rustdoc: add three-column layout for large desktops #120818

notriddle · 2024-02-09T00:53:53Z

Dependent on #120736

Summary

On very large displays, use a three-column layout, splitting up the TOC and ModNav.

Preview

http://notriddle.com/rustdoc-html-demo-9/three-column/rust/std/index.html

Motivation

Multiple people have asked for a doc layout that makes better use of the larger screens that Rust development itself is usually done on.

More importantly, people have asked for the navigation aids that rustdoc already has, but buries underneath the list of Methods and such. This is a side-effect of mixing together lateral navigation with the table of contents.

However, there is some nuance to how noticeable the local navigation should be. In particular, local navigation should not be more salient than the global navigation, because, if that happens, users may mistake the local navigation for the global one. Visual hierarchy should reflect information hierarchy.

It's not quite this simple, unfortunately. Because ModNav is loaded by JS, it populates after the TOC, which means if we put it on top we get a content jump. It cannot go above anything else.

The three-column layout avoids this no-no, and also does a better job of communicating the information hierarchy.

The module navigation is grey in an otherwise-white page, but the floating TOC is not. It's also paired with the logo, while the TOC is paired with the page's name. These are both meant to communicate the difference between the TOC and the ModNav.
By exposing the ModNav more easily, the You Are Here highlighted item name is more commonly visible. Look at the left sidebar in the screenshot.

That tabbed-out HashMap struct name under the Structs header under In std::collections is great.
Also, this is how MDN does it. Presumably, they know what they're doing.

Drawbacks

This is, really, a pretty serious backslide on the decluttering. If someone really needs to get rid of these things, they can. Click the Settings button, the hide the TOC. But that's probably not a great first impression.

Rationale and alternatives

Why are Sections and Methods both here

Clicking on a ModNav entry shouldn’t cause it to move at all.

That’s not easy to avoid on a narrow screen with one sidebar, but on a split layout it can (or if the TOC is hidden, as in this video).

Screencast.from.2024-07-23.08-48-15.webm

Since it’s not scrolling off every time you click it, “browsing” is a lot less an annoyance. It’s not as convenient as hashing all the information there, but there’s no space trade-off, and it’s less cluttered.

Why is the TOC in a box?

It's a scrollbar thing.

An earlier version of this feature divided the browser into three equally-tall sections. It's the way I wanted the feature to work. But, in doing so, I would have to pick between two bad options for the main document's scrolling behavior:

To put the scrollbar anywhere other than the rightmost edge of the browser window, the main scrolling area would have to be something other than the body tag. Doing this breaks a bunch of built-in browser behaviors.
If the scrollbar were put at the far right, it would stack two scrollbars directly beside each other that scroll different things. It would basically break scrolling with the scroll bar.

To side-step this problem, the box helps telegraph what's actually going on. The one inside the box scrolls the box that contains it, while the one outside the box scrolls the page.

Why isn't there a configuration switch to force the one-sidebar view?

Does anybody want this? There's already an option to turn the TOC off entirely, if it's distracting.

Why isn't there a way to resize the TOC box?

It fills all available space. What you'd get would be a way to resize the content area.

Resizing the content area, while it sounds nice, would require a bunch of layout optimization, because right now, resizing it requires too much layout work and is very very slow.

Prior art

This layout is very similar to MDN.

Unresolved questions

Is this enough to get across to new users the difference between the TOC and the navigation? If not, should we do something like MDN's "In This Article" labeling?
Should we highlight the currently-visible section in the sidebar, like MDN does? It might act a bit weird, since the Methods section is alphabetical but the page itself is not.

rustbot · 2024-02-09T00:54:01Z

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GuillaumeGomez · 2024-02-09T22:21:22Z

The UI is very weird, it adds new lines in the left sidebar and a floating menu on the right. Wouldn't it be possible to not make it stand out as much? Like just having a border on the left and making it take the "full space" on the right and top?

notriddle · 2024-02-10T00:27:47Z

I'm not sure what to add that I didn't already mention in the Rationale and Alternatives section:

Why is the TOC in a box?

