Lightweight syntax highlighter for the Fe₂O₃ Rust terminal suite. Hand-rolled, no syntect dependency, ~30 KB compiled. Ships ANSI-colored text for 18 source languages, plus dedicated renderers for HyperList, Markdown, LaTeX, plain text (URLs / emails / TODO), and email composition (RFC 822 headers, quote levels, signature, inline tokens).

Crate name on crates.io: fe2o3-highlight. Imports as highlight via [lib] name.

Why this exists

Three Fe₂O₃ apps need to color text identically:

• pointer previewing files in its right pane
• scribe rendering source files in its editor view + composing email
• kastrup rendering email bodies in its right pane

Without a shared crate, each app drifts to its own color rules. With one, an email opened in kastrup and the same email replied to in scribe show byte-for-byte identical text. A .rs file previewed in pointer and edited in scribe show the same colors. One source of truth.

What it does

use highlight::{highlight, highlight_hyperlist, highlight_markdown, set_theme};
set_theme("monokai");                        // monokai / solarized / nord / dracula / gruvbox / plain
let rust   = highlight(rust_source, "rs", 200);
let hl     = highlight_hyperlist(hl_source, 200);
let md     = highlight_markdown(md_source, 200);
let tex    = highlight_tex(tex_source, 200);
let txt    = highlight_text(txt_source, 200);

Each call returns an ANSI-styled String. Colors come from a curated 256-color palette, applied through crust::style::fg so output composes cleanly with surrounding pane bg.

Languages

Source code: Rust, Python, Ruby, JavaScript / TypeScript, Go, C / C++, Bash / Zsh / Fish, Lua, Java / Kotlin / Scala, TOML / YAML / INI, SQL, CSS / SCSS / LESS, HTML / XML, x86 / x86-64 ASM, Perl, XRPN, Zig, HyperList.

Specialised renderers (smarter than generic source mode):

• HyperList (.hl) — full token coloring per the HyperList 2.6 spec: operators (ALL-CAPS:), properties (Name:), qualifiers [...], references <...>, substitutions {...}, parentheticals, hash tags, multi-line indicators
• Markdown (.md) — headers (H1–H6), bold / italic / code / links / lists, fenced code blocks
• LaTeX (.tex) — commands, environments, comments, math mode
• Plain text (.txt, .log) — inline URL / email / TODO highlighting

Email mode

The email module renders RFC 822 messages and .eml / kastrup compose tempfiles:

use highlight::{line_style_email, EmailLineStyle, color_emails};
// Per-line block color (header / body / quote level / signature)
let style = line_style_email(line, idx, header_end, sig_start);
// Inline email-address coloring (177 magenta) overlaid on any base color
let with_emails = color_emails(line, Some(outer_fg));

Block colors mirror kastrup's right-pane palette 1-for-1:

Header KEY portion (left of :) is rendered bold. Inline overrides apply on top of any block color: email addresses → 177 (light purple), URLs → 4 (blue) + underline + OSC 8 hyperlink.

Themes

Six bundled themes (256-color, dark backgrounds):

highlight::set_theme("dracula");
let names: &[&str] = highlight::available_themes();

Theme is stored in a process-global Mutex so any caller reading highlight() output sees the current theme without explicit threading.

Install

In your Cargo.toml:

[dependencies]
highlight = { version = "0.1", package = "fe2o3-highlight" }

crust (fe2o3-crust) is required transitively for SGR helpers.

Build

PATH="/usr/bin:$PATH" cargo build --release

The PATH prefix dodges Claude Code's ~/bin/cc shadowing the C compiler invoked by build scripts.

Part of Fe₂O₃

Member of the Fe₂O₃ Rust terminal suite. Sister libraries:

• crust — TUI panes, ANSI colors, input handling
• glow — inline images (kitty / sixel / w3m / braille)
• orbit — moon phases, ephemeris

License

Public domain (Unlicense). Borrow or steal whatever you want.

— Geir Isene