rustdoc-search: count path edits with separate edit limit
Avoids strange-looking results like this one, where the path component seems to be ignored:
Since the two are counted separately elsewhere, they should get their own limits, too. The biggest problem with combining them is that paths are loosely checked by not requiring every component to match, which means that if they are short and matched loosely, they can easily find "drunk typist" matches that make no sense, like this old result:
std::collections::btree_map::itermut matching slice::itermut
maxEditDistance = ("slice::itermut".length) / 3 = 14 / 3 = 4
editDistance("std", "slice") = 4
editDistance("itermut", "itermut") = 0
4 + 0 <= 4 PASS
Of course, `slice::itermut` should not match stuff from btreemap. `slice` should not match `std`.
The new result counts them separately:
maxPathEditDistance = "slice".length / 3 = 5 / 3 = 1
maxEditDistance = "itermut".length / 3 = 7 / 3 = 2
editDistance("std", "slice") = 4
4 <= 1 FAIL
Effectively, this makes path queries less "typo-resistant". It's not zero, but it means `vec` won't match the `v1` prelude.
This commit also adds substring matching to paths. It's stricter than the substring matching in the main part, but loose enough that what I expect to match does.
Queries without parent paths are unchanged.
Since the two are counted separately elsewhere, they should get
their own limits, too. The biggest problem with combining them
is that paths are loosely checked by not requiring every component
to match, which means that if they are short and matched loosely,
they can easily find "drunk typist" matches that make no sense,
like this old result:
std::collections::btree_map::itermut matching slice::itermut
maxEditDistance = ("slice::itermut".length) / 3 = 14 / 3 = 4
editDistance("std", "slice") = 4
editDistance("itermut", "itermut") = 0
4 + 0 <= 4 PASS
Of course, `slice::itermut` should not match stuff from btreemap.
`slice` should not match `std`.
The new result counts them separately:
maxPathEditDistance = "slice".length / 3 = 5 / 3 = 1
maxEditDistance = "itermut".length / 3 = 7 / 3 = 2
editDistance("std", "slice") = 4
4 <= 1 FAIL
Effectively, this makes path queries less "typo-resistant".
It's not zero, but it means `vec` won't match the `v1` prelude.
Queries without parent paths are unchanged.
It doesn't look quite right, because the lines are too far apart,
and it's not going to be announced by screenreaders as a menu button,
since that's not what the symbol means.
This adds a real tooltip and uses a better drawing of the icon.
This is a redesign of the feature, with parts pulled from
https://github.com/rust-lang/rust/pull/119049
but with a button that looks more like a button and matches the
one used on other sidebar pages.
rustdoc-search: remove parallel searchWords array
This might have made sense if the algorithm could use `searchWords` to skip having to look at `searchIndex`, but since it always does a substring check on both the stock word and the normalizedName, it doesn't seem to help performance anyway.
Profile: http://notriddle.com/rustdoc-html-demo-8/searchwords/index.html
This might have made sense if the algorithm could use `searchWords`
to skip having to look at `searchIndex`, but since it always
does a substring check on both the stock word and the normalizedName,
it doesn't seem to help performance anyway.
Simplify `src-script.js` code
Instead of keeping this value in the global scope and still use it in the function in case it wasn't used outside, let's just use it inside the function.
r? ``@notriddle``
rustdoc: allow resizing the sidebar / hiding the top bar
Fixes#97306
Preview: http://notriddle.com/rustdoc-html-demo-4/sidebar-resize/std/index.html
## Summary
This feature adds:
1. A checkbox to the Settings popover to hide the persistent navigation bar (the sidebar on large viewports and the top bar on small ones).
2. On large viewports, it adds a resize handle to the persistent sidebar. Resizing it into nothing is equivalent to turning off the persistent navigation bar checkbox in Settings.
3. If the navigation bar is hidden, a toolbar button to the left of the search appears. Clicking it brings the navigation bar back.
## Motivation
While "mobile mode" is definitely a good default, it's not the only reason people have wanted to hide the sidebar:
* Some people use tiling window managers, and don't like rustdoc's current breakpoints. Changing the breakpoints might help with that, but there's no perfect solution, because there's a gap between "huge screen" and "smartphone" where reasonable people can disagree about whether it makes sense for the sidebar to be on-screen. https://github.com/rust-lang/rust/issues/97306
* Some people ask for ways to reduce on-screen clutter because it makes it easier to focus. There's not a media query for that (and if there was, privacy-conscious users would turn it off). https://github.com/rust-lang/rust/issues/59829
This feature is designed to avoid these problems. Resizing the sidebar especially helps, because it provides a way to hide the sidebar without adding a new top-level button (which would add clutter), and it provides a way to make rustdoc play nicer in complex, custom screen layouts.