It's a scrollbar thing.

An earlier version of this feature divided the browser into three equally-tall sections. It's the way I wanted the feature to work. But, in doing so, I would have to pick between two bad options for the main document's scrolling behavior:

To put the scrollbar anywhere other than the rightmost edge of the browser window, the main scrolling area would have to be something other than the body tag. Doing this breaks a bunch of built-in browser behaviors.

If the scrollbar were put at the far right, it would stack two scrollbars directly beside each other that scroll different things. It would basically break scrolling with the scroll bar.

To side-step this problem, the box helps telegraph what's actually going on. The one inside the box scrolls the box that contains it, while the one outside the box scrolls the page.

The line in the left sidebar could be removed, but is mostly meant to work like the one in the Source Files viewer, since its scroll behavior is the same.

GuillaumeGomez · 2024-02-10T11:00:19Z

Isn't it possible to "cheat" in order to make it look like a plain sidebar while keeping it in the same scroll interactions?

the8472 · 2024-02-12T12:05:54Z

If the scrollbar were put at the far right, it would stack two scrollbars directly beside each other that scroll different things. It would basically break scrolling with the scroll bar.

You could hide the scollbar of the sidebar and then manually scroll it via javascript to keep it in sync with the section the main page is showing. This would only be necessary if the TOC is longer than a screen height anyway.

GuillaumeGomez · 2024-02-12T12:31:37Z

If the scrollbar were put at the far right, it would stack two scrollbars directly beside each other that scroll different things. It would basically break scrolling with the scroll bar.

You could hide the scollbar of the sidebar and then manually scroll it via javascript to keep it in sync with the section the main page is showing. This would only be necessary if the TOC is longer than a screen height anyway.

Let's not. The content of the TOC can be part of the main page (so sharing the same scroll).

notriddle · 2024-02-12T17:58:40Z

The content of the TOC can be part of the main page (so sharing the same scroll).

Are you thinking of having it work like this?

Screencast.from.2024-02-12.10-31-32.webm

I'm not sure that's useful. The page is so much longer than the TOC. If you click anything in the TOC, it's basically guaranteed to disappear, and you have to scroll back to the top to get to it.

This would only be necessary if the TOC is longer than a screen height anyway.

That doesn't seem unusual, since trait implementations and methods are listed in there.

That's not a SpidersGeorg type. Those are all very basic, normall error-ish trait implementations, and there's enough of them to fill the page.

the8472 · 2024-02-12T18:28:18Z

Yeah I think vertical menus that only show the name and nothing else just take up way too much space for the limited value they provide. They just don't strike the right balance imo.
Yes, there are cases where one just wants to jump to a method or impl by name and in those cases they do the job, especially when they're the first hit via Ctrl+F.

But if one doesn't already know what one is looking for then a summary that's more verbose than just the name but more concise than the full docs would help.

For an alternative design look at javadocs.

For interfaces they have a horizontal list: https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/Map.html
Additionally they have summary tables (with a responsive design, that reflows at <800px): https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/Map.html#method-summary

I'm not saying javadocs strike the perfect balance on everything, but imo in at least those two aspects they're doing better than rustdoc

fmease · 2024-03-01T09:53:35Z

I haven't reviewed this yet because I'm assuming this is effectively S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). . If that's not the case, I can gladly review it.

bors · 2024-04-10T16:59:44Z

☔ The latest upstream changes (presumably #123725) made this pull request unmergeable. Please resolve the merge conflicts.

GuillaumeGomez · 2024-08-01T15:23:39Z

Looking at it again, apart from some small UI tweaks (like more padding and rounded corners), it seems fine to me.

The more I look at this feature, the more I like it :D

notriddle · 2024-08-01T15:58:33Z

Something like this?

border-radius: 6px; padding: var(--sidebar-elems-left-padding); padding-right: 0

Or are you thinking of something else? Like this (with 75px spacing on top and bottom)?

