alecthomas / chroma

A general purpose syntax highlighter in pure Go Chroma takes source code and other structured text and converts it into syntax highlighted HTML, ANSI-coloured text, etc. Chroma is based heavily on Pygments, and includes translators for Pygments lexers and styles. Table of Contents • Supported languages • Try it • Using the library • Quick start • Identifying the language • Formatting the output • The HTML formatter • More detail • Lexers • Formatters • Styles • Command-line interface • Testing lexers • What's missing compared to Pygments? Supported languages | Prefix | Language | :----: | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | A | ABAP, ABNF, ActionScript, ActionScript 3, Ada, Agda, AL, Alloy, AMPL, Angular2, ANTLR, ApacheConf, APL, AppleScript, ArangoDB AQL, Arduino, ArmAsm, ATL, AutoHotkey, AutoIt, Awk | B | Ballerina, Bash, Bash Session, Batchfile, Beef, BibTeX, Bicep, BlitzBasic, BNF, BQN, Brainfuck | C | C, C#, C++, C3, Caddyfile, Caddyfile Directives, Cap'n Proto, Cassandra CQL, Ceylon, CFEngine3, cfstatement, ChaiScript, Chapel, Cheetah, Clojure, CMake, COBOL, CoffeeScript, Common Lisp, Coq, Core, Crystal, CSS, CSV, CUE, Cython | D | D, Dart, Dax, Desktop file, Diff, Django/Jinja, dns, Docker, DTD, Dylan | E | EBNF, Elixir, Elm, EmacsLisp, Erlang | F | Factor, Fennel, Fish, Forth, Fortran, FortranFixed, FSharp | G | GAS, GDScript, GDScript3, Gemtext, Genshi, Genshi HTML, Genshi Text, Gettext, Gherkin, Gleam, GLSL, Gnuplot, Go, Go HTML Template, Go Template, Go Text Template, GraphQL, Groff, Groovy | H | Handlebars, Hare, Haskell, Haxe, HCL, Hexdump, HLB, HLSL, HolyC, HTML, HTTP, Hy | I | Idris, Igor, INI, Io, ISCdhcpd | J | J, Janet, Java, JavaScript, JSON, JSONata, Jsonnet, Julia, Jungle | K | Kakoune, Kotlin | L | Lean4, Lighttpd configuration file, LLVM, lox, Lua, Luau | M | Makefile, Mako, markdown, Markless, Mason, Materialize SQL dialect, Mathematica, Matlab, MCFunction, Meson, Metal, MiniZinc, MLIR, Modelica, Modula-2, Mojo, MonkeyC, MoonScript, MorrowindScript, Myghty, MySQL | N | NASM, Natural, NDISASM, Newspeak, Nginx configuration file, Nim, Nix, NSIS, Nu | O | Objective-C, ObjectPascal, OCaml, Octave, Odin, OnesEnterprise, OpenEdge ABL, OpenSCAD, Org Mode | P | PacmanConf, Perl, PHP, PHTML, Pig, PkgConfig, PL/pgSQL, plaintext, Plutus Core, Pony, PostgreSQL SQL dialect, PostScript, POVRay, PowerQuery, PowerShell, Prolog, Promela, PromQL, properties, Protocol Buffer, Protocol Buffer Text Format, PRQL, PSL, Puppet, Python, Python 2 | Q | QBasic, QML | R | R, Racket, Ragel, Raku, react, ReasonML, reg, Rego, reStructuredText, Rexx, RGBDS Assembly, Ring, RPGLE, RPMSpec, Ruby, Rust | S | SAS, Sass, Scala, Scheme, Scilab, SCSS, Sed, Sieve, Smali, Smalltalk, Smarty, SNBT, Snobol, Solidity, SourcePawn, Spade, SPARQL, SQL, SquidConf, Standard ML, stas, Stylus, Svelte, Swift, SYSTEMD, systemverilog | T | TableGen, Tal, TASM, Tcl, Tcsh, Termcap, Terminfo, Terraform, TeX, Thrift, TOML, TradingView, Transact-SQL, Turing, Turtle, Twig, TypeScript, TypoScript, TypoScriptCssData, TypoScriptHtmlData, Typst | U | ucode | V | V, V shell, Vala, VB.net, verilog, VHDL, VHS, VimL, vue | W | WDTE, WebAssembly Text Format, WebGPU Shading Language, WebVTT, Whiley | X | XML, Xorg | Y | YAML, YANG | Z | Z80 Assembly, Zed, Zig _I will attempt to keep this section up to date, but an authoritative list can be displayed with ._ Try it Try out various languages and styles on the Chroma Playground. Using the library This is version 2 of Chroma, use the import path: Chroma, like Pygments, has the concepts of lexers, formatters and styles. Lexers convert source text into a stream of tokens, styles specify how token types are mapped to colours, and formatters convert tokens and styles into formatted output. A package exists for each of these, containing a global variable with all of the registered implementations. There are also helper functions for using the registry in each package, such as looking up lexers by name or matching filenames, etc. In all cases, if a lexer, formatter or style can not be determined, will be returned. In this situation you may want to default to the value in each respective package, which provides sane defaults. Quick start A convenience function exists that can be used to simply format some source text, without any effort: Identifying the language To highlight code, you'll first have to identify what language the code is written in. There are three primary ways to do that: • Detect the language from its filename. • Explicitly specify the language by its Chroma syntax ID (a full list is available from ). • Detect the language from its content. In all cases, will be returned if the language can not be identified. At this point, it should be noted that some lexers can be extremely chatty. To mitigate this, you can use the coalescing lexer to coalesce runs of identical token types into a single token: Formatting the output Once a language is identified you will need to pick a formatter and a style (theme). Then obtain an iterator over the tokens: And finally, format the tokens from the iterator: The HTML formatter By default the registered formatter generates standalone HTML with embedded CSS. More flexibility is available through the package. Firstly, the output generated by the formatter can be customised with the following constructor options: • - generate standalone HTML with embedded CSS. • - use classes rather than inlined style attributes. • - prefix each generated CSS class. • - Set the rendered tab width, in characters. • - Render line numbers (style with ). • - Make the line numbers linkable and be a link to themselves. • - Highlight lines in these ranges (style with ). • - Use a table for formatting line numbers…