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- Issue #719888: Updated tokenize to use a bytes API. generate_tokens has been

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renamed tokenize and now works with bytes rather than strings. A new
  detect_encoding function has been added for determining source file encoding
  according to PEP-0263. Token sequences returned by tokenize always start
  with an ENCODING token which specifies the encoding used to decode the file.
  This token is used to encode the output of untokenize back to bytes.

Credit goes to Michael "I'm-going-to-name-my-first-child-unittest" Foord from Resolver Systems for this work.
This commit is contained in:
Trent Nelson 2008-03-18 22:41:35 +00:00
parent 112367a980
commit 428de65ca9
16 changed files with 609 additions and 182 deletions
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187
Lib/tokenize.py
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@ -1,8 +1,11 @@
"""Tokenization help for Python programs.
generate_tokens(readline) is a generator that breaks a stream of
text into Python tokens. It accepts a readline-like method which is called
repeatedly to get the next line of input (or "" for EOF). It generates
tokenize(readline) is a generator that breaks a stream of
bytes into Python tokens. It decodes the bytes according to
PEP-0263 for determining source file encoding.
It accepts a readline-like method which is called
repeatedly to get the next line of input (or b"" for EOF). It generates
5-tuples with these members:
the token type (see token.py)
@ -13,32 +16,32 @@ repeatedly to get the next line of input (or "" for EOF). It generates
It is designed to match the working of the Python tokenizer exactly, except
that it produces COMMENT tokens for comments and gives type OP for all
operators
Older entry points
tokenize_loop(readline, tokeneater)
tokenize(readline, tokeneater=printtoken)
are the same, except instead of generating tokens, tokeneater is a callback
function to which the 5 fields described above are passed as 5 arguments,
each time a new token is found."""
operators. Aditionally, all token lists start with an ENCODING token
which tells you which encoding was used to decode the bytes stream."""
__author__ = 'Ka-Ping Yee <ping@lfw.org>'
__credits__ = \
'GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, Skip Montanaro, Raymond Hettinger'
__credits__ = ('GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, '
'Skip Montanaro, Raymond Hettinger, Trent Nelson, '
'Michael Foord')
import string, re
import re, string, sys
from token import *
from codecs import lookup
from itertools import chain, repeat
cookie_re = re.compile("coding[:=]\s*([-\w.]+)")
import token
__all__ = [x for x in dir(token) if x[0] != '_'] + ["COMMENT", "tokenize",
"generate_tokens", "NL", "untokenize"]
"detect_encoding", "NL", "untokenize", "ENCODING"]
del token
COMMENT = N_TOKENS
tok_name[COMMENT] = 'COMMENT'
NL = N_TOKENS + 1
tok_name[NL] = 'NL'
N_TOKENS += 2
ENCODING = N_TOKENS + 2
tok_name[ENCODING] = 'ENCODING'
N_TOKENS += 3
def group(*choices): return '(' + '|'.join(choices) + ')'
def any(*choices): return group(*choices) + '*'
@ -132,33 +135,6 @@ class TokenError(Exception): pass
class StopTokenizing(Exception): pass
def printtoken(type, token, startrowcol, endrowcol, line): # for testing
(srow, scol), (erow, ecol) = startrowcol, endrowcol
print("%d,%d-%d,%d:\t%s\t%s" % \
(srow, scol, erow, ecol, tok_name[type], repr(token)))
def tokenize(readline, tokeneater=printtoken):
"""
The tokenize() function accepts two parameters: one representing the
input stream, and one providing an output mechanism for tokenize().
The first parameter, readline, must be a callable object which provides
the same interface as the readline() method of built-in file objects.
Each call to the function should return one line of input as a string.
The second parameter, tokeneater, must also be a callable object. It is
called once for each token, with five arguments, corresponding to the
tuples generated by generate_tokens().
"""
try:
tokenize_loop(readline, tokeneater)
except StopTokenizing:
pass
# backwards compatible interface
def tokenize_loop(readline, tokeneater):
for token_info in generate_tokens(readline):
tokeneater(*token_info)
class Untokenizer:
@ -166,6 +142,7 @@ class Untokenizer:
self.tokens = []
self.prev_row = 1
self.prev_col = 0
self.encoding = None
def add_whitespace(self, start):
row, col = start
@ -180,6 +157,9 @@ class Untokenizer:
self.compat(t, iterable)
break
tok_type, token, start, end, line = t
if tok_type == ENCODING:
self.encoding = token
continue
self.add_whitespace(start)
self.tokens.append(token)
self.prev_row, self.prev_col = end
@ -193,12 +173,16 @@ class Untokenizer:
indents = []
toks_append = self.tokens.append
toknum, tokval = token
if toknum in (NAME, NUMBER):
tokval += ' '
if toknum in (NEWLINE, NL):
startline = True
for tok in iterable:
toknum, tokval = tok[:2]
if toknum == ENCODING:
self.encoding = tokval
continue
if toknum in (NAME, NUMBER):
tokval += ' '
@ -216,8 +200,11 @@ class Untokenizer:
startline = False
toks_append(tokval)
def untokenize(iterable):
"""Transform tokens back into Python source code.
