cpython/Lib/tokenize.py

"""Tokenization help for Python programs.

This module exports a function called 'tokenize()' 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) and a "token-eater"
function which is called once for each token found.  The latter function is
passed the token type, a string containing the token, the starting and
ending (row, column) coordinates of the token, and the original line.  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."""

__author__ = 'Ka-Ping Yee <ping@lfw.org>'
__credits__ = \
    'GvR, ESR, Tim Peters, Thomas Wouters, Fred Drake, Skip Montanaro'

import string, re
from token import *

import token
__all__ = [x for x in dir(token) if x[0] != '_'] + ["COMMENT", "tokenize", "NL"]
del token

COMMENT = N_TOKENS
tok_name[COMMENT] = 'COMMENT'
NL = N_TOKENS + 1
tok_name[NL] = 'NL'
N_TOKENS += 2

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

Whitespace = r'[ \f\t]*'
Comment = r'#[^\r\n]*'
Ignore = Whitespace + any(r'\\\r?\n' + Whitespace) + maybe(Comment)
Name = r'[a-zA-Z_]\w*'

Hexnumber = r'0[xX][\da-fA-F]*[lL]?'
Octnumber = r'0[0-7]*[lL]?'
Decnumber = r'[1-9]\d*[lL]?'
Intnumber = group(Hexnumber, Octnumber, Decnumber)
Exponent = r'[eE][-+]?\d+'
Pointfloat = group(r'\d+\.\d*', r'\.\d+') + maybe(Exponent)
Expfloat = r'[1-9]\d*' + Exponent
Floatnumber = group(Pointfloat, Expfloat)
Imagnumber = group(r'0[jJ]', r'[1-9]\d*[jJ]', Floatnumber + r'[jJ]')
Number = group(Imagnumber, Floatnumber, Intnumber)

# 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("[uU]?[rR]?'''", '[uU]?[rR]?"""')
# Single-line ' or " string.
String = group(r"[uU]?[rR]?'[^\n'\\]*(?:\\.[^\n'\\]*)*'",
               r'[uU]?[rR]?"[^\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"[+\-*/%&|^=<>]=?",
                 r"~")

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

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

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

tokenprog, pseudoprog, single3prog, double3prog = map(
    re.compile, (Token, PseudoToken, Single3, Double3))
endprogs = {"'": re.compile(Single), '"': re.compile(Double),
            "'''": single3prog, '"""': double3prog,
            "r'''": single3prog, 'r"""': double3prog,
            "u'''": single3prog, 'u"""': double3prog,
            "ur'''": single3prog, 'ur"""': double3prog,
            "R'''": single3prog, 'R"""': double3prog,
            "U'''": single3prog, 'U"""': double3prog,
            "uR'''": single3prog, 'uR"""': double3prog,
            "Ur'''": single3prog, 'Ur"""': double3prog,
            "UR'''": single3prog, 'UR"""': double3prog,
            'r': None, 'R': None, 'u': None, 'U': None}

tabsize = 8

class TokenError(Exception): pass

class StopTokenizing(Exception): pass

def printtoken(type, token, (srow, scol), (erow, ecol), line): # for testing
    print "%d,%d-%d,%d:\t%s\t%s" % \
        (srow, scol, erow, ecol, tok_name[type], repr(token))

def tokenize(readline, tokeneater=printtoken):
    try:
        tokenize_loop(readline, tokeneater)
    except StopTokenizing:
        pass

# backwards compatible interface, probably not used
def tokenize_loop(readline, tokeneater):
    for token_info in generate_tokens(readline):
        apply(tokeneater, token_info)

def generate_tokens(readline):
    lnum = parenlev = continued = 0
    namechars, numchars = string.letters + '_', string.digits
    contstr, needcont = '', 0
    contline = None
    indents = [0]

    while 1:                                   # loop over lines in stream
        line = readline()
        lnum = 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 (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 (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 = column + 1
                elif line[pos] == '\t': column = (column/tabsize + 1)*tabsize
                elif line[pos] == '\f': column = 0
                else: break
                pos = pos + 1
            if pos == max: break

            if line[pos] in '#\r\n':           # skip comments or blank lines
                yield ((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 (INDENT, line[:pos], (lnum, 0), (lnum, pos), line)
            while column < indents[-1]:
                indents = indents[:-1]
                yield (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 = pseudoprog.match(line, pos)
            if pseudomatch:                                # scan for tokens
                start, end = pseudomatch.span(1)
                spos, epos, pos = (lnum, start), (lnum, end), end
                token, initial = line[start:end], line[start]

                if initial in numchars or \
                   (initial == '.' and token != '.'):      # ordinary number
                    yield (NUMBER, token, spos, epos, line)
                elif initial in '\r\n':
                    yield (parenlev > 0 and NL or NEWLINE,
                               token, spos, epos, line)
                elif initial == '#':
                    yield (COMMENT, token, spos, epos, line)
                elif token in ("'''", '"""',               # triple-quoted
                               "r'''", 'r"""', "R'''", 'R"""',
                               "u'''", 'u"""', "U'''", 'U"""',
                               "ur'''", 'ur"""', "Ur'''", 'Ur"""',
                               "uR'''", 'uR"""', "UR'''", 'UR"""'):
                    endprog = endprogs[token]
                    endmatch = endprog.match(line, pos)
                    if endmatch:                           # all on one line
                        pos = endmatch.end(0)
                        token = line[start:pos]
                        yield (STRING, token, spos, (lnum, pos), line)
                    else:
                        strstart = (lnum, start)           # multiple lines
                        contstr = line[start:]
                        contline = line
                        break
                elif initial in ("'", '"') or \
                    token[:2] in ("r'", 'r"', "R'", 'R"',
                                  "u'", 'u"', "U'", 'U"') or \
                    token[:3] in ("ur'", 'ur"', "Ur'", 'Ur"',
                                  "uR'", 'uR"', "UR'", 'UR"' ):
                    if token[-1] == '\n':                  # continued string
                        strstart = (lnum, start)
                        endprog = (endprogs[initial] or endprogs[token[1]] or
                                   endprogs[token[2]])
                        contstr, needcont = line[start:], 1
                        contline = line
                        break
                    else:                                  # ordinary string
                        yield (STRING, token, spos, epos, line)
                elif initial in namechars:                 # ordinary name
                    yield (NAME, token, spos, epos, line)
                elif initial == '\\':                      # continued stmt
                    continued = 1
                else:
                    if initial in '([{': parenlev = parenlev + 1
                    elif initial in ')]}': parenlev = parenlev - 1
                    yield (OP, token, spos, epos, line)
            else:
                yield (ERRORTOKEN, line[pos],
                           (lnum, pos), (lnum, pos+1), line)
                pos = pos + 1

    for indent in indents[1:]:                 # pop remaining indent levels
        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)