From b7ca9458773ee18c0b0bb4de55b670e06b70ecc5 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Wed, 4 Nov 2015 12:29:33 +0000
Subject: [PATCH] lib/mp-readline: Make it easy to exit auto-indent mode by
 pressing enter.

This patch allows you to stop auto-indent by pressing enter on a second
blank line.  Easier than having to use backspace, and prevents new users
from getting stuck in auto-indent mode.
---
 docs/reference/repl.rst    |  4 ++++
 lib/mp-readline/readline.c | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/docs/reference/repl.rst b/docs/reference/repl.rst
index c03cbfd38..0e481996f 100644
--- a/docs/reference/repl.rst
+++ b/docs/reference/repl.rst
@@ -49,6 +49,10 @@ Finally type ``print(i)``, press RETURN, press BACKSPACE and press RETURN again:
     3
     >>>
 
+Auto-indent won't be applied if the previous two lines were all spaces.  This
+means that you can finish entering a compound statment by pressing RETURN
+twice, and then a third press will finish and execute.
+
 Auto-completion
 ---------------
 
diff --git a/lib/mp-readline/readline.c b/lib/mp-readline/readline.c
index b7c64aec3..cbb99cc94 100644
--- a/lib/mp-readline/readline.c
+++ b/lib/mp-readline/readline.c
@@ -370,6 +370,18 @@ STATIC void readline_auto_indent(void) {
             }
         }
         // i=start of line; j=first non-space
+        if (i > 0 && j + 1 == line->len) {
+            // previous line is not first line and is all spaces
+            for (size_t k = i - 1; k > 0; --k) {
+                if (line->buf[k - 1] == '\n') {
+                    // don't auto-indent if last 2 lines are all spaces
+                    return;
+                } else if (line->buf[k - 1] != ' ') {
+                    // 2nd previous line is not all spaces
+                    break;
+                }
+            }
+        }
         int n = (j - i) / 4;
         if (line->buf[line->len - 2] == ':') {
             n += 1;