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📦 Turbo Rust   1# Reference: languages coloured
3> Neutral description of which files Turbo Rust colours, how it decides, and what each scanner recognises.
5## Recognition
7A file's **extension** decides whenever it is one of these:
Extension | Language |
--- | --- |
`.rs` | Rust |
`.toml` | TOML |
`.yaml`, `.yml` | YAML |
`.md`, `.markdown` | Markdown |
`.js`, `.mjs`, `.cjs` | JavaScript |
`.html`, `.htm` | HTML |
`.xml`, `.xsd`, `.xsl`, `.xslt`, `.svg`, `.plist`, `.csproj`, `.pom` | XML |
`.sh`, `.bash`, `.zsh` | Shell |
`.dockerfile`, `.containerfile` | Dockerfile |
21Extensions are matched case-insensitively, and only the last one counts: `main.rs.backup` is not Rust.
23A file whose extension decides nothing is looked up by **name** next. Only files that carry no useful extension need this:
Name | Language |
--- | --- |
`Dockerfile`, `Containerfile` | Dockerfile |
29A name matches on the whole of it or on the part before the first dot, ignoring case — so `Dockerfile`, `dockerfile` and `Dockerfile.dev` are all recognised, while `Dockerfile.md` is Markdown, because the extension is consulted first.
31A file that neither table claims is a **shell script** when its first line is a shebang naming a shell — `sh`, `bash`, `zsh`, `dash` or `ksh`, as a path element or as the argument to `env`. That is what colours `configure`, a git hook, or a script somebody renamed.
First line | Result |
--- | --- |
`#!/bin/sh` | Shell |
`#!/usr/bin/env bash` | Shell |
`#!/usr/bin/env -S bash -e` | Shell |
`#!/usr/bin/env python3` | Not coloured |
Anything not starting `#!` | Not coloured |
41The order is fixed — extension, then name, then first line — and the first to decide wins: a `.rs` file starting with a shebang is Rust.
43Everything else is shown in plain text. That is not an error — opening a PNG in the editor is not a mistake, it is just not coloured.
45
47Every scanner produces the same vocabulary of classes, and each maps to one theme key.
Class | Theme key | Produced by |
--- | --- | --- |
`identifier` | `syntax.identifier` | Rust, TOML, JavaScript, shell, YAML, Dockerfile |
`keyword` | `syntax.keyword` | Rust, JavaScript, shell, HTML (doctype), XML, Dockerfile |
`type` | `syntax.type` | Rust, TOML (table headers), YAML (tags) |
`builtin` | `syntax.builtin` | Rust, JavaScript, shell (builtins and expansions), YAML (anchors and aliases), Dockerfile (variables) |
`constant` | `syntax.constant` | Rust, TOML, JavaScript, shell, YAML, HTML and XML (entities) |
`function` | `syntax.function` | Rust, JavaScript, shell (the command) |
`string` | `syntax.string` | all |
`char` | `syntax.char` | Rust |
`number` | `syntax.number` | Rust, TOML, JavaScript, shell, YAML, Dockerfile |
`comment` | `syntax.comment` | Rust, TOML, JavaScript, shell, HTML, YAML, XML, Dockerfile |
`operator` | `syntax.operator` | Rust, TOML, JavaScript, shell, HTML, YAML (block scalar headers), XML, Dockerfile |
`punctuation` | `syntax.punctuation` | Rust, TOML, JavaScript, shell, Markdown, YAML, Dockerfile |
`heading` | `syntax.heading` | Markdown |
`tag` | `syntax.tag` | HTML, XML |
`attribute` | `syntax.attribute` | HTML, XML, Dockerfile (flags) |
`emphasis` | `syntax.emphasis` | Markdown |
`link` | `syntax.link` | Markdown |
71Hand-written, in `internal/rustlang`. Three constructs cross a line break and are carried exactly rather than guessed at: a block comment (with its nesting depth), a raw string (with its hash count), and an ordinary string.
