python中string模块各属性以及函数的用法

原文链接：http://blog.chinaunix.net/uid-25992400-id-3283846.html

任何语言都离不开字符，那就会涉及对字符的操作，尤其是脚本语言更是频繁，不管是生产环境还是面试考验都要面对字符串的操作。

python的字符串操作通过2部分的方法函数基本上就可以解决所有的字符串操作需求：

python的字符串属性函数
python的string模块

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

字符串属性函数

系统版本：CentOS release 6.2 (Final)2.6.32-220.el6.x86_64
python版本：Python 2.6.6

字符串属性方法

字符串格式输出对齐

[python] view
plaincopyprint?

1.>>> str='stRINg lEArn'



2.>>>



3.>>> str.center(20) #生成20个字符长度，str排中间



4.' stRINg lEArn '



5.>>>



6.>>> str.ljust(20) #str左对齐



7.'stRINg lEArn '



8.>>>



9.>>> str.rjust(20) #str右对齐



10.' stRINg lEArn'



11.>>>



12.>>> str.zfill(20) #str右对齐，左边填充0



13.'00000000stRINg lEArn'

大小写转换

[python] view
plaincopyprint?

1.>>> str='stRINg lEArn'



2.>>>



3.>>> str.upper() #转大写



4.'STRING LEARN'



5.>>>



6.>>> str.lower() #转小写



7.'string learn'



8.>>>



9.>>> str.capitalize() #字符串首为大写，其余小写



10.'String learn'



11.>>>



12.>>> str.swapcase() #大小写对换



13.'STrinG LeaRN'



14.>>>



15.>>> str.title() #以分隔符为标记，首字符为大写，其余为小写



16.'String Learn'

字符串条件判断



[python] view
plaincopyprint?

1.>>> str='0123'



2.>>> str.isalnum() #是否全是字母和数字，并至少有一个字符

3.True



4.>>> str.isdigit() #是否全是数字，并至少有一个字符

5.True



6.



7.>>> str='abcd'



8.>>> str.isalnum()



9.True



10.>>> str.isalpha() #是否全是字母，并至少有一个字符

11.True



12.>>> str.islower() #是否全是小写，当全是小写和数字一起时候，也判断为True

13.True



14.



15.>>> str='abcd0123'



16.>>> str.islower() #同上



17.True



18.>>> str.isalnum()



19.True



20.



21.>>> str=' '



22.>>> str.isspace() #是否全是空白字符，并至少有一个字符

23.True



24.>>> str='ABC'



25.>>> str.isupper() #是否全是大写，当全是大写和数字一起时候，也判断为True

26.True



27.>>> str='Abb Acc'



28.>>> str.istitle() #所有单词字首都是大写，标题

29.True

30.



31.>>> str='string learn'

32.>>> str.startswith('str') #判断字符串以'str'开头

33.True

34.>>> str.endswith('arn') #判读字符串以'arn'结尾

35.True

字符串搜索定位与替换

[python] view
plaincopyprint?

1.>>> str='string lEARn'



2.>>>



3.>>> str.find('a') #查找字符串，没有则返回-1，有则返回查到到第一个匹配的索引



4.-1



5.>>> str.find('n')



6.4



7.>>> str.rfind('n') #同上，只是返回的索引是最后一次匹配的



8.11



9.>>>



10.>>> str.index('a') #如果没有匹配则报错



11.Traceback (most recent call last):



12. File "<stdin>", line 1, in <module>



13.ValueError: substring not found



14.>>> str.index('n') #同find类似,返回第一次匹配的索引值



15.4



16.>>> str.rindex('n') #返回最后一次匹配的索引值



17.11



18.>>>



19.>>> str.count('a') #字符串中匹配的次数



20.0



21.>>> str.count('n') #同上



22.2



23.>>>



24.>>> str.replace('EAR','ear') #匹配替换



25.'string learn'



26.>>> str.replace('n','N')



27.'striNg lEARN'



28.>>> str.replace('n','N',1)



29.'striNg lEARn'



30.>>>



31.>>>



32.>>> str.strip('n') #删除字符串首尾匹配的字符，通常用于默认删除回车符



33.'string lEAR'



34.>>> str.lstrip('n') #左匹配



35.'string lEARn'



36.>>> str.rstrip('n') #右匹配



37.'string lEAR'



38.>>>



39.>>> str=' tab'



40.>>> str.expandtabs() #把制表符转为空格



41.' tab'



42.>>> str.expandtabs(2) #指定空格数



43.' tab'



字符串编码与解码

[python] view
plaincopyprint?

