t/moe/config.py

   1 #!/usr/bin/env python
   2
   3 import re
   4 import sys
   5
   6 key_pattern = re.compile('^[A-Za-z0-9_-]+$')
   7 ref_pattern = re.compile('^[A-Za-z0-9_-]+')
   8
   9 class MoeConfigInvalid(Exception):
  10     pass
  11
  12 class MoeConfigEvalErr(Exception):
  13     pass
  14
  15 class MoeConfig:
  16     """Moe configuration file."""
  17
  18     def __init__(self, file=None, name=None):
  19         self.cfg = {}
  20         if file is not None:
  21             self.load(file)
  22         elif name is not None:
  23             self.load(open(name, 'r'))
  24
  25     def load(self, file):
  26         for x in file.readlines():
  27             x = x.rstrip("\n").lstrip(" \t")
  28             if x=='' or x.startswith('#'):
  29                 pass
  30             else:
  31                 sep = x.find('=')
  32                 if sep >= 0:
  33                     k = x[:sep]
  34                     v = x[sep+1:]
  35                     if k.endswith("+"):
  36                         k = k[:-1]
  37                         if not self.cfg.has_key(k):
  38                             self.cfg[k] = [('a','')];
  39                     else:
  40                         self.cfg[k] = []
  41                     if not key_pattern.match(k):
  42                         raise MoeConfigInvalid, "Malformed name of configuration variable"
  43                     if v.startswith("'"):
  44                         v=v[1:]
  45                         if not v.endswith("'"):
  46                             raise MoeConfigInvalid, "Misquoted string"
  47                         self.cfg[k].append(('s', v[:-1]))
  48                     elif v.startswith('"'):
  49                         v=v[1:]
  50                         if not v.endswith('"'):
  51                             raise MoeConfigInvalid, "Misquoted string"
  52                         self.parse_interpolated(self.cfg[k], v[:-1])
  53                     else:
  54                         self.cfg[k].append(('s', v))
  55                 else:
  56                     ## FIXME: Report line numbers
  57                     raise MoeConfigInvalid, "Parse error"
  58
  59     def parse_interpolated(self, list, s):
  60         while s<>'':
  61             if s.startswith('$'):
  62                 s = s[1:]
  63                 if s.startswith('{'):
  64                     p = s.find('}')
  65                     if not p:
  66                         raise MoeConfigInvalid, "Unbalanced braces"
  67                     k, s = s[1:p], s[p+1:]
  68                     if not key_pattern.match(k):
  69                         raise MoeConfigInvalid, "Invalid variable name"
  70                 else:
  71                     m = ref_pattern.match(s)
  72                     if m:
  73                         k, s = s[:m.end()], s[m.end():]
  74                     else:
  75                         raise MoeConfigInvalid, "Invalid variable reference"
  76                 list.append(('i', k))
  77             else:
  78                 p = s.find('$')
  79                 if p < 0:
  80                     p = len(s)
  81                 list.append(('s', s[:p]))
  82                 s = s[p:]
  83
  84     def dump(self, file=sys.stdout):
  85         for k,v in self.cfg.items():
  86             file.write(k)
  87             if len(v) > 0 and v[0][0] == 'a':
  88                 file.write('+')
  89                 v = v[1:]
  90             file.write('=')
  91             for t,w in v:
  92                 if t == 's':
  93                     file.write("'" + w + "'")
  94                 elif t == 'i':
  95                     file.write('"$' + w + '"')
  96             file.write("\n")
  97
  98 class MoeConfigStack:
  99     """Stack of configuration files."""
 100
 101     def __init__(self, base=None):
 102         ## FIXME: Do we need to duplicate the config files themselves?
 103         if base:
 104             self.stk = base.stk[:]
 105         else:
 106             self.stk = []
 107         self.in_progress = {}
 108
 109     def push(self, cfg):
 110         self.stk.append(cfg)
 111
 112     def __getitem__(self, k):
 113         if self.in_progress.has_key(k):
 114             raise MoeConfigEvalErr, "Definition of $%s is recursive" % k;
 115         self.in_progress[k] = 1;
 116         v = self.do_get(k, len(self.stk)-1)
 117         del self.in_progress[k]
 118         return v
 119
 120     def do_get(self, k, pos):
 121         while pos >= 0:
 122             cfg = self.stk[pos]
 123             if cfg.cfg.has_key(k):
 124                 new = cfg.cfg[k]
 125                 if new[0][0] == 'a':
 126                     v = self.do_get(k, pos-1)
 127                 else:
 128                     v = ''
 129                 for op,arg in new:
 130                     if op == 's':
 131                         v = v + arg
 132                     elif op == 'i':
 133                         v = v + self[arg]
 134                 return v
 135             pos -= 1
 136         return ''