[Python-checkins] bpo-38870: Refactor delimiting with context managers in ast.unparse (GH-17612)
Pablo Galindo
webhook-mailer at python.org
Mon Dec 23 11:11:08 EST 2019
https://github.com/python/cpython/commit/4b3b1226e86df6cd45e921c8f2ad23c3639c43b2
commit: 4b3b1226e86df6cd45e921c8f2ad23c3639c43b2
branch: master
author: Batuhan Taşkaya <47358913+isidentical at users.noreply.github.com>
committer: Pablo Galindo <Pablogsal at gmail.com>
date: 2019-12-23T16:11:00Z
summary:
bpo-38870: Refactor delimiting with context managers in ast.unparse (GH-17612)
Co-Authored-By: Victor Stinner <vstinner at python.org>
Co-authored-by: Pablo Galindo <pablogsal at gmail.com>
files:
M Lib/ast.py
diff --git a/Lib/ast.py b/Lib/ast.py
index ee3f74358ee12..76e0cac838b92 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -26,6 +26,7 @@
"""
import sys
from _ast import *
+from contextlib import contextmanager, nullcontext
def parse(source, filename='<unknown>', mode='exec', *,
@@ -613,6 +614,21 @@ def __exit__(self, exc_type, exc_value, traceback):
def block(self):
return self._Block(self)
+ @contextmanager
+ def delimit(self, start, end):
+ """A context manager for preparing the source for expressions. It adds
+ *start* to the buffer and enters, after exit it adds *end*."""
+
+ self.write(start)
+ yield
+ self.write(end)
+
+ def delimit_if(self, start, end, condition):
+ if condition:
+ return self.delimit(start, end)
+ else:
+ return nullcontext()
+
def traverse(self, node):
if isinstance(node, list):
for item in node:
@@ -636,11 +652,10 @@ def visit_Expr(self, node):
self.traverse(node.value)
def visit_NamedExpr(self, node):
- self.write("(")
- self.traverse(node.target)
- self.write(" := ")
- self.traverse(node.value)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.traverse(node.target)
+ self.write(" := ")
+ self.traverse(node.value)
def visit_Import(self, node):
self.fill("import ")
@@ -669,11 +684,8 @@ def visit_AugAssign(self, node):
def visit_AnnAssign(self, node):
self.fill()
- if not node.simple and isinstance(node.target, Name):
- self.write("(")
- self.traverse(node.target)
- if not node.simple and isinstance(node.target, Name):
- self.write(")")
+ with self.delimit_if("(", ")", not node.simple and isinstance(node.target, Name)):
+ self.traverse(node.target)
self.write(": ")
self.traverse(node.annotation)
if node.value:
@@ -715,28 +727,25 @@ def visit_Nonlocal(self, node):
self.interleave(lambda: self.write(", "), self.write, node.names)
def visit_Await(self, node):
- self.write("(")
- self.write("await")
- if node.value:
- self.write(" ")
- self.traverse(node.value)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.write("await")
+ if node.value:
+ self.write(" ")
+ self.traverse(node.value)
def visit_Yield(self, node):
- self.write("(")
- self.write("yield")
- if node.value:
- self.write(" ")
- self.traverse(node.value)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.write("yield")
+ if node.value:
+ self.write(" ")
+ self.traverse(node.value)
def visit_YieldFrom(self, node):
- self.write("(")
- self.write("yield from")
- if node.value:
- self.write(" ")
- self.traverse(node.value)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.write("yield from")
+ if node.value:
+ self.write(" ")
+ self.traverse(node.value)
def visit_Raise(self, node):
self.fill("raise")
@@ -782,21 +791,20 @@ def visit_ClassDef(self, node):
self.fill("@")
self.traverse(deco)
self.fill("class " + node.name)
- self.write("(")
- comma = False
- for e in node.bases:
- if comma:
- self.write(", ")
- else:
- comma = True
- self.traverse(e)
- for e in node.keywords:
- if comma:
- self.write(", ")
- else:
- comma = True
