Highlight.js
Discourse has the ability to use highlight.js to do source code highlighting within a post. As this feature is CPU intensive, Discourse has an admin option to select which programming languages can be used with code blocks; see examples below.
If you use the fence ``` without a name it will default to Prolog.
If you don’t want any highlighting then use plaintext
Examples
Prolog
```prolog <code> ```
reverse(List, Reversed) :-
reverse(List, [], Reversed).
reverse([], Reversed, Reversed).
reverse([Head|Tail], SoFar, Reversed) :-
reverse(Tail, [Head|SoFar], Reversed).
Augmented Backus-Naur Form
```abnf <code> ```
; line comment
ruleset = [optional] *(group1 / group2 / SP) CRLF ; trailing comment
group1 = alt1
group1 =/ alt2
alt1 = %x41-4D / %d78-90
alt2 = %b00100001
group2 = *1DIGIT / 2*HEXDIG / 3*4OCTET
optional = hex-codes
/ literal
/ sensitive
/ insensitive
hex-codes = %x68.65.6C.6C.6F
literal = "string literal"
sensitive = %s"case-sensitive string"
insensitive = %i"case-insensitive string"
BASH
```bash <code> ```
#!/bin/bash
###### CONFIG
ACCEPTED_HOSTS="/root/.hag_accepted.conf"
BE_VERBOSE=false
if [ "$UID" -ne 0 ]
then
echo "Superuser rights required"
exit 2
fi
genApacheConf(){
echo -e "# Host ${HOME_DIR}$1/$2 :"
}
echo '"quoted"' | tr -d \" > text.txt
BNF ( Backus–Naur Form)
```bnf <code> ```
<syntax> ::= <rule> | <rule> <syntax>
<rule> ::= <opt-whitespace> "<" <rule-name> ">" <opt-whitespace> "::=" <opt-whitespace> <expression> <line-end>
<opt-whitespace> ::= " " <opt-whitespace> | ""
<expression> ::= <list> | <list> <opt-whitespace> "|" <opt-whitespace> <expression>
<line-end> ::= <opt-whitespace> <EOL> | <line-end> <line-end>
<list> ::= <term> | <term> <opt-whitespace> <list>
<term> ::= <literal> | "<" <rule-name> ">"
<literal> ::= '"' <text> '"' | "'" <text> "'"
CMake
```cmake <code> ```
cmake_minimum_required(VERSION 2.8.8)
project(cmake_example)
# Show message on Linux platform
if (${CMAKE_SYSTEM_NAME} MATCHES Linux)
message("Good choice, bro!")
endif()
# Tell CMake to run moc when necessary:
set(CMAKE_AUTOMOC ON)
# As moc files are generated in the binary dir,
# tell CMake to always look for includes there:
set(CMAKE_INCLUDE_CURRENT_DIR ON)
# Widgets finds its own dependencies.
find_package(Qt5Widgets REQUIRED)
add_executable(myproject main.cpp mainwindow.cpp)
qt5_use_modules(myproject Widgets)
C++
```cpp <code> ```
#include <iostream>
int main(int argc, char *argv[]) {
/* An annoying "Hello World" example */
for (auto i = 0; i < 0xFFFF; i++)
cout << "Hello, World!" << endl;
char c = '\n';
unordered_map <string, vector<string> > m;
m["key"] = "\\\\"; // this is an error
return -2e3 + 12l;
}
CSS
```css <code> ```
@font-face {
font-family: Chunkfive; src: url('Chunkfive.otf');
}
body, .usertext {
color: #F0F0F0; background: #600;
font-family: Chunkfive, sans;
--heading-1: 30px/32px Helvetica, sans-serif;
}
@import url(print.css);
@media print {
a[href^=http]::after {
content: attr(href)
}
}
Diff
```diff <code> ```
Index: languages/ini.js
===================================================================
--- languages/ini.js (revision 199)
+++ languages/ini.js (revision 200)
@@ -1,8 +1,7 @@
hljs.LANGUAGES.ini =
{
case_insensitive: true,
- defaultMode:
- {
+ defaultMode: {
contains: ['comment', 'title', 'setting'],
illegal: '[^\\s]'
},
*** /path/to/original timestamp
--- /path/to/new timestamp
***************
*** 1,3 ****
--- 1,9 ----
+ This is an important
+ notice! It should
+ therefore be located at
+ the beginning of this
+ document!
