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tokenize.py
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"""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 members: the token type (see token.py) 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 <ping@lfw.org>' __credits__ = ('GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, ' 'Skip Montanaro, Raymond Hettinger, Trent Nelson, ' 'Michael Foord') from builtins import open as _builtin_open from codecs import lookup, BOM_UTF8 import collections import functools from io import TextIOWrapper import itertools as _itertools import re import sys from token import * from token import EXACT_TOKEN_TYPES import _tokenize cookie_re = re.compile(br'^[ \t\f]*#.*?coding[:=][ \t]*([-\w.]+)', re.ASCII) blank_re = re.compile(br'^[ \t\f]*(?:[#\r\n]|$)', re.ASCII) import token __all__ = token.__all__ + ["tokenize", "generate_tokens", "detect_encoding", "untokenize", "TokenInfo", "open", "TokenError"] del token 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)' % self._replace(type=annotated_type)) @property def exact_type(self): if self.type == OP and self.string in EXACT_TOKEN_TYPES: return EXACT_TOKEN_TYPES[self.string] else: 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(?:_?0)*|[1-9](?:_?[0-9])*)' Intnumber = group(Hexnumber, Binnumber, Octnumber, Decnumber) Exponent = r'[eE][-+]?[0-9](?:_?[0-9])*' Pointfloat = group(r'[0-9](?:_?[0-9])*\.(?:[0-9](?:_?[0-9])*)?', r'\.[0-9](?:_?[0-9])*') + maybe(Exponent) Expfloat = r'[0-9](?:_?[0-9])*' + Exponent Floatnumber = group(Pointfloat, Expfloat) Imagnumber = group(r'[0-9](?:_?[0-9])*[jJ]', Floatnumber + r'[jJ]') Number = group(Imagnumber, Floatnumber, Intnumber) # Return the empty string, plus all of the valid string prefixes. def _all_string_prefixes(): # The valid string prefixes. Only contain the lower case versions, # and don't contain any permutations (include 'fr', but not # 'rf'). The various permutations will be generated. _valid_string_prefixes = ['b', 'r', 'u', 'f', 't', 'br', 'fr', 'tr'] # if we add binary f-strings, add: ['fb', 'fbr'] result = {''} for prefix in _valid_string_prefixes: for t in _itertools.permutations(prefix): # create a list with upper and lower versions of each # character for u in _itertools.product(*[(c, c.upper()) for c in t]): result.add(''.join(u)) return result @functools.lru_cache def _compile(expr): return re.compile(expr, re.UNICODE) # Note that since _all_string_prefixes includes the empty string, # StringPrefix can be the empty string (making it optional). StringPrefix = group(*_all_string_prefixes()) # 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"\\]*)*"') # Sorting in reverse order puts the long operators before their prefixes. # Otherwise if = came before ==, == would get recognized as two instances # of =. Special = group(*map(re.escape, sorted(EXACT_TOKEN_TYPES, reverse=True))) Funny = group(r'\r?\n', 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) # For a given string prefix plus quotes, endpats maps it to a regex # to match the remainder of that string. _prefix can be empty, for # a normal single or triple quoted string (with no prefix). endpats = {} for _prefix in _all_string_prefixes(): endpats[_prefix + "'"] = Single endpats[_prefix + '"'] = Double endpats[_prefix + "'''"] = Single3 endpats[_prefix + '"""'] = Double3 del _prefix # A set of all of the single and triple quoted string prefixes, # including the opening quotes. single_quoted = set() triple_quoted = set() for t in _all_string_prefixes(): for u in (t + '"', t + "'"): single_quoted.add(u) for u in (t + '"""', t + "'''"): triple_quoted.add(u) del t, u tabsize = 8 class TokenError(Exception): pass class Untokenizer: def __init__(self): self.tokens = [] self.prev_row = 1 self.prev_col = 0 self.prev_type = None self.prev_line = "" self.encoding = None def add_whitespace(self, start): row, col = start if row < self.prev_row or row == self.prev_row and col < self.prev_col: raise ValueError("start ({},{}) precedes previous end ({},{})" .format(row, col, self.prev_row, self.prev_col)) self.add_backslash_continuation(start) col_offset = col - self.prev_col if col_offset: self.tokens.append(" " * col_offset) def add_backslash_continuation(self, start): """Add backslash continuation characters if the row has increased without encountering a newline token. This also inserts the correct amount of whitespace before the backslash. """ row = start[0] row_offset = row - self.prev_row if row_offset == 0: return newline = '\r\n' if self.prev_line.endswith('\r\n') else '\n' line = self.prev_line.rstrip('\\\r\n') ws = ''.join(_itertools.takewhile(str.isspace, reversed(line))) self.tokens.append(ws + f"\\{newline}" * row_offset) self.prev_col = 0 def escape_brackets(self, token): characters = [] consume_until_next_bracket = False for character in token: if character == "}": if consume_until_next_bracket: consume_until_next_bracket = False else: characters.append(character) if character == "{": n_backslashes = sum( 1 for char in _itertools.takewhile( "\\".__eq__, characters[-2::-1] ) ) if n_backslashes % 2 == 0 or characters[-1] != "N": characters.append(character) else: consume_until_next_bracket = True characters.append(character) return "".join(characters) def untokenize(self, iterable): it = iter(iterable) indents = [] startline = False for t in it: if len(t) == 2: self.compat(t, it) break tok_type, token, start, end, line = t if tok_type == ENCODING: self.encoding = token continue if tok_type == ENDMARKER: break if tok_type == INDENT: indents.append(token) continue elif tok_type == DEDENT: indents.pop() self.prev_row, self.prev_col = end continue elif tok_type in (NEWLINE, NL): startline = True elif startline and indents: indent = indents[-1] if start[1] >= len(indent): self.tokens.append(indent) self.prev_col = len(indent) startline = False elif tok_type in {FSTRING_MIDDLE, TSTRING_MIDDLE}: if '{' in token or '}' in token: token = self.escape_brackets(token) last_line = token.splitlines()[-1] end_line, end_col = end extra_chars = last_line.count("{{") + last_line.count("}}") end = (end_line, end_col + extra_chars) self.add_whitespace(start) self.tokens.append(token) self.prev_row, self.prev_col = end if tok_type in (NEWLINE, NL): self.prev_row += 1 self.prev_col = 0 self.prev_type = tok_type self.prev_line = line return "".join(self.tokens) def compat(self, token, iterable): indents = [] toks_append = self.tokens.append startline = token[0] in (NEWLINE, NL) prevstring = False in_fstring_or_tstring = 0 for tok in _itertools.chain([token], iterable): toknum, tokval = tok[:2] if toknum == ENCODING: self.encoding = tokval continue if toknum in (NAME, NUMBER): tokval += ' ' # Insert a space between two consecutive strings if toknum == STRING: if prevstring: tokval = ' ' + tokval prevstring = True else: prevstring = False if toknum in {FSTRING_START, TSTRING_START}: in_fstring_or_tstring += 1 elif toknum in {FSTRING_END, TSTRING_END}: in_fstring_or_tstring -= 1 if toknum == INDENT: indents.append(tokval) continue elif toknum == DEDENT: indents.pop() continue elif toknum in (NEWLINE, NL): startline = True elif startline and indents: toks_append(indents[-1]) startline = False elif toknum in {FSTRING_MIDDLE, TSTRING_MIDDLE}: tokval = self.escape_brackets(tokval) # Insert a space between two consecutive brackets if we are in an f-string or t-string if tokval in {"{", "}"} and self.tokens and self.tokens[-1] == tokval and in_fstring_or_tstring: tokval = ' ' + tokval # Insert a space between two consecutive f-strings if toknum in (STRING, FSTRING_START) and self.prev_type in (STRING, FSTRING_END): self.tokens.append(" ") toks_append(tokval) self.prev_type = toknum 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. The result is guaranteed to tokenize back to match the input so that the conversion is lossless and round-trips are assured. The guarantee applies only to the token type and token string as the spacing between tokens (column positions) may change. """ 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 Parser/tokenizer/helpers.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 = readline.__self__.name except AttributeError: filename = None bom_found = False encoding = None default = 'utf-8' def read_or_stop(): try: return readline() except StopIteration: return b'' def check(line, encoding): # Check if the line matches the encoding. if 0 in line: raise SyntaxError("source code cannot contain null bytes") try: line.decode(encoding) except UnicodeDecodeError: msg = "invalid or missing encoding declaration" if filename is not None: msg = '{} for {!r}'.format(msg, filename) raise SyntaxError(msg) def find_cookie(line): match = cookie_re.match(line) if not match: return None encoding = _get_normal_name(match.group(1).decode()) 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: check(first, encoding) return encoding, [first] if not blank_re.match(first): check(first, default) return default, [first] second = read_or_stop() if not second: check(first, default) return default, [first] encoding = find_cookie(second) if encoding: check(first + second, encoding) return encoding, [first, second] check(first + second, default) return default, [first, second] def open(filename): """Open a file in read only mode using the encoding detected by detect_encoding(). """ buffer = _builtin_open(filename, 'rb') try: encoding, lines = detect_encoding(buffer.readline) buffer.seek(0) text = TextIOWrapper(buffer, encoding, line_buffering=True) text.mode = 'r' return text except: buffer.close() raise def tokenize(readline): """ The tokenize() generator requires one argument, 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. Alternatively, 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 physical line. 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) rl_gen = _itertools.chain(consumed, iter(readline, b"")) 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), '') yield from _generate_tokens_from_c_tokenizer(rl_gen.__next__, encoding, extra_tokens=True) def generate_tokens(readline): """Tokenize a source reading Python code as unicode strings. This has the same API as tokenize(), except that it expects the *readline* callable to return str objects instead of bytes. """ return _generate_tokens_from_c_tokenizer(readline, extra_tokens=True) def _main(args=None): import argparse # Helper error handling routines def perror(message): sys.stderr.write(message) sys.stderr.write('\n') 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(color=True) parser.add_argument(dest='filename', nargs='?', metavar='filename.py', 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(args) try: # Tokenize the input if args.filename: filename = args.filename with _builtin_open(filename, 'rb') as f: tokens = list(tokenize(f.readline)) else: filename = "<stdin>" tokens = _generate_tokens_from_c_tokenizer( sys.stdin.readline, extra_tokens=True) # 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 def _transform_msg(msg): """Transform error messages from the C tokenizer into the Python tokenize The C tokenizer is more picky than the Python one, so we need to massage the error messages a bit for backwards compatibility. """ if "unterminated triple-quoted string literal" in msg: return "EOF in multi-line string" return msg def _generate_tokens_from_c_tokenizer(source, encoding=None, extra_tokens=False): """Tokenize a source reading Python code as unicode strings using the internal C tokenizer""" if encoding is None: it = _tokenize.TokenizerIter(source, extra_tokens=extra_tokens) else: it = _tokenize.TokenizerIter(source, encoding=encoding, extra_tokens=extra_tokens) try: for info in it: yield TokenInfo._make(info) except SyntaxError as e: if type(e) != SyntaxError: raise e from None msg = _transform_msg(e.msg) raise TokenError(msg, (e.lineno, e.offset)) from None if __name__ == "__main__": _main()