- self.traverse(e)
- self.write(")")
+ with self.delimit("(", ")"):
+ comma = False
+ for e in node.bases:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
+ for e in node.keywords:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
with self.block():
self.traverse(node.body)
@@ -812,10 +820,10 @@ def __FunctionDef_helper(self, node, fill_suffix):
for deco in node.decorator_list:
self.fill("@")
self.traverse(deco)
- def_str = fill_suffix + " " + node.name + "("
+ def_str = fill_suffix + " " + node.name
self.fill(def_str)
- self.traverse(node.args)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.traverse(node.args)
if node.returns:
self.write(" -> ")
self.traverse(node.returns)
@@ -931,13 +939,12 @@ def _write_constant(self, value):
def visit_Constant(self, node):
value = node.value
if isinstance(value, tuple):
- self.write("(")
- if len(value) == 1:
- self._write_constant(value[0])
- self.write(",")
- else:
- self.interleave(lambda: self.write(", "), self._write_constant, value)
- self.write(")")
+ with self.delimit("(", ")"):
+ if len(value) == 1:
+ self._write_constant(value[0])
+ self.write(",")
+ else:
+ self.interleave(lambda: self.write(", "), self._write_constant, value)
elif value is ...:
self.write("...")
else:
@@ -946,39 +953,34 @@ def visit_Constant(self, node):
self._write_constant(node.value)
def visit_List(self, node):
- self.write("[")
- self.interleave(lambda: self.write(", "), self.traverse, node.elts)
- self.write("]")
+ with self.delimit("[", "]"):
+ self.interleave(lambda: self.write(", "), self.traverse, node.elts)
def visit_ListComp(self, node):
- self.write("[")
- self.traverse(node.elt)
- for gen in node.generators:
- self.traverse(gen)
- self.write("]")
+ with self.delimit("[", "]"):
+ self.traverse(node.elt)
+ for gen in node.generators:
+ self.traverse(gen)
def visit_GeneratorExp(self, node):
- self.write("(")
- self.traverse(node.elt)
- for gen in node.generators:
- self.traverse(gen)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.traverse(node.elt)
+ for gen in node.generators:
+ self.traverse(gen)
def visit_SetComp(self, node):
- self.write("{")
- self.traverse(node.elt)
- for gen in node.generators:
- self.traverse(gen)
- self.write("}")
+ with self.delimit("{", "}"):
+ self.traverse(node.elt)
+ for gen in node.generators:
+ self.traverse(gen)
def visit_DictComp(self, node):
- self.write("{")
- self.traverse(node.key)
- self.write(": ")
- self.traverse(node.value)
- for gen in node.generators:
- self.traverse(gen)
- self.write("}")
+ with self.delimit("{", "}"):
+ self.traverse(node.key)
+ self.write(": ")
+ self.traverse(node.value)
+ for gen in node.generators:
+ self.traverse(gen)
def visit_comprehension(self, node):
if node.is_async:
@@ -993,24 +995,20 @@ def visit_comprehension(self, node):
self.traverse(if_clause)
def visit_IfExp(self, node):
- self.write("(")
- self.traverse(node.body)
- self.write(" if ")
- self.traverse(node.test)
- self.write(" else ")
- self.traverse(node.orelse)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.traverse(node.body)
+ self.write(" if ")
+ self.traverse(node.test)
+ self.write(" else ")
+ self.traverse(node.orelse)
def visit_Set(self, node):
if not node.elts:
raise ValueError("Set node should has at least one item")
- self.write("{")
- self.interleave(lambda: self.write(", "), self.traverse, node.elts)
- self.write("}")
+ with self.delimit("{", "}"):
+ self.interleave(lambda: self.write(", "), self.traverse, node.elts)
def visit_Dict(self, node):
- self.write("{")
-
def write_key_value_pair(k, v):
self.traverse(k)
self.write(": ")
@@ -1026,29 +1024,27 @@ def write_item(item):
else:
write_key_value_pair(k, v)
