t/moe/config.py

   1 #!/usr/bin/env python
   2
   3 import re
   4 import sys
   5 import moe
   6
   7 key_pattern = re.compile("^[A-Za-z0-9_-]+$")
   8 ref_pattern = re.compile("^[A-Za-z0-9_-]+")
   9
  10 class MoeConfigInvalid(moe.MoeErr):
  11     pass
  12
  13 class MoeConfigEvalErr(moe.MoeErr):
  14     pass
  15
  16 class MoeConfig:
  17     """Moe configuration file. Should be immutable once a part of a stack."""
  18
  19     def __init__(self, file=None, name=None, type="<unnamed>"):
  20         self.vars = {}
  21         self.type = type
  22         if file is not None:
  23             self.load(file)
  24         elif name is not None:
  25             self.name = name
  26             try:
  27                 file = open(name, "r")
  28             except IOError, err:
  29                 raise MoeConfigInvalid, "Cannot open configuration file %s: %s" % (name, err.strerror)
  30             else:
  31                 self.load(file)
  32
  33     def set(self, k, v):
  34         self.vars[k] = [("s", v)]
  35
  36     def parse_line(self, x):
  37         x = x.rstrip("\n").lstrip(" \t")
  38         if x=="" or x.startswith("#"):
  39             pass
  40         else:
  41             sep = x.find("=")
  42             if sep >= 0:
  43                 k = x[:sep]
  44                 v = x[sep+1:]
  45                 if k.endswith("+"):
  46                     k = k[:-1]
  47                     if not self.vars.has_key(k):
  48                         self.vars[k] = [("a","")];
  49                 else:
  50                     self.vars[k] = []
  51                 if not key_pattern.match(k):
  52                     raise MoeConfigInvalid, "Malformed name of configuration variable"
  53                 if v.startswith("'"):
  54                     v=v[1:]
  55                     if not v.endswith("'"):
  56                         raise MoeConfigInvalid, "Misquoted string"
  57                     self.vars[k].append(("s", v[:-1]))
  58                 elif v.startswith('"'):
  59                     v=v[1:]
  60                     if not v.endswith('"'):
  61                         raise MoeConfigInvalid, "Misquoted string"
  62                     self.parse_interpolated(self.vars[k], v[:-1])
  63                 else:
  64                     self.parse_interpolated(self.vars[k], v)
  65             else:
  66                 raise MoeConfigInvalid, "Parse error"
  67
  68     def load(self, file):
  69         lino = 0
  70         for x in file.readlines():
  71             lino += 1
  72             try:
  73                 self.parse_line(x)
  74             except MoeConfigInvalid, x:
  75                 msg = x.message + " at line " + str(lino)
  76                 if hasattr(self, "name"):
  77                     msg += " of " + self.name
  78                 raise MoeConfigInvalid, msg
  79
  80     def parse_interpolated(self, list, s):
  81         while s<>"":
  82             if s.startswith("$"):
  83                 s = s[1:]
  84                 if s.startswith("{"):
  85                     p = s.find("}")
  86                     if not p:
  87                         raise MoeConfigInvalid, "Unbalanced braces"
  88                     k, s = s[1:p], s[p+1:]
  89                     if not key_pattern.match(k):
  90                         raise MoeConfigInvalid, "Invalid variable name"
  91                 else:
  92                     m = ref_pattern.match(s)
  93                     if m:
  94                         k, s = s[:m.end()], s[m.end():]
  95                     else:
  96                         raise MoeConfigInvalid, "Invalid variable reference"
  97                 list.append(("i", k))
  98             else:
  99                 p = s.find("$")
 100                 if p < 0:
 101                     p = len(s)
 102                 list.append(("s", s[:p]))
 103                 s = s[p:]
 104
 105     def dump(self, file=sys.stdout, prefix=""):
 106         for k,v in self.vars.items():
 107             file.write(prefix)
 108             file.write(k)
 109             if len(v) > 0 and v[0][0] == "a":
 110                 file.write("+")
 111                 v = v[1:]
 112             file.write("=")
 113             for t,w in v:
 114                 if t == "s":
 115                     file.write("'" + w + "'")
 116                 elif t == "i":
 117                     file.write('"$' + w + '"')
 118             file.write("\n")
 119
 120 class MoeConfigStack:
 121     """Stack of configuration files."""