Recognised | As |
--- | --- |
`fn`, `let`, `impl`, `struct`, `enum`, `trait`, `match`, `pub`, `mut`, `async`, `await`, `unsafe`, … | keyword |
the words reserved for future use — `become`, `priv`, `typeof`, `unsized`, … | keyword |
`bool`, `char`, `str`, `i8`…`i128`, `u8`…`u128`, `isize`, `usize`, `f32`, `f64`, `self`, `Self` | type |
any other name starting with a capital | type |
`true`, `false`, `None`, `Some`, `Ok`, `Err` | constant |
a name immediately before `(` | function |
`name!`, the `!` included | builtin |
`#[derive(Debug)]`, `#![no_std]` | attribute |
`"…"`, `b"…"`, across lines, escapes honoured | string |
`r"…"`, `r#"…"#`, `br##"…"##`, across lines | string |
`'x'`, `'\n'`, `'\u{1F600}'`, `b'x'` | char |
`'a`, `'static` | type |
`42`, `1_000`, `0xFF`, `0b1010`, `0o77`, `1.5e-3`, `42u8`, `3.0f64` | number |
`//`, `///`, `//!` to end of line | comment |
`/* … */`, **nested**, across lines | comment |
`..`, `..=` | operator |
`:`, `::` | punctuation |
runs of `+-*/%=<>!&\|^~?` | operator |
`()[]{},;.` | punctuation |
95**A lifetime is told from a character literal by looking for the closing quote** where a character would have to put it — one rune along, or further for an escape. `'a` is a lifetime, `'a'` is a character, `'static` is a lifetime, `'\u{1F600}'` is a character. Getting this wrong strings the rest of the line, which is why it has tests of its own.
97**A lifetime is coloured as a type**, because it is a generic parameter, declared and used in the same places one is.
99**A capital letter means a type.** Rust's naming convention is strong enough to lean on: a type, a trait and an enum variant are all `UpperCamelCase` and nothing else is. A constant in `SCREAMING_SNAKE_CASE` is coloured as a type by this rule, which is the one place it is visibly a heuristic.
101**`None`, `Some`, `Ok` and `Err` are Option's and Result's, not the language's.** They are coloured as constants because a reader meets them before any other variant and reads them as they read `true`.
103**Macros take their `!`.** `println!` is one span; `a != b` is not a macro, and the two are told apart by the `=` that follows.
105**A number takes its suffix.** `42u8` is one literal, and colouring the `u8` as a type would split a thing that is not two things.
107**An attribute that runs past the end of its line is coloured to the end and not carried.** Unlike a comment or a string, an unclosed attribute is nearly always a half-typed one, and carrying it would paint the rest of the file.
109**Not recognised**, each for a stated reason:
Not recognised | Because |
--- | --- |
Which macro is being invoked | `println!` and a macro you wrote yourself are both builtins; telling them apart needs the crate's expansion |
The inside of a macro body | `macro_rules!` bodies are coloured as ordinary Rust, which is usually right and sometimes not |
`SCREAMING_SNAKE_CASE` constants as constants | Indistinguishable from a type name by the leading-capital rule, and a second rule for it would mis-colour a type whose name is an acronym |
Doc-comment Markdown | A `///` comment is one comment, not a Markdown document |
Recognised | As |
--- | --- |
`# comment` | comment |
`[table]`, `[[array]]` | the name as a type, the brackets as punctuation |
`key =` | identifier, then operator |
`"basic"`, `'literal'`, `"""multi-line"""`, `'''multi-line'''` | string |
`true`, `false` | constant |
numbers, dates, times, `inf`, `nan` | number |
131A compose file, a Kubernetes manifest and a CI workflow are all this: there is no separate dialect, because a dialect would be somebody else's schema to keep in step with.
Recognised | As |
--- | --- |
`# comment` | comment |
`key:` before a space or the end of the line | the key as an identifier, the colon as punctuation |
`"quoted": 1`, `'quoted': 1` | the quoted key as an identifier |
`- ` opening a sequence entry | punctuation |
`"…"`, `'…'` | string |
`true`, `false`, `yes`, `no`, `on`, `off`, `null` | constant, whatever their case |
numbers, dates and times written without quotes | number |
`&anchor`, `*alias` | builtin |
`!!str`, `!Custom` | type |
`---`, `...` | the whole line as punctuation |
`{`, `}`, `[`, `]`, `,` | punctuation |
`\|`, `>`, with their chomping and indentation indicators | the header as an operator, the body as a string |
148**A colon is a separator only when a space or the end of the line follows it.** `image: nginx:1.27` is a key and one value, and `url: http://example.com/x` is a key and one URL — colouring the inner colons as separators would put every image tag and every URL in three colours.
150**A block scalar's extent is decided by indentation**, not by a delimiter. The first content line after `|` or `>` fixes the block's indentation; every line indented at least that far belongs to it, and the first line that is not ends it. **A blank line inside a block stays inside it**: a literal scalar keeps its empty lines, and ending the block at the first paragraph break would cut a shell script in a CI file in half.
152**A `#` needs a space before it to start a comment**, so `colour: ff#00aa` is one scalar.
Not recognised | Because |
--- | --- |
The schema of a compose file, a manifest or a workflow | Colouring `services:` differently from any other key means carrying somebody else's schema, and it goes stale the day they add a key |
Multi-document streams as separate documents | `---` is coloured, but nothing is reset at it; nothing in the colouring depends on document boundaries |
Whether a bare word is a string or a number to a parser | `1.2.3` is a version to a reader and a string to YAML; the scanner colours what it looks like |
160## Markdown
Recognised | As |
--- | --- |
`# Heading` … `###### Heading` | the whole line as a heading |
`**bold**`, `__bold__`, `*italic*`, `_italic_` | emphasis |
`` `code` `` | string |
`[text](target)`, `![alt](src)` | the whole thing as a link |
`- `, `* `, `+ `, `1. `, `1) ` | the marker as punctuation |
`>` | punctuation |
`---`, `***`, `___` | punctuation |
` ``` ` and `~~~` fences | the whole block, opening and closing lines included, as a string |
173A fenced block is **one colour whatever language it announces**: ```` ```rust ```` does not colour its contents as Rust. The run of markers that opens a block must be matched by the same character to close it, so a backtick fence is not closed by a tilde one. An unclosed fence colours to the end of the file.
175The run of markers opening emphasis must be matched by a run of the same length, so `**bold**` is one span rather than two italics.
177## JavaScript
Recognised | As |
--- | --- |
`const`, `let`, `function`, `class`, `async`, `await`, `import`, `export`, … | keyword |
`true`, `false`, `null`, `undefined`, `NaN`, `Infinity`, `this` | constant |
`console`, `document`, `window`, `Array`, `Object`, `Promise`, `Math`, `JSON`, … | builtin |
a name immediately before `(` | function |
`"…"`, `'…'` | string |
`` `…` ``, interpolations included, across lines | string |
`//` to end of line, `/* … */` across lines | comment |
`42`, `3.14`, `0x1f`, `0b1010`, `0o777`, `1_000_000`, `1e6`, `10n` | number |
runs of `+-*/%=<>!&|^~?:` | operator |
`()[]{},;.` | punctuation |
192**Regular-expression literals are not recognised.** Telling `/x/g` from a division needs to know whether the previous token could end an expression; a wrong guess colours the rest of a line as a string, which is worse than leaving a regex the colour of an operator.
194Globals are recognised by name, so a file that shadows `Math` still has it coloured as a builtin — the same rule Rust's primitive types follow.
Recognised | As |
--- | --- |
`<tag`, `</tag`, `>`, `/>` | tag |
attribute names, including `data-*`, `xlink:href`, `@click`, `v-bind.prop` | attribute |
`=` | operator |
`"…"`, `'…'` | string |
`<!-- … -->`, across lines | comment |
`&amp;`, `&#169;` | constant |
`<!DOCTYPE …>` and other declarations | keyword |
208Text between tags is not coloured. A bare `&` with no `;` within 32 characters is left alone, because it is legal text.
210**The contents of `<script>` and `<style>` are not coloured** as JavaScript and CSS.
214Its own scanner rather than HTML's, for one reason that matters: CDATA. The whole point of `<![CDATA[ … ]]>` is that its contents are *not* markup, and colouring the tags inside one as tags is exactly backwards.
Recognised | As |
--- | --- |
`<?xml version="1.0"?>` and other processing instructions | the target and `?>` as keyword, the pairs between as attributes and strings |
`<!DOCTYPE …>` and the other `<!` forms | keyword |
`<!-- … -->`, across lines | comment |
`<![CDATA[ … ]]>`, across lines | string |
`<tag`, `</tag`, `>`, `/>` | tag |
`<ns:tag>`, `xsi:type` | the prefix and the local name as **one** span |
attribute names | attribute |
`=` | operator |
`"…"`, `'…'` | string |
`&amp;`, `&#169;` | constant |
229**A comment and a CDATA section close on different delimiters**, and are carried separately: a `-->` inside a CDATA section does not end it.
