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. Should be immutable once a part of a stack."""
  17
  18     def __init__(self, file=None, name=None):
  19         self.vars = {}
  20         if file is not None:
  21             self.load(file)
  22         elif name is not None:
  23             self.name = name
  24             self.load(open(name, "r"))
  25
  26     def parse_line(self, x):
  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.vars.has_key(k):
  38                         self.vars[k] = [("a","")];
  39                 else:
  40                     self.vars[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.vars[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.vars[k], v[:-1])
  53                 else:
  54                     self.parse_interpolated(self.vars[k], v)
  55             else:
  56                 raise MoeConfigInvalid, "Parse error"
  57
  58     def load(self, file):
  59         lino = 0
  60         for x in file.readlines():
  61             lino += 1
  62             try:
  63                 self.parse_line(x)
  64             except MoeConfigInvalid, x:
  65                 msg = x.message + " at line " + str(lino)
  66                 if hasattr(self, "name"):
  67                     msg += " of " + self.name
  68                 raise MoeConfigInvalid, msg
  69
  70     def parse_interpolated(self, list, s):
  71         while s<>"":
  72             if s.startswith("$"):
  73                 s = s[1:]
  74                 if s.startswith("{"):
  75                     p = s.find("}")
  76                     if not p:
  77                         raise MoeConfigInvalid, "Unbalanced braces"
  78                     k, s = s[1:p], s[p+1:]
  79                     if not key_pattern.match(k):
  80                         raise MoeConfigInvalid, "Invalid variable name"
  81                 else:
  82                     m = ref_pattern.match(s)
  83                     if m:
  84                         k, s = s[:m.end()], s[m.end():]
  85                     else:
  86                         raise MoeConfigInvalid, "Invalid variable reference"
  87                 list.append(("i", k))
  88             else:
  89                 p = s.find("$")
  90                 if p < 0:
  91                     p = len(s)
  92                 list.append(("s", s[:p]))
  93                 s = s[p:]
  94
  95     def dump(self, file=sys.stdout):
  96         for k,v in self.vars.items():
  97             file.write(k)
  98             if len(v) > 0 and v[0][0] == "a":
  99                 file.write("+")
 100                 v = v[1:]
 101             file.write("=")
 102             for t,w in v:
 103                 if t == "s":
 104                     file.write("'" + w + "'")
 105                 elif t == "i":
 106                     file.write('"$' + w + '"')
 107             file.write("\n")
 108
 109 class MoeConfigStack:
 110     """Stack of configuration files."""
 111
 112     def __init__(self, base=None):
 113         ## FIXME: Do we need to duplicate the config files themselves?
 114         if base:
 115             self.stk = base.stk[:]
 116         else:
 117             self.stk = []
 118         self.in_progress = {}
 119         self.reset_cache()
 120
 121     def reset_cache(self):
 122         self.cache = {}
 123
 124     def push(self, cfg):
 125         self.stk.append(cfg)
 126         self.reset_cache()
 127
 128     def __getitem__(self, k):
 129         if self.cache.has_key(k):
 130             return self.cache[k]
 131         if self.in_progress.has_key(k):
 132             raise MoeConfigEvalErr, "Definition of $%s is recursive" % k;
 133         self.in_progress[k] = 1;
 134         v = self.do_get(k, len(self.stk)-1)
 135         del self.in_progress[k]
 136         self.cache[k] = v
 137         return v
 138
 139     def do_get(self, k, pos):
 140         while pos >= 0:
 141             cfg = self.stk[pos]
 142             if cfg.vars.has_key(k):
 143                 new = cfg.vars[k]
 144                 if new[0][0] == "a":
 145                     v = self.do_get(k, pos-1)
 146                 else:
 147                     v = ""
 148                 for op,arg in new:
 149                     if op == "s":
 150                         v = v + arg
 151                     elif op == "i":
 152                         v = v + self[arg]
 153                 return v
 154             pos -= 1
 155         return ""
 156
 157     def keys(self):
 158         seen = {}
 159         for cfg in self.stk:
 160             for k in cfg.vars.keys():
 161                 seen[k] = None
 162         return seen.keys()
 163
 164     def dump(self, file=sys.stdout):
 165         for k in self.keys():
 166             v = self[k]
 167             file.write("%s=%s\n" % (k,v))
 168
 169     def dump_defs(self, file=sys.stdout):
 170         file.write("Configuration stack:\n")
 171         level = 0
 172         for cfg in self.stk:
 173             level += 1
 174             file.write("(level %d)\n" % level)
 175             cfg.dump(file)
 176         file.write("(end)\n")
 177
 178     def apply_overrides(self, prefix):
 179         newstk = []
 180         for cfg in self.stk:
 181             over = MoeConfig()
 182             changed = False
 183             for k in cfg.vars.keys():
 184                 if k.startswith(prefix):
 185                     over.vars[k[len(prefix):]] = cfg.vars[k]
 186                     changed = True
 187             if changed:
 188                 clean = MoeConfig()
 189                 for k in cfg.vars.keys():
 190                     if not k.startswith(prefix):
 191                         clean.vars[k] = cfg.vars[k]
 192                 newstk.append(clean)
 193                 newstk.append(over)
 194             else:
 195                 newstk.append(cfg)
 196         self.stk = newstk
 197         self.reset_cache()