1 files changed, 55 insertions, 14 deletions
diff --git a/coverage/misc.py b/coverage/misc.py
index 28aa3b06..a923829d 100644
--- a/coverage/misc.py
+++ b/coverage/misc.py
@@ -1,5 +1,5 @@
 # Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
-# For details: https://bitbucket.org/ned/coveragepy/src/default/NOTICE.txt
+# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
 
 """Miscellaneous stuff for coverage.py."""
 
@@ -8,6 +8,7 @@ import hashlib
 import inspect
 import locale
 import os
+import re
 import sys
 import types
 
@@ -69,11 +70,11 @@ if env.TESTING:
         """Ensure that only one of the argnames is non-None."""
         def _decorator(func):
             argnameset = set(name.strip() for name in argnames.split(","))
-            def _wrapped(*args, **kwargs):
+            def _wrapper(*args, **kwargs):
                 vals = [kwargs.get(name) for name in argnameset]
                 assert sum(val is not None for val in vals) == 1
                 return func(*args, **kwargs)
-            return _wrapped
+            return _wrapper
         return _decorator
 else:                                           # pragma: not testing
     # We aren't using real PyContracts, so just define our decorators as
@@ -148,13 +149,12 @@ def expensive(fn):
     if env.TESTING:
         attr = "_once_" + fn.__name__
 
-        def _wrapped(self):
-            """Inner function that checks the cache."""
+        def _wrapper(self):
             if hasattr(self, attr):
                 raise AssertionError("Shouldn't have called %s more than once" % fn.__name__)
             setattr(self, attr, True)
             return fn(self)
-        return _wrapped
+        return _wrapper
     else:
         return fn                   # pragma: not testing
 
@@ -226,6 +226,7 @@ class Hasher(object):
                     continue
                 self.update(k)
                 self.update(a)
+        self.md5.update(b'.')
 
     def hexdigest(self):
         """Retrieve the hex digest of the hash."""
@@ -249,14 +250,54 @@ def _needs_to_implement(that, func_name):
         )
 
 
-class SimpleRepr(object):
-    """A mixin implementing a simple __repr__."""
-    def __repr__(self):
-        return "<{klass} @{id:x} {attrs}>".format(
-            klass=self.__class__.__name__,
-            id=id(self) & 0xFFFFFF,
-            attrs=" ".join("{}={!r}".format(k, v) for k, v in self.__dict__.items()),
-            )
+def substitute_variables(text, variables=os.environ):
+    """Substitute ``${VAR}`` variables in `text` with their values.
+
+    Variables in the text can take a number of shell-inspired forms::
+
+        $VAR
+        ${VAR}
+        ${VAR?}             strict: an error if VAR isn't defined.
+        ${VAR-missing}      defaulted: "missing" if VAR isn't defined.
+
+    A dollar can be inserted with ``$$``.
+
+    `variables` is a dictionary of variable values, defaulting to the
+    environment variables.
+
+    Returns the resulting text with values substituted.
+
+    """
+    def dollar_replace(m):
+        """Called for each $replacement."""
+        # Only one of the groups will have matched, just get its text.
+        word = ''.join(m.group(name) or '' for name in ['v1', 'v2', 'char'])
+        if word == "$":
+            return "$"
+        else:
+            strict = bool(m.group('strict'))
+            if strict:
+                if word not in variables:
+                    msg = "Variable {} is undefined: {}".format(word, text)
+                    raise CoverageException(msg)
+            return variables.get(word, m.group('defval') or '')
+
+    dollar_pattern = r"""(?x)   # Use extended regex syntax
+        \$(?:                   # A dollar sign, then
+        (?P<v1>\w+) |           #   a plain word,
+        (?P<char>\$) |          #   or a dollar sign.
+        {                       #   or a {-wrapped word,
+            (?P<v2>\w+)
+            (?:
+            (?P<strict>\?)      #       with a strict marker
+            |
+            -(?P<defval>[^}]*)  #       or a default value
+            )?
+        }
+        )
+        """
+    text = re.sub(dollar_pattern, dollar_replace, text)
+    return text
 
 
 class BaseCoverageException(Exception):