Use bisect to speed up finding the best fit

qrcode/main.py

@@ -112,16 +112,10 @@ def best_fit(self, start=None):
         """
         Find the minimum size required to fit in the data.
         """
-        size = start or 1
-        while True:
-            try:
-                self.data_cache = util.create_data(
-                    size, self.error_correction, self.data_list)
-            except exceptions.DataOverflowError:
-                size += 1
-            else:
-                self.version = size
-                return size
+        self.data_cache, self.version = (
+            util.BestFit(self.error_correction, self.data_list)
+            .data_and_version(start))
+        return self.version
 
     def best_mask_pattern(self):
         """

qrcode/util.py

@@ -1,3 +1,4 @@
+from bisect import bisect
 import re
 import math
 
@@ -533,3 +534,31 @@ def create_data(version, error_correction, data_list):
             buffer.put(PAD1, 8)
 
     return create_bytes(buffer, rs_blocks)
+
+
+class BestFit(object):
+
+    def __init__(self, error_correction, data_list):
+        self.error_correction = error_correction
+        self.data_list = data_list
+        self.iterations = 0
+
+    def data_and_version(self, start=None):
+        if not start:
+            start = 1
+        version = bisect(self, 0, start, 41)
+        if version == 41:
+            raise exceptions.DataOverflowError()
+        return self.data_cache, version
+
+    def __getitem__(self, size):
+        """
+        Returns 0 if it overflowed, 1 if it fit.
+        """
+        self.iterations += 1
+        try:
+            self.data_cache = create_data(
+                size, self.error_correction, self.data_list)
+        except exceptions.DataOverflowError:
+            return 0
+        return 1