Thanks Roger. Let's say you have a `String` that is structured in lines, and for each line you need to count the occurrences (0 or more) of some character. A way to process a line is to first search for the next '\n' from the current position, then to seach for that character starting from the same position but limiting the search up to the position of the '\n', update the current position after the character, iterate. You then advance to the next line and repeat the above.
There are other ways to achieve the same result, but they are probably either more complicated or less efficient. I’m proposing this addition because very similar, non-public methods already exist in the codebase, and which are already used to implement `indexOf()`. As for `lastIndexOf()`, in the forward search it's natural to have `toIndex` excluded from the search. There are many instance of right-open ranges [`fromIndex`, `toIndex`) in the codebase, so the proposal is to adopt this convention for `indexOf(ch, fromIndex, toIndex)`. For a backward search, however, this is less natural. The non-obvious part is to assign natural semantics to `toIndex` for `lastIndexOf(ch, fromIndex, toIndex)`. Currently, `lastIndexOf(ch, fromIndex)` operates in the closed range of indices [`0`, `fromIndex`]. Should the range be closed [`toIndex`, `fromIndex`] or the left-open (`toIndex`, `fromIndex`]? Should `lastIndexOf(ch, fromIndex)` be seen as an abbreviation for `lastIndexOf(ch, fromIndex, 0)` or for `lastIndexOf(ch, fromIndex, -1)`? Once there's consensus about this aspect, I can of course add `lastIndexOf(ch, fromIndex, toIndex)` as well. From: core-libs-dev <core-libs-dev-r...@openjdk.org> on behalf of Roger Riggs <roger.ri...@oracle.com> Date: Wednesday, 15 February 2023 at 18:03 To: core-libs-dev@openjdk.org <core-libs-dev@openjdk.org> Subject: Re: 8302590: Add String.indexOf(int ch, int fromIndex, int toIndex) Hi Raffaello, What's the use case, can you give an example? Seems reasonable; would you also add `lastIndexOf(int ch, int fromIndex, int toIndex)`? Not intrinsified, but for symmetry. Regards, Roger On 2/15/23 10:47 AM, Raffaello Giulietti wrote: Hello, Currently `String` does not expose a method `indexOf(int ch, int fromIndex, int toIndex)`, where the 3rd parameter limits the search to positions up to it (exclusive). JBS issue [1] has been filed as an “Enhancement” to add it to the codebase. Before preparing a PR and a CSR, I would like to gather opinions and suggestions. Greetings Raffaello ---- [1] https://bugs.openjdk.org/browse/JDK-8302590
