Issue #24619: Simplify async/await tokenization.
This commit simplifies async/await tokenization in tokenizer.c,
tokenize.py & lib2to3/tokenize.py. Previous solution was to keep
a stack of async-def & def blocks, whereas the new approach is just
to remember position of the outermost async-def block.
This change won't bring any parsing performance improvements, but
it makes the code much easier to read and validate.
diff --git a/Lib/lib2to3/pgen2/tokenize.py b/Lib/lib2to3/pgen2/tokenize.py
index 896b0fa..1ff1c61 100644
--- a/Lib/lib2to3/pgen2/tokenize.py
+++ b/Lib/lib2to3/pgen2/tokenize.py
@@ -366,10 +366,11 @@
contline = None
indents = [0]
- # 'stashed' and 'ctx' are used for async/await parsing
+ # 'stashed' and 'async_*' are used for async/await parsing
stashed = None
- ctx = [('sync', 0)]
- in_async = 0
+ async_def = False
+ async_def_indent = 0
+ async_def_nl = False
while 1: # loop over lines in stream
try:
@@ -438,15 +439,18 @@
("<tokenize>", lnum, pos, line))
indents = indents[:-1]
- cur_indent = indents[-1]
- while len(ctx) > 1 and ctx[-1][1] >= cur_indent:
- if ctx[-1][0] == 'async':
- in_async -= 1
- assert in_async >= 0
- ctx.pop()
+ if async_def and async_def_indent >= indents[-1]:
+ async_def = False
+ async_def_nl = False
+ async_def_indent = 0
yield (DEDENT, '', (lnum, pos), (lnum, pos), line)
+ if async_def and async_def_nl and async_def_indent >= indents[-1]:
+ async_def = False
+ async_def_nl = False
+ async_def_indent = 0
+
else: # continued statement
if not line:
raise TokenError("EOF in multi-line statement", (lnum, 0))
@@ -466,10 +470,13 @@
newline = NEWLINE
if parenlev > 0:
newline = NL
+ elif async_def:
+ async_def_nl = True
if stashed:
yield stashed
stashed = None
yield (newline, token, spos, epos, line)
+
elif initial == '#':
assert not token.endswith("\n")
if stashed:
@@ -508,7 +515,7 @@
yield (STRING, token, spos, epos, line)
elif initial in namechars: # ordinary name
if token in ('async', 'await'):
- if in_async:
+ if async_def:
yield (ASYNC if token == 'async' else AWAIT,
token, spos, epos, line)
continue
@@ -523,15 +530,13 @@
and stashed[0] == NAME
and stashed[1] == 'async'):
- ctx.append(('async', indents[-1]))
- in_async += 1
+ async_def = True
+ async_def_indent = indents[-1]
yield (ASYNC, stashed[1],
stashed[2], stashed[3],
stashed[4])
stashed = None
- else:
- ctx.append(('sync', indents[-1]))
if stashed:
yield stashed