Initial revision

Lib/string.py

@@ -0,0 +1,129 @@
+# 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
+
+# Find substring
+index_error = 'substring not found in string.index'
+def index(s, sub):
+	n = len(sub)
+	for i in range(len(s) - 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 = len(s)
+	if n >= width: return s
+	return s + ' '*(width-n)
+
+# Right-justify a string
+def rjust(s, width):
+	n = len(s)
+	if n >= width: return s
+	return ' '*(width-n) + s
+
+# Center a string
+def center(s, width):
+	n = len(s)
+	if n >= width: return s
+	return ' '*((width-n)/2) +  s + ' '*(width -(width-n)/2)
+
+# 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] = '-':
+		sign, s = '-', s[1:]
+	return sign + '0'*(width-n) + s