1.>>> str='字符串学习'



2.>>> str



3.'xe5xadx97xe7xacxa6xe4xb8xb2xe5xadxa6xe4xb9xa0'



4.>>>



5.>>> str.decode('utf-8') #解码过程，将utf-8解码为unicode



6.u'u5b57u7b26u4e32u5b66u4e60'



7.



8.>>> str.decode('utf-8').encode('gbk') #编码过程，将unicode编码为gbk



9.'xd7xd6xb7xfbxb4xaexd1xa7xcfxb0'



10.>>> str.decode('utf-8').encode('utf-8') #将unicode编码为utf-8



11.'xe5xadx97xe7xacxa6xe4xb8xb2xe5xadxa6xe4xb9xa0'

字符串分割变换

[python] view
plaincopyprint?

1.>>> str='Learn string'



2.>>> '-'.join(str)



3.'L-e-a-r-n- -s-t-r-i-n-g'



4.>>> l1=['Learn','string']



5.>>> '-'.join(l1)



6.'Learn-string'



7.>>>



8.>>> str.split('n')



9.['Lear', ' stri', 'g']



10.>>> str.split('n',1)



11.['Lear', ' string']



12.>>> str.rsplit('n',1)



13.['Learn stri', 'g']



14.>>>



15.>>> str.splitlines()



16.['Learn string']



17.>>>



18.>>> str.partition('n')



19.('Lear', 'n', ' string')



20.>>> str.rpartition('n')



21.('Learn stri', 'n', 'g')

string模块源代码

[python] view
plaincopyprint?

1."""A collection of string operations (most are no longer used).



2.



3.Warning: most of the code you see here isn't normally used nowadays.



4.Beginning with Python 1.6, many of these functions are implemented as



5.methods on the standard string object. They used to be implemented by



6.a built-in module 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 = ' tnrvf'



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.# Functions which aren't available as string methods.



43.



44.# Capitalize the words in a string, e.g. " aBc dEf " -> "Abc Def".



45.def 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



61.def 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.####################################################################



83.import re as _re



84.



85.class _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.



102.class _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.



124.class 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(self, *args, **kws):



149. if len(args) > 1:



150. raise TypeError('Too many positional arguments')



151. if not args:



152. mapping = kws



153. elif kws:



154. mapping = _multimap(kws, args[0])



155. else:



156. mapping = args[0]



157. # Helper function for .sub()



158. def convert(mo):



159. # Check the most common path first.



160. named = mo.group('named') or mo.group('braced')



161. if named is not None:



162. val = mapping[named]



163. # We use this idiom instead of str() because the latter will



164. # fail if val is a Unicode containing non-ASCII characters.



165. return '%s' % (val,)



166. if mo.group('escaped') is not None:



167. return self.delimiter



168. if mo.group('invalid') is not None:



169. self._invalid(mo)



170. raise ValueError('Unrecognized named group in pattern',



171. self.pattern)



172. return self.pattern.sub(convert, self.template)



173.



174. def safe_substitute(self, *args, **kws):



175. if len(args) > 1:



176. raise TypeError('Too many positional arguments')



177. if not args:



178. mapping = kws



179. elif kws:



180. mapping = _multimap(kws, args[0])



181. else:



182. mapping = args[0]



183. # Helper function for .sub()



184. def convert(mo):



185. named = mo.group('named')



186. if named is not None:



187. try:



188. # We use this idiom instead of str() because the latter



189. # will fail if val is a Unicode containing non-ASCII



190. return '%s' % (mapping[named],)



191. except KeyError:



192. return self.delimiter + named



193. braced = mo.group('braced')



194. if braced is not None:



195. try:



196. return '%s' % (mapping[braced],)



197. except KeyError:



198. return self.delimiter + '{' + braced + '}'



199. if mo.group('escaped') is not None:



200. return self.delimiter



201. if mo.group('invalid') is not None:



202. return self.delimiter



203. raise ValueError('Unrecognized named group in pattern',



204. self.pattern)



205. return self.pattern.sub(convert, self.template)



206.



207.



208.



209.####################################################################



210.# NOTE: Everything below here is deprecated. Use string methods instead.



211.# This stuff will go away in Python 3.0.



212.



