Reitroduce Stringlike trait and use it for Stringlike.find()

Signed-off-by: martinvuyk <[email protected]>

stdlib/src/builtin/string_literal.mojo

@@ -591,31 +591,37 @@ struct StringLiteral(
 
         writer.write(self.as_string_slice())
 
-    fn find(self, substr: StringLiteral, start: Int = 0) -> Int:
+    fn find[T: Stringlike, //](self, substr: T, start: Int = 0) -> Int:
         """Finds the offset of the first occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
+        Parameters:
+            T: The Stringlike type.
+
         Args:
           substr: The substring to find.
           start: The offset from which to find.
 
         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[T: Stringlike, //](self, substr: T, start: Int = 0) -> Int:
         """Finds the offset of the last occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
+        Parameters:
+            T: The Stringlike type.
+
         Args:
           substr: The substring to find.
           start: The offset from which to find.
 
         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

@@ -1707,35 +1707,37 @@ struct String(
         """
         return substr.as_string_slice() in self.as_string_slice()
 
-    fn find(self, substr: String, start: Int = 0) -> Int:
+    fn find[T: Stringlike, //](self, substr: T, start: Int = 0) -> Int:
         """Finds the offset of the first occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
+        Parameters:
+            T: The Stringlike type.
+
         Args:
           substr: The substring to find.
           start: The offset from which to find.
 
         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[T: Stringlike, //](self, substr: T, start: Int = 0) -> Int:
         """Finds the offset of the last occurrence of `substr` starting at
         `start`. If not found, returns -1.
 
+        Parameters:
+            The Stringlike type.
+
         Args:
           substr: The substring to find.
           start: The offset from which to find.
 
         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

@@ -885,10 +885,14 @@ struct StringSlice[is_mutable: Bool, //, origin: Origin[is_mutable]](
         """
         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[T: Stringlike, //](ref self, substr: T, start: Int = 0) -> Int:
         """Finds the offset of the first occurrence of `substr` starting at
         `start`. If not found, returns `-1`.
 
+        Parameters:
+            T: The Stringlike type.
+
         Args:
             substr: The substring to find.
             start: The offset from which to find.
@@ -918,10 +922,14 @@ struct StringSlice[is_mutable: Bool, //, origin: Origin[is_mutable]](
 
         return int(loc) - int(self.unsafe_ptr())
 
-    fn rfind(self, substr: StringSlice, start: Int = 0) -> Int:
+    # FIXME(#3526): this should return unicode codepoint offsets
+    fn rfind[T: Stringlike, //](self, substr: T, start: Int = 0) -> Int:
         """Finds the offset of the last occurrence of `substr` starting at
         `start`. If not found, returns `-1`.
 
+        Parameters:
+            T: The Stringlike type.
+
         Args:
             substr: The substring to find.
             start: The offset from which to find.
@@ -930,9 +938,9 @@ struct StringSlice[is_mutable: Bool, //, origin: Origin[is_mutable]](
             The offset of `substr` relative to the beginning of the string.
         """
         if not substr:
-            return len(self)
+            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`
@@ -1091,6 +1099,43 @@ struct StringSlice[is_mutable: Bool, //, origin: Origin[is_mutable]](
 # ===-----------------------------------------------------------------------===#
 
 
+trait Stringlike(CollectionElement, CollectionElementNew):
+    """Trait intended to be used as a generic entrypoint for all String-like
+    types."""
+
+    fn byte_length(self) -> Int:
+        """Get the string length in bytes.
+        Returns:
+            The length of this string in bytes.
+        Notes:
+            This does not include the trailing null terminator in the count.
+        """
+        ...
+
+    fn unsafe_ptr(self) -> UnsafePointer[Byte]:
+        """Get raw pointer to the underlying data.
+        Returns:
+            The raw pointer to the data.
+        """
+        ...
+
+    fn find[T: Stringlike, //](self, substr: T, start: Int = 0) -> Int:
+        """Finds the offset of the first occurrence of `substr` starting at
+        `start`. If not found, returns -1.
+
+        Parameters:
+            T: The type of the substring.
+
+        Args:
+            substr: The substring to find.
+            start: The offset from which to find.
+
+        Returns:
+            The offset of `substr` relative to the beginning of the string.
+        """
+        ...
+
+
 fn _to_string_list[
     T: CollectionElement,  # TODO(MOCO-1446): Make `T` parameter inferred
     len_fn: fn (T) -> Int,