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# Created by Danyang Zhang @X-Lance.
import abc
from typing import Iterable, Iterator, Union
from typing import List, Tuple
#import enum
import numpy as np
import itertools
class Item(abc.ABC):
# class Item {{{ #
@abc.abstractmethod
def instantiate(self) -> str:
"""
Samples from the underlying template a sentence.
Return:
str
"""
raise NotImplementedError()
@property
@abc.abstractmethod
def regex(self) -> str:
raise NotImplementedError()
@abc.abstractmethod
def get_targets(self) -> List[str]:
"""
Collects the target patterns from the nodes or the sub-nodes
recursively.
Return:
list of str
"""
raise NotImplementedError()
@abc.abstractmethod
def implement(self, targets: Iterator[str]):
"""
Implements the target slots by the real target values. It is expected
for `targets` to have the same length with `self.getTarget()`.
Args:
target: iterator of str
"""
raise NotImplementedError()
def __add__(self, item: "Item") -> "Item":
if self is Nil:
return item
elif item is Nil:
return self
return Concat(self, item)
def __str__(self) -> str:
raise NotImplementedError()
def __repr__(self) -> str:
raise NotImplementedError()
# }}} class Item #
Nil = type( "Nil", (Item,)
, { "instantiate": lambda self: ""
, "regex": ""
, "get_targets": lambda self: []
, "implement": lambda self, tgts: None
, "__str__": lambda self: ""
, "__repr__": lambda self: "Nil"
}
)()
class Concat(Item):
# class Concat {{{ #
def __init__(self, *items: Iterable[Item]):
super(Concat, self).__init__()
self._items: List[Item] = []
self._regex: str = ""
for itm in items:
self += itm
def __iter__(self) -> Iterator[Item]:
return iter(self._items)
def __iadd__(self, item: Item) -> Item:
if isinstance(item, Concat):
self._items += item
elif item is not Nil:
self._items.append(item)
self._regex += item.regex
return self
def instantiate(self) -> str:
return "".join(map(lambda itm: itm.instantiate(), self._items))
@property
def regex(self) -> str:
return self._regex
def get_targets(self) -> List[str]:
return list( itertools.chain.from_iterable(
map( lambda itm: itm.get_targets()
, self._items
)
)
)
def implement(self, targets: Iterator[str]):
for itm in self._items:
itm.implement(targets)
def __str__(self) -> str:
return "".join(map(str, self._items))
def __repr__(self) -> str:
return "Concat({:})".format(
", ".join( map( repr
, self._items
)
)
)
# }}} class Concat #
class Const(Item):
# class Const {{{ #
regex_meta_chars = str.maketrans( { ch: "\\" + ch
for ch in [ ".", "^", "$", "*"
, "+", "?", "{", "}"
, "\\", "[", "]", "|"
, "(", ")"
]
}
)
def __init__(self, value: str):
super(Const, self).__init__()
self.value: str = value
self._regex: str = self.value.translate(Const.regex_meta_chars)
def instantiate(self) -> str:
return self.value
@property
def regex(self) -> str:
return self._regex
def get_targets(self) -> List[str]:
return []
def implement(self, targets: Iterator[str]):
pass
def __str__(self) -> str:
return self.value
def __repr__(self) -> str:
return "Const({:})".format(repr(self.value))
# }}} class Const #
class Choice(Item):
# class Choice {{{ #
def __init__(self, *items: Iterable[Item]):
super(Choice, self).__init__()
self._items: List[Item] = list(
filter( lambda itm: itm is not Nil
, items
)
)
self._regex: str = "(?:" + "|".join(map(lambda itm: itm.regex, self._items)) + ")"
self._rng: np.random.Generator = np.random.default_rng()
def instantiate(self) -> str:
if len(self._items)==0:
return ""
return self._items[self._rng.integers(len(self._items))].instantiate()
@property
def regex(self) -> str:
return self._regex
@classmethod
def fromItem(cls, item: Item):
if isinstance(item, Concat):
return cls(*item)
else:
return cls(item)
def get_targets(self) -> List[str]:
return list( itertools.chain.from_iterable(
map( lambda itm: itm.get_targets()
, self._items
)
)
)
def implement(self, targets: Iterator[str]):
for itm in self._items:
itm.implement(targets)
def __str__(self) -> str:
return "({:})".format(
"/".join( map( str
, self._items
)
)
)
def __repr__(self) -> str:
return "Choice({:})".format(
", ".join( map( repr
, self._items
)
)
)
# }}} class Choice #
class Optional(Item):
# class Optional {{{ #
def __init__(self, item: Union[Item, str]):
super(Optional, self).__init__()
if isinstance(item, str):
item = Const(item)
self._item: Item = item
self._regex = "(?:" + self._item.regex + ")?"