213.# Backward compatible names for exceptions



214.index_error = ValueError



215.atoi_error = ValueError



216.atof_error = ValueError



217.atol_error = ValueError



218.



219.# convert UPPER CASE letters to lower case



220.def lower(s):



221. """lower(s) -> string



222.



223. Return a copy of the string s converted to lowercase.



224.



225. """



226. return s.lower()



227.



228.# Convert lower case letters to UPPER CASE



229.def upper(s):



230. """upper(s) -> string



231.



232. Return a copy of the string s converted to uppercase.



233.



234. """



235. return s.upper()



236.



237.# Swap lower case letters and UPPER CASE



238.def swapcase(s):



239. """swapcase(s) -> string



240.



241. Return a copy of the string s with upper case characters



242. converted to lowercase and vice versa.



243.



244. """



245. return s.swapcase()



246.



247.# Strip leading and trailing tabs and spaces



248.def strip(s, chars=None):



249. """strip(s [,chars]) -> string



250.



251. Return a copy of the string s with leading and trailing



252. whitespace removed.



253. If chars is given and not None, remove characters in chars instead.



254. If chars is unicode, S will be converted to unicode before stripping.



255.



256. """



257. return s.strip(chars)



258.



259.# Strip leading tabs and spaces



260.def lstrip(s, chars=None):



261. """lstrip(s [,chars]) -> string



262.



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



264. If chars is given and not None, remove characters in chars instead.



265.



266. """



267. return s.lstrip(chars)



268.



269.# Strip trailing tabs and spaces



270.def rstrip(s, chars=None):



271. """rstrip(s [,chars]) -> string



272.



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



274. If chars is given and not None, remove characters in chars instead.



275.



276. """



277. return s.rstrip(chars)



278.



279.



280.# Split a string into a list of space/tab-separated words



281.def split(s, sep=None, maxsplit=-1):



282. """split(s [,sep [,maxsplit]]) -> list of strings



283.



284. Return a list of the words in the string s, using sep as the



285. delimiter string. If maxsplit is given, splits at no more than



286. maxsplit places (resulting in at most maxsplit+1 words). If sep



287. is not specified or is None, any whitespace string is a separator.



288.



289. (split and splitfields are synonymous)



290.



291. """



292. return s.split(sep, maxsplit)



293.splitfields = split



294.



295.# Split a string into a list of space/tab-separated words



296.def rsplit(s, sep=None, maxsplit=-1):



297. """rsplit(s [,sep [,maxsplit]]) -> list of strings



298.



299. Return a list of the words in the string s, using sep as the



300. delimiter string, starting at the end of the string and working



301. to the front. If maxsplit is given, at most maxsplit splits are



302. done. If sep is not specified or is None, any whitespace string



303. is a separator.



304. """



305. return s.rsplit(sep, maxsplit)



306.



307.# Join fields with optional separator



308.def join(words, sep = ' '):



309. """join(list [,sep]) -> string



310.



311. Return a string composed of the words in list, with



312. intervening occurrences of sep. The default separator is a



313. single space.



314.



315. (joinfields and join are synonymous)



316.



317. """



318. return sep.join(words)



319.joinfields = join



320.



321.# Find substring, raise exception if not found



322.def index(s, *args):



323. """index(s, sub [,start [,end]]) -> int



324.



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



326.



327. """



328. return s.index(*args)



329.



330.# Find last substring, raise exception if not found



331.def rindex(s, *args):



332. """rindex(s, sub [,start [,end]]) -> int



333.



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



335.



336. """



337. return s.rindex(*args)



338.



339.# Count non-overlapping occurrences of substring



340.def count(s, *args):



341. """count(s, sub[, start[,end]]) -> int



342.



343. Return the number of occurrences of substring sub in string



344. s[start:end]. Optional arguments start and end are



345. interpreted as in slice notation.



346.



347. """



348. return s.count(*args)



349.



350.# Find substring, return -1 if not found



351.def find(s, *args):



352. """find(s, sub [,start [,end]]) -> in



353.



354. Return the lowest index in s where substring sub is found,



355. such that sub is contained within s[start,end]. Optional



356. arguments start and end are interpreted as in slice notation.



357.



358. Return -1 on failure.



359.



360. """



361. return s.find(*args)



362.



363.# Find last substring, return -1 if not found



364.def rfind(s, *args):



365. """rfind(s, sub [,start [,end]]) -> int



366.



