source file: /System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/string.py
file stats: 94 lines, 7 executed: 7.4% covered
   1. """A collection of string operations (most are no longer used in Python 1.6).
   2. 
   3. Warning: most of the code you see here isn't normally used nowadays.  With
   4. Python 1.6, many of these functions are implemented as methods on the
   5. standard string object. They used to be implemented by a built-in module
   6. called strop, but strop is now obsolete itself.
   7. 
   8. Public module variables:
   9. 
  10. whitespace -- a string containing all characters considered whitespace
  11. lowercase -- a string containing all characters considered lowercase letters
  12. uppercase -- a string containing all characters considered uppercase letters
  13. letters -- a string containing all characters considered letters
  14. digits -- a string containing all characters considered decimal digits
  15. hexdigits -- a string containing all characters considered hexadecimal digits
  16. octdigits -- a string containing all characters considered octal digits
  17. punctuation -- a string containing all characters considered punctuation
  18. printable -- a string containing all characters considered printable
  19. 
  20. """
  21. 
  22. # Some strings for ctype-style character classification
  23. whitespace = ' \t\n\r\v\f'
  24. lowercase = 'abcdefghijklmnopqrstuvwxyz'
  25. uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  26. letters = lowercase + uppercase
  27. ascii_lowercase = lowercase
  28. ascii_uppercase = uppercase
  29. ascii_letters = ascii_lowercase + ascii_uppercase
  30. digits = '0123456789'
  31. hexdigits = digits + 'abcdef' + 'ABCDEF'
  32. octdigits = '01234567'
  33. punctuation = """!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~"""
  34. printable = digits + letters + punctuation + whitespace
  35. 
  36. # Case conversion helpers
  37. # Use str to convert Unicode literal in case of -U
  38. l = map(chr, xrange(256))
  39. _idmap = str('').join(l)
  40. del l
  41. 
  42. # Backward compatible names for exceptions
  43. index_error = ValueError
  44. atoi_error = ValueError
  45. atof_error = ValueError
  46. atol_error = ValueError
  47. 
  48. # convert UPPER CASE letters to lower case
  49. def lower(s):
  50.     """lower(s) -> string
  51. 
  52.     Return a copy of the string s converted to lowercase.
  53. 
  54.     """
  55.     return s.lower()
  56. 
  57. # Convert lower case letters to UPPER CASE
  58. def upper(s):
  59.     """upper(s) -> string
  60. 
  61.     Return a copy of the string s converted to uppercase.
  62. 
  63.     """
  64.     return s.upper()
  65. 
  66. # Swap lower case letters and UPPER CASE
  67. def swapcase(s):
  68.     """swapcase(s) -> string
  69. 
  70.     Return a copy of the string s with upper case characters
  71.     converted to lowercase and vice versa.
  72. 
  73.     """
  74.     return s.swapcase()
  75. 
  76. # Strip leading and trailing tabs and spaces
  77. def strip(s, chars=None):
  78.     """strip(s [,chars]) -> string
  79. 
  80.     Return a copy of the string s with leading and trailing
  81.     whitespace removed.
  82.     If chars is given and not None, remove characters in chars instead.
  83.     If chars is unicode, S will be converted to unicode before stripping.
  84. 
  85.     """
  86.     return s.strip(chars)
  87. 
  88. # Strip leading tabs and spaces
  89. def lstrip(s, chars=None):
  90.     """lstrip(s [,chars]) -> string
  91. 
  92.     Return a copy of the string s with leading whitespace removed.
  93.     If chars is given and not None, remove characters in chars instead.
  94. 
  95.     """
  96.     return s.lstrip(chars)
  97. 
  98. # Strip trailing tabs and spaces
  99. def rstrip(s, chars=None):
 100.     """rstrip(s [,chars]) -> string
 101. 
 102.     Return a copy of the string s with trailing whitespace removed.
 103.     If chars is given and not None, remove characters in chars instead.
 104. 
 105.     """
 106.     return s.rstrip(chars)
 107. 
 108. 
 109. # Split a string into a list of space/tab-separated words
 110. def split(s, sep=None, maxsplit=-1):
 111.     """split(s [,sep [,maxsplit]]) -> list of strings
 112. 
 113.     Return a list of the words in the string s, using sep as the
 114.     delimiter string.  If maxsplit is given, splits at no more than
 115.     maxsplit places (resulting in at most maxsplit+1 words).  If sep
 116.     is not specified, any whitespace string is a separator.
 117. 
 118.     (split and splitfields are synonymous)
 119. 
 120.     """
 121.     return s.split(sep, maxsplit)
 122. splitfields = split
 123. 
 124. # Join fields with optional separator
 125. def join(words, sep = ' '):
 126.     """join(list [,sep]) -> string
 127. 
 128.     Return a string composed of the words in list, with
 129.     intervening occurrences of sep.  The default separator is a
 130.     single space.
 131. 
 132.     (joinfields and join are synonymous)
 133. 
 134.     """
 135.     return sep.join(words)
 136. joinfields = join
 137. 
 138. # Find substring, raise exception if not found
 139. def index(s, *args):
 140.     """index(s, sub [,start [,end]]) -> int
 141. 
 142.     Like find but raises ValueError when the substring is not found.
 143. 
 144.     """
 145.     return s.index(*args)
 146. 
 147. # Find last substring, raise exception if not found
 148. def rindex(s, *args):
 149.     """rindex(s, sub [,start [,end]]) -> int
 150. 
 151.     Like rfind but raises ValueError when the substring is not found.
 152. 
 153.     """
 154.     return s.rindex(*args)
 155. 
 156. # Count non-overlapping occurrences of substring
 157. def count(s, *args):
 158.     """count(s, sub[, start[,end]]) -> int
 159. 
 160.     Return the number of occurrences of substring sub in string
 161.     s[start:end].  Optional arguments start and end are
 162.     interpreted as in slice notation.
 163. 
 164.     """
 165.     return s.count(*args)
 166. 
 167. # Find substring, return -1 if not found
 168. def find(s, *args):
 169.     """find(s, sub [,start [,end]]) -> in
 170. 
 171.     Return the lowest index in s where substring sub is found,
 172.     such that sub is contained within s[start,end].  Optional
 173.     arguments start and end are interpreted as in slice notation.
 174. 
 175.     Return -1 on failure.
 176. 
 177.     """
 178.     return s.find(*args)
 179. 
 180. # Find last substring, return -1 if not found
 181. def rfind(s, *args):
 182.     """rfind(s, sub [,start [,end]]) -> int
 183. 
 184.     Return the highest index in s where substring sub is found,
 185.     such that sub is contained within s[start,end].  Optional
 186.     arguments start and end are interpreted as in slice notation.
 187. 
 188.     Return -1 on failure.
 189. 
 190.     """
 191.     return s.rfind(*args)
 192. 
 193. # for a bit of speed
 194. _float = float
 195. _int = int
 196. _long = long
 197. 
 198. # Convert string to float
 199. def atof(s):
 200.     """atof(s) -> float
 201. 
 202.     Return the floating point number represented by the string s.
 203. 
 204.     """
 205.     return _float(s)
 206. 
 207. 
 208. # Convert string to integer
 209. def atoi(s , base=10):
 210.     """atoi(s [,base]) -> int
 211. 
 212.     Return the integer represented by the string s in the given
 213.     base, which defaults to 10.  The string s must consist of one
 214.     or more digits, possibly preceded by a sign.  If base is 0, it
 215.     is chosen from the leading characters of s, 0 for octal, 0x or
 216.     0X for hexadecimal.  If base is 16, a preceding 0x or 0X is
 217.     accepted.
 218. 
 219.     """
 220.     return _int(s, base)
 221. 
 222. 
 223. # Convert string to long integer
 224. def atol(s, base=10):
 225.     """atol(s [,base]) -> long
 226. 
 227.     Return the long integer represented by the string s in the
 228.     given base, which defaults to 10.  The string s must consist
 229.     of one or more digits, possibly preceded by a sign.  If base
 230.     is 0, it is chosen from the leading characters of s, 0 for
 231.     octal, 0x or 0X for hexadecimal.  If base is 16, a preceding
 232.     0x or 0X is accepted.  A trailing L or l is not accepted,
 233.     unless base is 0.
 234. 
 235.     """
 236.     return _long(s, base)
 237. 
 238. 
 239. # Left-justify a string
 240. def ljust(s, width):
 241.     """ljust(s, width) -> string
 242. 
 243.     Return a left-justified version of s, in a field of the
 244.     specified width, padded with spaces as needed.  The string is
 245.     never truncated.
 246. 
 247.     """
 248.     return s.ljust(width)
 249. 
 250. # Right-justify a string
 251. def rjust(s, width):
 252.     """rjust(s, width) -> string
 253. 
 254.     Return a right-justified version of s, in a field of the
 255.     specified width, padded with spaces as needed.  The string is
 256.     never truncated.
 257. 
 258.     """
 259.     return s.rjust(width)
 260. 
 261. # Center a string
 262. def center(s, width):
 263.     """center(s, width) -> string
 264. 
 265.     Return a center version of s, in a field of the specified
 266.     width. padded with spaces as needed.  The string is never
 267.     truncated.
 268. 
 269.     """
 270.     return s.center(width)
 271. 
 272. # Zero-fill a number, e.g., (12, 3) --> '012' and (-3, 3) --> '-03'
 273. # Decadent feature: the argument may be a string or a number
 274. # (Use of this is deprecated; it should be a string as with ljust c.s.)
 275. def zfill(x, width):
 276.     """zfill(x, width) -> string
 277. 
 278.     Pad a numeric string x with zeros on the left, to fill a field
 279.     of the specified width.  The string x is never truncated.
 280. 
 281.     """
 282.     if not isinstance(x, basestring):
 283.         x = repr(x)
 284.     return x.zfill(width)
 285. 
 286. # Expand tabs in a string.
 287. # Doesn't take non-printing chars into account, but does understand \n.
 288. def expandtabs(s, tabsize=8):
 289.     """expandtabs(s [,tabsize]) -> string
 290. 
 291.     Return a copy of the string s with all tab characters replaced
 292.     by the appropriate number of spaces, depending on the current
 293.     column, and the tabsize (default 8).
 294. 
 295.     """
 296.     return s.expandtabs(tabsize)
 297. 
 298. # Character translation through look-up table.
 299. def translate(s, table, deletions=""):
 300.     """translate(s,table [,deletions]) -> string
 301. 
 302.     Return a copy of the string s, where all characters occurring
 303.     in the optional argument deletions are removed, and the
 304.     remaining characters have been mapped through the given
 305.     translation table, which must be a string of length 256.  The
 306.     deletions argument is not allowed for Unicode strings.
 307. 
 308.     """
 309.     if deletions:
 310.         return s.translate(table, deletions)
 311.     else:
 312.         # Add s[:0] so that if s is Unicode and table is an 8-bit string,
 313.         # table is converted to Unicode.  This means that table *cannot*
 314.         # be a dictionary -- for that feature, use u.translate() directly.
 315.         return s.translate(table + s[:0])
 316. 
 317. # Capitalize a string, e.g. "aBc  dEf" -> "Abc  def".
 318. def capitalize(s):
 319.     """capitalize(s) -> string
 320. 
 321.     Return a copy of the string s with only its first character
 322.     capitalized.
 323. 
 324.     """
 325.     return s.capitalize()
 326. 
 327. # Capitalize the words in a string, e.g. " aBc  dEf " -> "Abc Def".
 328. # See also regsub.capwords().
 329. def capwords(s, sep=None):
 330.     """capwords(s, [sep]) -> string
 331. 
 332.     Split the argument into words using split, capitalize each
 333.     word using capitalize, and join the capitalized words using
 334.     join. Note that this replaces runs of whitespace characters by
 335.     a single space.
 336. 
 337.     """
 338.     return join(map(capitalize, s.split(sep)), sep or ' ')
 339. 
 340. # Construct a translation string
 341. _idmapL = None
 342. def maketrans(fromstr, tostr):
 343.     """maketrans(frm, to) -> string
 344. 
 345.     Return a translation table (a string of 256 bytes long)
 346.     suitable for use in string.translate.  The strings frm and to
 347.     must be of the same length.
 348. 
 349.     """
 350.     if len(fromstr) != len(tostr):
 351.         raise ValueError, "maketrans arguments must have same length"
 352.     global _idmapL
 353.     if not _idmapL:
 354.         _idmapL = map(None, _idmap)
 355.     L = _idmapL[:]
 356.     fromstr = map(ord, fromstr)
 357.     for i in range(len(fromstr)):
 358.         L[fromstr[i]] = tostr[i]
 359.     return join(L, "")
 360. 
 361. # Substring replacement (global)
 362. def replace(s, old, new, maxsplit=-1):
 363.     """replace (str, old, new[, maxsplit]) -> string
 364. 
 365.     Return a copy of string str with all occurrences of substring
 366.     old replaced by new. If the optional argument maxsplit is
 367.     given, only the first maxsplit occurrences are replaced.
 368. 
 369.     """
 370.     return s.replace(old, new, maxsplit)
 371. 
 372. 
 373. # Try importing optional built-in module "strop" -- if it exists,
 374. # it redefines some string operations that are 100-1000 times faster.
 375. # It also defines values for whitespace, lowercase and uppercase
 376. # that match <ctype.h>'s definitions.
 377. 
 378. try:
 379.     from strop import maketrans, lowercase, uppercase, whitespace
 380.     letters = lowercase + uppercase
 381. except ImportError:
 382.     pass                                          # Use the original versions