Source code for tokenize

"""Tokenization help for Python programs.

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

    the token type (see
    the token (a string)
    the starting (row, column) indices of the token (a 2-tuple of ints)
    the ending (row, column) indices of the token (a 2-tuple of ints)
    the original line (string)

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.  Additionally, all token lists start with an ENCODING token
which tells you which encoding was used to decode the bytes stream.

__author__ = 'Ka-Ping Yee <>'
__credits__ = ('GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, '
               'Skip Montanaro, Raymond Hettinger, Trent Nelson, '
               'Michael Foord')
import builtins
import re
import sys
from token import *
from codecs import lookup, BOM_UTF8
import collections
from io import TextIOWrapper
cookie_re = re.compile(r'^[ \t\f]*#.*coding[:=][ \t]*([-\w.]+)', re.ASCII)
blank_re = re.compile(br'^[ \t\f]*(?:[#\r\n]|$)', re.ASCII)

import token
__all__ = token.__all__ + ["COMMENT", "tokenize", "detect_encoding",
                           "NL", "untokenize", "ENCODING", "TokenInfo"]
del token

tok_name[COMMENT] = 'COMMENT'
tok_name[NL] = 'NL'
    '(':   LPAR,
    ')':   RPAR,
    '[':   LSQB,
    ']':   RSQB,
    ':':   COLON,
    ',':   COMMA,
    ';':   SEMI,
    '+':   PLUS,
    '-':   MINUS,
    '*':   STAR,
    '/':   SLASH,
    '|':   VBAR,
    '&':   AMPER,
    '<':   LESS,
    '>':   GREATER,
    '=':   EQUAL,
    '.':   DOT,
    '%':   PERCENT,
    '{':   LBRACE,
    '}':   RBRACE,
    '==':  EQEQUAL,
    '!=':  NOTEQUAL,
    '<=':  LESSEQUAL,
    '>=':  GREATEREQUAL,
    '~':   TILDE,
    '^':   CIRCUMFLEX,
    '<<':  LEFTSHIFT,
    '>>':  RIGHTSHIFT,
    '**':  DOUBLESTAR,
    '+=':  PLUSEQUAL,
    '-=':  MINEQUAL,
    '*=':  STAREQUAL,
    '/=':  SLASHEQUAL,
    '%=':  PERCENTEQUAL,
    '&=':  AMPEREQUAL,
    '|=':  VBAREQUAL,
    '//':  DOUBLESLASH,
    '@':   AT

class TokenInfo(collections.namedtuple('TokenInfo', 'type string start end line')):
    def __repr__(self):
        annotated_type = '%d (%s)' % (self.type, tok_name[self.type])
        return ('TokenInfo(type=%s, string=%r, start=%r, end=%r, line=%r)' %

    def exact_type(self):
        if self.type == OP and self.string in EXACT_TOKEN_TYPES:
            return EXACT_TOKEN_TYPES[self.string]
            return self.type

def group(*choices): return '(' + '|'.join(choices) + ')'
def any(*choices): return group(*choices) + '*'
def maybe(*choices): return group(*choices) + '?'

# Note: we use unicode matching for names ("\w") but ascii matching for
# number literals.
Whitespace = r'[ \f\t]*'
Comment = r'#[^\r\n]*'
Ignore = Whitespace + any(r'\\\r?\n' + Whitespace) + maybe(Comment)
Name = r'\w+'

Hexnumber = r'0[xX][0-9a-fA-F]+'
Binnumber = r'0[bB][01]+'
Octnumber = r'0[oO][0-7]+'
Decnumber = r'(?:0+|[1-9][0-9]*)'
Intnumber = group(Hexnumber, Binnumber, Octnumber, Decnumber)
Exponent = r'[eE][-+]?[0-9]+'
Pointfloat = group(r'[0-9]+\.[0-9]*', r'\.[0-9]+') + maybe(Exponent)
Expfloat = r'[0-9]+' + Exponent
Floatnumber = group(Pointfloat, Expfloat)
Imagnumber = group(r'[0-9]+[jJ]', Floatnumber + r'[jJ]')
Number = group(Imagnumber, Floatnumber, Intnumber)

StringPrefix = r'(?:[bB][rR]?|[rR][bB]?|[uU])?'

