feat(cfn): add plugin

jc/parsers/cfn.py

@@ -0,0 +1,206 @@
+r"""
+jc - JSON Convert `CloudFormation` file parser
+
+> Note: `datetime` objects will be converted to strings.
+
+Usage (cli):
+
+    $ cat template.yaml | jc --cfn
+
+Usage (module):
+
+    import jc
+    result = jc.parse('cfn', yaml_file_output)
+
+Schema:
+
+YAML Document converted to a Dictionary.
+See https://pypi.org/project/ruamel.yaml for details.
+
+    [
+      {
+        "key1":     string/int/float/boolean/null/array/object,
+        "key2":     string/int/float/boolean/null/array/object
+      }
+    ]
+
+Examples:
+
+    $ cat template.yaml
+    AWSTemplateFormatVersion: "2010-09-09"
+    Parameters:
+      EnvType:
+        Type: "String"
+        Default: "test"
+    Conditions:
+      CreateProdResources: !Equals [ !Ref EnvType, prod ]
+    Resources:
+      MyInstance:
+        Type: "AWS::EC2::Instance"
+        Properties:
+          ImageId: "ami-1234567890abcdefg"
+          InstanceType: "t2.micro"
+
+
+    $ cat template.yaml | jc --cfn -p
+    [
+      {
+        "AWSTemplateFormatVersion": "2010-09-09",
+        "Parameters": {
+          "EnvType": {
+            "Type": "String",
+            "Default": "test"
+          }
+        },
+        "Conditions": {
+          "CreateProdResources": [
+            "EnvType",
+            "prod"
+          ]
+        },
+        "Resources": {
+          "MyInstance": {
+            "Type": "AWS::EC2::Instance",
+            "Properties": {
+              "ImageId": "ami-1234567890abcdefg",
+              "InstanceType": "t2.micro"
+            }
+          }
+        }
+      }
+    ]
+"""
+from dataclasses import dataclass
+from enum import Enum
+from typing import List
+import jc.utils
+from jc.exceptions import LibraryNotInstalled
+
+
+class info():
+    """Provides parser metadata (version, author, etc.)"""
+    version = '1.7'
+    description = 'YAML file parser'
+    author = 'Ron Green'
+    author_email = '[email protected]'
+    details = 'Using the ruamel.yaml library at https://pypi.org/project/ruamel.yaml'
+    compatible = ['linux', 'darwin', 'cygwin', 'win32', 'aix', 'freebsd']
+    tags = ['standard', 'file', 'string']
+
+
+__version__ = info.version
+
+
+def _process(proc_data):
+    """
+    Final processing to conform to the schema.
+
+    Parameters:
+
+        proc_data:   (List of Dictionaries) raw structured data to process
+
+    Returns:
+
+        List of Dictionaries. Each dictionary represents a YAML document.
+    """
+
+    # No further processing
+    return proc_data
+
+class Option(Enum):
+    scalar = 1
+    sequence = 2
+    mapping = 3
+
+
+@dataclass
+class CustomTag:
+    name: str
+    options: List[Option]
+
+
+custom_tags = [
+    CustomTag(name='!And', options=[Option.sequence]),
+    CustomTag(name='!Base64', options=[Option.scalar]),
+    CustomTag(name='!Cidr', options=[Option.scalar]),
+    CustomTag(name='!Condition', options=[Option.scalar]),
+    CustomTag(name='!Equals', options=[Option.scalar, Option.sequence]),
+    CustomTag(name='!FindInMap', options=[Option.sequence]),
+    CustomTag(name='!GetAZs', options=[Option.scalar]),
+    CustomTag(name='!GetAtt', options=[Option.scalar]),  # , Option.sequence]),
+    CustomTag(name='!If', options=[Option.sequence]),
+    CustomTag(name='!ImportValue', options=[Option.scalar]),
+    CustomTag(name='!Join', options=[Option.sequence]),
+    CustomTag(name='!Not', options=[Option.sequence]),
+    CustomTag(name='!Or', options=[Option.sequence]),
+    CustomTag(name='!Ref', options=[Option.scalar]),
+    CustomTag(name='!Select', options=[Option.sequence]),
+    CustomTag(name='!Split', options=[Option.sequence]),
+    CustomTag(name='!Sub', options=[Option.scalar]),
+    CustomTag(name='!Transform', options=[Option.mapping]),
+]
+
+
+def parse(data, raw=False, quiet=False):
+    """
+    Main text parsing function
+
+    Parameters:
+
+        data:        (string)  text data to parse
+        raw:         (boolean) unprocessed output if True
+        quiet:       (boolean) suppress warning messages if True
+
+    Returns:
+
+        List of Dictionaries representing the YAML documents.
+    """
+    # check if yaml library is installed and fail gracefully if it is not
+    try:
+        from ruamel.yaml import YAML
+        from ruamel.yaml.constructor import SafeConstructor
+
+    except Exception:
+        raise LibraryNotInstalled('The ruamel.yaml library is not installed.')
+
+    jc.utils.compatibility(__name__, info.compatible, quiet)
+    jc.utils.input_type_check(data)
+
+    raw_output = []
+
+    if jc.utils.has_data(data):
+
+        # monkey patch to disable plugins since we don't use them and in
+        # ruamel.yaml versions prior to 0.17.0 the use of __file__ in the
+        # plugin code is incompatible with the pyoxidizer packager
+        YAML.official_plug_ins = lambda a: []
+
+        yaml = YAML(typ='safe')
+        for custom_tag in custom_tags:
+          for option in custom_tag.options:
+              if option == Option.mapping:
+                yaml.constructor.add_constructor(custom_tag.name, lambda loader, node: loader.construct_mapping(node))
+                continue
+              if option == Option.sequence:
+                  yaml.constructor.add_constructor(custom_tag.name, lambda loader, node: loader.construct_sequence(node))
+                  continue
+              if option == Option.scalar:
+                  yaml.constructor.add_constructor(custom_tag.name, lambda loader, node: loader.construct_scalar(node))
+                  continue
+
+        # yaml.Constructor = SafeConstructor
+        # modify the timestamp constructor to output datetime objects as
+        # strings since JSON does not support datetime objects
+        yaml.constructor.yaml_constructors['tag:yaml.org,2002:timestamp'] = \
+            yaml.constructor.yaml_constructors['tag:yaml.org,2002:str']
+
+
+
+
+        for document in yaml.load_all(data):
+            raw_output.append(document)
+
+    if raw:
+        return raw_output
+    else:
+        return _process(raw_output)