Move arcz_to_arcs to misc so we can use it elsewhere

1 files changed, 39 insertions, 0 deletions

diff --git a/coverage/misc.py b/coverage/misc.py
index d87a7b89..ad7b834f 100644
--- a/coverage/misc.py
+++ b/coverage/misc.py
@@ -281,6 +281,45 @@ def substitute_variables(text, variables=os.environ):
     return text
 
 
+# Map chars to numbers for arcz_to_arcs
+_arcz_map = {'.': -1}
+_arcz_map.update(dict((c, ord(c) - ord('0')) for c in '123456789'))
+_arcz_map.update(dict(
+    (c, 10 + ord(c) - ord('A')) for c in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+))
+
+def arcz_to_arcs(arcz):
+    """Convert a compact textual representation of arcs to a list of pairs.
+
+    The text has space-separated pairs of letters.  Period is -1, 1-9 are
+    1-9, A-Z are 10 through 36.  The resulting list is sorted regardless of
+    the order of the input pairs.
+
+    ".1 12 2." --> [(-1,1), (1,2), (2,-1)]
+
+    Minus signs can be included in the pairs:
+
+    "-11, 12, 2-5" --> [(-1,1), (1,2), (2,-5)]
+
+    """
+    arcs = []
+    for pair in arcz.split():
+        asgn = bsgn = 1
+        if len(pair) == 2:
+            a, b = pair
+        else:
+            assert len(pair) == 3
+            if pair[0] == '-':
+                _, a, b = pair
+                asgn = -1
+            else:
+                assert pair[1] == '-'
+                a, _, b = pair
+                bsgn = -1
+        arcs.append((asgn * _arcz_map[a], bsgn * _arcz_map[b]))
+    return sorted(arcs)
+
+
 class BaseCoverageException(Exception):
     """The base of all Coverage exceptions."""
     pass