mirror of
https://github.com/python/cpython.git
synced 2025-11-04 03:44:55 +00:00
583 lines
15 KiB
Python
583 lines
15 KiB
Python
# module 'string' -- A collection of string operations
|
|
|
|
# Warning: most of the code you see here isn't normally used nowadays.
|
|
# At the end of this file most functions are replaced by built-in
|
|
# functions imported from built-in module "strop".
|
|
|
|
"""Common string manipulations.
|
|
|
|
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
|
|
|
|
"""
|
|
|
|
# Some strings for ctype-style character classification
|
|
whitespace = ' \t\n\r\v\f'
|
|
lowercase = 'abcdefghijklmnopqrstuvwxyz'
|
|
uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
|
|
letters = lowercase + uppercase
|
|
digits = '0123456789'
|
|
hexdigits = digits + 'abcdef' + 'ABCDEF'
|
|
octdigits = '01234567'
|
|
|
|
# Case conversion helpers
|
|
_idmap = ''
|
|
for i in range(256): _idmap = _idmap + chr(i)
|
|
_lower = _idmap[:ord('A')] + lowercase + _idmap[ord('Z')+1:]
|
|
_upper = _idmap[:ord('a')] + uppercase + _idmap[ord('z')+1:]
|
|
_swapcase = _upper[:ord('A')] + lowercase + _upper[ord('Z')+1:]
|
|
del i
|
|
|
|
# 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.
|
|
|
|
"""
|
|
res = ''
|
|
for c in s:
|
|
res = res + _lower[ord(c)]
|
|
return res
|
|
|
|
# Convert lower case letters to UPPER CASE
|
|
def upper(s):
|
|
"""upper(s) -> string
|
|
|
|
Return a copy of the string s converted to uppercase.
|
|
|
|
"""
|
|
res = ''
|
|
for c in s:
|
|
res = res + _upper[ord(c)]
|
|
return res
|
|
|
|
# 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.
|
|
|
|
"""
|
|
res = ''
|
|
for c in s:
|
|
res = res + _swapcase[ord(c)]
|
|
return res
|
|
|
|
# Strip leading and trailing tabs and spaces
|
|
def strip(s):
|
|
"""strip(s) -> string
|
|
|
|
Return a copy of the string s with leading and trailing
|
|
whitespace removed.
|
|
|
|
"""
|
|
i, j = 0, len(s)
|
|
while i < j and s[i] in whitespace: i = i+1
|
|
while i < j and s[j-1] in whitespace: j = j-1
|
|
return s[i:j]
|
|
|
|
# Strip leading tabs and spaces
|
|
def lstrip(s):
|
|
"""lstrip(s) -> string
|
|
|
|
Return a copy of the string s with leading whitespace removed.
|
|
|
|
"""
|
|
i, j = 0, len(s)
|
|
while i < j and s[i] in whitespace: i = i+1
|
|
return s[i:j]
|
|
|
|
# Strip trailing tabs and spaces
|
|
def rstrip(s):
|
|
"""rstrip(s) -> string
|
|
|
|
Return a copy of the string s with trailing whitespace
|
|
removed.
|
|
|
|
"""
|
|
i, j = 0, len(s)
|
|
while i < j and s[j-1] in whitespace: j = j-1
|
|
return s[i:j]
|
|
|
|
|
|
# Split a string into a list of space/tab-separated words
|
|
# NB: split(s) is NOT the same as splitfields(s, ' ')!
|
|
def split(s, sep=None, maxsplit=0):
|
|
"""split(str [,sep [,maxsplit]]) -> list of strings
|
|
|
|
Return a list of the words in the string s, using sep as the
|
|
delimiter string. If maxsplit is nonzero, splits into at most
|
|
maxsplit words If sep is not specified, any whitespace string
|
|
is a separator. Maxsplit defaults to 0.
|
|
|
|
(split and splitfields are synonymous)
|
|
|
|
"""
|
|
if sep is not None: return splitfields(s, sep, maxsplit)
|
|
res = []
|
|
i, n = 0, len(s)
|
|
if maxsplit <= 0: maxsplit = n
|
|
count = 0
|
|
while i < n:
|
|
while i < n and s[i] in whitespace: i = i+1
|
|
if i == n: break
|
|
if count >= maxsplit:
|
|
res.append(s[i:])
|
|
break
|
|
j = i
|
|
while j < n and s[j] not in whitespace: j = j+1
|
|
count = count + 1
|
|
res.append(s[i:j])
|
|
i = j
|
|
return res
|
|
|
|
# Split a list into fields separated by a given string
|
|
# NB: splitfields(s, ' ') is NOT the same as split(s)!
|
|
# splitfields(s, '') returns [s] (in analogy with split() in nawk)
|
|
def splitfields(s, sep=None, maxsplit=0):
|
|
"""splitfields(str [,sep [,maxsplit]]) -> list of strings
|
|
|
|
Return a list of the words in the string s, using sep as the
|
|
delimiter string. If maxsplit is nonzero, splits into at most
|
|
maxsplit words If sep is not specified, any whitespace string
|
|
is a separator. Maxsplit defaults to 0.
