UnicodeDecodeWithOffsets

Decodes each string in `input` into a sequence of Unicode code points.

The character codepoints for all strings are returned using a single vector `char_values`, with strings expanded to characters in row-major order. Similarly, the character start byte offsets are returned using a single vector `char_to_byte_starts`, with strings expanded in row-major order.

The `row_splits` tensor indicates where the codepoints and start offsets for each input string begin and end within the `char_values` and `char_to_byte_starts` tensors. In particular, the values for the `i`th string (in row-major order) are stored in the slice `[row_splits[i]:row_splits[i+1]]`. Thus:

• `char_values[row_splits[i]+j]` is the Unicode codepoint for the `j`th character in the `i`th string (in row-major order).
• `char_to_bytes_starts[row_splits[i]+j]` is the start byte offset for the `j`th character in the `i`th string (in row-major order).
• `row_splits[i+1] - row_splits[i]` is the number of characters in the `i`th string (in row-major order).