231**A bare `&` with no semicolon within 32 characters is left alone**, because it is legal text in plenty of documents and swallowing the rest of the line would be the bigger mistake.
233Text between tags is not coloured.
235
237Applies to `sh`, `bash` and `zsh` alike: the keywords recognised are the ones they share.
Recognised | As |
--- | --- |
`if`, `then`, `fi`, `for`, `while`, `case`, `esac`, `function`, `return`, … | keyword |
`true`, `false` | constant |
`echo`, `printf`, `export`, `local`, `read`, `cd`, `set`, `source`, … | builtin |
`$NAME`, `${…}`, `$(…)`, `$1`, `$?`, `$@` | builtin |
the **first bare word on a line** | function |
every later bare word, and `NAME` in `NAME=value` | identifier |
`'…'`, with nothing escaped or expanded inside | string |
`"…"`, with the expansions inside it coloured as expansions | string |
`#` to end of line | comment |
251`$(a $(b) c)` is one span: nesting is counted. An option such as `-euo` is one word, not a minus and a word.
253**Heredocs are not recognised.** `<<EOF` and the text after it are coloured as ordinary shell.
255## Dockerfile
Recognised | As |
--- | --- |
`FROM`, `RUN`, `COPY`, `ADD`, `ARG`, `ENV`, `CMD`, `ENTRYPOINT`, `EXPOSE`, `LABEL`, `USER`, `VOLUME`, `WORKDIR`, `HEALTHCHECK`, `ONBUILD`, `SHELL`, `STOPSIGNAL`, `MAINTAINER` | keyword, in any case |
`AS`, `NONE` | keyword |
`# comment`, including the `# syntax=` and `# escape=` directives | comment |
`--from=builder`, `--chown=me:me` | the flag name as an attribute |
`$NAME`, `${NAME}`, `${NAME:-default}` | builtin, as one span to the closing brace |
`"…"`, `'…'` | string |
a trailing `\` | operator |
numbers | number |
paths and image references — `/usr/local/bin`, `golang:1.26-alpine` | identifier, as **one** span |
269**Only the first word of a line can be an instruction**, and a word that is not one is an argument — which is what keeps a continuation line's first word out of the keyword colour.
271**Nothing crosses a line break.** A `\` joins two lines for Docker, but each half still reads as a command and is coloured on its own.
Not recognised | Because |
--- | --- |
The shell inside a `RUN` | It would mean running the shell scanner over part of a line and mapping its columns out, and `RUN` may hold any language |
Heredocs in a `RUN` | The same reason the shell scanner does not recognise them |
Which stage a `--from` names | Nothing here reads the rest of the file |
279## See also
281- [Theme file format](themes.md) — every key these classes resolve to
282- [Colouring and completion](../explanation/colouring-and-completion.md) — why the scanners are written this way
283- [How to write your own theme](../how-to/write-a-theme.md)

📦 Turbo Rust 713ea5c k33g 11h ago	1	# Reference: languages coloured
	2
	3	> Neutral description of which files Turbo Rust colours, how it decides, and what each scanner recognises.
	4
	5	## Recognition
	6
	7	A file's extension decides whenever it is one of these:
	8
	9	\| Extension \| Language \|
	10	\| --- \| --- \|
	11	\| `.rs` \| Rust \|
	12	\| `.toml` \| TOML \|
	13	\| `.yaml`, `.yml` \| YAML \|
	14	\| `.md`, `.markdown` \| Markdown \|
	15	\| `.js`, `.mjs`, `.cjs` \| JavaScript \|
	16	\| `.html`, `.htm` \| HTML \|
	17	\| `.xml`, `.xsd`, `.xsl`, `.xslt`, `.svg`, `.plist`, `.csproj`, `.pom` \| XML \|
	18	\| `.sh`, `.bash`, `.zsh` \| Shell \|
	19	\| `.dockerfile`, `.containerfile` \| Dockerfile \|
	20
	21	Extensions are matched case-insensitively, and only the last one counts: `main.rs.backup` is not Rust.
	22
	23	A file whose extension decides nothing is looked up by name next. Only files that carry no useful extension need this:
	24
	25	\| Name \| Language \|
	26	\| --- \| --- \|
	27	\| `Dockerfile`, `Containerfile` \| Dockerfile \|
	28
	29	A name matches on the whole of it or on the part before the first dot, ignoring case — so `Dockerfile`, `dockerfile` and `Dockerfile.dev` are all recognised, while `Dockerfile.md` is Markdown, because the extension is consulted first.
