Reconstruct regexes in generated code

Previously, regexes where being pickled in generated code, which makes
it more difficult to understand and debug.

To improve this situation, this change proposes reconstructing the call
to the `re.compile` function.

Author: abravalheri

fastjsonschema/generator.py

@@ -1,6 +1,5 @@
 from collections import OrderedDict
 import re
-import pickle
 
 from .exceptions import JsonSchemaValueException, JsonSchemaDefinitionException
 from .indent import indent
@@ -101,12 +100,16 @@ def global_state_code(self):
                 '',
                 '',
             ])
+        regex_patterns = (
+            repr(k) + ": " + _repr_regex(v)
+            for k, v in self._compile_regexps.items()
+        )
         return '\n'.join(self._extra_imports_lines + [
-            'import re, pickle',
+            'import re',
             'from fastjsonschema import JsonSchemaValueException',
             '',
             '',
-            'REGEX_PATTERNS = pickle.loads(' + str(pickle.dumps(self._compile_regexps)) + ')',
+            'REGEX_PATTERNS = {\n    ' + ",\n    ".join(regex_patterns) + "\n}",
             '',
         ])
 
@@ -293,3 +296,7 @@ def create_variable_is_dict(self):
             return
         self._variables.add(variable_name)
         self.l('{variable}_is_dict = isinstance({variable}, dict)')
+
+
+def _repr_regex(regex):
+    return "re.compile({!r}, {!r})".format(regex.pattern, regex.flags)