|
|
|
|
(split and splitfields are synonymous)
|
|
|
|
"""
|
|
if sep is None: return split(s, None, maxsplit)
|
|
res = []
|
|
nsep = len(sep)
|
|
if nsep == 0:
|
|
return [s]
|
|
ns = len(s)
|
|
if maxsplit <= 0: maxsplit = ns
|
|
i = j = 0
|
|
count = 0
|
|
while j+nsep <= ns:
|
|
if s[j:j+nsep] == sep:
|
|
count = count + 1
|
|
res.append(s[i:j])
|
|
i = j = j + nsep
|
|
if count >= maxsplit: break
|
|
else:
|
|
j = j + 1
|
|
res.append(s[i:])
|
|
return res
|
|
|
|
# Join words with spaces between them
|
|
def join(words, sep = ' '):
|
|
"""join(list [,sep]) -> string
|
|
|
|
Return a string composed of the words in list, with
|
|
intervening occurences of sep. Sep defaults to a single
|
|
space.
|
|
|
|
(joinfields and join are synonymous)
|
|
|
|
"""
|
|
return joinfields(words, sep)
|
|
|
|
# Join fields with optional separator
|
|
def joinfields(words, sep = ' '):
|
|
"""joinfields(list [,sep]) -> string
|
|
|
|
Return a string composed of the words in list, with
|
|
intervening occurences of sep. The default separator is a
|
|
single space.
|
|
|
|
(joinfields and join are synonymous)
|
|
|
|
"""
|
|
res = ''
|
|
for w in words:
|
|
res = res + (sep + w)
|
|
return res[len(sep):]
|
|
|
|
# Find substring, raise exception if not found
|
|
def index(s, sub, i = 0, last=None):
|
|
"""index(s, sub [,start [,end]]) -> int
|
|
|
|
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.
|
|
|
|
Raise ValueError if not found.
|
|
|
|
"""
|
|
if last is None: last = len(s)
|
|
res = find(s, sub, i, last)
|
|
if res < 0:
|
|
raise ValueError, 'substring not found in string.index'
|
|
return res
|
|
|
|
# Find last substring, raise exception if not found
|
|
def rindex(s, sub, i = 0, last=None):
|
|
"""rindex(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.
|
|
|
|
Raise ValueError if not found.
|
|
|
|
"""
|
|
if last is None: last = len(s)
|
|
res = rfind(s, sub, i, last)
|
|
if res < 0:
|
|
raise ValueError, 'substring not found in string.index'
|
|
return res
|
|
|
|
# Count non-overlapping occurrences of substring
|
|
def count(s, sub, i = 0, last=None):
|
|
"""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.
|
|
|
|
"""
|
|
Slen = len(s) # cache this value, for speed
|
|
if last is None:
|
|
last = Slen
|
|
elif last < 0:
|
|
last = max(0, last + Slen)
|
|
elif last > Slen:
|
|
last = Slen
|
|
if i < 0: i = max(0, i + Slen)
|
|
n = len(sub)
|
|
m = last + 1 - n
|
|
if n == 0: return m-i
|
|
r = 0
|
|
while i < m:
|
|
if sub == s[i:i+n]:
|
|
r = r+1
|
|
i = i+n
|
|
else:
|
|
i = i+1
|
|
return r
|
|
|
|
# Find substring, return -1 if not found
|
|
def find(s, sub, i = 0, last=None):
|
|
"""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.
|
|
|
|
"""
|
|
Slen = len(s) # cache this value, for speed
|
|
if last is None:
|
|
last = Slen
|
|
elif last < 0:
|
|
last = max(0, last + Slen)
|
|
elif last > Slen:
|
|
last = Slen
|
|
if i < 0: i = max(0, i + Slen)
|
|
n = len(sub)
|
|
m = last + 1 - n
|
|
while i < m:
|
|
if sub == s[i:i+n]: return i
|
|
i = i+1
|
|
return -1
|
|
|
|
# Find last substring, return -1 if not found
|
|
def rfind(s, sub, i = 0, last=None):
|
|
"""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.
|
|
|
|
"""
|
|
Slen = len(s) # cache this value, for speed
|
|
if last is None:
|
|
last = Slen
|
|
elif last < 0:
|
|
last = max(0, last + Slen)
|
|
elif last > Slen:
|
|
last = Slen
|
|
if i < 0: i = max(0, i + Slen)
|
|
n = len(sub)
|
|
m = last + 1 - n
|
|
r = -1
|
|
while i < m:
|
|
if sub == s[i:i+n]: r = i
|
|
i = i+1
|
|
return r
|
|
|
|
# "Safe" environment for eval()
|
|
safe_env = {"__builtins__": {}}
|
|
|
|
# Convert string to float
|
|
re = None
|
|
def atof(str):
|
|
"""atof(s) -> float
|
|
|
|
Return the floating point number represented by the string s.