	30
	31	A file that neither table claims is a shell script when its first line is a shebang naming a shell — `sh`, `bash`, `zsh`, `dash` or `ksh`, as a path element or as the argument to `env`. That is what colours `configure`, a git hook, or a script somebody renamed.
	32
	33	\| First line \| Result \|
	34	\| --- \| --- \|
	35	\| `#!/bin/sh` \| Shell \|
	36	\| `#!/usr/bin/env bash` \| Shell \|
	37	\| `#!/usr/bin/env -S bash -e` \| Shell \|
	38	\| `#!/usr/bin/env python3` \| Not coloured \|
	39	\| Anything not starting `#!` \| Not coloured \|
	40
	41	The order is fixed — extension, then name, then first line — and the first to decide wins: a `.rs` file starting with a shebang is Rust.
	42
	43	Everything else is shown in plain text. That is not an error — opening a PNG in the editor is not a mistake, it is just not coloured.
	44
	45	## Classes
	46
	47	Every scanner produces the same vocabulary of classes, and each maps to one theme key.
	48
	49	\| Class \| Theme key \| Produced by \|
	50	\| --- \| --- \| --- \|
	51	\| `identifier` \| `syntax.identifier` \| Rust, TOML, JavaScript, shell, YAML, Dockerfile \|
	52	\| `keyword` \| `syntax.keyword` \| Rust, JavaScript, shell, HTML (doctype), XML, Dockerfile \|
	53	\| `type` \| `syntax.type` \| Rust, TOML (table headers), YAML (tags) \|
	54	\| `builtin` \| `syntax.builtin` \| Rust, JavaScript, shell (builtins and expansions), YAML (anchors and aliases), Dockerfile (variables) \|
	55	\| `constant` \| `syntax.constant` \| Rust, TOML, JavaScript, shell, YAML, HTML and XML (entities) \|
	56	\| `function` \| `syntax.function` \| Rust, JavaScript, shell (the command) \|
	57	\| `string` \| `syntax.string` \| all \|
	58	\| `char` \| `syntax.char` \| Rust \|
	59	\| `number` \| `syntax.number` \| Rust, TOML, JavaScript, shell, YAML, Dockerfile \|
	60	\| `comment` \| `syntax.comment` \| Rust, TOML, JavaScript, shell, HTML, YAML, XML, Dockerfile \|
	61	\| `operator` \| `syntax.operator` \| Rust, TOML, JavaScript, shell, HTML, YAML (block scalar headers), XML, Dockerfile \|
	62	\| `punctuation` \| `syntax.punctuation` \| Rust, TOML, JavaScript, shell, Markdown, YAML, Dockerfile \|
	63	\| `heading` \| `syntax.heading` \| Markdown \|
	64	\| `tag` \| `syntax.tag` \| HTML, XML \|
65	\| `attribute` \| `syntax.attribute` \| HTML, XML, Dockerfile (flags) \|
66	\| `emphasis` \| `syntax.emphasis` \| Markdown \|
67	\| `link` \| `syntax.link` \| Markdown \|
68
69	## Rust
70
71	Hand-written, in `internal/rustlang`. Three constructs cross a line break and are carried exactly rather than guessed at: a block comment (with its nesting depth), a raw string (with its hash count), and an ordinary string.
72
73	\| Recognised \| As \|
74	\| --- \| --- \|
75	\| `fn`, `let`, `impl`, `struct`, `enum`, `trait`, `match`, `pub`, `mut`, `async`, `await`, `unsafe`, … \| keyword \|
76	\| the words reserved for future use — `become`, `priv`, `typeof`, `unsized`, … \| keyword \|
77	\| `bool`, `char`, `str`, `i8`…`i128`, `u8`…`u128`, `isize`, `usize`, `f32`, `f64`, `self`, `Self` \| type \|
78	\| any other name starting with a capital \| type \|
79	\| `true`, `false`, `None`, `Some`, `Ok`, `Err` \| constant \|
80	\| a name immediately before `(` \| function \|
81	\| `name!`, the `!` included \| builtin \|
82	\| `#[derive(Debug)]`, `#![no_std]` \| attribute \|
83	\| `"…"`, `b"…"`, across lines, escapes honoured \| string \|
84	\| `r"…"`, `r#"…"#`, `br##"…"##`, across lines \| string \|
85	\| `'x'`, `'\n'`, `'\u{1F600}'`, `b'x'` \| char \|
86	\| `'a`, `'static` \| type \|
87	\| `42`, `1_000`, `0xFF`, `0b1010`, `0o77`, `1.5e-3`, `42u8`, `3.0f64` \| number \|
88	\| `//`, `///`, `//!` to end of line \| comment \|
89	\| `/* … /`, nested*, across lines \| comment \|
90	\| `..`, `..=` \| operator \|
91	\| `:`, `::` \| punctuation \|
92	\| runs of `+-*/%=<>!&\\|^~?` \| operator \|
93	\| `()[]{},;.` \| punctuation \|
94
95	A lifetime is told from a character literal by looking for the closing quote where a character would have to put it — one rune along, or further for an escape. `'a` is a lifetime, `'a'` is a character, `'static` is a lifetime, `'\u{1F600}'` is a character. Getting this wrong strings the rest of the line, which is why it has tests of its own.
96
97	A lifetime is coloured as a type, because it is a generic parameter, declared and used in the same places one is.
98
99	A capital letter means a type. Rust's naming convention is strong enough to lean on: a type, a trait and an enum variant are all `UpperCamelCase` and nothing else is. A constant in `SCREAMING_SNAKE_CASE` is coloured as a type by this rule, which is the one place it is visibly a heuristic.
100
101	`None`, `Some`, `Ok` and `Err` are Option's and Result's, not the language's. They are coloured as constants because a reader meets them before any other variant and reads them as they read `true`.
102
103	Macros take their `!`. `println!` is one span; `a != b` is not a macro, and the two are told apart by the `=` that follows.
104
105	A number takes its suffix. `42u8` is one literal, and colouring the `u8` as a type would split a thing that is not two things.
106
107	An attribute that runs past the end of its line is coloured to the end and not carried. Unlike a comment or a string, an unclosed attribute is nearly always a half-typed one, and carrying it would paint the rest of the file.
108
109	Not recognised, each for a stated reason:
110
111	\| Not recognised \| Because \|
112	\| --- \| --- \|
113	\| Which macro is being invoked \| `println!` and a macro you wrote yourself are both builtins; telling them apart needs the crate's expansion \|
114	\| The inside of a macro body \| `macro_rules!` bodies are coloured as ordinary Rust, which is usually right and sometimes not \|
115	\| `SCREAMING_SNAKE_CASE` constants as constants \| Indistinguishable from a type name by the leading-capital rule, and a second rule for it would mis-colour a type whose name is an acronym \|
116	\| Doc-comment Markdown \| A `///` comment is one comment, not a Markdown document \|
117
118	## TOML
119
120	\| Recognised \| As \|
121	\| --- \| --- \|
122	\| `# comment` \| comment \|
123	\| `[table]`, `[[array]]` \| the name as a type, the brackets as punctuation \|
124	\| `key =` \| identifier, then operator \|
125	\| `"basic"`, `'literal'`, `"""multi-line"""`, `'''multi-line'''` \| string \|
126	\| `true`, `false` \| constant \|
127	\| numbers, dates, times, `inf`, `nan` \| number \|
128
129	## YAML
130
131	A compose file, a Kubernetes manifest and a CI workflow are all this: there is no separate dialect, because a dialect would be somebody else's schema to keep in step with.
132
133	\| Recognised \| As \|
134	\| --- \| --- \|
135	\| `# comment` \| comment \|
136	\| `key:` before a space or the end of the line \| the key as an identifier, the colon as punctuation \|
137	\| `"quoted": 1`, `'quoted': 1` \| the quoted key as an identifier \|
138	\| `- ` opening a sequence entry \| punctuation \|
139	\| `"…"`, `'…'` \| string \|
140	\| `true`, `false`, `yes`, `no`, `on`, `off`, `null` \| constant, whatever their case \|
141	\| numbers, dates and times written without quotes \| number \|
142	\| `&anchor`, `*alias` \| builtin \|
143	\| `!!str`, `!Custom` \| type \|
144	\| `---`, `...` \| the whole line as punctuation \|
145	\| `{`, `}`, `[`, `]`, `,` \| punctuation \|
146	\| `\\|`, `>`, with their chomping and indentation indicators \| the header as an operator, the body as a string \|
147
148	A colon is a separator only when a space or the end of the line follows it. `image: nginx:1.27` is a key and one value, and `url: http://example.com/x` is a key and one URL — colouring the inner colons as separators would put every image tag and every URL in three colours.