367. Return the highest index in s where substring sub is found,



368. such that sub is contained within s[start,end]. Optional



369. arguments start and end are interpreted as in slice notation.



370.



371. Return -1 on failure.



372.



373. """



374. return s.rfind(*args)



375.



376.# for a bit of speed



377._float = float



378._int = int



379._long = long



380.



381.# Convert string to float



382.def atof(s):



383. """atof(s) -> float



384.



385. Return the floating point number represented by the string s.



386.



387. """



388. return _float(s)



389.



390.



391.# Convert string to integer



392.def atoi(s , base=10):



393. """atoi(s [,base]) -> int



394.



395. Return the integer represented by the string s in the given



396. base, which defaults to 10. The string s must consist of one



397. or more digits, possibly preceded by a sign. If base is 0, it



398. is chosen from the leading characters of s, 0 for octal, 0x or



399. 0X for hexadecimal. If base is 16, a preceding 0x or 0X is



400. accepted.



401.



402. """



403. return _int(s, base)



404.



405.



406.# Convert string to long integer



407.def atol(s, base=10):



408. """atol(s [,base]) -> long



409.



410. Return the long integer represented by the string s in the



411. given base, which defaults to 10. The string s must consist



412. of one or more digits, possibly preceded by a sign. If base



413. is 0, it is chosen from the leading characters of s, 0 for



414. octal, 0x or 0X for hexadecimal. If base is 16, a preceding



415. 0x or 0X is accepted. A trailing L or l is not accepted,



416. unless base is 0.



417.



418. """



419. return _long(s, base)



420.



421.



422.# Left-justify a string



423.def ljust(s, width, *args):



424. """ljust(s, width[, fillchar]) -> string



425.



426. Return a left-justified version of s, in a field of the



427. specified width, padded with spaces as needed. The string is



428. never truncated. If specified the fillchar is used instead of spaces.



429.



430. """



431. return s.ljust(width, *args)



432.



433.# Right-justify a string



434.def rjust(s, width, *args):



435. """rjust(s, width[, fillchar]) -> string



436.



437. Return a right-justified version of s, in a field of the



438. specified width, padded with spaces as needed. The string is



439. never truncated. If specified the fillchar is used instead of spaces.



440.



441. """



442. return s.rjust(width, *args)



443.



444.# Center a string



445.def center(s, width, *args):



446. """center(s, width[, fillchar]) -> string



447.



448. Return a center version of s, in a field of the specified



449. width. padded with spaces as needed. The string is never



450. truncated. If specified the fillchar is used instead of spaces.



451.



452. """



453. return s.center(width, *args)



454.



455.# Zero-fill a number, e.g., (12, 3) --> '012' and (-3, 3) --> '-03'



456.# Decadent feature: the argument may be a string or a number



457.# (Use of this is deprecated; it should be a string as with ljust c.s.)



458.def zfill(x, width):



459. """zfill(x, width) -> string



460.



461. Pad a numeric string x with zeros on the left, to fill a field



462. of the specified width. The string x is never truncated.



463.



464. """



465. if not isinstance(x, basestring):



466. x = repr(x)



467. return x.zfill(width)



468.



469.# Expand tabs in a string.



470.# Doesn't take non-printing chars into account, but does understand n.



471.def expandtabs(s, tabsize=8):



472. """expandtabs(s [,tabsize]) -> string



473.



474. Return a copy of the string s with all tab characters replaced



475. by the appropriate number of spaces, depending on the current



476. column, and the tabsize (default 8).



477.



478. """



479. return s.expandtabs(tabsize)



480.



481.# Character translation through look-up table.



482.def translate(s, table, deletions=""):



483. """translate(s,table [,deletions]) -> string



484.



485. Return a copy of the string s, where all characters occurring



486. in the optional argument deletions are removed, and the



487. remaining characters have been mapped through the given



488. translation table, which must be a string of length 256. The



489. deletions argument is not allowed for Unicode strings.



490.



491. """



492. if deletions or table is None:



493. return s.translate(table, deletions)



494. else:



495. # Add s[:0] so that if s is Unicode and table is an 8-bit string,



496. # table is converted to Unicode. This means that table *cannot*



497. # be a dictionary -- for that feature, use u.translate() directly.



498. return s.translate(table + s[:0])



499.



500.# Capitalize a string, e.g. "aBc dEf" -> "Abc def".