- self.interleave(
- lambda: self.write(", "), write_item, zip(node.keys, node.values)
- )
- self.write("}")
+ with self.delimit("{", "}"):
+ self.interleave(
+ lambda: self.write(", "), write_item, zip(node.keys, node.values)
+ )
def visit_Tuple(self, node):
- self.write("(")
- if len(node.elts) == 1:
- elt = node.elts[0]
- self.traverse(elt)
- self.write(",")
- else:
- self.interleave(lambda: self.write(", "), self.traverse, node.elts)
- self.write(")")
+ with self.delimit("(", ")"):
+ if len(node.elts) == 1:
+ elt = node.elts[0]
+ self.traverse(elt)
+ self.write(",")
+ else:
+ self.interleave(lambda: self.write(", "), self.traverse, node.elts)
unop = {"Invert": "~", "Not": "not", "UAdd": "+", "USub": "-"}
def visit_UnaryOp(self, node):
- self.write("(")
- self.write(self.unop[node.op.__class__.__name__])
- self.write(" ")
- self.traverse(node.operand)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.write(self.unop[node.op.__class__.__name__])
+ self.write(" ")
+ self.traverse(node.operand)
binop = {
"Add": "+",
@@ -1067,11 +1063,10 @@ def visit_UnaryOp(self, node):
}
def visit_BinOp(self, node):
- self.write("(")
- self.traverse(node.left)
- self.write(" " + self.binop[node.op.__class__.__name__] + " ")
- self.traverse(node.right)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.traverse(node.left)
+ self.write(" " + self.binop[node.op.__class__.__name__] + " ")
+ self.traverse(node.right)
cmpops = {
"Eq": "==",
@@ -1087,20 +1082,18 @@ def visit_BinOp(self, node):
}
def visit_Compare(self, node):
- self.write("(")
- self.traverse(node.left)
- for o, e in zip(node.ops, node.comparators):
- self.write(" " + self.cmpops[o.__class__.__name__] + " ")
- self.traverse(e)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.traverse(node.left)
+ for o, e in zip(node.ops, node.comparators):
+ self.write(" " + self.cmpops[o.__class__.__name__] + " ")
+ self.traverse(e)
- boolops = {And: "and", Or: "or"}
+ boolops = {"And": "and", "Or": "or"}
def visit_BoolOp(self, node):
- self.write("(")
- s = " %s " % self.boolops[node.op.__class__]
- self.interleave(lambda: self.write(s), self.traverse, node.values)
- self.write(")")
+ with self.delimit("(", ")"):
+ s = " %s " % self.boolops[node.op.__class__.__name__]
+ self.interleave(lambda: self.write(s), self.traverse, node.values)
def visit_Attribute(self, node):
self.traverse(node.value)
@@ -1114,27 +1107,25 @@ def visit_Attribute(self, node):
def visit_Call(self, node):
self.traverse(node.func)
- self.write("(")
- comma = False
- for e in node.args:
- if comma:
- self.write(", ")
- else:
- comma = True
- self.traverse(e)
- for e in node.keywords:
- if comma:
- self.write(", ")
- else:
- comma = True
- self.traverse(e)
- self.write(")")
+ with self.delimit("(", ")"):
+ comma = False
+ for e in node.args:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
+ for e in node.keywords:
+ if comma:
+ self.write(", ")
+ else:
+ comma = True
+ self.traverse(e)
def visit_Subscript(self, node):
self.traverse(node.value)
- self.write("[")
- self.traverse(node.slice)
- self.write("]")
+ with self.delimit("[", "]"):
+ self.traverse(node.slice)
def visit_Starred(self, node):
self.write("*")
@@ -1225,12 +1216,11 @@ def visit_keyword(self, node):
self.traverse(node.value)
def visit_Lambda(self, node):
- self.write("(")
- self.write("lambda ")
- self.traverse(node.args)
- self.write(": ")
- self.traverse(node.body)
- self.write(")")
+ with self.delimit("(", ")"):
+ self.write("lambda ")
+ self.traverse(node.args)
+ self.write(": ")
+ self.traverse(node.body)
def visit_alias(self, node):
self.write(node.name)
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