Lontar

Comprehensive document generation library for Rust — write once, render everywhere.

Lontar is a Rust library for creating documents programmatically and exporting them to multiple formats: DOCX, PPTX, PDF, XLSX, HTML, Markdown, LaTeX, and plain text.

Features

• Multi-format output: Generate DOCX, PPTX, PDF, XLSX, HTML, Markdown, LaTeX, and plain text from a single document AST
• Feature-gated backends: Only compile the backends you need
• Text shaping: Full Unicode support with BiDi, complex scripts (Balinese, Devanagari, Arabic, etc.)
• Native diagram engine: Auto-layout flowcharts, trees, and graphs with format-specific rendering
• Citations & bibliography: BibTeX/BibLaTeX integration with multiple citation styles
• Cross-references: Automatic numbering and references for figures, tables, equations, and sections
• Template system: Declarative document templates via Tera

Quick Start

Add Lontar to your Cargo.toml:

[dependencies]
lontar = { version = "0.1", features = ["docx", "pdf", "html"] }

Example

use lontar::prelude::*;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let doc = DocumentBuilder::new()
        .title("My Document")
        .add_heading("Introduction", 1)
        .add_paragraph("This is a sample document.")
        .add_heading("Features", 1)
        .add_list(vec![
            "Multi-format output",
            "Unicode support",
            "Citations and cross-references",
        ])
        .build();

    // Export to DOCX
    DocxWriter::new().write(&doc, "output.docx")?;
    
    // Export to PDF
    PdfWriter::new().write(&doc, "output.pdf")?;
    
    // Export to HTML
    HtmlWriter::new().write(&doc, "output.html")?;

    Ok(())
}

Feature Flags

Lontar uses feature flags to enable specific backends and functionality:

Default Features

By default, no features are enabled. Enable only what you need:

# Minimal: Markdown and plain text only
lontar = { version = "0.1", features = ["md", "txt"] }

# Office formats only
lontar = { version = "0.1", features = ["docx", "pptx", "xlsx"] }

# Everything
lontar = { version = "0.1", features = ["full"] }

Supported Formats

Input

• Programmatic AST construction via builder API
• Template-based generation (with template feature)

Output

• DOCX: Microsoft Word documents (Office Open XML)
• PPTX: Microsoft PowerPoint presentations
• PDF: Portable Document Format
• XLSX: Microsoft Excel spreadsheets
• HTML: Self-contained HTML with inline CSS
• Markdown: CommonMark-compatible Markdown
• LaTeX: XeLaTeX/LuaLaTeX source files with BibLaTeX
• TXT: Plain text with ASCII art tables

Architecture

Lontar uses a single-crate architecture with feature-gated modules:

lontar/
├── core/       - AST types (Block, Inline, Document, styles)
├── aksara/     - Text shaping, BiDi, font management
├── diagram/    - Diagram layout engine
├── template/   - Tera template integration
└── backends/   - Format-specific writers
    ├── docx/
    ├── pptx/
    ├── pdf/
    ├── xlsx/
    ├── md/
    ├── html/
    └── txt/

Multi-Script Support

Lontar supports complex text shaping for:

• Latin, Cyrillic, Greek, Georgian
• Indic scripts: Devanagari, Bengali, Tamil, Telugu, Kannada, Malayalam
• Southeast Asian: Balinese (ᬮᭀᬦ᭄ᬢᬭ᭄), Javanese, Thai, Lao, Khmer, Myanmar
• RTL scripts: Arabic, Hebrew, Syriac
• CJK: Chinese, Japanese, Korean
• Tibetan and other complex scripts

Text shaping is automatically enabled when using binary format backends (docx, pptx, pdf).

Citation & Bibliography

use lontar::prelude::*;

let doc = DocumentBuilder::new()
    .load_bibliography("references.bib")?
    .add_paragraph("According to ")
    .add_citation("knuth1984", CitationMode::Narrative)
    .add_text(", TeX is a typesetting system.")
    .add_bibliography()
    .build();

Supports:

• BibTeX/BibLaTeX input
• CSL-JSON import (Zotero, Mendeley, EndNote)
• Multiple citation styles: numeric, author-year, Vancouver, APA, etc.

Diagrams

use lontar::prelude::*;

let diagram = DiagramBuilder::new()
    .add_node("start", "Start")
    .add_node("process", "Process")
    .add_node("end", "End")
    .add_edge("start", "process")
    .add_edge("process", "end")
    .layout(LayoutAlgorithm::Layered)
    .build();

doc.add_diagram(diagram);

Renders to:

• DOCX/PPTX: DrawingML shapes
• PDF: Vector graphics
• HTML: SVG
• LaTeX: TikZ
• Markdown: Mermaid
• TXT: ASCII art

Minimum Supported Rust Version (MSRV)

Rust 1.88 or later.

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

Links

• Documentation
• Repository
• Crates.io
• Issue Tracker