Refactors to_bytes

The original logic was not intuitive.
Changed the code for better readability.

Change-Id: I0d96105d4ff22eed827ed61466a26f69f33addd1

1 files changed, 23 insertions, 21 deletions

diff --git a/openstack/common/strutils.py b/openstack/common/strutils.py
index 05c178c..a3fb53a 100644
--- a/openstack/common/strutils.py
+++ b/openstack/common/strutils.py
@@ -35,7 +35,7 @@ BYTE_MULTIPLIERS = {
     'm': 1024 ** 2,
     'k': 1024,
 }
-
+BYTE_REGEX = re.compile(r'(^-?\d+)(\D*)')
 
 TRUE_STRINGS = ('1', 't', 'true', 'on', 'y', 'yes')
 FALSE_STRINGS = ('0', 'f', 'false', 'off', 'n', 'no')
@@ -162,31 +162,33 @@ def safe_encode(text, incoming=None,
 
 
 def to_bytes(text, default=0):
-    """Try to turn a string into a number of bytes. Looks at the last
-    characters of the text to determine what conversion is needed to
-    turn the input text into a byte number.
+    """Converts a string into an integer of bytes.
+
+    Looks at the last characters of the text to determine
+    what conversion is needed to turn the input text into a byte number.
+    Supports "B, K(B), M(B), G(B), and T(B)". (case insensitive)
 
-    Supports: B/b, K/k, M/m, G/g, T/t (or the same with b/B on the end)
+    :param text: String input for bytes size conversion.
+    :param default: Default return value when text is blank.
 
     """
-    # Take off everything not number 'like' (which should leave
-    # only the byte 'identifier' left)
-    mult_key_org = text.lstrip('-1234567890')
-    mult_key = mult_key_org.lower()
-    mult_key_len = len(mult_key)
-    if mult_key.endswith("b"):
-        mult_key = mult_key[0:-1]
-    try:
-        multiplier = BYTE_MULTIPLIERS[mult_key]
-        if mult_key_len:
-            # Empty cases shouldn't cause text[0:-0]
-            text = text[0:-mult_key_len]
-        return int(text) * multiplier
-    except KeyError:
-        msg = _('Unknown byte multiplier: %s') % mult_key_org
+    match = BYTE_REGEX.search(text)
+    if match:
+        magnitude = int(match.group(1))
+        mult_key_org = match.group(2)
+        if not mult_key_org:
+            return magnitude
+    elif text:
+        msg = _('Invalid string format: %s') % text
         raise TypeError(msg)
-    except ValueError:
+    else:
         return default
+    mult_key = mult_key_org.lower().replace('b', '', 1)
+    multiplier = BYTE_MULTIPLIERS.get(mult_key)
+    if multiplier is None:
+        msg = _('Unknown byte multiplier: %s') % mult_key_org
+        raise TypeError(msg)
+    return magnitude * multiplier
 
 
 def to_slug(value, incoming=None, errors="strict"):