! compress the size of the
! changes.
It is important to spell
Dockerfile
```dockerfile <code> ```
# Example instructions from https://docs.docker.com/reference/builder/
FROM ubuntu:14.04
MAINTAINER example@example.com
ENV foo /bar
WORKDIR ${foo} # WORKDIR /bar
ADD . $foo # ADD . /bar
COPY \$foo /quux # COPY $foo /quux
ARG VAR=FOO
RUN apt-get update && apt-get install -y software-properties-common\
zsh curl wget git htop\
unzip vim telnet
RUN ["/bin/bash", "-c", "echo hello ${USER}"]
CMD ["executable","param1","param2"]
CMD command param1 param2
EXPOSE 1337
ENV myName="John Doe" myDog=Rex\ The\ Dog \
myCat=fluffy
ENV myName John Doe
ENV myDog Rex The Dog
ENV myCat fluffy
ADD hom* /mydir/ # adds all files starting with "hom"
ADD hom?.txt /mydir/ # ? is replaced with any single character
COPY hom* /mydir/ # adds all files starting with "hom"
COPY hom?.txt /mydir/ # ? is replaced with any single character
COPY --from=foo / .
ENTRYPOINT ["executable", "param1", "param2"]
ENTRYPOINT command param1 param2
VOLUME ["/data"]
USER daemon
LABEL com.example.label-with-value="foo"
LABEL version="1.0"
LABEL description="This text illustrates \
that label-values can span multiple lines."
WORKDIR /path/to/workdir
ONBUILD ADD . /app/src
STOPSIGNAL SIGKILL
HEALTHCHECK --retries=3 cat /health
SHELL ["/bin/bash", "-c"]
HTML,XML
```xml <code> ```
<!DOCTYPE html>
<title>Title</title>
<style>body {width: 500px;}</style>
<script type="application/javascript">
function $init() {return true;}
</script>
<body>
<p checked class="title" id='title'>Title</p>
<!-- here goes the rest of the page -->
</body>
ini,TOML
```ini <text> ```
; boilerplate
[package]
name = "some_name"
authors = ["Author"]
description = "This is \
a description"
[[lib]]
name = ${NAME}
default = True
auto = no
counter = 1_000
Java
```java <code> ```
/**
* @author John Smith <john.smith@example.com>
*/
package l2f.gameserver.model;
public abstract strictfp class L2Char extends L2Object {
public static final Short ERROR = 0x0001;
public void moveTo(int x, int y, int z) {
_ai = null;
log("Should not be called");
if (1 > 5) { // wtf!?
return;
}
}
}
JavaScript
```javascript <code> ```
function $initHighlight(block, cls) {
try {
if (cls.search(/\bno\-highlight\b/) != -1)
return process(block, true, 0x0F) +
` class="${cls}"`;
} catch (e) {
/* handle exception */
}
for (var i = 0 / 2; i < classes.length; i++) {
if (checkCondition(classes[i]) === undefined)
console.log('undefined');
}
return (
<div>
<web-component>{block}</web-component>
</div>
)
}
export $initHighlight;
JSON
```json <code> ```
[
{
"title": "apples",
"count": [12000, 20000],
"description": {"text": "...", "sensitive": false}
},
{
"title": "oranges",
"count": [17500, null],
"description": {"text": "...", "sensitive": false}
}
]
LaTeX
```latex <code> ```
\documentclass{article}
\usepackage[koi8-r]{inputenc}
\hoffset=0pt
\voffset=.3em
\tolerance=400
\newcommand{\eTiX}{\TeX}
\begin{document}
\section*{Highlight.js}
\begin{table}[c|c]
$\frac 12\, + \, \frac 1{x^3}\text{Hello \! world}$ & \textbf{Goodbye\~ world} \\\eTiX $ \pi=400 $
\end{table}
Ch\'erie, \c{c}a ne me pla\^\i t pas! % comment \b
G\"otterd\"ammerung~45\%=34.
$$
\int\limits_{0}^{\pi}\frac{4}{x-7}=3
$$
\end{document}
Makefile
```Makefile <code> ```
# Makefile
BUILDDIR = _build
EXTRAS ?= $(BUILDDIR)/extras
.PHONY: main clean
main:
@echo "Building main facility..."
build_main $(BUILDDIR)
clean:
rm -rf $(BUILDDIR)/*
Markdown
```markdown <code> ```
# hello world
you can write text [with links](http://example.com) inline or [link references][1].
