--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/piecrust/configuration.py	Sat Dec 21 14:44:02 2013 -0800
@@ -0,0 +1,106 @@
+import re
+import yaml
+
+
+class Configuration(object):
+    def __init__(self, values=None, validate=True):
+        self._values = {}
+        if values is not None:
+            self.set_all(values, validate)
+
+    def set_all(self, values, validate=True):
+        if validate:
+            self._validateAll(values)
+        self._values = values
+
+    def get(self, key_path=None):
+        self._ensureLoaded()
+        if key_path is None:
+            return self._values
+        bits = key_path.split('/')
+        cur = self._values
+        for b in bits:
+            cur = cur.get(b)
+            if cur is None:
+                return None
+        return cur
+
+    def set(self, key_path, value):
+        self._ensureLoaded()
+        value = self._validateValue(key_path, value)
+        bits = key_path.split('/')
+        bitslen = len(bits)
+        cur = self._values
+        for i, b in enumerate(bits):
+            if i == bitslen - 1:
+                cur[b] = value
+            else:
+                if b not in cur:
+                    cur[b] = {}
+                cur = cur[b]
+
+    def has(self, key_path):
+        self._ensureLoaded()
+        bits = key_path.split('/')
+        cur = self._values
+        for b in bits:
+            cur = cur.get(b)
+            if cur is None:
+                return False
+        return True
+
+    def merge(self, other):
+        self._ensureLoaded()
+        merge_dicts(self._values, other._values,
+                validator=self._validateValue)
+
+    def _ensureLoaded(self):
+        if self._values is None:
+            self._load()
+
+    def _load(self):
+        self._values = self._validateAll({})
+
+    def _validateAll(self, values):
+        return values
+
+    def _validateValue(self, key_path, value):
+        return value
+
+
+def merge_dicts(local_cur, incoming_cur, parent_path=None, validator=None):
+    if validator is None:
+        validator = lambda k, v: v
+
+    for k, v in incoming_cur.iteritems():
+        key_path = k
+        if parent_path is not None:
+            key_path = parent_path + '/' + k
+
+        local_v = local_cur.get(k)
+        if local_v is not None:
+            if isinstance(v, dict) and isinstance(local_v, dict):
+                local_cur[k] = merge_dicts(local_v, v)
+            elif isinstance(v, list) and isinstance(local_v, list):
+                local_cur[k] = v + local_v
+            else:
+                local_cur[k] = validator(key_path, v)
+        else:
+            local_cur[k] = validator(key_path, v)
+
+
+header_regex = re.compile(
+        r'(---\s*\n)(?P<header>(.*\n)*?)^(---\s*\n)', re.MULTILINE)
+
+
+def parse_config_header(text):
+    m = header_regex.match(text)
+    if m is not None:
+        header = unicode(m.group('header'))
+        config = yaml.safe_load(header)
+        offset = m.end()
+    else:
+        config = {}
+        offset = 0
+    return config, offset
+