## Guide and Reference-level explanation
On a desktop or laptop with a mouse, resize the sidebar by dragging its right edge.
On any browser, including mobile phones, the sticky top bar or side bar can be hidden from the Settings area (the button with the cog wheel, next to the search bar). When it's hidden, a convenient button will appear on the search bar's left.
## Drawbacks
This adds more JavaScript code to the render blocking area.
## Rationale and alternatives
The most obvious way to allow people to hide the sidebar would have been to let them "manually enter mobile mode." The upside is that it's a feature we already have. The downside is that it's actually really hard to come up with a terse description. Is it:
* A Setting that forces desktop viewers to always have the mobile-style top bar? If so, how do we label it? Should it be visible on mobile, and, if so, does it just not do anything?
* A persistent hide/show sidebar button, present on desktop, just like on mobile? That's clutter that I'd like to avoid.
## Prior art
* The new file browser in GitHub uses a similar divider with a mouse-over indicator
* mdBook and macOS Finder both allow you to resize the sidebar to nothing as a gesture to hide it
* https://www.nngroup.com/articles/drag-drop/
## Future possibilities
https://rust-lang.zulipchat.com/#narrow/stream/266220-rustdoc/topic/Table.20of.20contents proposes a new, second sidebar (a table of contents). How should it fit in with this feature? Should it be resizeable? Hideable? Can it be accessed on mobile?
The hash changes are based on some tests with `arti` and various
specific queries, aimed at reducing the false positive rate.
Sorting the query elements so that generics always come first is
instead aimed at reducing the number of Map operations on mgens,
assuming if the bloom filter does find a false positive, it'll
be able to reject the row without having to track a mapping.
- https://hur.st/bloomfilter/?n=3&p=&m=96&k=6
Different functions have different amounts of inputs, and
unification isn't very slow anyway, so figuring out a single
ideal number of hash functions is nasty, but 6 keeps things
low even up to 10 inputs.
- https://web.archive.org/web/20210927123933/https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.72.2442&rep=rep1&type=pdf
This is the `h1` and `h2`, both derived from `h0`.
This commit adds ranking and quick filtering to type-based search,
improving performance and having it order results based on their
type signatures.
Motivation
----------
If I write a query like `str -> String`, a lot of functions come up.
That's to be expected, but `String::from_str` should come up on top, and
it doesn't right now. This is because the sorting algorithm is based
on the functions name, and doesn't consider the type signature at all.
`slice::join` even comes up above it!
To fix this, the sorting should take into account the function's
signature, and the closer match should come up on top.
Guide-level description
-----------------------
When searching by type signature, types with a "closer" match will
show up above types that match less precisely.
Reference-level explanation
---------------------------
Functions signature search works in three major phases:
* A compact "fingerprint," based on the [bloom filter] technique, is used to
check for matches and to estimate the distance. It sometimes has false
positive matches, but it also operates on 128 bit contiguous memory and
requires no backtracking, so it performs a lot better than real
unification.
The fingerprint represents the set of items in the type signature, but it
does not represent nesting, and it ignores when the same item appears more
than once.
The result is rejected if any query bits are absent in the function, or
if the distance is higher than the current maximum and 200
results have already been found.
* The second step performs unification. This is where nesting and true bag
semantics are taken into account, and it has no false positives. It uses a
recursive, backtracking algorithm.
The result is rejected if any query elements are absent in the function.
[bloom filter]: https://en.wikipedia.org/wiki/Bloom_filter
Drawbacks
---------
This makes the code bigger.
More than that, this design is a subtle trade-off. It makes the cases I've
tested against measurably faster, but it's not clear how well this extends
to other crates with potentially more functions and fewer types.
The more complex things get, the more important it is to gather a good set
of data to test with (this is arguably more important than the actual
benchmarking ifrastructure right now).
Rationale and alternatives
--------------------------
Throwing a bloom filter in front makes it faster.
More than that, it tries to take a tactic where the system can not only check
for potential matches, but also gets an accurate distance function without
needing to do unification. That way it can skip unification even on items
that have the needed elems, as long as they have more items than the
currently found maximum.
If I didn't want to be able to cheaply do set operations on the fingerprint,
a [cuckoo filter] is supposed to have better performance.
But the nice bit-banging set intersection doesn't work AFAIK.
I also looked into [minhashing], but since it's actually an unbiased
estimate of the similarity coefficient, I'm not sure how it could be used
to skip unification (I wouldn't know if the estimate was too low or
too high).
This function actually uses the number of distinct items as its
"distance function."
This should give the same results that it would have gotten from a Jaccard
Distance $1-\frac{|F\cap{}Q|}{|F\cup{}Q|}$, while being cheaper to compute.
This is because:
* The function $F$ must be a superset of the query $Q$, so their union is
just $F$ and the intersection is $Q$ and it can be reduced to
$1-\frac{|Q|}{|F|}.
* There are no magic thresholds. These values are only being used to
compare against each other while sorting (and, if 200 results are found,
to compare with the maximum match). This means we only care if one value
is bigger than the other, not what it's actual value is, and since $Q$ is
the same for everything, it can be safely left out, reducing the formula
to $1-\frac{1}{|F|} = \frac{|F|}{|F|}-\frac{1}{|F|} = |F|-1$. And, since
the values are only being compared with each other, $|F|$ is fine.
Prior art
---------
This is significantly different from how Hoogle does it.
It doesn't account for order, and it has no special account for nesting,
though `Box<t>` is still two items, while `t` is only one.
This should give the same results that it would have gotten from a Jaccard
Distance $1-\frac{|A\cap{}B|}{|A\cup{}B|}$, while being cheaper to compute.
Unresolved questions
--------------------
`[]` and `()`, the slice/array and tuple/union operators, are ignored while
building the signature for the query. This is because they match more than
one thing, making them ambiguous. Unfortunately, this also makes them
a performance cliff. Is this likely to be a problem?
Right now, the system just stashes the type distance into the
same field that levenshtein distance normally goes in. This means exact
query matches show up on top (for example, if you have a function like
`fn nothing(a: Nothing, b: i32)`, then searching for `nothing` will show it
on top even if there's another function with `fn bar(x: Nothing)` that's
technically a closer match in type signature.
Future possibilities
--------------------
It should be possible to adopt more sorting criteria to act as a tie breaker,
which could be determined during unification.
[cuckoo filter]: https://en.wikipedia.org/wiki/Cuckoo_filter
[minhashing]: https://en.wikipedia.org/wiki/MinHash
This function dates back to 9a45c9d7c6 and
seems to have been made obsolete when `addIntoResult` grew the ability to
check the levenshtein distance matching with commit
ba824ec52b.
Clean up variables in `search.js`
While reviewing https://github.com/rust-lang/rust/pull/118402, I saw a few small clean ups that were needed, mostly about variables creation.
r? ```@notriddle```
The `c === "="` was redundant when `isSeparatorCharacter` already
checks that.
The function `isStopCharacter` and `isEndCharacter` functions
did exactly the same thing and have synonymous names.
There doesn't seem much point in having both.
rustdoc: remove unused parameter `reversed` from onEach(Lazy)
This feature was added in edec5807ac to support JavaScript-based toggles that were later replaced with HTML `<details>`.
rustdoc: `div.where` instead of fmt-newline class
This is about equally readable, a lot more terse, and stops special-casing functions and methods.
```console
$ du -hs doc-old/ doc-new/
671M doc-old/
670M doc-new/
```
This is about equally readable, a lot more terse, and stops
special-casing functions and methods.
```console
$ du -hs doc-old/ doc-new/
671M doc-old/
670M doc-new/
```
This restriction made sense back when spaces separated function
parameters, but now that they separate path components, there's
no real ambiguity any more.
Additionally, the Rust language allows it.
The search sorting code already sorts by item type discriminant,
putting things with smaller discriminants first. There was
also a special case for sorting keywords and primitives earlier,
and this commit removes it by giving them lower discriminants.
The sorting code has another criteria where items with descriptions
appear earlier than items without, and that criteria has higher
priority than the item type. This shouldn't matter, though,
because primitives and keywords normally only appear in the
standard library, and it always gives them descriptions.
This computes the same result with less code by computing many of
the old checks at once:
* It won't enter the loop if clength > length, because then the
result of length - clength will be negative and the
loop conditional will fail.
* i + clength will never be greater than length, because it
starts out as i = length - clength, implying that i + clength
equals length, and it only goes down from there.
* The aborted variable is replaced with control flow.
This is significantly faster, because
- It allows the one-element fast path to kick in on multi-
element queries.
- It constructs intermediate data structures more lazily
than the old system did.
It's measurably faster than the old algo even without the fast path, but
that fast path still helps significantly.
Short queries, in addition to being common, are also the base
case for a lot of more complicated queries. We can avoid
most of the backtracking data structures, and use simple
recursive matching instead, by special casing them.
Profile output:
https://notriddle.com/rustdoc-html-demo-5/profile-3/index.html