self._rng: np.random.Generator = np.random.default_rng()
def instantiate(self) -> str:
return self._item.instantiate() if self._rng.random()<0.5 else ""
@property
def regex(self) -> str:
return self._regex
def get_targets(self) -> List[str]:
return self._item.get_targets()
def implement(self, targets: Iterator[str]):
self._item.implement(targets)
def __str__(self) -> str:
return "[" + str(self._item) + "]"
def __repr__(self) -> str:
return "Optional(" + repr(self._item) + ")"
# }}} class Optional #
class Target(Item):
# class Target {{{ #
def __init__(self, pattern: str):
super(Target, self).__init__()
self._pattern: str = pattern
self._value: str = ""
def instantiate(self) -> str:
return self._value
@property
def regex(self) -> str:
return "(.+)"
def get_targets(self) -> List[str]:
return [self._pattern]
def implement(self, targets: Iterator[str]):
try:
value = next(targets)
self._value = value
except StopIteration:
pass
def __str__(self) -> str:
return "{" + self._pattern + "}"
def __repr__(self) -> str:
return "Target(" + repr(self._pattern) + ")"
# }}} class Target #
def read_plain(pattern: str) -> Tuple[Union[Const, type(Nil)], str]:
# function read_plain {{{ #
plain = "".join(
itertools.takewhile( lambda ch: ch not in { "(", "/", ")"
, "[", "]"
, "{", "}"
}
, pattern
)
)
return Const(plain) if len(plain)>0 else Nil\
, pattern[len(plain):]
# }}} function read_plain #
def read_until(stop: str, pattern: str) -> Tuple[str, str]:
# function read_until {{{ #
"""
Args:
stop: char
pattern: str
Return:
- str as the output
- str as the remaining
"""
plain = "".join(
itertools.takewhile( lambda ch: ch!=stop
, pattern
)
)
return plain, pattern[len(plain):]
# }}} function read_until #
def read_while(while_char: str, pattern: str) -> Tuple[List[Item], str]:
# function read_while {{{ #
"""
Args:
while_char: char
pattern: str
Return:
- list of Item
- str
"""
(item, char), remaining = read_item(pattern)
items = [item]
while char==while_char:
(item, char), remaining = read_item(remaining)
items.append(item)
return items, remaining
# }}} function read_while #
def read_item(pattern: str) -> Tuple[ Tuple [ Item
, str
]
, str
]:
# function read_item {{{ #
"""
Args:
pattern: str
Return:
- tuple like (Item, char)
- str
"""
prelude, remaining = read_plain(pattern)
if len(remaining)==0:
return (prelude, "$"), ""
head, tail = remaining[0], remaining[1:]
if head=="(":
choices, remaining = read_while("/", tail)
(others, end), remaining = read_item(remaining)
return ( prelude\
+ Choice(*choices)\
+ others\
, end
)\
, remaining
elif head=="/":
return (prelude, "/")\
, tail
elif head==")":
return (prelude, ")")\
, tail
elif head=="[":
(option, _), remaining = read_item(tail)
(others, end), remaining = read_item(remaining)
return ( prelude\
+ Optional(option)\
+ others\
, end
)\
, remaining
elif head=="]":
return (prelude, "]")\
, tail
elif head=="{":
target, remaining = read_until("}", tail)
(others, end), remaining = read_item(remaining[1:])
return ( prelude\
+ Target(target)\
+ others\
, end
)\
, remaining
# }}} function read_item #
def parse_pattern(pattern: str) -> Item:
(item, end), remaining = read_item(pattern)
assert len(remaining)==0 and end=="$"
return item
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