lhtml-markup 2.0.0

Lightweight HTML markup language — simplifies HTML authoring with shorthand syntax

LHTML — Lightweight HTML

LHTML is a markup language that simplifies HTML authoring with embedded CSS styling. It is designed to be HTML-first: raw HTML passes through untouched, and only a few shorthand symbols (::, *, =, **, __) trigger conversions.

LHTML is used to build static websites and presentation slides, typically combined with Jinja2 templates.

Installation

pip install .

Or in development mode:

pip install -e .

Dependencies: lark, pygments, pyyaml (installed automatically).

Quick Start

Command Line

lhtml input.l.html                    # Convert to stdout
lhtml input.l.html -o output.html     # Convert to file
lhtml input.l.html -w                 # Wrap in full HTML document
python -m lhtml input.l.html          # Alternative invocation

Python API

import lhtml

html = lhtml.run('= Hello World\nSome **bold** text.\n')

html = lhtml.run(text, {
    'wrap-auto': True,
    'title': 'My Page',
    'css': ['style.css'],
    'js': ['script.js'],
})

Syntax Reference

Headings

= Main Title
== Subtitle
=== Level 3

Output:

<h1>Main Title</h1>
<h2>Subtitle</h2>
<h3>Level 3</h3>

With classes/IDs:

=(.highlight #intro) Styled Title

<h1 class="highlight" id="intro">Styled Title</h1>

Lists

* First item
* Second item
** Nested item A
** Nested item B
*** Deep nested
* Back to top level

Produces nested <ul><li> structures.

Inline Formatting

This is **bold** text.
This is __italic__ text.
This is `inline code` text.

Output:

This is <strong>bold</strong> text.
This is <em>italic</em> text.
This is <code class="code-inline">inline code</code> text.

Tag Elements (the :: system)

The core of LHTML. The general syntax is:

tagName::(.classes #id)[cssStyle]{htmlAttributes} content ::

All bracket groups are optional. If tagName is omitted, defaults to div.

Div / Span with Styles

div::[color:red; font-size:120%;]
This text is big and red.
::

span::(.highlight)[font-weight:bold;] inline content ::

Output:

<div style="color:red; font-size:120%;">
This text is big and red.
</div>

<span class="highlight" style="font-weight:bold;"> inline content </span>

Anonymous Div (no tag name)

::[padding:10px; background:#eee;]
Content in a styled div.
::

Output:

<div style="padding:10px; background:#eee;">
Content in a styled div.
</div>

Classes, IDs, and Inline Attributes

::(.classA .classB #myId)[margin:10px;]{data-role="main"}
Content
::

Output:

<div class="classA classB" id="myId" style="margin:10px;" data-role="main">
Content
</div>

Self-Closing (inline)

End the content with :: on the same line:

div::[color:blue;] short text ::

Output:

<div style="color:blue;"> short text </div>

Links

link::https://example.com[Click here]
link::page.html(.nav)[Back to home]

Output:

<a href="https://example.com">Click here</a>
<a class="nav" href="page.html">Back to home</a>

Images

img::photo.jpg[width:400px;]

Output:

<img style="width:400px;" src="photo.jpg" alt="photo.jpg">

Videos

video::assets/clip.mp4[width:600px;]
videoplay::assets/clip.mp4[width:600px;]

videoplay adds autoplay loop muted attributes. The parser automatically detects transcoded codec variants (-vp9.webm, -h265.mp4, -h264.mp4) and poster images (-poster.jpg).

Code Blocks

code::[python]
def hello():
    print("Hello, world!")
code::[-]

Syntax highlighting is powered by Pygments. Any language supported by Pygments can be used.

Spacer

::nl

Output:

<div style="height:1em;"></div>

Verbatim (raw passthrough)

Content inside verbatim blocks is preserved exactly as-is, with no LHTML processing:

verbatim::[]
This = is not a title
**not bold** __not italic__
div::[not a tag]
verbatim::[-]

Comments

Some text ::# This comment will be removed

File Inclusion

include::header.html
include::components/nav.html

Included files are recursively processed (up to 20 levels).

YAML Front Matter

---
title: "My Page"
css: ["style.css", "theme.css"]
js: "app.js"
wrap-auto: true
---

= Page content starts here

Supported metadata keys:

Key	Type	Description
title	string	Page title (used in HTML wrapper)
css	string or list	CSS files to include
js	string or list	JavaScript files to include
wrap-auto	boolean	Wrap output in full HTML document
directory_include	list	Directories to search for includes

Plugin System

Custom Tag Handlers

Register handlers for new :: tag types:

from lhtml.pipeline import tag_registry

def handle_alert(element, tag_to_close, current_directory):
    style = element.get('[]', '')
    text = element.get('text', '')
    return f'<div class="alert" style="{style}">{text}</div>', True

tag_registry.register('alert', handle_alert)

Then use in LHTML:

alert::[background:yellow; padding:10px;] Warning message ::

Custom Code Lexers

Register custom Pygments lexers for syntax highlighting:

from lhtml.pipeline import lexer_registry
from pygments.lexers import PythonLexer

lexer_registry.register('mypython', PythonLexer)

Custom Pipeline

Create an isolated pipeline with its own tag registry:

from lhtml.pipeline import ProcessingPipeline, TagRegistry

registry = TagRegistry()
registry.register('note', my_note_handler)

pipeline = ProcessingPipeline(registry=registry)
html = pipeline.run(text, {'wrap-auto': True})

Configuration Reference

All keys for the meta dict passed to lhtml.run():

{
    'wrap-auto': False,        # Wrap in HTML document
    'title': 'Webpage',        # Document title
    'css': [],                 # CSS files (string or list)
    'js': [],                  # JS files (string or list)
    'directory_include': [],   # Search paths for include::
    'current_directory': '',   # Base directory for video codec detection
}

Design Principles

• HTML-first: Raw HTML is never modified. Only LHTML syntax triggers conversions.
• Island grammar: LHTML syntax "islands" float in a sea of opaque content (HTML, Jinja2 templates, LaTeX, etc.) that passes through untouched.
• Minimal: A few symbols (::, =, *, **, __, `) cover most needs. No complex configuration required.
• Composable: LHTML works seamlessly with Jinja2 templates, making it suitable for static site generators.

Project Structure

src/lhtml/
  __init__.py          # Public API: run(), analyse_tag(), read_yaml()
  cli.py               # Command-line interface
  pipeline.py          # ProcessingPipeline, TagRegistry, LexerRegistry
  process.py           # Core transformation functions
  patterns.py          # Centralized regex patterns and utilities
  tag_parser.py        # Lark-based parser for :: bracket syntax
  tag_element.lark     # Lark grammar definition
  export_html.py       # HTML generation for tag elements
  listing.py           # List processing
  code.py              # Code syntax highlighting (Pygments)
  wrap_html.py         # HTML document wrapping
  ast_nodes.py         # AST node dataclasses
  errors.py            # Structured error types

License

MIT