| # |
| # 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 not self.dict.has_key(name): |
| 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() |
