mirror of
https://github.com/python/cpython.git
synced 2024-12-01 03:01:36 +01:00
148 lines
3.3 KiB
Python
148 lines
3.3 KiB
Python
# module 'string' -- A collection of string operations
|
|
|
|
# XXX Some of these operations are incredibly slow and should be built in
|
|
|
|
# Some strings for ctype-style character classification
|
|
whitespace = ' \t\n'
|
|
lowercase = 'abcdefghijklmnopqrstuvwxyz'
|
|
uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
|
|
letters = lowercase + uppercase
|
|
digits = '0123456789'
|
|
hexdigits = digits + 'abcdef' + 'ABCDEF'
|
|
octdigits = '01234567'
|
|
|
|
# Case conversion helpers
|
|
_caseswap = {}
|
|
for i in range(26):
|
|
_caseswap[lowercase[i]] = uppercase[i]
|
|
_caseswap[uppercase[i]] = lowercase[i]
|
|
del i
|
|
|
|
# convert UPPER CASE letters to lower case
|
|
def lower(s):
|
|
res = ''
|
|
for c in s:
|
|
if 'A' <= c <= 'Z': c = _caseswap[c]
|
|
res = res + c
|
|
return res
|
|
|
|
# Convert lower case letters to UPPER CASE
|
|
def upper(s):
|
|
res = ''
|
|
for c in s:
|
|
if 'a' <= c <= 'z': c = _caseswap[c]
|
|
res = res + c
|
|
return res
|
|
|
|
# Swap lower case letters and UPPER CASE
|
|
def swapcase(s):
|
|
res = ''
|
|
for c in s:
|
|
if 'a' <= c <= 'z' or 'A' <= c <= 'Z': c = _caseswap[c]
|
|
res = res + c
|
|
return res
|
|
|
|
# Strip leading and trailing tabs and spaces
|
|
def strip(s):
|
|
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]
|
|
|
|
# Split a string into a list of space/tab-separated words
|
|
# NB: split(s) is NOT the same as splitfields(s, ' ')!
|
|
def split(s):
|
|
res = []
|
|
i, n = 0, len(s)
|
|
while i < n:
|
|
while i < n and s[i] in whitespace: i = i+1
|
|
if i = n: break
|
|
j = i
|
|
while j < n and s[j] not in whitespace: j = j+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)!
|
|
def splitfields(s, sep):
|
|
res = []
|
|
ns = len(s)
|
|
nsep = len(sep)
|
|
i = j = 0
|
|
while j+nsep <= ns:
|
|
if s[j:j+nsep] = sep:
|
|
res.append(s[i:j])
|
|
i = j = j + nsep
|
|
else:
|
|
j = j + 1
|
|
res.append(s[i:])
|
|
return res
|
|
|
|
# Join words with spaces between them
|
|
def join(words):
|
|
res = ''
|
|
for w in words:
|
|
res = res + (' ' + w)
|
|
return res[1:]
|
|
|
|
# Join fields with separator
|
|
def joinfields(words, sep):
|
|
res = ''
|
|
for w in words:
|
|
res = res + (sep + w)
|
|
return res[len(sep):]
|
|
|
|
# Find substring
|
|
index_error = 'substring not found in string.index'
|
|
def index(s, sub):
|
|
n = len(sub)
|
|
for i in range(len(s) + 1 - n):
|
|
if sub = s[i:i+n]: return i
|
|
raise index_error, (s, sub)
|
|
|
|
# Convert string to integer
|
|
atoi_error = 'non-numeric argument to string.atoi'
|
|
def atoi(str):
|
|
s = str
|
|
if s[:1] in '+-': s = s[1:]
|
|
if not s: raise atoi_error, str
|
|
for c in s:
|
|
if c not in digits: raise atoi_error, str
|
|
return eval(str)
|
|
|
|
# Left-justify a string
|
|
def ljust(s, width):
|
|
n = width - len(s)
|
|
if n <= 0: return s
|
|
return s + ' '*n
|
|
|
|
# Right-justify a string
|
|
def rjust(s, width):
|
|
n = width - len(s)
|
|
if n <= 0: return s
|
|
return ' '*n + s
|
|
|
|
# Center a string
|
|
def center(s, width):
|
|
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):
|
|
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
|