• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1"""A collection of string operations (most are no longer used).
2
3Warning: most of the code you see here isn't normally used nowadays.
4Beginning with Python 1.6, many of these functions are implemented as
5methods on the standard string object. They used to be implemented by
6a built-in module called strop, but strop is now obsolete itself.
7
8Public module variables:
9
10whitespace -- a string containing all characters considered whitespace
11lowercase -- a string containing all characters considered lowercase letters
12uppercase -- a string containing all characters considered uppercase letters
13letters -- a string containing all characters considered letters
14digits -- a string containing all characters considered decimal digits
15hexdigits -- a string containing all characters considered hexadecimal digits
16octdigits -- a string containing all characters considered octal digits
17punctuation -- a string containing all characters considered punctuation
18printable -- a string containing all characters considered printable
19
20"""
21
22# Some strings for ctype-style character classification
23whitespace = ' \t\n\r\v\f'
24lowercase = 'abcdefghijklmnopqrstuvwxyz'
25uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
26letters = lowercase + uppercase
27ascii_lowercase = lowercase
28ascii_uppercase = uppercase
29ascii_letters = ascii_lowercase + ascii_uppercase
30digits = '0123456789'
31hexdigits = digits + 'abcdef' + 'ABCDEF'
32octdigits = '01234567'
33punctuation = """!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~"""
34printable = digits + letters + punctuation + whitespace
35
36# Case conversion helpers
37# Use str to convert Unicode literal in case of -U
38l = map(chr, xrange(256))
39_idmap = str('').join(l)
40del l
41
42# Functions which aren't available as string methods.
43
44# Capitalize the words in a string, e.g. " aBc  dEf " -> "Abc Def".
45def capwords(s, sep=None):
46    """capwords(s [,sep]) -> string
47
48    Split the argument into words using split, capitalize each
49    word using capitalize, and join the capitalized words using
50    join.  If the optional second argument sep is absent or None,
51    runs of whitespace characters are replaced by a single space
52    and leading and trailing whitespace are removed, otherwise
53    sep is used to split and join the words.
54
55    """
56    return (sep or ' ').join(x.capitalize() for x in s.split(sep))
57
58
59# Construct a translation string
60_idmapL = None
61def maketrans(fromstr, tostr):
62    """maketrans(frm, to) -> string
63
64    Return a translation table (a string of 256 bytes long)
65    suitable for use in string.translate.  The strings frm and to
66    must be of the same length.
67
68    """
69    if len(fromstr) != len(tostr):
70        raise ValueError, "maketrans arguments must have same length"
71    global _idmapL
72    if not _idmapL:
73        _idmapL = list(_idmap)
74    L = _idmapL[:]
75    fromstr = map(ord, fromstr)
76    for i in range(len(fromstr)):
77        L[fromstr[i]] = tostr[i]
78    return ''.join(L)
79
80
81
82####################################################################
83import re as _re
84
85class _multimap:
86    """Helper class for combining multiple mappings.
87
88    Used by .{safe_,}substitute() to combine the mapping and keyword
89    arguments.
90    """
91    def __init__(self, primary, secondary):
92        self._primary = primary
93        self._secondary = secondary
94
95    def __getitem__(self, key):
96        try:
97            return self._primary[key]
98        except KeyError:
99            return self._secondary[key]
100
101
102class _TemplateMetaclass(type):
103    pattern = r"""
104    %(delim)s(?:
105      (?P<escaped>%(delim)s) |   # Escape sequence of two delimiters
106      (?P<named>%(id)s)      |   # delimiter and a Python identifier
107      {(?P<braced>%(id)s)}   |   # delimiter and a braced identifier
108      (?P<invalid>)              # Other ill-formed delimiter exprs
109    )
110    """
111
112    def __init__(cls, name, bases, dct):
113        super(_TemplateMetaclass, cls).__init__(name, bases, dct)
114        if 'pattern' in dct:
115            pattern = cls.pattern
116        else:
117            pattern = _TemplateMetaclass.pattern % {
118                'delim' : _re.escape(cls.delimiter),
119                'id'    : cls.idpattern,
120                }
121        cls.pattern = _re.compile(pattern, _re.IGNORECASE | _re.VERBOSE)
122
123
124class Template:
125    """A string class for supporting $-substitutions."""
