summaryrefslogtreecommitdiffstats
path: root/Lib/string.py
blob: 021469c78c7bb97bc5de712752e2cf105febbe33 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
"""A collection of string operations (most are no longer used in Python 1.6).

Warning: most of the code you see here isn't normally used nowadays.  With
Python 1.6, many of these functions are implemented as methods on the
standard string object. They used to be implemented by a built-in module
called strop, but strop is now obsolete itself.

Public module variables:

whitespace -- a string containing all characters considered whitespace
lowercase -- a string containing all characters considered lowercase letters
uppercase -- a string containing all characters considered uppercase letters
letters -- a string containing all characters considered letters
digits -- a string containing all characters considered decimal digits
hexdigits -- a string containing all characters considered hexadecimal digits
octdigits -- a string containing all characters considered octal digits
punctuation -- a string containing all characters considered punctuation
printable -- a string containing all characters considered printable

"""

# Some strings for ctype-style character classification
whitespace = ' \t\n\r\v\f'
lowercase = 'abcdefghijklmnopqrstuvwxyz'
uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
letters = lowercase + uppercase
ascii_lowercase = lowercase
ascii_uppercase = uppercase
ascii_letters = ascii_lowercase + ascii_uppercase
digits = '0123456789'
hexdigits = digits + 'abcdef' + 'ABCDEF'
octdigits = '01234567'
punctuation = """!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~"""
printable = digits + letters + punctuation + whitespace

# Case conversion helpers
# Use str to convert Unicode literal in case of -U
l = map(chr, xrange(256))
_idmap = str('').join(l)
del l

# Backward compatible names for exceptions
index_error = ValueError
atoi_error = ValueError
atof_error = ValueError
atol_error = ValueError

# convert UPPER CASE letters to lower case
def lower(s):
    """lower(s) -> string

    Return a copy of the string s converted to lowercase.

    """
    return s.lower()

# Convert lower case letters to UPPER CASE
def upper(s):
    """upper(s) -> string

    Return a copy of the string s converted to uppercase.

    """
    return s.upper()

# Swap lower case letters and UPPER CASE
def swapcase(s):
    """swapcase(s) -> string

    Return a copy of the string s with upper case characters
    converted to lowercase and vice versa.

    """
    return s.swapcase()

# Strip leading and trailing tabs and spaces
def strip(s, chars=None):
    """strip(s [,chars]) -> string

    Return a copy of the string s with leading and trailing
    whitespace removed.
    If chars is given and not None, remove characters in sep instead.
    If chars is unicode, S will be converted to unicode before stripping.

    """
    return s.strip(chars)

# Strip leading tabs and spaces
def lstrip(s):
    """lstrip(s) -> string

    Return a copy of the string s with leading whitespace removed.

    """
    return s.lstrip()

# Strip trailing tabs and spaces
def rstrip(s):
    """rstrip(s) -> string

    Return a copy of the string s with trailing whitespace
    removed.

    """
    return s.rstrip()


# Split a string into a list of space/tab-separated words
def split(s, sep=None, maxsplit=-1):
    """split(s [,sep [,maxsplit]]) -> list of strings

    Return a list of the words in the string s, using sep as the
    delimiter string.  If maxsplit is given, splits at no more than
    maxsplit places (resulting in at most maxsplit+1 words).  If sep
    is not specified, any whitespace string is a separator.

    (split and splitfields are synonymous)

    """
    return s.split(sep, maxsplit)
splitfields = split

# Join fields with optional separator
def join(words, sep = ' '):
    """join(list [,sep]) -> string

    Return a string composed of the words in list, with
    intervening occurrences of sep.  The default separator is a
    single space.

    (joinfields and join are synonymous)

    """
    return sep.join(words)
joinfields = join

# Find substring, raise exception if not found
def index(s, *args):
    """index(s, sub [,start [,end]]) -> int

    Like find but raises ValueError when the substring is not found.

    """
    return s.index(*args)

# Find last substring, raise exception if not found
def rindex(s, *args):
    """rindex(s, sub [,start [,end]]) -> int

    Like rfind but raises ValueError when the substring is not found.

    """
    return s.rindex(*args)

# Count non-overlapping occurrences of substring
def count(s, *args):
    """count(s, sub[, start[,end]]) -> int

    Return the number of occurrences of substring sub in string
    s[start:end].  Optional arguments start and end are
    interpreted as in slice notation.

    """
    return s.count(*args)

# Find substring, return -1 if not found
def find(s, *args):
    """find(s, sub [,start [,end]]) -> in

    Return the lowest index in s where substring sub is found,
    such that sub is contained within s[start,end].  Optional
    arguments start and end are interpreted as in slice notation.

    Return -1 on failure.

    """
    return s.find(*args)

# Find last substring, return -1 if not found
def rfind(s, *args):
    """rfind(s, sub [,start [,end]]) -> int

    Return the highest index in s where substring sub is found,
    such that sub is contained within s[start,end].  Optional
    arguments start and end are interpreted as in slice notation.

    Return -1 on failure.

    """
    return s.rfind(*args)

# for a bit of speed
_float = float
_int = int
_long = long

# Convert string to float
def atof(s):
    """atof(s) -> float

    Return the floating point number represented by the string s.

    """
    return _float(s)


# Convert string to integer
def atoi(s , base=10):
    """atoi(s [,base]) -> int

    Return the integer represented by the string s in the given
    base, which defaults to 10.  The string s must consist of one
    or more digits, possibly preceded by a sign.  If base is 0, it
    is chosen from the leading characters of s, 0 for octal, 0x or
    0X for hexadecimal.  If base is 16, a preceding 0x or 0X is
    accepted.

    """
    return _int(s, base)


# Convert string to long integer
def atol(s, base=10):
    """atol(s [,base]) -> long

    Return the long integer represented by the string s in the
    given base, which defaults to 10.  The string s must consist
    of one or more digits, possibly preceded by a sign.  If base
    is 0, it is chosen from the leading characters of s, 0 for
    octal, 0x or 0X for hexadecimal.  If base is 16, a preceding
    0x or 0X is accepted.  A trailing L or l is not accepted,
    unless base is 0.

    """
    return _long(s, base)


# Left-justify a string
def ljust(s, width):
    """ljust(s, width) -> string

    Return a left-justified version of s, in a field of the
    specified width, padded with spaces as needed.  The string is
    never truncated.

    """
    return s.ljust(width)

# Right-justify a string
def rjust(s, width):
    """rjust(s, width) -> string

    Return a right-justified version of s, in a field of the
    specified width, padded with spaces as needed.  The string is
    never truncated.

    """
    return s.rjust(width)

# Center a string
def center(s, width):
    """center(s, width) -> string

    Return a center version of s, in a field of the specified
    width. padded with spaces as needed.  The string is never
    truncated.

    """
    return s.center(width)

# Zero-fill a number, e.g., (12, 3) --> '012' and (-3, 3) --> '-03'
# Decadent feature: the argument may be a string or a number
# (Use of this is deprecated; it should be a string as with ljust c.s.)
def zfill(x, width):
    """zfill(x, width) -> string

    Pad a numeric string x with zeros on the left, to fill a field
    of the specified width.  The string x is never truncated.

    """
    if not isinstance(x, basestring):
        x = repr(x)
    return x.zfill(width)

# Expand tabs in a string.
# Doesn't take non-printing chars into account, but does understand \n.
def expandtabs(s, tabsize=8):
    """expandtabs(s [,tabsize]) -> string

    Return a copy of the string s with all tab characters replaced
    by the appropriate number of spaces, depending on the current
    column, and the tabsize (default 8).

    """
    return s.expandtabs(tabsize)

# Character translation through look-up table.
def translate(s, table, deletions=""):
    """translate(s,table [,deletions]) -> string

    Return a copy of the string s, where all characters occurring
    in the optional argument deletions are removed, and the
    remaining characters have been mapped through the given
    translation table, which must be a string of length 256.  The
    deletions argument is not allowed for Unicode strings.

    """
    if deletions:
        return s.translate(table, deletions)
    else:
        # Add s[:0] so that if s is Unicode and table is an 8-bit string,
        # table is converted to Unicode.  This means that table *cannot*
        # be a dictionary -- for that feature, use u.translate() directly.
        return s.translate(table + s[:0])

# Capitalize a string, e.g. "aBc  dEf" -> "Abc  def".
def capitalize(s):
    """capitalize(s) -> string

    Return a copy of the string s with only its first character
    capitalized.

    """
    return s.capitalize()

# Capitalize the words in a string, e.g. " aBc  dEf " -> "Abc Def".
# See also regsub.capwords().
def capwords(s, sep=None):
    """capwords(s, [sep]) -> string

    Split the argument into words using split, capitalize each
    word using capitalize, and join the capitalized words using
    join. Note that this replaces runs of whitespace characters by
    a single space.

    """
    return join(map(capitalize, s.split(sep)), sep or ' ')

# Construct a translation string
_idmapL = None
def maketrans(fromstr, tostr):
    """maketrans(frm, to) -> string

    Return a translation table (a string of 256 bytes long)
    suitable for use in string.translate.  The strings frm and to
    must be of the same length.

    """
    if len(fromstr) != len(tostr):
        raise ValueError, "maketrans arguments must have same length"
    global _idmapL
    if not _idmapL:
        _idmapL = map(None, _idmap)
    L = _idmapL[:]
    fromstr = map(ord, fromstr)
    for i in range(len(fromstr)):
        L[fromstr[i]] = tostr[i]
    return join(L, "")

# Substring replacement (global)
def replace(s, old, new, maxsplit=-1):
    """replace (str, old, new[, maxsplit]) -> string

    Return a copy of string str with all occurrences of substring
    old replaced by new. If the optional argument maxsplit is
    given, only the first maxsplit occurrences are replaced.

    """
    return s.replace(old, new, maxsplit)


# Try importing optional built-in module "strop" -- if it exists,
# it redefines some string operations that are 100-1000 times faster.
# It also defines values for whitespace, lowercase and uppercase
# that match <ctype.h>'s definitions.

try:
    from strop import maketrans, lowercase, uppercase, whitespace
    letters = lowercase + uppercase
except ImportError:
    pass                                          # Use the original versions