 122
 123     def __init__(self, base=None):
 124         ## FIXME: Do we need to duplicate the config files themselves?
 125         if base:
 126             self.stk = base.stk[:]
 127         else:
 128             self.stk = []
 129         self.in_progress = {}
 130         self.reset_cache()
 131
 132     def reset_cache(self):
 133         self.cache = {}
 134
 135     def push(self, cfg):
 136         self.stk.append(cfg)
 137         self.reset_cache()
 138
 139     def __getitem__(self, k):
 140         if self.cache.has_key(k):
 141             return self.cache[k]
 142         if self.in_progress.has_key(k):
 143             raise MoeConfigEvalErr, "Definition of $%s is recursive" % k;
 144         self.in_progress[k] = 1;
 145         v = self.do_get(k, len(self.stk)-1)
 146         del self.in_progress[k]
 147         ## FIXME: This is disabled, because the immutability invariant is broken!
 148         # self.cache[k] = v
 149         return v
 150
 151     def do_get(self, k, pos):
 152         while pos >= 0:
 153             cfg = self.stk[pos]
 154             if cfg.vars.has_key(k):
 155                 new = cfg.vars[k]
 156                 if len(new) > 0 and new[0][0] == "a":
 157                     v = self.do_get(k, pos-1)
 158                 else:
 159                     v = ""
 160                 for op,arg in new:
 161                     if op == "s":
 162                         v = v + arg
 163                     elif op == "i":
 164                         v = v + self[arg]
 165                 return v
 166             pos -= 1
 167         return ""
 168
 169     def keys(self):
 170         seen = {}
 171         for cfg in self.stk:
 172             for k in cfg.vars.keys():
 173                 seen[k] = None
 174         return seen.keys()
 175
 176     def dump(self, file=sys.stdout, prefix=""):
 177         for k in sorted(self.keys()):
 178             v = self[k]
 179             file.write("%s%s=%s\n" % (prefix,k,v))
 180
 181     def dump_defs(self, file=sys.stdout, prefix=""):
 182         level = 0
 183         for cfg in self.stk:
 184             level += 1
 185             file.write("%s(level %d: %s)\n" % (prefix,level,cfg.type))
 186             cfg.dump(file, prefix + "\t")
 187         file.write("%s(end)\n" % prefix)
 188
 189     def apply_overrides(self, prefix):
 190         newstk = []
 191         for cfg in self.stk:
 192             over = MoeConfig(type = cfg.type + '-overrides')
 193             changed = False
 194             for k in cfg.vars.keys():
 195                 if k.startswith(prefix):
 196                     over.vars[k[len(prefix):]] = cfg.vars[k]
 197                     changed = True
 198             if changed:
 199                 clean = MoeConfig(type = cfg.type)
 200                 for k in cfg.vars.keys():
 201                     if not k.startswith(prefix):
 202                         clean.vars[k] = cfg.vars[k]
 203                 newstk.append(clean)
 204                 newstk.append(over)
 205             else:
 206                 newstk.append(cfg)
 207         self.stk = newstk
 208         self.reset_cache()
 209
 210 def parse_overrides(argv):
 211     cfg = None
 212     argv0 = argv.pop(0)
 213     while len(argv) > 0 and argv[0].find("=") >= 0:
 214         if cfg is None:
 215             cfg = MoeConfig(type='cmdline')
 216         cfg.parse_line(argv.pop(0))
 217     argv.insert(0, argv0)
 218     return cfg