Decouple parser definition from argparse (#1293)

httpie/cli/constants.py

@@ -90,13 +90,19 @@ OUTPUT_OPTIONS = frozenset({
 })
 
 # Pretty
+
+
+class PrettyOptions(enum.Enum):
+    STDOUT_TTY_ONLY = enum.auto()
+
+
 PRETTY_MAP = {
     'all': ['format', 'colors'],
     'colors': ['colors'],
     'format': ['format'],
     'none': []
 }
-PRETTY_STDOUT_TTY_ONLY = object()
+PRETTY_STDOUT_TTY_ONLY = PrettyOptions.STDOUT_TTY_ONLY
 
 
 DEFAULT_FORMAT_OPTIONS = [

httpie/cli/options.py

@@ -0,0 +1,189 @@
+import argparse
+import textwrap
+import typing
+from dataclasses import dataclass, field
+from enum import Enum, auto
+from typing import Any, Optional, Dict, List, Type, TypeVar
+
+from httpie.cli.argparser import HTTPieArgumentParser
+from httpie.cli.utils import LazyChoices
+
+
+class Qualifiers(Enum):
+    OPTIONAL = auto()
+    ZERO_OR_MORE = auto()
+    SUPPRESS = auto()
+
+
+def map_qualifiers(
+    configuration: Dict[str, Any], qualifier_map: Dict[Qualifiers, Any]
+) -> Dict[str, Any]:
+    return {
+        key: qualifier_map[value] if isinstance(value, Qualifiers) else value
+        for key, value in configuration.items()
+    }
+
+
+PARSER_SPEC_VERSION = '0.0.1a0'
+
+
+@dataclass
+class ParserSpec:
+    program: str
+    description: Optional[str] = None
+    epilog: Optional[str] = None
+    groups: List['Group'] = field(default_factory=list)
+
+    def finalize(self) -> 'ParserSpec':
+        if self.description:
+            self.description = textwrap.dedent(self.description)
+        if self.epilog:
+            self.epilog = textwrap.dedent(self.epilog)
+        for group in self.groups:
+            group.finalize()
+        return self
+
+    def add_group(self, name: str, **kwargs) -> 'Group':
+        group = Group(name, **kwargs)
+        self.groups.append(group)
+        return group
+
+    def serialize(self) -> Dict[str, Any]:
+        return {
+            'name': self.program,
+            'description': self.description,
+            'groups': [group.serialize() for group in self.groups],
+        }
+
+
+@dataclass
+class Group:
+    name: str
+    description: str = ''
+    is_mutually_exclusive: bool = False
+    arguments: List['Argument'] = field(default_factory=list)
+
+    def finalize(self) -> None:
+        if self.description:
+            self.description = textwrap.dedent(self.description)
+
+    def add_argument(self, *args, **kwargs):
+        argument = Argument(list(args), kwargs.copy())
+        self.arguments.append(argument)
+        return argument
+
+    def serialize(self) -> Dict[str, Any]:
+        return {
+            'name': self.name,
+            'description': self.description or None,
+            'is_mutually_exclusive': self.is_mutually_exclusive,
+            'args': [argument.serialize() for argument in self.arguments],
+        }
+
+
+class Argument(typing.NamedTuple):
+    aliases: List[str]
+    configuration: Dict[str, Any]
+
+    def serialize(self) -> Dict[str, Any]:
+        configuration = self.configuration.copy()
+
+        # Unpack the dynamically computed choices, since we
+        # will need to store the actual values somewhere.
+        action = configuration.pop('action', None)
+        if action == 'lazy_choices':
+            choices = LazyChoices(self.aliases, **{'dest': None, **configuration})
+            configuration['choices'] = list(choices.load())
+            configuration['help'] = choices.help
+
+        result = {}
+        if self.aliases:
+            result['options'] = self.aliases.copy()
+        else:
+            result['options'] = [configuration['metavar']]
+            result['is_positional'] = True
+
+        qualifiers = JSON_QUALIFIER_TO_OPTIONS[configuration.get('nargs', Qualifiers.SUPPRESS)]
+        result.update(qualifiers)
+
+        help_msg = configuration.get('help')
+        if help_msg and help_msg is not Qualifiers.SUPPRESS:
+            result['description'] = help_msg.strip()
+
+        python_type = configuration.get('type')
+        if python_type is not None:
+            if hasattr(python_type, '__name__'):
+                type_name = python_type.__name__
+            else:
+                type_name = type(python_type).__name__
+
+            result['python_type_name'] = type_name
+
+        result.update({
+            key: value
+            for key, value in configuration.items()
+            if key in JSON_DIRECT_MIRROR_OPTIONS
+        })
+
+        return result
+
+    def __getattr__(self, attribute_name):
+        if attribute_name in self.configuration:
+            return self.configuration[attribute_name]
+        else:
+            raise AttributeError(attribute_name)
+
+
+ParserType = TypeVar('ParserType', bound=Type[argparse.ArgumentParser])
+
+ARGPARSE_QUALIFIER_MAP = {
+    Qualifiers.OPTIONAL: argparse.OPTIONAL,
+    Qualifiers.SUPPRESS: argparse.SUPPRESS,
+    Qualifiers.ZERO_OR_MORE: argparse.ZERO_OR_MORE,
+}
+
+
+def to_argparse(
+    abstract_options: ParserSpec,
+    parser_type: ParserType = HTTPieArgumentParser,
+) -> ParserType:
+    concrete_parser = parser_type(
+        prog=abstract_options.program,
+        description=abstract_options.description,
+        epilog=abstract_options.epilog,
+    )
+    concrete_parser.register('action', 'lazy_choices', LazyChoices)
+
+    for abstract_group in abstract_options.groups:
+        concrete_group = concrete_parser.add_argument_group(
+            title=abstract_group.name, description=abstract_group.description
+        )
+        if abstract_group.is_mutually_exclusive:
+            concrete_group = concrete_group.add_mutually_exclusive_group(required=False)
+
+        for abstract_argument in abstract_group.arguments:
+            concrete_group.add_argument(
+                *abstract_argument.aliases,
+                **map_qualifiers(
+                    abstract_argument.configuration, ARGPARSE_QUALIFIER_MAP
+                )
+            )
+
+    return concrete_parser
+
+
+JSON_DIRECT_MIRROR_OPTIONS = (
+    'choices',
+    'metavar'
+)
+
+
+JSON_QUALIFIER_TO_OPTIONS = {
+    Qualifiers.OPTIONAL: {'is_optional': True},
+    Qualifiers.ZERO_OR_MORE: {'is_optional': True, 'is_variadic': True},
+    Qualifiers.SUPPRESS: {}
+}
+
+
+def to_data(abstract_options: ParserSpec) -> Dict[str, Any]:
+    return {'version': PARSER_SPEC_VERSION, 'spec': abstract_options.serialize()}