bpo-32940: IDLE: Simplify StringTranslatePseudoMapping in pyparse (GH-5862)
The new code also runs faster.
(cherry picked from commit f0daa880a405c8de6743e44fa46006754aa145c9)
Co-authored-by: Cheryl Sabella <cheryl.sabella@gmail.com>
diff --git a/Lib/idlelib/pyparse.py b/Lib/idlelib/pyparse.py
index 443d198..6196c2b 100644
--- a/Lib/idlelib/pyparse.py
+++ b/Lib/idlelib/pyparse.py
@@ -1,6 +1,6 @@
"""Define partial Python code Parser used by editor and hyperparser.
-Instances of StringTranslatePseudoMapping are used with str.translate.
+Instances of ParseMap are used with str.translate.
The following bound search and match functions are defined:
_synchre - start of popular statement;
@@ -10,7 +10,6 @@
_closere - line that must be followed by dedent.
_chew_ordinaryre - non-special characters.
"""
-from collections.abc import Mapping
import re
import sys
@@ -101,46 +100,27 @@
""", re.VERBOSE).match
-class StringTranslatePseudoMapping(Mapping):
- r"""Utility class to be used with str.translate()
+class ParseMap(dict):
+ r"""Dict subclass that maps anything not in dict to 'x'.
- This Mapping class wraps a given dict. When a value for a key is
- requested via __getitem__() or get(), the key is looked up in the
- given dict. If found there, the value from the dict is returned.
- Otherwise, the default value given upon initialization is returned.
+ This is designed to be used with str.translate in study1.
+ Anything not specifically mapped otherwise becomes 'x'.
+ Example: replace everything except whitespace with 'x'.
- This allows using str.translate() to make some replacements, and to
- replace all characters for which no replacement was specified with
- a given character instead of leaving them as-is.
-
- For example, to replace everything except whitespace with 'x':
-
- >>> whitespace_chars = ' \t\n\r'
- >>> preserve_dict = {ord(c): ord(c) for c in whitespace_chars}
- >>> mapping = StringTranslatePseudoMapping(preserve_dict, ord('x'))
- >>> text = "a + b\tc\nd"
- >>> text.translate(mapping)
+ >>> keepwhite = ParseMap((ord(c), ord(c)) for c in ' \t\n\r')
+ >>> "a + b\tc\nd".translate(keepwhite)
'x x x\tx\nx'
"""
- def __init__(self, non_defaults, default_value):
- self._non_defaults = non_defaults
- self._default_value = default_value
+ # Calling this triples access time; see bpo-32940
+ def __missing__(self, key):
+ return 120 # ord('x')
- def _get(key, _get=non_defaults.get, _default=default_value):
- return _get(key, _default)
- self._get = _get
- def __getitem__(self, item):
- return self._get(item)
-
- def __len__(self):
- return len(self._non_defaults)
-
- def __iter__(self):
- return iter(self._non_defaults)
-
- def get(self, key, default=None):
- return self._get(key)
+# Map all ascii to 120 to avoid __missing__ call, then replace some.
+trans = ParseMap.fromkeys(range(128), 120)
+trans.update((ord(c), ord('(')) for c in "({[") # open brackets => '(';
+trans.update((ord(c), ord(')')) for c in ")}]") # close brackets => ')'.
+trans.update((ord(c), ord(c)) for c in "\"'\\\n#") # Keep these.
class Parser:
@@ -224,16 +204,6 @@
if lo > 0:
self.code = self.code[lo:]
- # Build a translation table to map uninteresting chars to 'x', open
- # brackets to '(', close brackets to ')' while preserving quotes,
- # backslashes, newlines and hashes. This is to be passed to
- # str.translate() in _study1().
- _tran = {}
- _tran.update((ord(c), ord('(')) for c in "({[")
- _tran.update((ord(c), ord(')')) for c in ")}]")
- _tran.update((ord(c), ord(c)) for c in "\"'\\\n#")
- _tran = StringTranslatePseudoMapping(_tran, default_value=ord('x'))
-
def _study1(self):
"""Find the line numbers of non-continuation lines.
@@ -250,7 +220,7 @@
# uninteresting characters. This can cut the number of chars
# by a factor of 10-40, and so greatly speed the following loop.
code = self.code
- code = code.translate(self._tran)
+ code = code.translate(trans)
code = code.replace('xxxxxxxx', 'x')
code = code.replace('xxxx', 'x')
code = code.replace('xx', 'x')