Allow launching plugins with Alt + plugin's key (#569)

* Allow launching plugins with Alt + plugin's key

* Fix Alt key in filter/prompts modes

* Fix handling Alt key in nextsel()

In filter mode: run the associated plugin.
In prompt mode: just throw out the Alt+key input.
In nextsel(): differentiate Alt+key and Esc

nnn.1

@@ -338,8 +338,10 @@ separated by \fI;\fR:
     export NNN_PLUG='f:finder;o:fzopen;p:mocplay;d:diffs;t:nmount;v:imgview'
 
     NOTES:
-    1. To run a plugin directly, press \fI;\fR followed by the plugin key.
-    2. To skip directory refresh after running a plugin, prefix with \fB-\fR.
+    1. To run a plugin directly, press \fI;\fR followed by the key_char.
+    2. Alternative way to run a plugin directly -
+       prefix with \fIAlt\fR (i.e. \fIAlt+key_char\fR).
+    3. To skip directory refresh after running a plugin, prefix with \fB-\fR.
 
     export NNN_PLUG='m:-mediainf'
 .Ed

plugins/README.md

@@ -78,7 +78,7 @@ Plugins are installed to `${XDG_CONFIG_HOME:-$HOME/.config}/nnn/plugins`.
 
 ## Invoking a plugin
 
-Press the plugin shortcut (<kbd>;</kbd> or <kbd>^S</kbd>) followed by the assigned key. E.g., with the below config:
+Press the plugin shortcut (<kbd>;</kbd> or <kbd>^S</kbd>) followed by the assigned key character. E.g., with the below config:
 
 ```sh
 export NNN_PLUG='f:finder;o:fzopen;p:mocplay;d:diffs;t:nmount;v:imgview'
@@ -86,6 +86,8 @@ export NNN_PLUG='f:finder;o:fzopen;p:mocplay;d:diffs;t:nmount;v:imgview'
 
 Plugin `finder` can be run with the keybind <kbd>;f</kbd>, `fzopen` can be run with <kbd>;o</kbd> and so on... The key vs. plugin pairs are shown in the help and config screen.
 
+Alternative way to run a plugin directly - prefix with <kbd>Alt</kbd> (i.e. <kbd>Alt+key_char</kbd>).
+
 To select and invoke a plugin from the plugin directory, press <kbd>Enter</kbd> (to _enter_ the plugin dir) after the plugin shortcut.
 
 #### Skip directory refresh after running a plugin

src/nnn.c

@@ -2284,6 +2284,18 @@ static int reventrycmp(const void *va, const void *vb)
 
 static int (*entrycmpfn)(const void *va, const void *vb) = &entrycmp;
 
+/* In case of an error, resets *wch to Esc */
+static int handle_alt_key(wint_t *wch)
+{
+	timeout(0);
+	int r = get_wch(wch);
+	if (r == ERR)
+		*wch = 27;
+	cleartimeout();
+
+	return r;
+}
+
 /*
  * Returns SEL_* if key is bound and 0 otherwise.
  * Also modifies the run and env pointers (used on SEL_{RUN,RUNARG}).
@@ -2311,6 +2323,18 @@ static int nextsel(int presel)
 		//DPRINTF_D(c);
 		//DPRINTF_S(keyname(c));
 
+		/* Handle Alt+key */
+		if (c == 27) {
+			timeout(0);
+			c = getch();
+			if (c != ERR) {
+				ungetch(c);
+				c = CONTROL('S');
+			} else
+				c = 27;
+			settimeout();
+		}
+
 		if (c == ERR && presel == MSGWAIT)
 			c = (cfg.filtermode || filterset()) ? FILTER : CONTROL('L');
 		else if (c == FILTER || c == CONTROL('L'))
@@ -2564,7 +2588,11 @@ static int filterentries(char *path, char *lastname)
 #ifndef NOMOUSE
 		case KEY_MOUSE: // fallthrough
 #endif
-		case 27: /* Exit filter mode on Escape */
+		case 27: /* Exit filter mode on Escape and Alt+key */
+			if (handle_alt_key(ch) != ERR) {
+				unget_wch(*ch);
+				*ch = CONTROL('S');
+			}
 			goto end;
 		}
 
@@ -2776,7 +2804,10 @@ static char *xreadline(const char *prefill, const char *prompt)
 				len -= pos;
 				pos = 0;
 				continue;
-			case 27: /* Exit prompt on Escape */
+			case 27: /* Exit prompt on Escape, but just filter out Alt+key */
+				if (handle_alt_key(ch) != ERR)
+					continue;
+
 				len = 0;
 				goto END;
 			}
@@ -4097,7 +4128,7 @@ static void show_help(const char *path)
 	       "9x ^X  Delete%-18cE  Edit sel\n"
 	          "c*  Toggle exe%-14c>  Export list\n"
 		"1MISC\n"
-	       "9; ^S  Select plugin%-11c=  Launch app\n"
+	   "5Alt ; ^S  Select plugin%-11c=  Launch app\n"
 	       "9! ^]  Shell%-19c]  Cmd prompt\n"
 		  "cc  Connect remote%-10cu  Unmount\n"
 	       "9t ^T  Sort toggles%-12cs  Manage session\n"