def match_region(ch, pattern):
""" region: a list of comparation chars and ranges in [] or [^]"""
if pattern[1]=='^': booly = False; booln = True; i=2
else: booly = True; booln = False; i=1
while i < len(pattern):
if pattern[i] == '\\' and pattern[i+1] in (']', '\\','-'):
if ch== pattern[i+1]: return booly
else: i+=2
elif i<len(pattern)-2 and pattern[i+1]=='-':
if pattern[i]<=ch<=pattern[i+2]: return booly
else: i+= 2
elif pattern[i]==ch: return booly
else: i+=1
return booln
def match_token(ch, token):
if token.startswith('['): return match_region(ch,token)
elif token.startswith('\\'):
tkc=token[1]
if tkc=='s': return (ch in (' ','\t','\r','\n','\f','\v'))
elif tkc=='S': return (ch not in (' ','\t','\r','\n','\f','\v'))
else: return (ch==tkc)
elif token=='.': return True
else: return (ch==token[0])
TokenListCache = {} # essential with nesting, otherwise only here for optimization
to_escape = ('.','*','+','?','\\','[',']'); esc_brackets = to_escape + ('(', ')')
def parse_pattern(pattern, nested):
"""
tokens are:
1. patterns included in brackets (parsing is recursive)
2. regions
3. \\ together with the escaped character
4. periods
5. simple characters
6. quantifiers, only following tokens 1-5
"""
if nested: ESC = esc_brackets
else: ESC = to_escape
tokens = []
i = 0
while i < len(pattern):
c = pattern[i]
if c=='[':
k = pattern.find(']', i)
if k==-1: raise ValueError('Unmatched [ in '+pattern)
while pattern[k-1] == '\\':
k = pattern.find(']', k+1)
if k==-1: raise ValueError('Unmatched [ in '+pattern)
tokens.append(pattern[i:k+1])
i=k+1
elif c == '.':
tokens.append('.'); i+=1
elif c == '\\':
if i<len(pattern)-1 and pattern[i+1] in ESC:
tokens.append(pattern[i:i+2]); i+=2
else:
raise ValueError('Bad successor of a backslash')
elif nested and c=='(':
resu = '('; k=i+1; lv=1
while lv > 0:
cc = pattern[k]
if cc =='\\': resu+=cc; resu+=pattern[k+1]; k+=2; continue
if cc == '(': lv+=1
elif cc == ')': lv-=1
resu+=cc; k+=1
if resu not in TokenListCache.keys():
TokenListCache[resu]=parse_pattern(resu[1:-1], nested=True)
tokens.append(resu)
if k<len(pattern) and pattern[k] in ('*', '+', '?'):
tokens.append(pattern[k]); k+=1
i = k+1
else:
tokens.append(c); i+=1
if i<len(pattern) and pattern[i] in ('*', '+', '?'):
tokens.append(pattern[i]); i+=1
TokenListCache[pattern]=tokens
return tokens
def try_index(sarg, start, tokens, nested):
compix = start; tix = 0; tkL = len(tokens)
while tix<tkL:
if compix == len(sarg): return 0
ctk = tokens[tix]
if nested and ctk[0] == '(':
subtokens = TokenListCache[ctk]
subcompix = try_index(sarg, compix, subtokens, True)
c = 'n'
if tix<tkL-1: c = tokens[tix+1]
if not subcompix:
if c in ('?', '*'): tix+=2; compix=subcompix; continue
else: return 0
elif c in ('*', '+'):
while subcompix:
compix = subcompix
subcompix = try_index(sarg, compix, subtokens, nested)
tix+=2; continue
qua = 'n'
if tix<tkL-1: qua = tokens[tix+1]
if qua=='?':
if match_token(sarg[compix], ctk): tix+=2; compix+=1
continue
if qua=='+':
if not match_token(sarg[compix], ctk): return 0
compix+=1
if qua in ('*','+'):
if tix<tkL-2:
while compix<len(sarg) and match_token(sarg[compix], ctk) and\
not match_token(sarg[compix], tokens[tix+2]):
compix+=1
else:
while compix<len(sarg) and match_token(sarg[compix], ctk):
compix+=1
tix+=2
else:
if not match_token(sarg[compix], ctk): return 0
else: compix+=1; tix+=1
return compix
def xsearch(sarg, pattern, start=0, nested=False):
try: tokens = TokenListCache[pattern]
except: tokens = parse_pattern(pattern, nested)
argix=start
while argix<len(sarg):
n = try_index(sarg, argix, tokens, nested)
if n: return (argix, n)
argix += 1
return (0,0)
def xplit(sarg, pattern, nested=False):
resu = []; xpair = xsearch(sarg, pattern, nested=nested); residue=0
while (xpair[0]):
resu.append(sarg[:xpair[0]])
residue = xpair[1]
xpair = xsearch(sarg, pattern, xpair[1], nested)
return resu+sarg[residue:]
def xreplace(sarg, pattern, f, nested=False):
to_replace=[]; s=sarg; xpair=xsearch(sarg, pattern, nested=nested)
while (xpair[0]):
to_replace.append(xpair); xpair=xsearch(sarg, pattern, xpair[1], nested)
for xpair in reversed(to_replace):
s = s[:xpair[0]]+f+s[xpair[1]:]
return s
def xfuncreplace(sarg, pattern, f, nested=False):
to_replace=[]; s=sarg; xpair=xsearch(sarg, pattern, nested=nested)
while (xpair[0]):
to_replace.append(xpair); xpair=xsearch(sarg, pattern, xpair[1], nested)
for xpair in reversed(to_replace):
s[:xpair[0]]+f(s[xpair[0]:xpair[1]])+s[xpair[1]:]
return s
Diff to Previous Revision
--- revision 4 2010-06-02 09:50:24
+++ revision 5 2010-06-02 09:59:56
@@ -16,10 +16,10 @@
def match_token(ch, token):
if token.startswith('['): return match_region(ch,token)
elif token.startswith('\\'):
- tkc==token[1]
+ tkc=token[1]
if tkc=='s': return (ch in (' ','\t','\r','\n','\f','\v'))
elif tkc=='S': return (ch not in (' ','\t','\r','\n','\f','\v'))
- else return (ch==tkc)
+ else: return (ch==tkc)
elif token=='.': return True
else: return (ch==token[0])
@@ -149,5 +149,5 @@
while (xpair[0]):
to_replace.append(xpair); xpair=xsearch(sarg, pattern, xpair[1], nested)
for xpair in reversed(to_replace):
- s[:xpair[0]]+f(s[xpair[0]:xpair[1])+s[xpair[1]:]
+ s[:xpair[0]]+f(s[xpair[0]:xpair[1]])+s[xpair[1]:]
return s