GuillaumeGomez · 2024-08-01T17:05:43Z

Radius and padding look good! For the top position, I'd put it at the same level as the search input. Like that it's not fully at the top but also doesn't stand out too much (although, the second image's position would be ok for me too).

notriddle · 2024-08-02T02:10:38Z

Radius and padding look good! For the top position, I'd put it at the same level as the search input.

Okay, I pushed up a new version, but I put it at the same level as the item-decl. That is, I made it look like this (dash line added for visibility; there's also a goml test for it), and also gave them the same border-radius:

GuillaumeGomez · 2024-08-02T08:47:39Z

Looks all good to me now, thanks!

bors · 2024-08-20T23:14:01Z

☔ The latest upstream changes (presumably #128252) made this pull request unmergeable. Please resolve the merge conflicts.

rustdoc: add header map to the table of contents ## Summary Add header sections to the sidebar TOC. ### Preview ![image](https://github.com/user-attachments/assets/eae4df02-86aa-4df4-8c61-a95685cd8829) * http://notriddle.com/rustdoc-html-demo-9/toc/rust/std/index.html * http://notriddle.com/rustdoc-html-demo-9/toc/rust-derive-builder/derive_builder/index.html ## Motivation Some pages are very wordy, like these. | crate | word count | |--|--| | [std::option](https://doc.rust-lang.org/stable/std/option/index.html) | 2,138 | [derive_builder](https://docs.rs/derive_builder/0.13.0/derive_builder/index.html) | 2,403 | [tracing](https://docs.rs/tracing/0.1.40/tracing/index.html) | 3,912 | [regex](https://docs.rs/regex/1.10.3/regex/index.html) | 8,412 This kind of very long document is more navigable with a table of contents, like Wikipedia's or the one [GitHub recently added](https://github.blog/changelog/2021-04-13-table-of-contents-support-in-markdown-files/) for READMEs. In fact, the use case is so compelling, that it's been requested multiple times and implemented in an extension: * rust-lang#80858 * rust-lang#28056 * rust-lang#14475 * https://rust.extension.sh/#show-table-of-content (Some of these issues ask for more than this, so don’t close them.) It's also been implemented by hand in some crates, because the author really thought it was needed. Protip: for a more exhaustive list, run [`site:docs.rs table of contents`](https://duckduckgo.com/?t=ffab&q=site%3Adocs.rs+table+of+contents&ia=web), though some of them are false positives. * https://docs.rs/figment/0.10.14/figment/index.html#table-of-contents * https://docs.rs/csv/1.3.0/csv/tutorial/index.html#table-of-contents * https://docs.rs/axum/0.7.4/axum/response/index.html#table-of-contents * https://docs.rs/regex-automata/0.4.5/regex_automata/index.html#table-of-contents Unfortunately for these hand-built ToCs, because they're just part of the docs, there's no consistent way to turn them off if the reader doesn't want them. It's also more complicated to ensure they stay in sync with the docs they're supposed to describe, and they don't stay with you when you scroll like Wikipedia's [does now](https://uxdesign.cc/design-notes-on-the-2023-wikipedia-redesign-d6573b9af28d). ## Guide-level explanation When writing docs for a top-level item, the first and second level of headers will be shown in an outline in the sidebar. In this context, "top level" means "not associated". This means, if you're writing very long guides or explanations, and you want it to have a table of contents in the sidebar for its headings, the ideal place to attach it is usually the *module* or *crate*, because this page has fewer other things on it (and is the ideal place to describe "cross-cutting concerns" for its child items). If you're reading documentation, and want to get rid of the table of contents, open the ![image](https://github.com/rust-lang/rust/assets/1593513/2ad82466-5fe3-4684-b1c2-6be4c99a8666) Settings panel and checkmark "Hide table of contents." ## Reference-level explanation Top-level items have an outline generated. This works for potentially-malformed header trees by pairing a header with the nearest header with a higher level. For example: ```markdown ## A # B # C ## D ## E ``` A, B, and C are all siblings, and D and E are children of C. Rustdoc only presents two layers of tree, but it tracks up to the full depth of 6 while preparing it. That means that these two doc comment both generate the same outline: ```rust /// # First /// ## Second struct One; /// ## First /// ### Second struct Two; ``` ## Drawbacks The biggest drawback is adding more stuff to the sidebar. My crawl through docs.rs shows this to, surprisingly, be less of a problem than I thought. The manually-built tables of contents, and the pages with dozens of headers, usually seem to be modules or crates, not types (where extreme scrolling would become a problem, since they already have methods to deal with). The best example of a type with many headers is [vec::Vec](https://doc.rust-lang.org/1.75.0/std/vec/struct.Vec.html), which still only has five headers, not dozens like [axum::extract](https://docs.rs/axum/0.7.4/axum/extract/index.html). ## Rationale and alternatives ### Why in the existing sidebar? The method links and the top-doc header links have more in common with each other than either of them do with the "In [parent module]" links, and should go together. ### Why limited to two levels? The sidebar is pretty narrow, and I don't want too much space used by indentation. Making the sidebar wider, while it has some upsides, also takes up more space on middling-sized screens or tiled WMs. ### Why not line wrap? That behaves strangely when resizing. ## Prior art ### Doc generators that have TOC for headers https://hexdocs.pm/phoenix/Phoenix.Controller.html is very close, in the sense that it also has header sections directly alongside functions and types. Another example, referenced as part of the [early sidebar discussion](rust-lang#37856) that added methods, Ruby will show a table of contents in the sidebar (for example, on the [ARGF](https://docs.ruby-lang.org/en/master/ARGF.html) class). According to their changelog, [they added it in 2013](https://github.com/ruby/rdoc/blob/06137bde8ccc48cd502bc28178bcd8f2dfe37624/History.rdoc#400--2013-02-24-). Haskell seems to mix text and functions even more freely than Elixir. For example, this [Naming conventions](https://hackage.haskell.org/package/base-4.19.0.0/docs/Control-Monad.html#g:3) is plain text, and is immediately followed by functions. And the [Pandoc top level](https://hackage.haskell.org/package/pandoc-3.1.11.1/docs/Text-Pandoc.html) has items split up by function, rather than by kind. Their TOC matches exactly with the contents of the page. ### Doc generators that don't have header TOC, but still have headers Elm, interestingly enough, seems to have the same setup that Rust used to have: sibling navigation between modules, and no index within a single page. [They keep Haskell's habit of named sections with machine-generated type signatures](https://package.elm-lang.org/packages/elm/browser/latest/Browser-Dom), though. [PHP](https://www.php.net/manual/en/book.datetime.php), like elm, also has a right-hand sidebar with sibling navigation. However, PHP has a single page for a single method, unlike Rust's page for an entire "class." So even though these pages have headers, it's never more than ten at most. And when they have guides, those guides are also multi-page. ## Unresolved questions * Writing recommendations for anyone who wants to take advantage of this. * Right now, it does not line wrap. That might be a bad idea: a lot of these are getting truncated. * Split sidebars, which I [tried implementing](https://rust-lang.zulipchat.com/#narrow/stream/266220-t-rustdoc/topic/Table.20of.20contents), are not required. The TOC can be turned off, if it's really a problem. Implemented in rust-lang#120818, but needs more, separate, discussion. ## Future possibilities I would like to do a better job of distinguishing global navigation from local navigation. Rustdoc has a pretty reasonable information architecture, if only we did a better job of communicating it. This PR aims, mostly, to help doc authors help their users by writing docs that can be more effectively skimmed. But it doesn't do anything to make it easier to tell the TOC and the Module Nav apart.

Rollup merge of rust-lang#120736 - notriddle:notriddle/toc, r=t-rustdoc rustdoc: add header map to the table of contents ## Summary Add header sections to the sidebar TOC. ### Preview ![image](https://github.com/user-attachments/assets/eae4df02-86aa-4df4-8c61-a95685cd8829) * http://notriddle.com/rustdoc-html-demo-9/toc/rust/std/index.html * http://notriddle.com/rustdoc-html-demo-9/toc/rust-derive-builder/derive_builder/index.html ## Motivation Some pages are very wordy, like these. | crate | word count | |--|--| | [std::option](https://doc.rust-lang.org/stable/std/option/index.html) | 2,138 | [derive_builder](https://docs.rs/derive_builder/0.13.0/derive_builder/index.html) | 2,403 | [tracing](https://docs.rs/tracing/0.1.40/tracing/index.html) | 3,912 | [regex](https://docs.rs/regex/1.10.3/regex/index.html) | 8,412 This kind of very long document is more navigable with a table of contents, like Wikipedia's or the one [GitHub recently added](https://github.blog/changelog/2021-04-13-table-of-contents-support-in-markdown-files/) for READMEs. In fact, the use case is so compelling, that it's been requested multiple times and implemented in an extension: * rust-lang#80858 * rust-lang#28056 * rust-lang#14475 * https://rust.extension.sh/#show-table-of-content (Some of these issues ask for more than this, so don’t close them.) It's also been implemented by hand in some crates, because the author really thought it was needed. Protip: for a more exhaustive list, run [`site:docs.rs table of contents`](https://duckduckgo.com/?t=ffab&q=site%3Adocs.rs+table+of+contents&ia=web), though some of them are false positives. * https://docs.rs/figment/0.10.14/figment/index.html#table-of-contents * https://docs.rs/csv/1.3.0/csv/tutorial/index.html#table-of-contents * https://docs.rs/axum/0.7.4/axum/response/index.html#table-of-contents * https://docs.rs/regex-automata/0.4.5/regex_automata/index.html#table-of-contents Unfortunately for these hand-built ToCs, because they're just part of the docs, there's no consistent way to turn them off if the reader doesn't want them. It's also more complicated to ensure they stay in sync with the docs they're supposed to describe, and they don't stay with you when you scroll like Wikipedia's [does now](https://uxdesign.cc/design-notes-on-the-2023-wikipedia-redesign-d6573b9af28d). ## Guide-level explanation When writing docs for a top-level item, the first and second level of headers will be shown in an outline in the sidebar. In this context, "top level" means "not associated". This means, if you're writing very long guides or explanations, and you want it to have a table of contents in the sidebar for its headings, the ideal place to attach it is usually the *module* or *crate*, because this page has fewer other things on it (and is the ideal place to describe "cross-cutting concerns" for its child items). If you're reading documentation, and want to get rid of the table of contents, open the ![image](https://github.com/rust-lang/rust/assets/1593513/2ad82466-5fe3-4684-b1c2-6be4c99a8666) Settings panel and checkmark "Hide table of contents." ## Reference-level explanation Top-level items have an outline generated. This works for potentially-malformed header trees by pairing a header with the nearest header with a higher level. For example: ```markdown ## A # B # C ## D ## E ``` A, B, and C are all siblings, and D and E are children of C. Rustdoc only presents two layers of tree, but it tracks up to the full depth of 6 while preparing it. That means that these two doc comment both generate the same outline: ```rust /// # First /// ## Second struct One; /// ## First /// ### Second struct Two; ``` ## Drawbacks The biggest drawback is adding more stuff to the sidebar. My crawl through docs.rs shows this to, surprisingly, be less of a problem than I thought. The manually-built tables of contents, and the pages with dozens of headers, usually seem to be modules or crates, not types (where extreme scrolling would become a problem, since they already have methods to deal with). The best example of a type with many headers is [vec::Vec](https://doc.rust-lang.org/1.75.0/std/vec/struct.Vec.html), which still only has five headers, not dozens like [axum::extract](https://docs.rs/axum/0.7.4/axum/extract/index.html). ## Rationale and alternatives ### Why in the existing sidebar? The method links and the top-doc header links have more in common with each other than either of them do with the "In [parent module]" links, and should go together. ### Why limited to two levels? The sidebar is pretty narrow, and I don't want too much space used by indentation. Making the sidebar wider, while it has some upsides, also takes up more space on middling-sized screens or tiled WMs. ### Why not line wrap? That behaves strangely when resizing. ## Prior art ### Doc generators that have TOC for headers https://hexdocs.pm/phoenix/Phoenix.Controller.html is very close, in the sense that it also has header sections directly alongside functions and types. Another example, referenced as part of the [early sidebar discussion](rust-lang#37856) that added methods, Ruby will show a table of contents in the sidebar (for example, on the [ARGF](https://docs.ruby-lang.org/en/master/ARGF.html) class). According to their changelog, [they added it in 2013](https://github.com/ruby/rdoc/blob/06137bde8ccc48cd502bc28178bcd8f2dfe37624/History.rdoc#400--2013-02-24-). Haskell seems to mix text and functions even more freely than Elixir. For example, this [Naming conventions](https://hackage.haskell.org/package/base-4.19.0.0/docs/Control-Monad.html#g:3) is plain text, and is immediately followed by functions. And the [Pandoc top level](https://hackage.haskell.org/package/pandoc-3.1.11.1/docs/Text-Pandoc.html) has items split up by function, rather than by kind. Their TOC matches exactly with the contents of the page. ### Doc generators that don't have header TOC, but still have headers Elm, interestingly enough, seems to have the same setup that Rust used to have: sibling navigation between modules, and no index within a single page. [They keep Haskell's habit of named sections with machine-generated type signatures](https://package.elm-lang.org/packages/elm/browser/latest/Browser-Dom), though. [PHP](https://www.php.net/manual/en/book.datetime.php), like elm, also has a right-hand sidebar with sibling navigation. However, PHP has a single page for a single method, unlike Rust's page for an entire "class." So even though these pages have headers, it's never more than ten at most. And when they have guides, those guides are also multi-page. ## Unresolved questions * Writing recommendations for anyone who wants to take advantage of this. * Right now, it does not line wrap. That might be a bad idea: a lot of these are getting truncated. * Split sidebars, which I [tried implementing](https://rust-lang.zulipchat.com/#narrow/stream/266220-t-rustdoc/topic/Table.20of.20contents), are not required. The TOC can be turned off, if it's really a problem. Implemented in rust-lang#120818, but needs more, separate, discussion. ## Future possibilities I would like to do a better job of distinguishing global navigation from local navigation. Rustdoc has a pretty reasonable information architecture, if only we did a better job of communicating it. This PR aims, mostly, to help doc authors help their users by writing docs that can be more effectively skimmed. But it doesn't do anything to make it easier to tell the TOC and the Module Nav apart.

rustdoc: add header map to the table of contents ## Summary Add header sections to the sidebar TOC. ### Preview ![image](https://github.com/user-attachments/assets/eae4df02-86aa-4df4-8c61-a95685cd8829) * http://notriddle.com/rustdoc-html-demo-9/toc/rust/std/index.html * http://notriddle.com/rustdoc-html-demo-9/toc/rust-derive-builder/derive_builder/index.html ## Motivation Some pages are very wordy, like these. | crate | word count | |--|--| | [std::option](https://doc.rust-lang.org/stable/std/option/index.html) | 2,138 | [derive_builder](https://docs.rs/derive_builder/0.13.0/derive_builder/index.html) | 2,403 | [tracing](https://docs.rs/tracing/0.1.40/tracing/index.html) | 3,912 | [regex](https://docs.rs/regex/1.10.3/regex/index.html) | 8,412 This kind of very long document is more navigable with a table of contents, like Wikipedia's or the one [GitHub recently added](https://github.blog/changelog/2021-04-13-table-of-contents-support-in-markdown-files/) for READMEs. In fact, the use case is so compelling, that it's been requested multiple times and implemented in an extension: * rust-lang/rust#80858 * rust-lang/rust#28056 * rust-lang/rust#14475 * https://rust.extension.sh/#show-table-of-content (Some of these issues ask for more than this, so don’t close them.) It's also been implemented by hand in some crates, because the author really thought it was needed. Protip: for a more exhaustive list, run [`site:docs.rs table of contents`](https://duckduckgo.com/?t=ffab&q=site%3Adocs.rs+table+of+contents&ia=web), though some of them are false positives. * https://docs.rs/figment/0.10.14/figment/index.html#table-of-contents * https://docs.rs/csv/1.3.0/csv/tutorial/index.html#table-of-contents * https://docs.rs/axum/0.7.4/axum/response/index.html#table-of-contents * https://docs.rs/regex-automata/0.4.5/regex_automata/index.html#table-of-contents Unfortunately for these hand-built ToCs, because they're just part of the docs, there's no consistent way to turn them off if the reader doesn't want them. It's also more complicated to ensure they stay in sync with the docs they're supposed to describe, and they don't stay with you when you scroll like Wikipedia's [does now](https://uxdesign.cc/design-notes-on-the-2023-wikipedia-redesign-d6573b9af28d). ## Guide-level explanation When writing docs for a top-level item, the first and second level of headers will be shown in an outline in the sidebar. In this context, "top level" means "not associated". This means, if you're writing very long guides or explanations, and you want it to have a table of contents in the sidebar for its headings, the ideal place to attach it is usually the *module* or *crate*, because this page has fewer other things on it (and is the ideal place to describe "cross-cutting concerns" for its child items). If you're reading documentation, and want to get rid of the table of contents, open the ![image](https://github.com/rust-lang/rust/assets/1593513/2ad82466-5fe3-4684-b1c2-6be4c99a8666) Settings panel and checkmark "Hide table of contents." ## Reference-level explanation Top-level items have an outline generated. This works for potentially-malformed header trees by pairing a header with the nearest header with a higher level. For example: ```markdown ## A # B # C ## D ## E ``` A, B, and C are all siblings, and D and E are children of C. Rustdoc only presents two layers of tree, but it tracks up to the full depth of 6 while preparing it. That means that these two doc comment both generate the same outline: ```rust /// # First /// ## Second struct One; /// ## First /// ### Second struct Two; ``` ## Drawbacks The biggest drawback is adding more stuff to the sidebar. My crawl through docs.rs shows this to, surprisingly, be less of a problem than I thought. The manually-built tables of contents, and the pages with dozens of headers, usually seem to be modules or crates, not types (where extreme scrolling would become a problem, since they already have methods to deal with). The best example of a type with many headers is [vec::Vec](https://doc.rust-lang.org/1.75.0/std/vec/struct.Vec.html), which still only has five headers, not dozens like [axum::extract](https://docs.rs/axum/0.7.4/axum/extract/index.html). ## Rationale and alternatives ### Why in the existing sidebar? The method links and the top-doc header links have more in common with each other than either of them do with the "In [parent module]" links, and should go together. ### Why limited to two levels? The sidebar is pretty narrow, and I don't want too much space used by indentation. Making the sidebar wider, while it has some upsides, also takes up more space on middling-sized screens or tiled WMs. ### Why not line wrap? That behaves strangely when resizing. ## Prior art ### Doc generators that have TOC for headers https://hexdocs.pm/phoenix/Phoenix.Controller.html is very close, in the sense that it also has header sections directly alongside functions and types. Another example, referenced as part of the [early sidebar discussion](rust-lang/rust#37856) that added methods, Ruby will show a table of contents in the sidebar (for example, on the [ARGF](https://docs.ruby-lang.org/en/master/ARGF.html) class). According to their changelog, [they added it in 2013](https://github.com/ruby/rdoc/blob/06137bde8ccc48cd502bc28178bcd8f2dfe37624/History.rdoc#400--2013-02-24-). Haskell seems to mix text and functions even more freely than Elixir. For example, this [Naming conventions](https://hackage.haskell.org/package/base-4.19.0.0/docs/Control-Monad.html#g:3) is plain text, and is immediately followed by functions. And the [Pandoc top level](https://hackage.haskell.org/package/pandoc-3.1.11.1/docs/Text-Pandoc.html) has items split up by function, rather than by kind. Their TOC matches exactly with the contents of the page. ### Doc generators that don't have header TOC, but still have headers Elm, interestingly enough, seems to have the same setup that Rust used to have: sibling navigation between modules, and no index within a single page. [They keep Haskell's habit of named sections with machine-generated type signatures](https://package.elm-lang.org/packages/elm/browser/latest/Browser-Dom), though. [PHP](https://www.php.net/manual/en/book.datetime.php), like elm, also has a right-hand sidebar with sibling navigation. However, PHP has a single page for a single method, unlike Rust's page for an entire "class." So even though these pages have headers, it's never more than ten at most. And when they have guides, those guides are also multi-page. ## Unresolved questions * Writing recommendations for anyone who wants to take advantage of this. * Right now, it does not line wrap. That might be a bad idea: a lot of these are getting truncated. * Split sidebars, which I [tried implementing](https://rust-lang.zulipchat.com/#narrow/stream/266220-t-rustdoc/topic/Table.20of.20contents), are not required. The TOC can be turned off, if it's really a problem. Implemented in rust-lang/rust#120818, but needs more, separate, discussion. ## Future possibilities I would like to do a better job of distinguishing global navigation from local navigation. Rustdoc has a pretty reasonable information architecture, if only we did a better job of communicating it. This PR aims, mostly, to help doc authors help their users by writing docs that can be more effectively skimmed. But it doesn't do anything to make it easier to tell the TOC and the Module Nav apart.

