## Summary
Fixes#9663 and also improves the fixes for
[RUF055](https://docs.astral.sh/ruff/rules/unnecessary-regular-expression/)
since regular expressions are often written as raw strings.
This doesn't include raw f-strings.
## Test Plan
Existing snapshots for RUF055 and PT009, plus a new `Generator` test and
a regression test for the reported `PIE810` issue.
This PR modifies our AST so that nodes for string literals, bytes literals and f-strings all retain the following information:
- The quoting style used (double or single quotes)
- Whether the string is triple-quoted or not
- Whether the string is raw or not
This PR is a followup to #10256. Like with that PR, this PR does not, in itself, fix any bugs. However, it means that we will have the necessary information to preserve quoting style and rawness of strings in the `ExprGenerator` in a followup PR, which will allow us to provide a fix for https://github.com/astral-sh/ruff/issues/7799.
The information is recorded on the AST nodes using a bitflag field on each node, similarly to how we recorded the information on `Tok::String`, `Tok::FStringStart` and `Tok::FStringMiddle` tokens in #10298. Rather than reusing the bitflag I used for the tokens, however, I decided to create a custom bitflag for each AST node.
Using different bitflags for each node allows us to make invalid states unrepresentable: it is valid to set a `u` prefix on a string literal, but not on a bytes literal or an f-string. It also allows us to have better debug representations for each AST node modified in this PR.
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## Summary
When I was looking at the v0.2.0 release, this method showed up in a
CodSpeed regression (we were calling it more), so I decided to quickly
look at speeding it up. @BurntSushi suggested using Aho-Corasick, and it
looks like it's about 7 or 8x faster:
```text
Parser/AhoCorasick time: [8.5646 ns 8.5914 ns 8.6191 ns]
Parser/Iterator time: [64.992 ns 65.124 ns 65.271 ns]
```
## Test Plan
`cargo test`
## Summary
In https://github.com/astral-sh/ruff/pull/6512, we added a flag to the
AST to mark implicitly-concatenated string expressions. This PR makes
use of that flag to remove the `is_implicit_concatenation` method.
## Test Plan
`cargo test`
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## Summary
This PR implements formatting for non-f-string Strings that do not use implicit concatenation.
Docstring formatting is out of the scope of this PR.
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## Test Plan
I added a few tests for simple string literals.
## Performance
Ouch. This is hitting performance somewhat hard. This is probably because we now iterate each string a couple of times:
1. To detect if it is an implicit string continuation
2. To detect if the string contains any new lines
3. To detect the preferred quote
4. To normalize the string
Edit: I integrated the detection of newlines into the preferred quote detection so that we only iterate the string three time.
We can probably do better by merging the implicit string continuation with the quote detection and new line detection by iterating till the end of the string part and returning the offset. We then use our simple tokenizer to skip over any comments or whitespace until we find the first non trivia token. From there we keep continue doing this in a loop until we reach the end o the string. I'll leave this improvement for later.
## Summary
In the rare event that a docstring contains an implicit string concatenation, we currently have the potential to panic, because we assume that if a string starts with triple quotes, it _ends_ with triple quotes. But with implicit concatenation, that's not the case: a single `Expr` could start and end with different quote styles, because it can contain multiple string tokens.
Supporting these "properly" is pretty hard. In some cases it's hard to even know what the "right" behavior is. So for now, I'm just detecting and warning, which is better than a panic.
Closes#3543.
Closes#3585.
# Summary
We need to support CR line endings (as opposed to LF and CRLF line endings, which are already supported). They're rare, but they do appear in Python code, and we tend to panic on any file that uses them.
Our `Locator` abstraction now supports CR line endings. However, Rust's `str#lines` implementation does _not_.
This PR adds a `UniversalNewlineIterator` implementation that respects all of CR, LF, and CRLF line endings, and plugs it into most of the `.lines()` call sites.
As an alternative design, it could be nice if we could leverage `Locator` for this. We've already computed all of the line endings, so we could probably iterate much more efficiently?
# Test Plan
Largely relying on automated testing, however, also ran over some known failure cases, like #3404.
