Highlighter instance. Holds loaded grammars and tokenization state.

Load a highlighter from grammar JSON strings.

Each pair is (lang_id, json_content) where lang_id is the language identifier and json_content is the raw TextMate grammar JSON.

Returns Error msg when a grammar fails to parse.

match Ochre.load [ ("ocaml", Tm_grammar_ocaml.json) ] with
| Ok hl ->
    Ochre.to_html hl ~theme:Ochre.Theme.nord ~lang:"ocaml" code
| Error msg ->
    failwith msg

Like load but raises on failure.

let hl = Ochre.load_exn [ ("ocaml", Tm_grammar_ocaml.json) ]

Load a highlighter from grammar files on disk.

Each grammar is a path to a .tmLanguage.json file. The language identifier is derived from the filename (e.g. "ocaml.tmLanguage.json" registers as "ocaml").

Returns Error msg when a file cannot be read or a grammar fails to parse.

match
  Ochre.load_from_files [ "/usr/share/grammars/ocaml.tmLanguage.json" ]
with
| Ok hl ->
    Ochre.to_html hl ~theme:Ochre.Theme.nord ~lang:"ocaml" code
| Error msg ->
    failwith msg

Like load_from_files but raises on failure.

let hl =
  Ochre.load_from_files_exn [ "/usr/share/grammars/ocaml.tmLanguage.json" ]

Highlight source code and return structured tokens. Use this when you need full control over rendering.

When ~decorations or ~transforms are provided, decorations are applied after tokenization and transforms run after decorations.

Raises Failure if the grammar for lang cannot be found. The languages "plaintext", "text", and "txt" never raise: they yield unstyled tokens.

let tokens = Ochre.to_tokens hl ~theme ~lang:"ocaml" code in
List.iter
  (fun line ->
    List.iter
      (fun (tok : Ochre.Token.styled_token) -> Printf.printf "%s" tok.text)
      line
  )
  tokens

Highlight source code to HTML.

Single theme

Pass ~theme for a self-contained block with inline styles:

Ochre.to_html hl ~theme:Ochre.Theme.nord ~lang:"ocaml" "let x = 42"

Multiple themes

Pass ~extra_themes with labelled extra themes. Each label becomes a CSS custom property prefix (--ochre-<label>). The default theme is emitted as base fallback variables (var(--ochre-bg,<bg>), var(--ochre,<fg>)), while extra themes are emitted as label-scoped variables.

Ochre.to_html hl ~theme:Ochre.Theme.light
  ~extra_themes:[ ("dark", Ochre.Theme.nord) ]
  ~lang:"ocaml" "let x = 42"

Options

Pass ~options to control rendering behaviour:

let opts =
  Ochre.Html_options.make ~line_numbers:true ~default_color:No_default_color
    ()
in
Ochre.to_html hl ~options:opts ~theme ~lang:"ocaml" code

When ~theme is omitted but ~extra_themes is provided, the first entry becomes the default. When neither ~theme nor ~extra_themes is provided, Theme.dark is used as the default.

Pair with html_theme_css to activate alternate themes via CSS.

html_theme_css label returns a CSS rule that maps base variables (--ochre-*) to the label-scoped variables (--ochre-<label>-*).

Wrap this in your own selector (a media query, a .dark class, a data-theme attribute selector, etc.) to control when the theme activates.

Printf.sprintf ".dark {\n  %s\n}" (Ochre.html_theme_css "dark")

html_render_theme_css ~class_prefix theme code generates a complete CSS stylesheet for the given theme and highlighted code when using Html_options.style_mode.Css_classes mode. Walks all tokens to discover unique styles and maps each to a deterministic class name prefixed with class_prefix.

let tokens = Ochre.to_tokens hl ~theme ~lang:"ocaml" code in
let css = Ochre.html_render_theme_css ~class_prefix:"oc-" theme tokens in
Printf.printf "<style>%s</style>" css

Highlight source code to ANSI terminal escape sequences.

Produces text with embedded 24-bit ANSI color codes for terminal display. Raises Failure if the grammar for lang cannot be found.

let ansi = Ochre.to_ansi hl ~theme:Ochre.Theme.nord ~lang:"ocaml" code in
print_string ansi

Highlight source code to LaTeX with \textcolor commands.

Produces a block wrapped in an ochrehighlight environment. Requires the xcolor and soul LaTeX packages. Raises Failure if the grammar for lang cannot be found.

let latex = Ochre.to_latex hl ~theme:Ochre.Theme.nord ~lang:"ocaml" code in
Printf.printf "\\begin{document}\n%s\n\\end{document}" latex

Highlight source code to a self-contained SVG element.

Produces an <svg> with monospace <text> elements and per-token <tspan> styling. Suitable for embedding in documents or rendering as an image. Raises Failure if the grammar for lang cannot be found.

let svg = Ochre.to_svg hl ~theme:Ochre.Theme.nord ~lang:"ocaml" code

Highlight source code and render each token as {text}[scope1,scope2,...].

Useful for debugging grammar and scope matching. Raises Failure if the grammar for lang cannot be found.

let debug =
  Ochre.to_debug_tokens hl ~theme:Ochre.Theme.nord ~lang:"ocaml" code
in
print_string debug

Mapping of format names to typed variants.

Convert a format variant to its canonical lowercase name.

Parse a format name into a variant. Returns None for unrecognised names.

Highlight source code to one of the supported output formats.

~options and ~extra_themes apply only when format is Html; the other formats ignore them. See to_html for their meaning.

let output = Ochre.to_string hl ~format:Html ~theme ~lang:"ocaml" code