# Tail end of ' string.
Single = r"[^'\\]*(?:\\.[^'\\]*)*'"
# Tail end of " string.
Double = r'[^"\\]*(?:\\.[^"\\]*)*"'
# Tail end of ''' string.
Single3 = r"[^'\\]*(?:(?:\\.|'(?!''))[^'\\]*)*'''"
# Tail end of """ string.
Double3 = r'[^"\\]*(?:(?:\\.|"(?!""))[^"\\]*)*"""'
Triple = group(StringPrefix + "'''", StringPrefix + '"""')
# Single-line ' or " string.
String = group(StringPrefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*'",
               StringPrefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*"')

# Because of leftmost-then-longest match semantics, be sure to put the
# longest operators first (e.g., if = came before ==, == would get
# recognized as two instances of =).
Operator = group(r"\*\*=?", r">>=?", r"<<=?", r"!=",
                 r"//=?", r"->",

Bracket = '[][(){}]'
Special = group(r'\r?\n', r'\.\.\.', r'[:;.,@]')
Funny = group(Operator, Bracket, Special)

PlainToken = group(Number, Funny, String, Name)
Token = Ignore + PlainToken

# First (or only) line of ' or " string.
ContStr = group(StringPrefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*" +
                group("'", r'\\\r?\n'),
                StringPrefix + r'"[^\n"\\]*(?:\\.[^\n"\\]*)*' +
                group('"', r'\\\r?\n'))
PseudoExtras = group(r'\\\r?\n|\Z', Comment, Triple)
PseudoToken = Whitespace + group(PseudoExtras, Number, Funny, ContStr, Name)

def _compile(expr):
    return re.compile(expr, re.UNICODE)

endpats = {"'": Single, '"': Double,
           "'''": Single3, '"""': Double3,
           "r'''": Single3, 'r"""': Double3,
           "b'''": Single3, 'b"""': Double3,
           "R'''": Single3, 'R"""': Double3,
           "B'''": Single3, 'B"""': Double3,
           "br'''": Single3, 'br"""': Double3,
           "bR'''": Single3, 'bR"""': Double3,
           "Br'''": Single3, 'Br"""': Double3,
           "BR'''": Single3, 'BR"""': Double3,
           "rb'''": Single3, 'rb"""': Double3,
           "Rb'''": Single3, 'Rb"""': Double3,
           "rB'''": Single3, 'rB"""': Double3,
           "RB'''": Single3, 'RB"""': Double3,
           "u'''": Single3, 'u"""': Double3,
           "R'''": Single3, 'R"""': Double3,
           "U'''": Single3, 'U"""': Double3,
           'r': None, 'R': None, 'b': None, 'B': None,
           'u': None, 'U': None}

triple_quoted = {}
for t in ("'''", '"""',
          "r'''", 'r"""', "R'''", 'R"""',
          "b'''", 'b"""', "B'''", 'B"""',
          "br'''", 'br"""', "Br'''", 'Br"""',
          "bR'''", 'bR"""', "BR'''", 'BR"""',
          "rb'''", 'rb"""', "rB'''", 'rB"""',
          "Rb'''", 'Rb"""', "RB'''", 'RB"""',
          "u'''", 'u"""', "U'''", 'U"""',
    triple_quoted[t] = t
single_quoted = {}
for t in ("'", '"',
          "r'", 'r"', "R'", 'R"',
          "b'", 'b"', "B'", 'B"',
          "br'", 'br"', "Br'", 'Br"',
          "bR'", 'bR"', "BR'", 'BR"' ,
          "rb'", 'rb"', "rB'", 'rB"',
          "Rb'", 'Rb"', "RB'", 'RB"' ,
          "u'", 'u"', "U'", 'U"',
    single_quoted[t] = t