149
150	A block scalar's extent is decided by indentation, not by a delimiter. The first content line after `\|` or `>` fixes the block's indentation; every line indented at least that far belongs to it, and the first line that is not ends it. A blank line inside a block stays inside it: a literal scalar keeps its empty lines, and ending the block at the first paragraph break would cut a shell script in a CI file in half.
151
152	A `#` needs a space before it to start a comment, so `colour: ff#00aa` is one scalar.
153
154	\| Not recognised \| Because \|
155	\| --- \| --- \|
156	\| The schema of a compose file, a manifest or a workflow \| Colouring `services:` differently from any other key means carrying somebody else's schema, and it goes stale the day they add a key \|
157	\| Multi-document streams as separate documents \| `---` is coloured, but nothing is reset at it; nothing in the colouring depends on document boundaries \|
158	\| Whether a bare word is a string or a number to a parser \| `1.2.3` is a version to a reader and a string to YAML; the scanner colours what it looks like \|
159
160	## Markdown
161
162	\| Recognised \| As \|
163	\| --- \| --- \|
164	\| `# Heading` … `###### Heading` \| the whole line as a heading \|
165	\| `bold`, `__bold__`, `italic`, `_italic_` \| emphasis \|
166	\| `` `code` `` \| string \|
167	\| `[text](target)`, `![alt](src)` \| the whole thing as a link \|
168	\| `- `, `* `, `+ `, `1. `, `1) ` \| the marker as punctuation \|
169	\| `>` \| punctuation \|
170	\| `---`, `***`, `___` \| punctuation \|
171	\| ` ``` ` and `~~~` fences \| the whole block, opening and closing lines included, as a string \|
172
173	A fenced block is one colour whatever language it announces: ```` ```rust ```` does not colour its contents as Rust. The run of markers that opens a block must be matched by the same character to close it, so a backtick fence is not closed by a tilde one. An unclosed fence colours to the end of the file.
174
175	The run of markers opening emphasis must be matched by a run of the same length, so `bold` is one span rather than two italics.
176
177	## JavaScript
178
179	\| Recognised \| As \|
180	\| --- \| --- \|
181	\| `const`, `let`, `function`, `class`, `async`, `await`, `import`, `export`, … \| keyword \|
182	\| `true`, `false`, `null`, `undefined`, `NaN`, `Infinity`, `this` \| constant \|
183	\| `console`, `document`, `window`, `Array`, `Object`, `Promise`, `Math`, `JSON`, … \| builtin \|
184	\| a name immediately before `(` \| function \|
185	\| `"…"`, `'…'` \| string \|
186	\| `` `…` ``, interpolations included, across lines \| string \|
187	\| `//` to end of line, `/* … */` across lines \| comment \|
188	\| `42`, `3.14`, `0x1f`, `0b1010`, `0o777`, `1_000_000`, `1e6`, `10n` \| number \|
189	\| runs of `+-*/%=<>!&\|^~?:` \| operator \|
190	\| `()[]{},;.` \| punctuation \|
191
192	Regular-expression literals are not recognised. Telling `/x/g` from a division needs to know whether the previous token could end an expression; a wrong guess colours the rest of a line as a string, which is worse than leaving a regex the colour of an operator.
193
194	Globals are recognised by name, so a file that shadows `Math` still has it coloured as a builtin — the same rule Rust's primitive types follow.
195
196	## HTML
197
198	\| Recognised \| As \|
199	\| --- \| --- \|
200	\| `<tag`, `</tag`, `>`, `/>` \| tag \|
201	\| attribute names, including `data-*`, `xlink:href`, `@click`, `v-bind.prop` \| attribute \|
202	\| `=` \| operator \|
203	\| `"…"`, `'…'` \| string \|
204	\| `<!-- … -->`, across lines \| comment \|
205	\| `&`, `©` \| constant \|
206	\| `<!DOCTYPE …>` and other declarations \| keyword \|
207
208	Text between tags is not coloured. A bare `&` with no `;` within 32 characters is left alone, because it is legal text.
209
210	The contents of `<script>` and `<style>` are not coloured as JavaScript and CSS.
211
212	## XML
213
214	Its own scanner rather than HTML's, for one reason that matters: CDATA. The whole point of `<![CDATA[ … ]]>` is that its contents are not markup, and colouring the tags inside one as tags is exactly backwards.
