From a5e25817144d3f9f8b08a8d6899e28d1a599e22f Mon Sep 17 00:00:00 2001
From: Terry Jan Reedy <tjreedy@udel.edu>
Date: Wed, 2 Feb 2022 21:27:18 -0500
Subject: [PATCH] [3.9] bpo-45975: Use walrus operator for some idlelib while
 loops

co-authored by Nick Drozd
cherrypicked from 51a95be1d035a717ab29e98056b8831a98e61125
---
 Lib/idlelib/pyparse.py | 12 ++++--------
 Lib/idlelib/replace.py |  7 ++-----
 Lib/idlelib/run.py     |  4 +---
 3 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/Lib/idlelib/pyparse.py b/Lib/idlelib/pyparse.py
index d34872b4396e1e..a94327533d865a 100644
--- a/Lib/idlelib/pyparse.py
+++ b/Lib/idlelib/pyparse.py
@@ -179,14 +179,10 @@ def find_good_parse_start(self, is_char_in_string):
         # Peeking back worked; look forward until _synchre no longer
         # matches.
         i = pos + 1
-        while 1:
-            m = _synchre(code, i)
-            if m:
-                s, i = m.span()
-                if not is_char_in_string(s):
-                    pos = s
-            else:
-                break
+        while (m := _synchre(code, i)):
+            s, i = m.span()
+            if not is_char_in_string(s):
+                pos = s
         return pos
 
     def set_lo(self, lo):
diff --git a/Lib/idlelib/replace.py b/Lib/idlelib/replace.py
index 6be034af9626b3..70d761db126308 100644
--- a/Lib/idlelib/replace.py
+++ b/Lib/idlelib/replace.py
@@ -156,11 +156,8 @@ def replace_all(self, event=None):
         first = last = None
         # XXX ought to replace circular instead of top-to-bottom when wrapping
         text.undo_block_start()
-        while True:
-            res = self.engine.search_forward(text, prog, line, col,
-                                             wrap=False, ok=ok)
-            if not res:
-                break
+        while (res := self.engine.search_forward(
+                text, prog, line, col, wrap=False, ok=ok)):
             line, m = res
             chars = text.get("%d.0" % line, "%d.0" % (line+1))
             orig = m.group()
diff --git a/Lib/idlelib/run.py b/Lib/idlelib/run.py
index dda9711dcf7aed..4246f497cb382b 100644
--- a/Lib/idlelib/run.py
+++ b/Lib/idlelib/run.py
@@ -468,9 +468,7 @@ def read(self, size=-1):
         result = self._line_buffer
         self._line_buffer = ''
         if size < 0:
-            while True:
-                line = self.shell.readline()
-                if not line: break
+            while (line := self.shell.readline()):
                 result += line
         else:
             while len(result) < size: