FEAT: simple wait-for-key function test file

Author: Oldes

src/tests/test-wait-for-key.r3

@@ -0,0 +1,58 @@
+Rebol [
+	name:    wait-for-key
+	title:   "Simple Rebol `wait-for-key` function"
+	purpose: "Demonstrate how to get simple user keyboard input from console without need to press ENTER"
+	author:  "Oldes"
+	needs:   3.12.0  ; https://github.com/Oldes/Rebol3
+]
+
+wait-for-key: func[
+	"Wait for single key press and return char as a result"
+	/only chars [bitset! string!] "Limit input to specified chars"
+	/local port old-awake
+][
+	; using existing input port
+	port: system/ports/input
+	; store awake actor and enter turn off read-line mode
+	old-awake: :port/awake
+	modify port 'line false
+	; store optional chars limit in port's extra
+	port/extra: chars
+	; clear old data (in case user cancel's waiting)
+	port/data: none
+	; define new awake, which checks single key
+	port/awake: func[event][
+		all[
+			'key = event/type
+			any [
+				none? port/extra
+				find port/extra event/key
+			]
+			event/port/data: event/key 
+			true
+		]
+	]
+	; wait for user input
+	wait/only port
+	; put back original awake actor and read-line mode
+	port/awake: :old-awake
+	modify port 'line true
+	; return result and clear port's data
+	also port/data port/data: none
+]
+
+;-- Usage example ------------------------------------------------------
+print "Press any key!"
+char: wait-for-key
+print ["You pressed:" mold char]
+
+print "Press ENTER!"
+wait-for-key/only CRLF
+
+print "Press any number!"
+char: wait-for-key/only charset [#"0" - #"9"]
+print ["You pressed:" char]
+print "Good choice!^/"
+print "That's all... good bye!"
+wait-for-key
+