501.def capitalize(s):



502. """capitalize(s) -> string



503.



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



505. capitalized.



506.



507. """



508. return s.capitalize()



509.



510.# Substring replacement (global)



511.def replace(s, old, new, maxsplit=-1):



512. """replace (str, old, new[, maxsplit]) -> string



513.



514. Return a copy of string str with all occurrences of substring



515. old replaced by new. If the optional argument maxsplit is



516. given, only the first maxsplit occurrences are replaced.



517.



518. """



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



520.



521.



522.# Try importing optional built-in module "strop" -- if it exists,



523.# it redefines some string operations that are 100-1000 times faster.



524.# It also defines values for whitespace, lowercase and uppercase



525.# that match <ctype.h>'s definitions.



526.



527.try:



528. from strop import maketrans, lowercase, uppercase, whitespace



529. letters = lowercase + uppercase



530.except ImportError:



531. pass # Use the original versions



532.



533.########################################################################



534.# the Formatter class



535.# see PEP 3101 for details and purpose of this class



536.



537.# The hard parts are reused from the C implementation. They're exposed as "_"



538.# prefixed methods of str and unicode.



539.



540.# The overall parser is implemented in str._formatter_parser.



541.# The field name parser is implemented in str._formatter_field_name_split



542.



543.class Formatter(object):



544. def format(self, format_string, *args, **kwargs):



545. return self.vformat(format_string, args, kwargs)



546.



547. def vformat(self, format_string, args, kwargs):



548. used_args = set()



549. result = self._vformat(format_string, args, kwargs, used_args, 2)



550. self.check_unused_args(used_args, args, kwargs)



551. return result



552.



553. def _vformat(self, format_string, args, kwargs, used_args, recursion_depth):



554. if recursion_depth < 0:



555. raise ValueError('Max string recursion exceeded')



556. result = []



557. for literal_text, field_name, format_spec, conversion in



558. self.parse(format_string):



559.



560. # output the literal text



561. if literal_text:



562. result.append(literal_text)



563.



564. # if there's a field, output it



565. if field_name is not None:



566. # this is some markup, find the object and do



567. # the formatting



568.



569. # given the field_name, find the object it references



570. # and the argument it came from



571. obj, arg_used = self.get_field(field_name, args, kwargs)



572. used_args.add(arg_used)



573.



574. # do any conversion on the resulting object



575. obj = self.convert_field(obj, conversion)



576.



577. # expand the format spec, if needed



578. format_spec = self._vformat(format_spec, args, kwargs,



579. used_args, recursion_depth-1)



580.



581. # format the object and append to the result



582. result.append(self.format_field(obj, format_spec))



583.



584. return ''.join(result)



585.



586.



587. def get_value(self, key, args, kwargs):



588. if isinstance(key, (int, long)):



589. return args[key]



590. else:



591. return kwargs[key]



592.



593.



594. def check_unused_args(self, used_args, args, kwargs):



595. pass



596.



597.



598. def format_field(self, value, format_spec):



599. return format(value, format_spec)



600.



601.



602. def convert_field(self, value, conversion):



603. # do any conversion on the resulting object



604. if conversion == 'r':



605. return repr(value)



606. elif conversion == 's':



607. return str(value)



608. elif conversion is None:



609. return value



610. raise ValueError("Unknown converion specifier {0!s}".format(conversion))



611.



612.



613. # returns an iterable that contains tuples of the form:



614. # (literal_text, field_name, format_spec, conversion)



615. # literal_text can be zero length



616. # field_name can be None, in which case there's no



617. # object to format and output



618. # if field_name is not None, it is looked up, formatted



619. # with format_spec and conversion and then used



620. def parse(self, format_string):



621. return format_string._formatter_parser()



622.



623.



624. # given a field_name, find the object it references.



625. # field_name: the field being looked up, e.g. "0.name"



626. # or "lookup[3]"



627. # used_args: a set of which args have been used



628. # args, kwargs: as passed in to vformat



629. def get_field(self, field_name, args, kwargs):



630. first, rest = field_name._formatter_field_name_split()



631.



632. obj = self.get_value(first, args, kwargs)



633.



634. # loop through the rest of the field_name, doing



635. # getattr or getitem as needed



636. for is_attr, i in rest:



637. if is_attr:



638. obj = getattr(obj, i)



639. else:



640. obj = obj[i]



641.



642. return obj, first