215
216	\| Recognised \| As \|
217	\| --- \| --- \|
218	\| `<?xml version="1.0"?>` and other processing instructions \| the target and `?>` as keyword, the pairs between as attributes and strings \|
219	\| `<!DOCTYPE …>` and the other `<!` forms \| keyword \|
220	\| `<!-- … -->`, across lines \| comment \|
221	\| `<![CDATA[ … ]]>`, across lines \| string \|
222	\| `<tag`, `</tag`, `>`, `/>` \| tag \|
223	\| `<ns:tag>`, `xsi:type` \| the prefix and the local name as one span \|
224	\| attribute names \| attribute \|
225	\| `=` \| operator \|
226	\| `"…"`, `'…'` \| string \|
227	\| `&`, `©` \| constant \|
228
229	A comment and a CDATA section close on different delimiters, and are carried separately: a `-->` inside a CDATA section does not end it.
230
231	A bare `&` with no semicolon within 32 characters is left alone, because it is legal text in plenty of documents and swallowing the rest of the line would be the bigger mistake.
232
233	Text between tags is not coloured.
234
235	## Shell
236
237	Applies to `sh`, `bash` and `zsh` alike: the keywords recognised are the ones they share.
238
239	\| Recognised \| As \|
240	\| --- \| --- \|
241	\| `if`, `then`, `fi`, `for`, `while`, `case`, `esac`, `function`, `return`, … \| keyword \|
242	\| `true`, `false` \| constant \|
243	\| `echo`, `printf`, `export`, `local`, `read`, `cd`, `set`, `source`, … \| builtin \|
244	\| `$NAME`, `${…}`, `$(…)`, `$1`, `$?`, `$@` \| builtin \|
245	\| the first bare word on a line \| function \|
246	\| every later bare word, and `NAME` in `NAME=value` \| identifier \|
247	\| `'…'`, with nothing escaped or expanded inside \| string \|
248	\| `"…"`, with the expansions inside it coloured as expansions \| string \|
249	\| `#` to end of line \| comment \|
250
251	`$(a $(b) c)` is one span: nesting is counted. An option such as `-euo` is one word, not a minus and a word.
252
253	Heredocs are not recognised. `<<EOF` and the text after it are coloured as ordinary shell.
254
255	## Dockerfile
256
257	\| Recognised \| As \|
258	\| --- \| --- \|
259	\| `FROM`, `RUN`, `COPY`, `ADD`, `ARG`, `ENV`, `CMD`, `ENTRYPOINT`, `EXPOSE`, `LABEL`, `USER`, `VOLUME`, `WORKDIR`, `HEALTHCHECK`, `ONBUILD`, `SHELL`, `STOPSIGNAL`, `MAINTAINER` \| keyword, in any case \|
260	\| `AS`, `NONE` \| keyword \|
261	\| `# comment`, including the `# syntax=` and `# escape=` directives \| comment \|
262	\| `--from=builder`, `--chown=me:me` \| the flag name as an attribute \|
263	\| `$NAME`, `${NAME}`, `${NAME:-default}` \| builtin, as one span to the closing brace \|
264	\| `"…"`, `'…'` \| string \|
265	\| a trailing `\` \| operator \|
266	\| numbers \| number \|
267	\| paths and image references — `/usr/local/bin`, `golang:1.26-alpine` \| identifier, as one span \|
268
269	Only the first word of a line can be an instruction, and a word that is not one is an argument — which is what keeps a continuation line's first word out of the keyword colour.
270
271	Nothing crosses a line break. A `\` joins two lines for Docker, but each half still reads as a command and is coloured on its own.
272
273	\| Not recognised \| Because \|
274	\| --- \| --- \|
275	\| The shell inside a `RUN` \| It would mean running the shell scanner over part of a line and mapping its columns out, and `RUN` may hold any language \|
276	\| Heredocs in a `RUN` \| The same reason the shell scanner does not recognise them \|
277	\| Which stage a `--from` names \| Nothing here reads the rest of the file \|
278
279	## See also
280
281	- [Theme file format](themes.md) — every key these classes resolve to
282	- [Colouring and completion](../explanation/colouring-and-completion.md) — why the scanners are written this way
283	- [How to write your own theme](../how-to/write-a-theme.md)