From 4574d9c6b1e2e9425f1919233a03a123b38a5e70 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Sat, 8 Aug 2009 16:23:44 +0200
Subject: [PATCH] Added a prototype of the configuration module.

---
 t/moe/config.py | 131 ++++++++++++++++++++++++++++++++++++++++++++++--
 t/test.py       |  19 +++++--
 2 files changed, 143 insertions(+), 7 deletions(-)

diff --git a/t/moe/config.py b/t/moe/config.py
index 3075d80..3280283 100644
--- a/t/moe/config.py
+++ b/t/moe/config.py
@@ -1,13 +1,136 @@
 #!/usr/bin/env python
 
+import re
+import sys
+
+key_pattern = re.compile('^[A-Za-z0-9_-]+$')
+ref_pattern = re.compile('^[A-Za-z0-9_-]+')
+
+class MoeConfigInvalid(Exception):
+    pass
+
+class MoeConfigEvalErr(Exception):
+    pass
+
 class MoeConfig:
     """Moe configuration file."""
 
-    def __init__(self):
-        cfg = { 'XYZZY' : 'brum' }
+    def __init__(self, file=None, name=None):
+        self.cfg = {}
+	if file is not None:
+	    self.load(file)
+	elif name is not None:
+	    self.load(open(name, 'r'))
+
+    def load(self, file):
+	for x in file.readlines():
+	    x = x.rstrip("\n").lstrip(" \t")
+	    if x=='' or x.startswith('#'):
+		pass
+	    else:
+		sep = x.find('=')
+		if sep >= 0:
+		    k = x[:sep]
+		    v = x[sep+1:]
+		    if k.endswith("+"):
+			k = k[:-1]
+			if not self.cfg.has_key(k):
+			    self.cfg[k] = [('a','')];
+		    else:
+		        self.cfg[k] = []
+		    if not key_pattern.match(k):
+		    	raise MoeConfigInvalid, "Malformed name of configuration variable"
+		    if v.startswith("'"):
+		        v=v[1:]
+			if not v.endswith("'"):
+			    raise MoeConfigInvalid, "Misquoted string"
+			self.cfg[k].append(('s', v[:-1]))
+		    elif v.startswith('"'):
+		        v=v[1:]
+			if not v.endswith('"'):
+			    raise MoeConfigInvalid, "Misquoted string"
+			self.parse_interpolated(self.cfg[k], v[:-1])
+		    else:
+		    	self.cfg[k].append(('s', v))
+		else:
+		    ## FIXME: Report line numbers
+		    raise MoeConfigInvalid, "Parse error"
+
+    def parse_interpolated(self, list, s):
+        while s<>'':
+	    if s.startswith('$'):
+	        s = s[1:]
+		if s.startswith('{'):
+		    p = s.find('}')
+		    if not p:
+		    	raise MoeConfigInvalid, "Unbalanced braces"
+		    k, s = s[1:p], s[p+1:]
+		    if not key_pattern.match(k):
+		        raise MoeConfigInvalid, "Invalid variable name"
+		else:
+		    m = ref_pattern.match(s)
+		    if m:
+		        k, s = s[:m.end()], s[m.end():]
+		    else:
+			raise MoeConfigInvalid, "Invalid variable reference"
+		list.append(('i', k))
+	    else:
+	        p = s.find('$')
+		if p < 0:
+		    p = len(s)
+		list.append(('s', s[:p]))
+		s = s[p:]
+
+    def dump(self, file=sys.stdout):
+        for k,v in self.cfg.items():
+	    file.write(k)
+	    if len(v) > 0 and v[0][0] == 'a':
+	        file.write('+')
+		v = v[1:]
+	    file.write('=')
+	    for t,w in v:
+	        if t == 's':
+		    file.write("'" + w + "'")
+		elif t == 'i':
+		    file.write('"$' + w + '"')
+	    file.write("\n")
 
 class MoeConfigStack:
     """Stack of configuration files."""
 
-    def __init__(self):
-        stk = []
+    def __init__(self, base=None):
+    	## FIXME: Do we need to duplicate the config files themselves?
+        if base:
+	    self.stk = base.stk[:]
+	else:
+	    self.stk = []
+	self.in_progress = {}
+
+    def push(self, cfg):
+    	self.stk.append(cfg)
+
+    def __getitem__(self, k):
+        if self.in_progress.has_key(k):
+	    raise MoeConfigEvalErr, "Definition of $%s is recursive" % k;
+	self.in_progress[k] = 1;
+        v = self.do_get(k, len(self.stk)-1)
+	del self.in_progress[k]
+	return v
+
+    def do_get(self, k, pos):
+        while pos >= 0:
+	    cfg = self.stk[pos]
+	    if cfg.cfg.has_key(k):
+		new = cfg.cfg[k]
+		if new[0][0] == 'a':
+		    v = self.do_get(k, pos-1)
+		else:
+		    v = ''
+		for op,arg in new:
+		    if op == 's':
+			v = v + arg
+		    elif op == 'i':
+			v = v + self[arg]
+		return v
+	    pos -= 1
+	return ''
diff --git a/t/test.py b/t/test.py
index e928214..2460a21 100755
--- a/t/test.py
+++ b/t/test.py
@@ -4,7 +4,20 @@ import sys
 sys.path.append('.')
 
 import moe.meta
+import moe.config
 
-m = moe.meta.MoeMeta()
-m['a'] = '1'
-m.write()
+#m = moe.meta.MoeMeta()
+#m['a'] = '1'
+#m.write()
+
+c = moe.config.MoeConfig(name='/dev/stdin')
+c.dump()
+
+d = moe.config.MoeConfig(name='/dev/stdin')
+d.dump()
+
+s = moe.config.MoeConfigStack()
+s.push(c)
+s.push(d)
+
+print s['a']
-- 
2.39.5