[stdlib] Reintroduce Stringlike trait and use it for Stringlike.find()

stdlib/src/builtin/string_literal.mojo

@@ -24,7 +24,7 @@ from memory import UnsafePointer, memcpy, Span
 from utils import StaticString, StringRef, 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
+from utils.string_slice import Stringlike, _StringSliceIter, _to_string_list
 
 # ===-----------------------------------------------------------------------===#
 # StringLiteral
@@ -34,9 +34,9 @@ from utils.string_slice import _StringSliceIter, _to_string_list
 @lldb_formatter_wrapping_type
 @register_passable("trivial")
 struct StringLiteral(
+    Stringlike,
     Boolable,
     Comparable,
-    CollectionElementNew,
     Writable,
     IntableRaising,
     KeyElement,
@@ -593,7 +593,7 @@ struct StringLiteral(
 
         writer.write(self.as_string_slice())
 
-    fn find(self, substr: StringLiteral, start: Int = 0) -> Int:
+    fn find(self, substr: StringSlice, start: Int = 0) -> Int:
         """Finds the offset of the first occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
@@ -604,9 +604,9 @@ 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:
+    fn rfind(self, substr: StringSlice, start: Int = 0) -> Int:
         """Finds the offset of the last occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
@@ -617,7 +617,7 @@ 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/collections/string.mojo

@@ -44,6 +44,7 @@ from utils._unicode import (
 )
 from utils.format import _CurlyEntryFormattable, _FormatCurlyEntry
 from utils.string_slice import (
+    Stringlike,
     _shift_unicode_to_utf8,
     _StringSliceIter,
     _to_string_list,
@@ -742,6 +743,7 @@ fn isprintable(c: UInt8) -> Bool:
 
 @value
 struct String(
+    Stringlike,
     Sized,
     Stringable,
     AsBytes,
@@ -752,7 +754,6 @@ struct String(
     Boolable,
     Writable,
     Writer,
-    CollectionElementNew,
     FloatableRaising,
     _HashableWithHasher,
 ):
@@ -1595,8 +1596,7 @@ struct String(
         return String(buf^)
 
     fn unsafe_ptr(
-        ref self,
-    ) -> UnsafePointer[
+        ref self    ) -> UnsafePointer[
         Byte,
         mut = Origin(__origin_of(self)).is_mutable,
         origin = __origin_of(self),
@@ -1712,7 +1712,7 @@ struct String(
         """
         return substr.as_string_slice() in self.as_string_slice()
 
-    fn find(self, substr: String, start: Int = 0) -> Int:
+    fn find(self, substr: StringSlice, start: Int = 0) -> Int:
         """Finds the offset of the first occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
@@ -1723,10 +1723,9 @@ struct String(
         Returns:
           The offset of `substr` relative to the beginning of the string.
         """
+        return self.as_string_slice().find(substr, start)
 
-        return self.as_string_slice().find(substr.as_string_slice(), start)
-
-    fn rfind(self, substr: String, start: Int = 0) -> Int:
+    fn rfind(self, substr: StringSlice, start: Int = 0) -> Int:
         """Finds the offset of the last occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
@@ -1737,10 +1736,7 @@ struct String(
         Returns:
           The offset of `substr` relative to the beginning of the string.
         """
-
-        return self.as_string_slice().rfind(
-            substr.as_string_slice(), start=start
-        )
+        return self.as_string_slice().rfind(substr, start=start)
 
     fn isspace(self) -> Bool:
         """Determines whether every character in the given String is a

stdlib/src/utils/string_slice.mojo

@@ -235,11 +235,10 @@ struct _StringSliceIter[
 @value
 @register_passable("trivial")
 struct StringSlice[mut: Bool, //, origin: Origin[mut]](
+    Stringlike,
     Stringable,
     Sized,
     Writable,
-    CollectionElement,
-    CollectionElementNew,
     Hashable,
 ):
     """A non-owning view to encoded string data.
@@ -905,7 +904,8 @@ struct StringSlice[mut: Bool, //, origin: Origin[mut]](
         """
         return _FormatCurlyEntry.format(self, args)
 
-    fn find(ref self, substr: StringSlice, start: Int = 0) -> Int:
+    # FIXME(#3526): this should return unicode codepoint offsets
+    fn find(self, substr: StringSlice, start: Int = 0) -> Int:
         """Finds the offset of the first occurrence of `substr` starting at
         `start`. If not found, returns `-1`.
 