126    __metaclass__ = _TemplateMetaclass
127
128    delimiter = '$'
129    idpattern = r'[_a-z][_a-z0-9]*'
130
131    def __init__(self, template):
132        self.template = template
133
134    # Search for $$, $identifier, ${identifier}, and any bare $'s
135
136    def _invalid(self, mo):
137        i = mo.start('invalid')
138        lines = self.template[:i].splitlines(True)
139        if not lines:
140            colno = 1
141            lineno = 1
142        else:
143            colno = i - len(''.join(lines[:-1]))
144            lineno = len(lines)
145        raise ValueError('Invalid placeholder in string: line %d, col %d' %
146                         (lineno, colno))
147
148    def substitute(*args, **kws):
149        if not args:
150            raise TypeError("descriptor 'substitute' of 'Template' object "
151                            "needs an argument")
152        self, args = args[0], args[1:]  # allow the "self" keyword be passed
153        if len(args) > 1:
154            raise TypeError('Too many positional arguments')
155        if not args:
156            mapping = kws
157        elif kws:
158            mapping = _multimap(kws, args[0])
159        else:
160            mapping = args[0]
161        # Helper function for .sub()
162        def convert(mo):
163            # Check the most common path first.
164            named = mo.group('named') or mo.group('braced')
165            if named is not None:
166                val = mapping[named]
167                # We use this idiom instead of str() because the latter will
168                # fail if val is a Unicode containing non-ASCII characters.
169                return '%s' % (val,)
170            if mo.group('escaped') is not None:
171                return self.delimiter
172            if mo.group('invalid') is not None:
173                self._invalid(mo)
174            raise ValueError('Unrecognized named group in pattern',
175                             self.pattern)
176        return self.pattern.sub(convert, self.template)
177
178    def safe_substitute(*args, **kws):
179        if not args:
180            raise TypeError("descriptor 'safe_substitute' of 'Template' object "
181                            "needs an argument")
182        self, args = args[0], args[1:]  # allow the "self" keyword be passed
183        if len(args) > 1:
184            raise TypeError('Too many positional arguments')
185        if not args:
186            mapping = kws
187        elif kws:
188            mapping = _multimap(kws, args[0])
189        else:
190            mapping = args[0]
191        # Helper function for .sub()
192        def convert(mo):
193            named = mo.group('named') or mo.group('braced')
194            if named is not None:
195                try:
196                    # We use this idiom instead of str() because the latter
197                    # will fail if val is a Unicode containing non-ASCII
198                    return '%s' % (mapping[named],)
199                except KeyError:
200                    return mo.group()
201            if mo.group('escaped') is not None:
202                return self.delimiter
203            if mo.group('invalid') is not None:
204                return mo.group()
205            raise ValueError('Unrecognized named group in pattern',
206                             self.pattern)
207        return self.pattern.sub(convert, self.template)
208
209
210
211####################################################################
212# NOTE: Everything below here is deprecated.  Use string methods instead.
213# This stuff will go away in Python 3.0.
214
215# Backward compatible names for exceptions
216index_error = ValueError
217atoi_error = ValueError
218atof_error = ValueError
219atol_error = ValueError
220
221# convert UPPER CASE letters to lower case
222def lower(s):
223    """lower(s) -> string
224
225    Return a copy of the string s converted to lowercase.
226
227    """
228    return s.lower()
229
230# Convert lower case letters to UPPER CASE
231def upper(s):
232    """upper(s) -> string
233
234    Return a copy of the string s converted to uppercase.
235
236    """
237    return s.upper()
238
239# Swap lower case letters and UPPER CASE
240def swapcase(s):
241    """swapcase(s) -> string
242
243    Return a copy of the string s with upper case characters
244    converted to lowercase and vice versa.
245
246    """
247    return s.swapcase()
248
249# Strip leading and trailing tabs and spaces
250def strip(s, chars=None):
251    """strip(s [,chars]) -> string
252
253    Return a copy of the string s with leading and trailing
254    whitespace removed.
255    If chars is given and not None, remove characters in chars instead.
256    If chars is unicode, S will be converted to unicode before stripping.
257
258    """
259    return s.strip(chars)
260
261# Strip leading tabs and spaces
262def lstrip(s, chars=None):
263    """lstrip(s [,chars]) -> string
264
265    Return a copy of the string s with leading whitespace removed.
266    If chars is given and not None, remove characters in chars instead.
267
268    """
269    return s.lstrip(chars)
270
271# Strip trailing tabs and spaces
272def rstrip(s, chars=None):
273    """rstrip(s [,chars]) -> string
274
275    Return a copy of the string s with trailing whitespace removed.
276    If chars is given and not None, remove characters in chars instead.
277
278    """
279    return s.rstrip(chars)
280
281
282# Split a string into a list of space/tab-separated words
283def split(s, sep=None, maxsplit=-1):
284    """split(s [,sep [,maxsplit]]) -> list of strings
285
286    Return a list of the words in the string s, using sep as the
287    delimiter string.  If maxsplit is given, splits at no more than
288    maxsplit places (resulting in at most maxsplit+1 words).  If sep
289    is not specified or is None, any whitespace string is a separator.
290
291    (split and splitfields are synonymous)
292
293    """
294    return s.split(sep, maxsplit)
295splitfields = split
296
297# Split a string into a list of space/tab-separated words
298def rsplit(s, sep=None, maxsplit=-1):
299    """rsplit(s [,sep [,maxsplit]]) -> list of strings
300
301    Return a list of the words in the string s, using sep as the
302    delimiter string, starting at the end of the string and working
303    to the front.  If maxsplit is given, at most maxsplit splits are
304    done. If sep is not specified or is None, any whitespace string
305    is a separator.
306    """
307    return s.rsplit(sep, maxsplit)
308
309# Join fields with optional separator
310def join(words, sep = ' '):
311    """join(list [,sep]) -> string
312
313    Return a string composed of the words in list, with
314    intervening occurrences of sep.  The default separator is a
315    single space.
316
317    (joinfields and join are synonymous)
318
319    """
320    return sep.join(words)
321joinfields = join
322
323# Find substring, raise exception if not found
324def index(s, *args):
325    """index(s, sub [,start [,end]]) -> int
326
327    Like find but raises ValueError when the substring is not found.
328
329    """
330    return s.index(*args)
331
332# Find last substring, raise exception if not found
333def rindex(s, *args):
334    """rindex(s, sub [,start [,end]]) -> int
335
336    Like rfind but raises ValueError when the substring is not found.
337
338    """
339    return s.rindex(*args)
340
341# Count non-overlapping occurrences of substring
342def count(s, *args):
343    """count(s, sub[, start[,end]]) -> int
344
345    Return the number of occurrences of substring sub in string
346    s[start:end].  Optional arguments start and end are
347    interpreted as in slice notation.
348
349    """
350    return s.count(*args)
351
352# Find substring, return -1 if not found
353def find(s, *args):
354    """find(s, sub [,start [,end]]) -> in
355
356    Return the lowest index in s where substring sub is found,
357    such that sub is contained within s[start,end].  Optional
358    arguments start and end are interpreted as in slice notation.
359
360    Return -1 on failure.
361
362    """
363    return s.find(*args)
364
365# Find last substring, return -1 if not found
366def rfind(s, *args):
367    """rfind(s, sub [,start [,end]]) -> int
368
369    Return the highest index in s where substring sub is found,
370    such that sub is contained within s[start,end].  Optional
371    arguments start and end are interpreted as in slice notation.
372
373    Return -1 on failure.
374
375    """
376    return s.rfind(*args)
377
378# for a bit of speed
379_float = float
380_int = int
381_long = long
382
383# Convert string to float
384def atof(s):
385    """atof(s) -> float
386
387    Return the floating point number represented by the string s.
388
389    """
390    return _float(s)
391
392
393# Convert string to integer
394def atoi(s , base=10):
395    """atoi(s [,base]) -> int
396
397    Return the integer represented by the string s in the given
398    base, which defaults to 10.  The string s must consist of one
399    or more digits, possibly preceded by a sign.  If base is 0, it
400    is chosen from the leading characters of s, 0 for octal, 0x or
401    0X for hexadecimal.  If base is 16, a preceding 0x or 0X is
402    accepted.
403
404    """
405    return _int(s, base)
406
407
408# Convert string to long integer
409def atol(s, base=10):
410    """atol(s [,base]) -> long
411
412    Return the long integer represented by the string s in the
413    given base, which defaults to 10.  The string s must consist
414    of one or more digits, possibly preceded by a sign.  If base
415    is 0, it is chosen from the leading characters of s, 0 for
416    octal, 0x or 0X for hexadecimal.  If base is 16, a preceding
417    0x or 0X is accepted.  A trailing L or l is not accepted,
418    unless base is 0.
419
420    """
421    return _long(s, base)
422
423
424# Left-justify a string
425def ljust(s, width, *args):
426    """ljust(s, width[, fillchar]) -> string
427
428    Return a left-justified version of s, in a field of the
429    specified width, padded with spaces as needed.  The string is
430    never truncated.  If specified the fillchar is used instead of spaces.
431
432    """
433    return s.ljust(width, *args)
434
435# Right-justify a string
436def rjust(s, width, *args):
437    """rjust(s, width[, fillchar]) -> string
438
439    Return a right-justified version of s, in a field of the
440    specified width, padded with spaces as needed.  The string is
441    never truncated.  If specified the fillchar is used instead of spaces.
442
443    """
444    return s.rjust(width, *args)
445
446# Center a string
447def center(s, width, *args):
448    """center(s, width[, fillchar]) -> string
449
450    Return a center version of s, in a field of the specified
451    width. padded with spaces as needed.  The string is never
452    truncated.  If specified the fillchar is used instead of spaces.
453
454    """
455    return s.center(width, *args)
456
457# Zero-fill a number, e.g., (12, 3) --> '012' and (-3, 3) --> '-03'
458# Decadent feature: the argument may be a string or a number
459# (Use of this is deprecated; it should be a string as with ljust c.s.)
460def zfill(x, width):
461    """zfill(x, width) -> string
462
463    Pad a numeric string x with zeros on the left, to fill a field
464    of the specified width.  The string x is never truncated.
465
466    """
467    if not isinstance(x, basestring):
468        x = repr(x)
469    return x.zfill(width)
470
471# Expand tabs in a string.
472# Doesn't take non-printing chars into account, but does understand \n.
473def expandtabs(s, tabsize=8):
474    """expandtabs(s [,tabsize]) -> string
475
476    Return a copy of the string s with all tab characters replaced
477    by the appropriate number of spaces, depending on the current
478    column, and the tabsize (default 8).
479
480    """
481    return s.expandtabs(tabsize)
482
483# Character translation through look-up table.
484def translate(s, table, deletions=""):
485    """translate(s,table [,deletions]) -> string
486
487    Return a copy of the string s, where all characters occurring
488    in the optional argument deletions are removed, and the
489    remaining characters have been mapped through the given
490    translation table, which must be a string of length 256.  The
491    deletions argument is not allowed for Unicode strings.
492
493    """
494    if deletions or table is None:
495        return s.translate(table, deletions)
496    else:
497        # Add s[:0] so that if s is Unicode and table is an 8-bit string,
498        # table is converted to Unicode.  This means that table *cannot*
499        # be a dictionary -- for that feature, use u.translate() directly.
500        return s.translate(table + s[:0])
501
502# Capitalize a string, e.g. "aBc  dEf" -> "Abc  def".
503def capitalize(s):
504    """capitalize(s) -> string
505
506    Return a copy of the string s with only its first character
507    capitalized.
508
509    """
510    return s.capitalize()
511
512# Substring replacement (global)
513def replace(s, old, new, maxreplace=-1):
514    """replace (str, old, new[, maxreplace]) -> string
515
516    Return a copy of string str with all occurrences of substring
517    old replaced by new. If the optional argument maxreplace is
518    given, only the first maxreplace occurrences are replaced.
519
520    """
521    return s.replace(old, new, maxreplace)
522
523
524# Try importing optional built-in module "strop" -- if it exists,
525# it redefines some string operations that are 100-1000 times faster.
