Merge pull request #75 from katunilya/73-add-predicate-function-builder

73 add predicate function builder

Author: katunilya

tests/test_predicate.py

@@ -0,0 +1,98 @@
+import pytest
+
+from tibia.predicate import all_, any_, not_, when, when_or, where
+from tibia.value import Value
+
+
+@pytest.mark.parametrize(
+    ("value", "target"),
+    [
+        ("", False),
+        ("abc", False),
+        ("abc123", True),
+    ],
+)
+def test_all(value: str, target: bool) -> None:
+    pfn = all_(
+        lambda s: "a" in s,
+        lambda s: "1" in s,
+    )
+
+    assert pfn(value) == target
+
+
+@pytest.mark.parametrize(
+    ("value", "target"),
+    [
+        ("", False),
+        ("abc", True),
+        ("abc123", True),
+    ],
+)
+def test_any(value: str, target: bool) -> None:
+    pfn = any_(
+        lambda s: "a" in s,
+        lambda s: "1" in s,
+    )
+
+    assert pfn(value) == target
+
+
+@pytest.mark.parametrize(
+    ("value", "target", "target_not"),
+    [
+        ("", False, True),
+        ("abc", True, False),
+        ("123", False, True),
+    ],
+)
+def test_not(value: str, target: bool, target_not: bool) -> None:
+    not_pnf = not_(str.__contains__, "abc")
+
+    assert ("abc" in value) == target
+    assert not_pnf(value) == target_not
+
+
+@pytest.mark.parametrize(
+    ("value", "target"),
+    [
+        ("", False),
+        ("abc", True),
+        ("abc123", True),
+    ],
+)
+def test_where(value: str, target: bool) -> None:
+    pfn = (
+        where(str.__contains__, "a")
+        .and_(str.__contains__, "b")
+        .or_(str.__contains__, "c12")
+        .unwrap()
+    )
+
+    assert pfn(value) == target
+
+
+@pytest.mark.parametrize(
+    ("value", "target"),
+    [
+        (0, 0),
+        (1, 2),
+    ],
+)
+def test_when(value: int, target: int) -> None:
+    result = Value(value).map(when, lambda i: i > 0, lambda i: i + 1).unwrap()
+
+    assert result == target
+
+
+@pytest.mark.parametrize(
+    ("value", "target"),
+    [
+        (0, "no"),
+        (1, "1"),
+    ],
+)
+def test_when_or(value: int, target: str) -> None:
+    result = Value(value).map(when_or, lambda i: i > 0, "no", str).unwrap()
+
+    assert result == target

tibia/__init__.py

@@ -2,6 +2,7 @@
 from .future_maybe import FutureMaybe
 from .future_result import FutureResult
 from .maybe import Empty, Maybe, Some
+from .predicate import all_, any_, not_, where
 from .result import Err, Ok, Result
 from .value import Value
 
@@ -12,6 +13,10 @@
     "Empty",
     "Maybe",
     "Some",
+    "all_",
+    "any_",
+    "not_",
+    "where",
     "Err",
     "Ok",
     "Result",

tibia/predicate.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+from typing import Callable, Concatenate
+
+
+def all_[T](*pfns: Callable[[T], bool]) -> Callable[[T], bool]:
+    return lambda t: all(fn(t) for fn in pfns)
+
+
+def any_[T](*pfns: Callable[[T], bool]) -> Callable[[T], bool]:
+    return lambda t: any(fn(t) for fn in pfns)
+
+
+def not_[T, **P](
+    pfn: Callable[Concatenate[T, P], bool],
+    *args: P.args,
+    **kwargs: P.kwargs,
+) -> Callable[[T], bool]:
+    return lambda t: not pfn(t, *args, **kwargs)
+
+
+class where[T, **P]:
+    pfn: Callable[[T], bool]
+
+    def __init__(
+        self,
+        pfn: Callable[Concatenate[T, P], bool],
+        *args: P.args,
+        **kwargs: P.kwargs,
+    ):
+        self.pfn = lambda t: pfn(t, *args, **kwargs)
+
+    def __call__(self, value: T) -> bool:
+        return self.pfn(value)
+
+    def or_[**P_](
+        self,
+        pfn: Callable[Concatenate[T, P_], bool],
+        *args: P_.args,
+        **kwargs: P_.kwargs,
+    ) -> where[T]:
+        return where(lambda t: self.pfn(t) or pfn(t, *args, **kwargs))
+
+    def and_[**P_](
+        self,
+        pfn: Callable[Concatenate[T, P_], bool],
+        *args: P_.args,
+        **kwargs: P_.kwargs,
+    ) -> where[T]:
+        return where(lambda t: self.pfn(t) and pfn(t, *args, **kwargs))
+
+    def unwrap(self) -> Callable[[T], bool]:
+        return self
+
+
+def when[T, **P](
+    value: T,
+    pfn: Callable[[T], bool],
+    fn: Callable[Concatenate[T, P], T],
+    *args: P.args,
+    **kwargs: P.kwargs,
+) -> T:
+    return fn(value, *args, **kwargs) if pfn(value) else value
+
+
+def when_or[T, **P, R](
+    value: T,
+    pfn: Callable[[T], bool],
+    other: R,
+    fn: Callable[Concatenate[T, P], R],
+    *args: P.args,
+    **kwargs: P.kwargs,
+) -> R:
+    return fn(value, *args, **kwargs) if pfn(value) else other