* one _thing_ has *em*phasis
* two __things__ are **bold**
[1]: http://example.com
---
hello world
===========
<this_is inline="xml"></this_is>
> markdown is so cool
so are code segments
1. one thing (yeah!)
2. two thing `i can write code`, and `more` wipee!
PostgreSQL and PL/pgSQL
```pgsql <code> ```
BEGIN;
SELECT sum(salary) OVER w, avg(salary) OVER w
FROM empsalary
WINDOW w AS (PARTITION BY depname ORDER BY salary DESC);
END;
CREATE FUNCTION days_of_week() RETURNS SETOF text AS $$
BEGIN
FOR i IN 7 .. 13 LOOP
RETURN NEXT to_char(to_date(i::text,'J'),'TMDy');
END LOOP;
END;
$$ STABLE LANGUAGE plpgsql;
plaintext
```plaintext <text> ```
id | description
----+-------------
1 | one
2 | two
3 | three
(3 rows)
Python
```python <text> ```
@requires_authorization(roles=["ADMIN"])
def somefunc(param1='', param2=0):
r'''A docstring'''
if param1 > param2: # interesting
print 'Gre\'ater'
return (param2 - param1 + 1 + 0b10l) or None
class SomeClass:
pass
>>> message = '''interpreter
... prompt'''
SHELL
```shell <text> ```
$ echo $EDITOR
vim
$ git checkout main
Switched to branch 'main'
Your branch is up-to-date with 'origin/main'.
$ git push
Everything up-to-date
$ echo 'All
> done!'
All
done!
SQL
```sql <text> ```
CREATE TABLE "topic" (
"id" serial NOT NULL PRIMARY KEY,
"forum_id" integer NOT NULL,
"subject" varchar(255) NOT NULL
);
ALTER TABLE "topic"
ADD CONSTRAINT forum_id FOREIGN KEY ("forum_id")
REFERENCES "forum" ("id");
-- Initials
insert into "topic" ("forum_id", "subject")
values (2, 'D''artagnian');
TypeScript
```typescript <text> ```
class MyClass {
public static myValue: string;
constructor(init: string) {
this.myValue = init;
}
}
import fs = require("fs");
module MyModule {
export interface MyInterface extends Other {
myProperty: any;
}
}
declare magicNumber number;
myArray.forEach(() => { }); // fat arrow syntax
Windows DOS
AKA Command Prompt
```dos <commands> ```
cd \
copy a b
ping 192.168.0.1
@rem ping 192.168.0.1
net stop sharedaccess
del %tmp% /f /s /q
del %temp% /f /s /q
ipconfig /flushdns
taskkill /F /IM JAVA.EXE /T
cd Photoshop/Adobe Photoshop CS3/AMT/
if exist application.sif (
ren application.sif _application.sif
) else (
ren _application.sif application.sif
)
taskkill /F /IM proquota.exe /T
sfc /SCANNOW
set path = test
xcopy %1\*.* %2
WebAssembly
```webassembly <text> ```
(module
(import "js" "memory" (memory 1))
(import "js" "table" (table 1 funcref))
(type $void_to_i32 (func (result i32)))
(func (export "doIt") (result i32)
i32.const 0
i32.const 42
i32.store ;; store 42 at address 0
i32.const 0
call_indirect (type $void_to_i32))
)
YAML
```yaml <text> ```
---
# comment
string_1: "Bar"
string_2: 'bar'
string_3: bar
inline_keys_ignored: sompath/name/file.jpg
keywords_in_yaml:
- true
- false
- TRUE
- FALSE
- 21
- 21.0
- !!str 123
"quoted_key": &foobar
bar: foo
foo:
"foo": bar
reference: *foobar
multiline_1: |
Multiline
String
multiline_2: >
Multiline
String
multiline_3: "
Multiline string
"
ansible_variables: "foo {{variable}}"
array_nested:
- a
- b: 1
c: 2
- b
- comment
Currently Hightlight.js does not support Turtle for use with RDF. 