526# It also defines values for whitespace, lowercase and uppercase
527# that match <ctype.h>'s definitions.
528
529try:
530    from strop import maketrans, lowercase, uppercase, whitespace
531    letters = lowercase + uppercase
532except ImportError:
533    pass                                          # Use the original versions
534
535########################################################################
536# the Formatter class
537# see PEP 3101 for details and purpose of this class
538
539# The hard parts are reused from the C implementation.  They're exposed as "_"
540# prefixed methods of str and unicode.
541
542# The overall parser is implemented in str._formatter_parser.
543# The field name parser is implemented in str._formatter_field_name_split
544
545class Formatter(object):
546    def format(*args, **kwargs):
547        if not args:
548            raise TypeError("descriptor 'format' of 'Formatter' object "
549                            "needs an argument")
550        self, args = args[0], args[1:]  # allow the "self" keyword be passed
551        try:
552            format_string, args = args[0], args[1:] # allow the "format_string" keyword be passed
553        except IndexError:
554            if 'format_string' in kwargs:
555                format_string = kwargs.pop('format_string')
556            else:
557                raise TypeError("format() missing 1 required positional "
558                                "argument: 'format_string'")
559        return self.vformat(format_string, args, kwargs)
560
561    def vformat(self, format_string, args, kwargs):
562        used_args = set()
563        result = self._vformat(format_string, args, kwargs, used_args, 2)
564        self.check_unused_args(used_args, args, kwargs)
565        return result
566
567    def _vformat(self, format_string, args, kwargs, used_args, recursion_depth):
568        if recursion_depth < 0:
569            raise ValueError('Max string recursion exceeded')
570        result = []
571        for literal_text, field_name, format_spec, conversion in \
572                self.parse(format_string):
573
574            # output the literal text
575            if literal_text:
576                result.append(literal_text)
577
578            # if there's a field, output it
579            if field_name is not None:
580                # this is some markup, find the object and do
581                #  the formatting
582
583                # given the field_name, find the object it references
584                #  and the argument it came from
585                obj, arg_used = self.get_field(field_name, args, kwargs)
586                used_args.add(arg_used)
587
588                # do any conversion on the resulting object
589                obj = self.convert_field(obj, conversion)
590
591                # expand the format spec, if needed
592                format_spec = self._vformat(format_spec, args, kwargs,
593                                            used_args, recursion_depth-1)
594
595                # format the object and append to the result
596                result.append(self.format_field(obj, format_spec))
597
598        return ''.join(result)
599
600
601    def get_value(self, key, args, kwargs):
602        if isinstance(key, (int, long)):
603            return args[key]
604        else:
605            return kwargs[key]
606
607
608    def check_unused_args(self, used_args, args, kwargs):
609        pass
610
611
612    def format_field(self, value, format_spec):
613        return format(value, format_spec)
614
615
616    def convert_field(self, value, conversion):
617        # do any conversion on the resulting object
618        if conversion is None:
619            return value
620        elif conversion == 's':
621            return str(value)
622        elif conversion == 'r':
623            return repr(value)
624        raise ValueError("Unknown conversion specifier {0!s}".format(conversion))
625
626
627    # returns an iterable that contains tuples of the form:
628    # (literal_text, field_name, format_spec, conversion)
629    # literal_text can be zero length
630    # field_name can be None, in which case there's no
631    #  object to format and output
632    # if field_name is not None, it is looked up, formatted
633    #  with format_spec and conversion and then used
634    def parse(self, format_string):
635        return format_string._formatter_parser()
636
637
638    # given a field_name, find the object it references.
639    #  field_name:   the field being looked up, e.g. "0.name"
640    #                 or "lookup[3]"
641    #  used_args:    a set of which args have been used
642    #  args, kwargs: as passed in to vformat
643    def get_field(self, field_name, args, kwargs):
644        first, rest = field_name._formatter_field_name_split()
645
646        obj = self.get_value(first, args, kwargs)
647
648        # loop through the rest of the field_name, doing
649        #  getattr or getitem as needed
650        for is_attr, i in rest:
651            if is_attr:
652                obj = getattr(obj, i)
653            else:
654                obj = obj[i]
655
656        return obj, first
657