It returns a bytes object, encoded using the ENCODING
token, which is the first token sequence output by tokenize.
Each element returned by the iterable must be a token sequence
with at least two elements, a token number and token value. If
@ -227,24 +214,89 @@ def untokenize(iterable):
Untokenized source will match input source exactly
Round-trip invariant for limited intput:
# Output text will tokenize the back to the input
t1 = [tok[:2] for tok in generate_tokens(f.readline)]
# Output bytes will tokenize the back to the input
t1 = [tok[:2] for tok in tokenize(f.readline)]
newcode = untokenize(t1)
readline = iter(newcode.splitlines(1)).__next__
t2 = [tok[:2] for tokin generate_tokens(readline)]
readline = BytesIO(newcode).readline
t2 = [tok[:2] for tok in tokenize(readline)]
assert t1 == t2
"""
ut = Untokenizer()
return ut.untokenize(iterable)
out = ut.untokenize(iterable)
if ut.encoding is not None:
out = out.encode(ut.encoding)
return out
def generate_tokens(readline):
def detect_encoding(readline):
"""
The generate_tokens() generator requires one argment, readline, which
The detect_encoding() function is used to detect the encoding that should
be used to decode a Python source file. It requires one argment, readline,
in the same way as the tokenize() generator.
It will call readline a maximum of twice, and return the encoding used
(as a string) and a list of any lines (left as bytes) it has read
in.
It detects the encoding from the presence of a utf-8 bom or an encoding
cookie as specified in pep-0263. If both a bom and a cookie are present,
but disagree, a SyntaxError will be raised.
If no encoding is specified, then the default of 'utf-8' will be returned.
"""
utf8_bom = b'\xef\xbb\xbf'
bom_found = False
encoding = None
def read_or_stop():
try:
return readline()
except StopIteration:
return b''
def find_cookie(line):
try:
line_string = line.decode('ascii')
except UnicodeDecodeError:
pass
else:
matches = cookie_re.findall(line_string)
if matches:
encoding = matches[0]
if bom_found and lookup(encoding).name != 'utf-8':
# This behaviour mimics the Python interpreter
raise SyntaxError('encoding problem: utf-8')
return encoding
first = read_or_stop()
if first.startswith(utf8_bom):
bom_found = True
first = first[3:]
if not first:
return 'utf-8', []
encoding = find_cookie(first)
if encoding:
return encoding, [first]
second = read_or_stop()
if not second:
return 'utf-8', [first]
encoding = find_cookie(second)
if encoding:
return encoding, [first, second]
return 'utf-8', [first, second]
def tokenize(readline):
"""
The tokenize() generator requires one argment, readline, which
must be a callable object which provides the same interface as the
readline() method of built-in file objects. Each call to the function
should return one line of input as a string. Alternately, readline
should return one line of input as bytes. Alternately, readline
can be a callable function terminating with StopIteration:
readline = open(myfile).__next__ # Example of alternate readline
readline = open(myfile, 'rb').__next__ # Example of alternate readline
The generator produces 5-tuples with these members: the token type; the
token string; a 2-tuple (srow, scol) of ints specifying the row and
@ -252,18 +304,38 @@ def generate_tokens(readline):
ints specifying the row and column where the token ends in the source;
and the line on which the token was found. The line passed is the
logical line; continuation lines are included.
The first token sequence will always be an ENCODING token
which tells you which encoding was used to decode the bytes stream.
"""
encoding, consumed = detect_encoding(readline)
def readline_generator():
while True:
try:
yield readline()
except StopIteration:
return
chained = chain(consumed, readline_generator())
return _tokenize(chained.__next__, encoding)
def _tokenize(readline, encoding):
lnum = parenlev = continued = 0
namechars, numchars = string.ascii_letters + '_', '0123456789'
contstr, needcont = '', 0
contline = None
indents = [0]
if encoding is not None:
yield (ENCODING, encoding, (0, 0), (0, 0), '')
while 1: # loop over lines in stream
try:
line = readline()
except StopIteration:
line = ''
line = b''
if encoding is not None:
line = line.decode(encoding)
lnum = lnum + 1
pos, max = 0, len(line)
@ -385,7 +457,8 @@ def generate_tokens(readline):
yield (DEDENT, '', (lnum, 0), (lnum, 0), '')
yield (ENDMARKER, '', (lnum, 0), (lnum, 0), '')
if __name__ == '__main__': # testing
import sys
if len(sys.argv) > 1: tokenize(open(sys.argv[1]).readline)
else: tokenize(sys.stdin.readline)
# An undocumented, backwards compatible, API for all the places in the standard
# library that expect to be able to use tokenize with strings
def generate_tokens(readline):
return _tokenize(readline, None)