In raw mode, return Escape immediately. (#224)

CHANGELOG.md

@@ -16,6 +16,7 @@
 - **Breaking Change** Moved `Terminal.info.width` and `height` to `Terminal.size.width` and `height`.
 - **Breaking Change** `TerminalInterface.info` is now a method with parameters instead of a property.
 - **Breaking Change** Moved `Markdown` widget to separate `mordant-markdown` module, which is not included by default. If you use markdown rendering, you need to add that module to you dependencies.
+- In raw mode on POSIX systems, pressing the escape key once will now immediately return an `Escape` event. [(#193)](https://github.com/ajalt/mordant/issues/193)
 
 ### Removed
 - Removed constructor overloads for `Terminal`. There is now one constructor with all default parameters. 

docs/input.md

@@ -159,11 +159,7 @@ app and operating system. Some things to keep in mind:
   other than Windows.
 - Some key combinations aren't reported because they're intercepted by the terminal app to perform
   actions like switching tabs or closing the window.
-- On Linux and macOS, the Escape key isn't reported as a key press; instead, it begins a "VTI escape
-  sequence" that the terminal uses to report key presses. For example if you press `Escape`, then `[`,
-  then `d`, the terminal will report that as the left arrow key being pressed. It's up to you whether
-  you consider this a feature or a limitation. 
-- Raw mode is supported on JS or wasmJS targets on Node.js only. You can also use Node.js's
+- For JS or wasmJS targets, raw mode is supported on Node.js only. You can also use Node.js's
   `readline` module to read input with callbacks instead of blocking, or in the browser you can use
   the `keydown` and `mousedown` events.
 

mordant/src/commonMain/kotlin/com/github/ajalt/mordant/terminal/terminalinterface/PosixEventParser.kt

@@ -5,6 +5,7 @@ import com.github.ajalt.mordant.input.KeyboardEvent
 import com.github.ajalt.mordant.input.MouseEvent
 import com.github.ajalt.mordant.internal.codepointToString
 import com.github.ajalt.mordant.internal.readBytesAsUtf8
+import kotlin.time.Duration
 import kotlin.time.Duration.Companion.milliseconds
 import kotlin.time.TimeMark
 import kotlin.time.TimeSource
@@ -36,8 +37,8 @@ internal class PosixEventParser(
         val s = StringBuilder()
         var ch: Char
 
-        fun read(): Char? {
-            ch = readRawByte(timeout)?.toChar() ?: return null
+        fun read(t:TimeMark = timeout): Char? {
+            ch = readRawByte(t)?.toChar() ?: return null
             s.append(ch)
             return ch
         }
@@ -51,7 +52,10 @@ internal class PosixEventParser(
 
         if (ch == ESC) {
             escaped = true
-            read() ?: return KeyboardEvent("Escape")
+            // If there's nothing else in the buffer, return "Escape" immediately. This means that
+            // you can't manually type in escape sequences, but that's a pretty rare use case
+            // compared to just pressing escape.
+            read(TimeSource.Monotonic.markNow() + 5.milliseconds) ?: return KeyboardEvent("Escape")
             if (ch == ESC) {
                 return KeyboardEvent("Escape")
             }