[#107430] [Ruby master Feature#18566] Merge `io-wait` gem into core IO — "byroot (Jean Boussier)" <noreply@...>
Issue #18566 has been reported by byroot (Jean Boussier).
22 messages
2022/02/02
[ruby-core:107709] [Ruby master Feature#18598] Add String#bytesplice
From:
"Eregon (Benoit Daloze)" <noreply@...>
Date:
2022-02-22 10:48:43 UTC
List:
ruby-core #107709
Issue #18598 has been updated by Eregon (Benoit Daloze). Shouldn't a text editor use the ropes representation for Strings instead? ( https://en.wikipedia.org/wiki/Rope_(data_structure) ) This sounds very inefficient because bytesplice will need to copy everything after the insert if the `inserted_bytes.length != length`. That's more of a personal opinion but I always found `splice` arguments and semantics confusing, also in JavaScript. `[]=` at least makes it much clearer, but `s.bytesplice(2, 3, "x")` sounds like a C API to me. If we do add this I would suggest only adding the Range version for simplicity. I think for byteindex & byteoffset in #13110 there was good motivation, and Ruby internally would anyway need to use byte offsets so exposing those to the user seemed relatively harmless, and it needed as you showed very complex hacks. But here I question the need for it, because the code before bytesplice seems reasonable enough, i.e., the code before https://github.com/shugo/textbringer/pull/31/files seems fine enough. It's also a very specific use case, I would like to see other use cases if we add a core method to String. There are also other ways to solve this, where I think you semantically want a byte array/buffer which can be shown as text and searched: * Use UTF-32LE/UTF-32BE to have constant indexing of Strings, then `[]=` works fine * Can the String be kept as Encoding::BINARY all the time, why does it need to be UTF-8? Can it just be reencoded to UTF-8 in the few places which really need it? * Do not use String and e.g. use an Array of byte values or a C extension * Use Ropes or similar implemented in Ruby, which would avoid extra copying and might not need to use byte offsets at all * Add some way to have a "cursor object" in a String, which knows both the byte index and the character index, and have its own methods, that would be much more general and could help improve the performance in far more cases (e.g., could also yield such a cursor in some `each_char_with_cursor` method). It's probably too tricky to implement correctly when the String is mutable though. ---------------------------------------- Feature #18598: Add String#bytesplice https://bugs.ruby-lang.org/issues/18598#change-96630 * Author: shugo (Shugo Maeda) * Status: Open * Priority: Normal ---------------------------------------- I withdrew the proposal of String#bytesplice in #13110 because it may cause problems if the specified offset does not land on character boundary. But how about to raise IndexError in such cases? ``` # encoding: utf-8 s = "あいうえおかきくけこ" s.bytesplice(9, 6, "xx") p s #=> "あいうxxかきくけこ" s.bytesplice(2, 3, "x") #=> offset 2 does not land on character boundary (IndexError) s.bytesplice(3, 4, "x") #=> offset 7 does not land on character boundary (IndexError) ``` ## Pull request https://github.com/ruby/ruby/pull/5584 ## Spec ``` bytesplice(index, length, str) -> string bytesplice(range, str) -> string ``` Replaces some or all of the content of +self+ with +str+, and returns +str+. The portion of the string affected is determined using the same criteria as String#byteslice, except that +length+ cannot be omitted. If the replacement string is not the same length as the text it is replacing, the string will be adjusted accordingly. The form that take an Integer will raise an IndexError if the value is out of range; the Range form will raise a RangeError. If the beginning or ending offset does not land on character (codepoint) boundary, an IndexError will be raised. ## Motivation On a text editor [Textbringer](https://github.com/shugo/textbringer/pull/31/files), the content of a buffer is represented by a String whose encoding is ASCII-8BIT, and `force_encoding(Encoding::UTF_8)` is called when necessary. It's because point (cursor position) and marks are represented by byte offsets for performance, and currently there is no way to modify UTF-8 strings with byte offsets. If String#bytesplice is introduced, the content of a text buffer can be represented by a UTF-8 string, and force_encoding can be removed: https://github.com/shugo/textbringer/pull/31/files -- https://bugs.ruby-lang.org/ Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>