tabsize = 8

class TokenError(Exception): pass

class StopTokenizing(Exception): pass

class Untokenizer:

    def __init__(self):
        self.tokens = []
        self.prev_row = 1
        self.prev_col = 0
        self.encoding = None

    def add_whitespace(self, start):
        row, col = start
        assert row <= self.prev_row
        col_offset = col - self.prev_col
        if col_offset:
            self.tokens.append(" " * col_offset)

    def untokenize(self, iterable):
        for t in iterable:
            if len(t) == 2:
                self.compat(t, iterable)
            tok_type, token, start, end, line = t
            if tok_type == ENCODING:
                self.encoding = token
            self.prev_row, self.prev_col = end
            if tok_type in (NEWLINE, NL):
                self.prev_row += 1
                self.prev_col = 0
        return "".join(self.tokens)

    def compat(self, token, iterable):
        startline = False
        indents = []
        toks_append = self.tokens.append
        toknum, tokval = token

        if toknum in (NAME, NUMBER):
            tokval += ' '
        if toknum in (NEWLINE, NL):
            startline = True
        prevstring = False
        for tok in iterable:
            toknum, tokval = tok[:2]
            if toknum == ENCODING:
                self.encoding = tokval

            if toknum in (NAME, NUMBER):
                tokval += ' '

            # Insert a space between two consecutive strings
            if toknum == STRING:
                if prevstring:
                    tokval = ' ' + tokval
                prevstring = True
                prevstring = False

            if toknum == INDENT:
            elif toknum == DEDENT:
            elif toknum in (NEWLINE, NL):
                startline = True
            elif startline and indents:
                startline = False

