[stdlib] Remove StringLiteral StringRef dependencies

stdlib/src/builtin/string_literal.mojo

@@ -21,7 +21,7 @@ from sys.ffi import c_char
 
 from memory import UnsafePointer, memcpy, Span
 
-from utils import StaticString, StringRef, StringSlice, Writable, Writer
+from utils import StaticString, StringSlice, Writable, Writer
 from utils._visualizers import lldb_formatter_wrapping_type
 from utils.format import _CurlyEntryFormattable, _FormatCurlyEntry
 from utils.string_slice import _StringSliceIter, _to_string_list
@@ -241,7 +241,7 @@ struct StringLiteral(
         Returns:
             True if they are not equal.
         """
-        return StringRef(self) != StringRef(rhs)
+        return self.as_string_slice() != rhs.as_string_slice()
 
     @always_inline("nodebug")
     fn __eq__(self, rhs: StringSlice) -> Bool:
@@ -277,7 +277,7 @@ struct StringLiteral(
         Returns:
             True if this StringLiteral is strictly less than the RHS StringLiteral and False otherwise.
         """
-        return StringRef(self) < StringRef(rhs)
+        return self.as_string_slice() < rhs.as_string_slice()
 
     @always_inline("nodebug")
     fn __le__(self, rhs: StringLiteral) -> Bool:
@@ -324,7 +324,7 @@ struct StringLiteral(
         Returns:
           True if the string contains the substring.
         """
-        return substr in StringRef(self)
+        return substr in self.as_string_slice()
 
     # ===-------------------------------------------------------------------===#
     # Trait implementations
@@ -606,7 +606,7 @@ struct StringLiteral(
         Returns:
           The offset of `substr` relative to the beginning of the string.
         """
-        return StringRef(self).find(substr, start=start)
+        return self.as_string_slice().find(substr, start=start)
 
     fn rfind(self, substr: StringLiteral, start: Int = 0) -> Int:
         """Finds the offset of the last occurrence of `substr` starting at
@@ -619,7 +619,7 @@ struct StringLiteral(
         Returns:
           The offset of `substr` relative to the beginning of the string.
         """
-        return StringRef(self).rfind(substr, start=start)
+        return self.as_string_slice().rfind(substr, start=start)
 
     fn replace(self, old: StringLiteral, new: StringLiteral) -> StringLiteral:
         """Return a copy of the string with all occurrences of substring `old`

stdlib/src/utils/string_slice.mojo

@@ -427,17 +427,15 @@ struct StringSlice[is_mutable: Bool, //, origin: Origin[is_mutable]](
         Returns:
             If the `StringSlice` is equal to the input in length and contents.
         """
-        if not self and not rhs:
-            return True
-        if len(self) != len(rhs):
+
+        var s_len = self.byte_length()
+        s_ptr, rhs_ptr = self.unsafe_ptr(), rhs.unsafe_ptr()
+        if s_len != rhs.byte_length():
             return False
         # same pointer and length, so equal
-        if self._slice.unsafe_ptr() == rhs._slice.unsafe_ptr():
+        elif s_len == 0 or s_ptr == rhs_ptr:
             return True
-        for i in range(len(self)):
-            if self._slice[i] != rhs._slice.unsafe_ptr()[i]:
-                return False
-        return True
+        return memcmp(s_ptr, rhs_ptr, s_len) == 0
 
     @always_inline
     fn __eq__(self, rhs: String) -> Bool: