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Mini Shell
Mini Shell
"""Classes for representing match statement patterns."""
from typing import TypeVar, List, Optional, Union
from mypy_extensions import trait
from mypy.nodes import Node, RefExpr, NameExpr, Expression
from mypy.visitor import PatternVisitor
T = TypeVar('T')
@trait
class Pattern(Node):
"""A pattern node."""
__slots__ = ()
def accept(self, visitor: PatternVisitor[T]) -> T:
raise RuntimeError('Not implemented')
class AsPattern(Pattern):
"""The pattern <pattern> as <name>"""
# The python ast, and therefore also our ast merges capture, wildcard and as patterns into one
# for easier handling.
# If pattern is None this is a capture pattern. If name and pattern are both none this is a
# wildcard pattern.
# Only name being None should not happen but also won't break anything.
pattern: Optional[Pattern]
name: Optional[NameExpr]
def __init__(self, pattern: Optional[Pattern], name: Optional[NameExpr]) -> None:
super().__init__()
self.pattern = pattern
self.name = name
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_as_pattern(self)
class OrPattern(Pattern):
"""The pattern <pattern> | <pattern> | ..."""
patterns: List[Pattern]
def __init__(self, patterns: List[Pattern]) -> None:
super().__init__()
self.patterns = patterns
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_or_pattern(self)
class ValuePattern(Pattern):
"""The pattern x.y (or x.y.z, ...)"""
expr: Expression
def __init__(self, expr: Expression):
super().__init__()
self.expr = expr
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_value_pattern(self)
class SingletonPattern(Pattern):
# This can be exactly True, False or None
value: Union[bool, None]
def __init__(self, value: Union[bool, None]):
super().__init__()
self.value = value
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_singleton_pattern(self)
class SequencePattern(Pattern):
"""The pattern [<pattern>, ...]"""
patterns: List[Pattern]
def __init__(self, patterns: List[Pattern]):
super().__init__()
self.patterns = patterns
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_sequence_pattern(self)
class StarredPattern(Pattern):
# None corresponds to *_ in a list pattern. It will match multiple items but won't bind them to
# a name.
capture: Optional[NameExpr]
def __init__(self, capture: Optional[NameExpr]):
super().__init__()
self.capture = capture
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_starred_pattern(self)
class MappingPattern(Pattern):
keys: List[Expression]
values: List[Pattern]
rest: Optional[NameExpr]
def __init__(self, keys: List[Expression], values: List[Pattern],
rest: Optional[NameExpr]):
super().__init__()
assert len(keys) == len(values)
self.keys = keys
self.values = values
self.rest = rest
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_mapping_pattern(self)
class ClassPattern(Pattern):
"""The pattern Cls(...)"""
class_ref: RefExpr
positionals: List[Pattern]
keyword_keys: List[str]
keyword_values: List[Pattern]
def __init__(self, class_ref: RefExpr, positionals: List[Pattern], keyword_keys: List[str],
keyword_values: List[Pattern]):
super().__init__()
assert len(keyword_keys) == len(keyword_values)
self.class_ref = class_ref
self.positionals = positionals
self.keyword_keys = keyword_keys
self.keyword_values = keyword_values
def accept(self, visitor: PatternVisitor[T]) -> T:
return visitor.visit_class_pattern(self)
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