Added cli_serializer & from_cli function (#311)

* Added cli_serializer & from_cli function

* Removed cli serializer exit_on_error option

* Invalid arg test, static CLISerializer func & vars

Author: Denperidge

benedict/dicts/io/io_dict.py

@@ -173,6 +173,16 @@ def from_yaml(cls, s, **kwargs):
         """
         return cls(s, format="yaml", **kwargs)
 
+    @classmethod
+    def from_cli(cls, s, **kwargs):
+        """
+        Load and decode data from a string of CLI arguments.
+        ArgumentParser specific options can be passed using kwargs:
+        https://docs.python.org/3/library/argparse.html#argparse.ArgumentParser
+        Return a new dict instance. A ValueError is raised in case of failure.
+        """
+        return cls(s, format="cli", **kwargs)
+
     def to_base64(self, subformat="json", encoding="utf-8", **kwargs):
         """
         Encode the current dict instance in Base64 format

benedict/serializers/__init__.py

@@ -2,6 +2,7 @@
 
 from benedict.serializers.abstract import AbstractSerializer
 from benedict.serializers.base64 import Base64Serializer
+from benedict.serializers.cli import CLISerializer
 from benedict.serializers.csv import CSVSerializer
 from benedict.serializers.ini import INISerializer
 from benedict.serializers.json import JSONSerializer
@@ -16,6 +17,7 @@
 __all__ = [
     "AbstractSerializer",
     "Base64Serializer",
+    "CLISerializer",
     "CSVSerializer",
     "INISerializer",
     "JSONSerializer",
@@ -29,6 +31,7 @@
 ]
 
 _BASE64_SERIALIZER = Base64Serializer()
+_CLI_SERIALIZER = CLISerializer()
 _CSV_SERIALIZER = CSVSerializer()
 _INI_SERIALIZER = INISerializer()
 _JSON_SERIALIZER = JSONSerializer()
@@ -42,6 +45,7 @@
 
 _SERIALIZERS_LIST = [
     _BASE64_SERIALIZER,
+    _CLI_SERIALIZER,
     _CSV_SERIALIZER,
     _INI_SERIALIZER,
     _JSON_SERIALIZER,

benedict/serializers/cli.py

@@ -0,0 +1,104 @@
+from argparse import ArgumentError, ArgumentParser
+from collections import Counter
+from re import finditer
+
+from benedict.serializers.abstract import AbstractSerializer
+from benedict.utils import type_util
+
+
+class CLISerializer(AbstractSerializer):
+    """
+    This class describes a CLI serializer.
+    """
+
+    regex_keys_with_values = r"-+\w+(?=\s[^\s-])"
+    """
+    Regex string.
+    Used to search for keys (e.g. -STRING or --STRING)
+    that *aren't* followed by another key
+
+    Example input: script.py --username example --verbose -d -e [email protected]
+    - Matches: --username, -e
+    - Doesn't match: script.py, example, --verbose, -d, [email protected]
+    """
+
+    regex_all_keys = r"-+\w+"
+    """
+    Regex string.
+    Used to search for keys (e.g. -STRING or --STRING)
+    no matter if they are followed by another key
+
+    Example input: script.py --username example --verbose -d -e [email protected]
+    - Matches: --username, --verbose, -d, -e
+    - Doesn't match: script.py, example, [email protected]
+    """
+
+    def __init__(self):
+        super().__init__(
+            extensions=["cli"],
+        )
+
+    @staticmethod
+    def parse_keys(regex, string):
+        # For some reason findall didn't work
+        results = [match.group(0) for match in finditer(regex, string)]
+        return results
+
+    """Helper method, returns a list of --keys based on the regex used"""
+
+    @staticmethod
+    def _get_parser(options):
+        parser = ArgumentParser(**options)
+        return parser
+
+    def decode(self, s=None, **kwargs):
+        parser = self._get_parser(options=kwargs)
+
+        keys_with_values = set(self.parse_keys(self.regex_keys_with_values, s))
+        all_keys = Counter(self.parse_keys(self.regex_all_keys, s))
+        for key in all_keys:
+            count = all_keys[key]
+
+            try:
+                # If the key has a value...
+                if key in keys_with_values:
+                    # and is defined once, collect the values
+                    if count == 1:
+                        parser.add_argument(
+                            key,
+                            nargs="*",
+                            # This puts multiple values in a list
+                            # even though this won't always be wanted
+                            # This is adressed after the dict is generated
+                            required=False,
+                        )
+                    # and is defined multiple times, collect the values
+                    else:
+                        parser.add_argument(key, action="append", required=False)
+
+                # If the key doesn't have a value...
+                else:
+                    # and is defined once, store as bool
+                    if count <= 1:
+                        parser.add_argument(key, action="store_true", required=False)
+                    # and is defined multiple times, count how many times
+                    else:
+                        parser.add_argument(key, action="count", required=False)
+
+            except ArgumentError as error:
+                raise ValueError from error
+
+        try:
+            args = parser.parse_args(s.split())
+        except BaseException as error:
+            raise ValueError from error
+
+        dict = vars(args)
+        for key in dict:
+            value = dict[key]
+            # If only one value was written,
+            # return that value instead of a list
+            if type_util.is_list(value) and len(value) == 1:
+                dict[key] = value[0]
+
+        return dict

tests/dicts/io/test_io_dict_cli.py

@@ -0,0 +1,47 @@
+from benedict.dicts.io import IODict
+
+from .test_io_dict import io_dict_test_case
+
+
+class io_dict_cli_test_case(io_dict_test_case):
+    """
+    This class describes an IODict / cli test case.
+    """
+
+    def test_from_cli_with_valid_data(self):
+        s = """--url "https://github.com" --usernames another handle --languages Python --languages JavaScript -v --count --count --count"""
+        # static method
+        r = {
+            "url": '"https://github.com"',
+            "usernames": ["another", "handle"],
+            "languages": ["Python", "JavaScript"],
+            "v": True,
+            "count": 3,
+        }
+
+        d = IODict.from_cli(s)
+        self.assertTrue(isinstance(d, dict))
+        self.assertEqual(d, r)
+        # constructor
+        d = IODict(s, format="cli")
+        self.assertTrue(isinstance(d, dict))
+        self.assertEqual(d, r)
+
+    def test_from_cli_with_invalid_arguments(self):
+        s = """--help -h"""
+
+        # static method
+        with self.assertRaises(ValueError):
+            IODict.from_cli(s)
+        # constructor
+        with self.assertRaises(ValueError):
+            IODict(s, format="cli")
+
+    def test_from_cli_with_invalid_data(self):
+        s = "Lorem ipsum est in ea occaecat nisi officia."
+        # static method
+        with self.assertRaises(ValueError):
+            IODict.from_cli(s)
+        # constructor
+        with self.assertRaises(ValueError):
+            IODict(s, format="cli")