57 lines
1.4 KiB
Python
57 lines
1.4 KiB
Python
#
|
|
# Variable substitution. Variables are $delimited$
|
|
#
|
|
import re
|
|
|
|
error = 'varsubst.error'
|
|
|
|
class Varsubst:
|
|
def __init__(self, dict):
|
|
self.dict = dict
|
|
self.prog = re.compile('\$([a-zA-Z0-9_]*)\$')
|
|
self.do_useindent = 0
|
|
|
|
def useindent(self, onoff):
|
|
self.do_useindent = onoff
|
|
|
|
def subst(self, s):
|
|
rv = ''
|
|
while 1:
|
|
m = self.prog.search(s)
|
|
if not m:
|
|
return rv + s
|
|
rv = rv + s[:m.start()]
|
|
s = s[m.end():]
|
|
if m.end() - m.start() == 2:
|
|
# Escaped dollar
|
|
rv = rv + '$'
|
|
s = s[2:]
|
|
continue
|
|
name = m.group(1)
|
|
if name not in self.dict:
|
|
raise error('No such variable: '+name)
|
|
value = self.dict[name]
|
|
if self.do_useindent and '\n' in value:
|
|
value = self._modindent(value, rv)
|
|
rv = rv + value
|
|
|
|
def _modindent(self, value, old):
|
|
lastnl = old.rfind('\n', 0) + 1
|
|
lastnl = len(old) - lastnl
|
|
sub = '\n' + (' '*lastnl)
|
|
return re.sub('\n', sub, value)
|
|
|
|
def _test():
|
|
import sys
|
|
import os
|
|
|
|
sys.stderr.write('-- Copying stdin to stdout with environment map --\n')
|
|
c = Varsubst(os.environ)
|
|
c.useindent(1)
|
|
d = sys.stdin.read()
|
|
sys.stdout.write(c.subst(d))
|
|
sys.exit(1)
|
|
|
|
if __name__ == '__main__':
|
|
_test()
|