. */
-int vega_web(PureApp *, const VegaScreen *, const char *listen, unsigned port);
+ * {"port":N}); runs until SIGINT or SIGTERM. reload, when given, is asked
+ * a few times a second whether the module was replaced (the screen with it). */
+int vega_web(PureApp *, const VegaScreen *, const char *listen, unsigned port, bool (*reload)(void));
 
 /* TUI: a grid of cells, redrawn from the app on every change. first keeps each
  * list's scroll between frames; the focused row stays visible. shown is what