[docs]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 only two tokens are passed, the resulting output is poor. Round-trip invariant for full input: Untokenized source will match input source exactly Round-trip invariant for limited intput: # Output bytes will tokenize the back to the input t1 = [tok[:2] for tok in tokenize(f.readline)] newcode = untokenize(t1) readline = BytesIO(newcode).readline t2 = [tok[:2] for tok in tokenize(readline)] assert t1 == t2 """ ut = Untokenizer() out = ut.untokenize(iterable) if ut.encoding is not None: out = out.encode(ut.encoding) return out
def _get_normal_name(orig_enc): """Imitates get_normal_name in tokenizer.c.""" # Only care about the first 12 characters. enc = orig_enc[:12].lower().replace("_", "-") if enc == "utf-8" or enc.startswith("utf-8-"): return "utf-8" if enc in ("latin-1", "iso-8859-1", "iso-latin-1") or \ enc.startswith(("latin-1-", "iso-8859-1-", "iso-latin-1-")): return "iso-8859-1" return orig_enc def detect_encoding(readline): """ The detect_encoding() function is used to detect the encoding that should be used to decode a Python source file. It requires one argument, 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 the encoding cookie is an invalid charset, raise a SyntaxError. Note that if a utf-8 bom is found, 'utf-8-sig' is returned. If no encoding is specified, then the default of 'utf-8' will be returned. """ try: filename = except AttributeError: filename = None bom_found = False encoding = None default = 'utf-8' def read_or_stop(): try: return readline() except StopIteration: return b'' def find_cookie(line): try: # Decode as UTF-8. Either the line is an encoding declaration, # in which case it should be pure ASCII, or it must be UTF-8 # per default encoding. line_string = line.decode('utf-8') except UnicodeDecodeError: msg = "invalid or missing encoding declaration" if filename is not None: msg = '{} for {!r}'.format(msg, filename) raise SyntaxError(msg) match = cookie_re.match(line_string) if not match: return None encoding = _get_normal_name( try: codec = lookup(encoding) except LookupError: # This behaviour mimics the Python interpreter if filename is None: msg = "unknown encoding: " + encoding else: msg = "unknown encoding for {!r}: {}".format(filename, encoding) raise SyntaxError(msg) if bom_found: if encoding != 'utf-8': # This behaviour mimics the Python interpreter if filename is None: msg = 'encoding problem: utf-8' else: msg = 'encoding problem for {!r}: utf-8'.format(filename) raise SyntaxError(msg) encoding += '-sig' return encoding first = read_or_stop() if first.startswith(BOM_UTF8): bom_found = True first = first[3:] default = 'utf-8-sig' if not first: return default, [] encoding = find_cookie(first) if encoding: return encoding, [first] if not blank_re.match(first): return default, [first] second = read_or_stop() if not second: return default, [first] encoding = find_cookie(second) if encoding: return encoding, [first, second] return default, [first, second] def open(filename): """Open a file in read only mode using the encoding detected by detect_encoding(). """ buffer =, 'rb') encoding, lines = detect_encoding(buffer.readline) text = TextIOWrapper(buffer, encoding, line_buffering=True) text.mode = 'r' return text
[docs]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 bytes. Alternately, readline can be a callable function terminating with StopIteration: 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 column where the token begins in the source; a 2-tuple (erow, ecol) of 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. """ # This import is here to avoid problems when the itertools module is not # built yet and tokenize is imported. from itertools import chain, repeat encoding, consumed = detect_encoding(readline) rl_gen = iter(readline, b"") empty = repeat(b"") return _tokenize(chain(consumed, rl_gen, empty).__next__, encoding)
def _tokenize(readline, encoding): lnum = parenlev = continued = 0 numchars = '0123456789' contstr, needcont = '', 0 contline = None indents = [0] if encoding is not None: if encoding == "utf-8-sig": # BOM will already have been stripped. encoding = "utf-8" yield TokenInfo(ENCODING, encoding, (0, 0), (0, 0), '') while True: # loop over lines in stream try: line = readline() except StopIteration: line = b'' if encoding is not None: line = line.decode(encoding) lnum += 1 pos, max = 0, len(line) if contstr: # continued string if not line: raise TokenError("EOF in multi-line string", strstart) endmatch = endprog.match(line) if endmatch: pos = end = endmatch.end(0) yield TokenInfo(STRING, contstr + line[:end], strstart, (lnum, end), contline + line) contstr, needcont = '', 0 contline = None elif needcont and line[-2:] != '\\\n' and line[-3:] != '\\\r\n': yield TokenInfo(ERRORTOKEN, contstr + line, strstart, (lnum, len(line)), contline) contstr = '' contline = None continue else: contstr = contstr + line