rustbot · 2024-09-12T22:49:23Z

Some changes occurred in HTML/CSS/JS.

cc @GuillaumeGomez, @jsha

Some changes occurred in GUI tests.

cc @GuillaumeGomez

src/librustdoc/html/templates/sidebar.html

This commit adds a floating TOC box to the right, leaving the sibling/module/crate navigation on the left. This kicks in at a size a little below 1920x1080, where desktops with very wide monitors are: it's also around the point where the content area can be full width while allowing two sidebars. It only kicks in if the browser supports grid layouts, but that should be most of them, and we can't get rid of the two-column layout anyway, since it's the layout you get on something like a portrait iPad. This design, where it can be used, is meant to clearly split up the table of contents and the site navigation, so the right side floating box has the same color as the page while the left sidebar does not. It also pushes it down further, so that it's not as high as the search bar, though that's a bit more subtle than the color.

bors · 2024-09-24T09:06:12Z

☔ The latest upstream changes (presumably #130768) made this pull request unmergeable. Please resolve the merge conflicts.

GuillaumeGomez · 2024-12-11T14:56:53Z

Should we start the FCP here or is there something else you want to modify?

notriddle · 2024-12-11T16:15:07Z

I'd like to get a consensus on #133279 first, since these two changes both impact each other. In particular, if that PR gets merged, then the three-column mode would probably look like this:

Otherwise, I would have to come up with something else.

rustbot assigned fmease Feb 9, 2024

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rustdoc: add header map to the table of contents #120736

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notriddle added T-rustdoc-frontend Relevant to the rustdoc-frontend team, which will review and decide on the web UI/UX output. and removed T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Sep 12, 2024

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Add tidy check for missing {# #} tag in rustdoc templates #130559

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rustdoc: add three-column layout for large desktops #120818

rustdoc: add three-column layout for large desktops #120818

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Why is the TOC in a box?

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rustdoc: add three-column layout for large desktops #120818

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rustdoc: add three-column layout for large desktops #120818

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notriddle commented Feb 9, 2024 • edited Loading

Summary

Preview

Motivation

Drawbacks

Rationale and alternatives

Why are Sections and Methods both here

Why is the TOC in a box?

Why isn't there a configuration switch to force the one-sidebar view?

Why isn't there a way to resize the TOC box?

Prior art

Unresolved questions

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Why is the TOC in a box?

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