|
|
|
|
"""
|
|
global re
|
|
if re is None:
|
|
# Don't fail if re doesn't exist -- just skip the syntax check
|
|
try:
|
|
import re
|
|
except ImportError:
|
|
re = 0
|
|
sign = ''
|
|
s = strip(str)
|
|
if s and s[0] in '+-':
|
|
sign = s[0]
|
|
s = s[1:]
|
|
if not s:
|
|
raise ValueError, 'non-float argument to string.atof'
|
|
while s[0] == '0' and len(s) > 1 and s[1] in digits: s = s[1:]
|
|
if re and not re.match('[0-9]*(\.[0-9]*)?([eE][-+]?[0-9]+)?$', s):
|
|
raise ValueError, 'non-float argument to string.atof'
|
|
try:
|
|
return float(eval(sign + s, safe_env))
|
|
except SyntaxError:
|
|
raise ValueError, 'non-float argument to string.atof'
|
|
|
|
# Convert string to integer
|
|
def atoi(str, 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.
|
|
|
|
"""
|
|
if base != 10:
|
|
# We only get here if strop doesn't define atoi()
|
|
raise ValueError, "this string.atoi doesn't support base != 10"
|
|
sign = ''
|
|
s = str
|
|
if s and s[0] in '+-':
|
|
sign = s[0]
|
|
s = s[1:]
|
|
if not s:
|
|
raise ValueError, 'non-integer argument to string.atoi'
|
|
while s[0] == '0' and len(s) > 1: s = s[1:]
|
|
for c in s:
|
|
if c not in digits:
|
|
raise ValueError, 'non-integer argument to string.atoi'
|
|
return eval(sign + s, safe_env)
|
|
|
|
# Convert string to long integer
|
|
def atol(str, 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.
|
|
|
|
"""
|
|
if base != 10:
|
|
# We only get here if strop doesn't define atol()
|
|
raise ValueError, "this string.atol doesn't support base != 10"
|
|
sign = ''
|
|
s = str
|
|
if s and s[0] in '+-':
|
|
sign = s[0]
|
|
s = s[1:]
|
|
if not s:
|
|
raise ValueError, 'non-integer argument to string.atol'
|
|
while s[0] == '0' and len(s) > 1: s = s[1:]
|
|
for c in s:
|
|
if c not in digits:
|
|
raise ValueError, 'non-integer argument to string.atol'
|
|
return eval(sign + s + 'L', safe_env)
|
|
|
|
# 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.
|
|
|
|
"""
|
|
n = width - len(s)
|
|
if n <= 0: return s
|
|
return s + ' '*n
|
|
|
|
# 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.
|
|
|
|
"""
|
|
n = width - len(s)
|
|
if n <= 0: return s
|
|
return ' '*n + s
|
|
|
|
# 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.
|
|
|
|
"""
|
|
n = width - len(s)
|
|
if n <= 0: return s
|
|
half = n/2
|
|
if n%2 and width%2:
|
|
# This ensures that center(center(s, i), j) = center(s, j)
|
|
half = half+1
|
|
return ' '*half + s + ' '*(n-half)
|
|
|
|
# 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 type(x) == type(''): s = x
|
|
else: s = `x`
|
|
n = len(s)
|
|
if n >= width: return s
|
|
sign = ''
|
|
if s[0] in ('-', '+'):
|
|
sign, s = s[0], s[1:]
|
|
return sign + '0'*(width-n) + s
|
|
|
|
# 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).
|
|
|
|
"""
|
|
res = line = ''
|
|
for c in s:
|
|
if c == '\t':
|
|
c = ' '*(tabsize - len(line)%tabsize)
|
|
line = line + c
|
|
if c == '\n':
|
|
res = res + line
|
|
line = ''
|
|
return res + line
|
|
|
|
# Character translation through look-up table.
|
|
def translate(s, table, deletions=""):
|
|
"""translate(s,table [,deletechars]) -> string
|
|
|
|
Return a copy of the string s, where all characters occurring
|
|
in the optional argument deletechars are removed, and the
|
|
remaining characters have been mapped through the given
|
|
translation table, which must be a string of length 256.
|
|
|
|
"""
|
|
if type(table) != type('') or len(table) != 256:
|
|
raise TypeError, "translation table must be 256 characters long"
|
|
res = ""
|
|
for c in s:
|
|
if c not in deletions:
|
|
res = res + table[ord(c)]
|
|
return res
|
|
|
|
# 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 upper(s[:1]) + lower(s[1:])
|
|
|
|
# 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, split(s, 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 joinfields(L, "")
|
|
|
|
# Substring replacement (global)
|
|
def replace(str, old, new, maxsplit=0):
|
|
"""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 joinfields(splitfields(str, old, maxsplit), new)
|
|
|
|
|
|
# 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 *
|
|
letters = lowercase + uppercase
|
|
except ImportError:
|
|
pass # Use the original, slow versions
|