contline = contline + line continue elif parenlev == 0 and not continued: # new statement if not line: break column = 0 while pos < max: # measure leading whitespace if line[pos] == ' ': column += 1 elif line[pos] == '\t': column = (column//tabsize + 1)*tabsize elif line[pos] == '\f': column = 0 else: break pos += 1 if pos == max: break if line[pos] in '#\r\n': # skip comments or blank lines if line[pos] == '#': comment_token = line[pos:].rstrip('\r\n') nl_pos = pos + len(comment_token) yield TokenInfo(COMMENT, comment_token, (lnum, pos), (lnum, pos + len(comment_token)), line) yield TokenInfo(NL, line[nl_pos:], (lnum, nl_pos), (lnum, len(line)), line) else: yield TokenInfo((NL, COMMENT)[line[pos] == '#'], line[pos:], (lnum, pos), (lnum, len(line)), line) continue if column > indents[-1]: # count indents or dedents indents.append(column) yield TokenInfo(INDENT, line[:pos], (lnum, 0), (lnum, pos), line) while column < indents[-1]: if column not in indents: raise IndentationError( "unindent does not match any outer indentation level", ("<tokenize>", lnum, pos, line)) indents = indents[:-1] yield TokenInfo(DEDENT, '', (lnum, pos), (lnum, pos), line) else: # continued statement if not line: raise TokenError("EOF in multi-line statement", (lnum, 0)) continued = 0 while pos < max: pseudomatch = _compile(PseudoToken).match(line, pos) if pseudomatch: # scan for tokens start, end = pseudomatch.span(1) spos, epos, pos = (lnum, start), (lnum, end), end if start == end: continue token, initial = line[start:end], line[start] if (initial in numchars or # ordinary number (initial == '.' and token != '.' and token != '...')): yield TokenInfo(NUMBER, token, spos, epos, line) elif initial in '\r\n': yield TokenInfo(NL if parenlev > 0 else NEWLINE, token, spos, epos, line) elif initial == '#': assert not token.endswith("\n") yield TokenInfo(COMMENT, token, spos, epos, line) elif token in triple_quoted: endprog = _compile(endpats[token]) endmatch = endprog.match(line, pos) if endmatch: # all on one line pos = endmatch.end(0) token = line[start:pos] yield TokenInfo(STRING, token, spos, (lnum, pos), line) else: strstart = (lnum, start) # multiple lines contstr = line[start:] contline = line break elif initial in single_quoted or \ token[:2] in single_quoted or \ token[:3] in single_quoted: if token[-1] == '\n': # continued string strstart = (lnum, start) endprog = _compile(endpats[initial] or endpats[token[1]] or endpats[token[2]]) contstr, needcont = line[start:], 1 contline = line break else: # ordinary string yield TokenInfo(STRING, token, spos, epos, line) elif initial.isidentifier(): # ordinary name yield TokenInfo(NAME, token, spos, epos, line) elif initial == '\\': # continued stmt continued = 1 else: if initial in '([{': parenlev += 1 elif initial in ')]}': parenlev -= 1 yield TokenInfo(OP, token, spos, epos, line) else: yield TokenInfo(ERRORTOKEN, line[pos], (lnum, pos), (lnum, pos+1), line) pos += 1 for indent in indents[1:]: # pop remaining indent levels yield TokenInfo(DEDENT, '', (lnum, 0), (lnum, 0), '') yield TokenInfo(ENDMARKER, '', (lnum, 0), (lnum, 0), '') # An undocumented, backwards compatible, API for all the places in the standard # library that expect to be able to use tokenize with strings
[docs]def generate_tokens(readline): return _tokenize(readline, None)
def main(): import argparse # Helper error handling routines def perror(message): print(message, file=sys.stderr) def error(message, filename=None, location=None): if location: args = (filename,) + location + (message,) perror("%s:%d:%d: error: %s" % args) elif filename: perror("%s: error: %s" % (filename, message)) else: perror("error: %s" % message) sys.exit(1) # Parse the arguments and options parser = argparse.ArgumentParser(prog='python -m tokenize') parser.add_argument(dest='filename', nargs='?', metavar='', help='the file to tokenize; defaults to stdin') parser.add_argument('-e', '--exact', dest='exact', action='store_true', help='display token names using the exact type') args = parser.parse_args() try: # Tokenize the input if args.filename: filename = args.filename with, 'rb') as f: tokens = list(tokenize(f.readline)) else: filename = "<stdin>" tokens = _tokenize(sys.stdin.readline, None) # Output the tokenization for token in tokens: token_type = token.type if args.exact: token_type = token.exact_type token_range = "%d,%d-%d,%d:" % (token.start + token.end) print("%-20s%-15s%-15r" % (token_range, tok_name[token_type], token.string)) except IndentationError as err: line, column = err.args[1][1:3] error(err.args[0], filename, (line, column)) except TokenError as err: line, column = err.args[1] error(err.args[0], filename, (line, column)) except SyntaxError as err: error(err, filename) except OSError as err: error(err) except KeyboardInterrupt: print("interrupted\n") except Exception as err: perror("unexpected error: %s" % err) raise if __name__ == "__main__": main()