Removing start and end parameters from starts_with.

bitformat/_bits.py

@@ -698,22 +698,19 @@ def set(self, value: Any, pos: int | Iterable[int] | None = None) -> Bits:
             s._bitstore = self._bitstore.set_from_iterable(v, pos)
         return s
 
-    def starts_with(self, prefix: BitsType, start: int | None = None, end: int | None = None) -> bool:
+    def starts_with(self, prefix: BitsType) -> bool:
         """Return whether the current Bits starts with prefix.
 
         :param prefix: The Bits to search for.
         :type prefix: BitsType
-        :param start: The bit position to start from. Defaults to 0.
-        :type start: int, optional
-        :param end: The bit position to end at. Defaults to len(self).
-        :type end: int, optional
         :return: True if the Bits starts with the prefix, otherwise False.
         :rtype: bool
 
         """
         prefix = self.from_auto(prefix)
-        start, end = self._validate_slice(start, end)
-        return self._slice_copy(start, start + len(prefix)) == prefix if end >= start + len(prefix) else False
+        if len(prefix) <= len(self):
+            return self._slice_copy(0, len(prefix)) == prefix
+        return False
 
     def to_bytes(self) -> bytes:
         """Return the Bits as bytes, padding with zero bits if needed.
@@ -781,8 +778,7 @@ def unpack(self, fmt: Dtype | str | list[Dtype | str], /) -> Any | list[Any]:
 
     # ----- Private Methods -----
 
-    def _findall(self, bs: Bits, count: int | None,
-                 bytealigned: bool) -> Iterable[int]:
+    def _findall(self, bs: Bits, count: int | None, bytealigned: bool) -> Iterable[int]:
         c = 0
         for i in self._bitstore.findall(bs._bitstore, bytealigned):
             if count is not None and c >= count:
@@ -852,7 +848,6 @@ def _setuint(self, i: int | str, length: int | None = None) -> None:
                 raise ValueError(f"Unsigned integers cannot be initialised with the negative number {i}.")
             raise e
 
-
     def _getuint(self) -> int:
         """Return data as an unsigned int."""
         if len(self) == 0:

tests/test_bitstream.py

@@ -909,13 +909,13 @@ def test_startswith(self):
 
     def test_startswith_start_end(self):
         s = Bits('0x123456')
-        assert s.starts_with('0x234', 4)
-        assert not s.starts_with('0x123', end=11)
-        assert s.starts_with('0x123', end=12)
-        assert s.starts_with('0x34', 8, 16)
-        assert not s.starts_with('0x34', 7, 16)
-        assert not s.starts_with('0x34', 9, 16)
-        assert not s.starts_with('0x34', 8, 15)
+        assert s[4:].starts_with('0x234')
+        assert not s[:11].starts_with('0x123')
+        assert s[:12].starts_with('0x123')
+        assert s[8:16].starts_with('0x34')
+        assert not s[7:16].starts_with('0x34')
+        assert not s[9:16].starts_with('0x34')
+        assert not s[8:15].starts_with('0x34')
 
     def test_endswith(self):
         a = Bits()
@@ -1299,9 +1299,9 @@ def test_function_negative_indices(self):
 
         # startswith
         s = Bits('0xfe0012fe1200fe')
-        assert s.starts_with('0x00f', start=-16)
-        assert s.starts_with('0xfe00', end=-40)
-        assert not s.starts_with('0xfe00', end=-41)
+        assert s[-16:].starts_with('0x00f')
+        assert s[:-40].starts_with('0xfe00')
+        assert not s[:-41].starts_with('0xfe00')
 
         # endswith
         assert s[-16:].ends_with('0x00fe')