@@ -916,7 +916,7 @@ struct StringSlice[mut: Bool, //, origin: Origin[mut]](
         Returns:
             The offset of `substr` relative to the beginning of the string.
         """
-        if not substr:
+        if substr.byte_length() == 0:
             return 0
 
         if self.byte_length() < substr.byte_length() + start:
@@ -938,6 +938,7 @@ struct StringSlice[mut: Bool, //, origin: Origin[mut]](
 
         return int(loc) - int(self.unsafe_ptr())
 
+    # FIXME(#3526): this should return unicode codepoint offsets
     fn rfind(self, substr: StringSlice, start: Int = 0) -> Int:
         """Finds the offset of the last occurrence of `substr` starting at
         `start`. If not found, returns `-1`.
@@ -949,10 +950,10 @@ struct StringSlice[mut: Bool, //, origin: Origin[mut]](
         Returns:
             The offset of `substr` relative to the beginning of the string.
         """
-        if not substr:
-            return len(self)
+        if substr.byte_length() == 0:
+            return self.byte_length()
 
-        if len(self) < len(substr) + start:
+        if self.byte_length() < substr.byte_length() + start:
             return -1
 
         # The substring to search within, offset from the beginning if `start`
@@ -961,9 +962,9 @@ struct StringSlice[mut: Bool, //, origin: Origin[mut]](
 
         var loc = _memrmem(
             haystack_str.unsafe_ptr(),
-            len(haystack_str),
+            haystack_str.byte_length(),
             substr.unsafe_ptr(),
-            len(substr),
+            substr.byte_length(),
         )
 
         if not loc:
@@ -1111,6 +1112,77 @@ struct StringSlice[mut: Bool, //, origin: Origin[mut]](
 # ===-----------------------------------------------------------------------===#
 
 
+trait StringLike(CollectionElement, CollectionElementNew):
+    """Trait intended to be used as a generic entrypoint for all String-like
+    types."""
+    ...
+
+trait StringOwnerLike(StringLike):
+    fn as_bytes(ref self) -> Span[Byte, __origin_of(self)]:
+        """Returns a contiguous slice of the bytes owned by this string.
+
+        Returns:
+            A contiguous slice pointing to the bytes owned by this string.
+
+        Notes:
+            This does not include the trailing null terminator.
+        """
+        ...
+
+    fn as_string_slice(ref self) -> StringSlice[__origin_of(self)]:
+        """Returns a string slice of the data owned by this string.
+
+        Returns:
+            A string slice pointing to the data owned by this string.
+        """
+        ...
+
+trait StringSliceLike(StringLike):
+    alias mut: Bool
+    """The mutability of the origin."""
+    alias origin: Origin[mut]
+    """The origin of the data."""
+
+    fn as_bytes(self) -> Span[Byte, origin]:
+        """Returns a contiguous slice of the bytes.
+
+        Returns:
+            A contiguous slice pointing to the bytes.
+
+        Notes:
+            This does not include the trailing null terminator.
+        """
+        ...
+
+    fn as_string_slice(self) -> StringSlice[origin]:
+        """Returns a string slice of the data.
+
+        Returns:
+            A string slice pointing to the data.
+        """
+        ...
+
+trait StringLiteralLike(StringLike):
+    fn as_bytes(self) -> Span[Byte, StaticConstantOrigin]:
+        """Returns a contiguous slice of the bytes.
+
+        Returns:
+            A contiguous slice pointing to the bytes.
+
+        Notes:
+            This does not include the trailing null terminator.
+        """
+        ...
+
+    fn as_string_slice(self) -> StringSlice[StaticConstantOrigin]:
+        """Returns a string slice of the data.
+
+        Returns:
+            A string slice pointing to the data.
+        """
+        ...
+
+
 fn _to_string_list[
     T: CollectionElement,  # TODO(MOCO-1446): Make `T` parameter inferred
     len_fn: fn (T) -> Int,