A fast, extensible, and well-structured markdown parser for Go, optimized for simplicity and performance.

Features

• 🚀 Fast & Lightweight: Simple token-based parsing with excellent performance
• 🧩 Extensible: Modular architecture with configurable extensions
• 📝 Standards Compliant: Supports CommonMark with useful extensions
• 🔄 Roundtrip Support: Parse → modify → restore back to markdown
• 🛡️ Type Safe: Clean Go interfaces with comprehensive error handling
• 🧪 Well Tested: Comprehensive test suite with high coverage

Supported Markdown Features

Core Markdown

• Text formatting: Bold, italic, bold-italic, strikethrough
• Code: Inline code and fenced code blocks
• Links & Images: Manual links, auto-links, and images
• Lists: Ordered, unordered, and task lists
• Structure: Headings, paragraphs, blockquotes, horizontal rules

Extensions

• Tables: GitHub-flavored table syntax
• Math: Inline ($math$) and block ($$math$$) expressions
• Highlighting: ==highlighted text==
• Subscript/Superscript: ~sub~ and ^super^
• Spoilers: ||spoiler text||
• Tags: #hashtag syntax
• Referenced Content: [[wiki-style]] links
• Embedded Content: ![[embeds]]
• HTML Elements: <kbd>, <br>, <img>, <small>, <mark>, and more

Quick Start

gomark is designed for zero-configuration usage - all features are enabled by default:

package main

import (
    "fmt"
    "github.com/usememos/gomark"
    "github.com/usememos/gomark/renderer/html"
)

func main() {
    // All features enabled by default - no configuration needed!
    markdown := `# Hello Memos!

**Bold** and *italic* text with ==highlighting==.

Press <kbd>Ctrl</kbd>+<kbd>C</kbd> to copy.

Math: $E = mc^2$ and task lists:
- [x] HTML elements supported
- [ ] Even more features coming

#gomark ||works great||!`

    // Parse with all features enabled
    doc, err := gomark.Parse(markdown)
    if err != nil {
        panic(err)
    }

    // Render to HTML
    renderer := html.NewHTMLRenderer()
    html := renderer.RenderDocument(doc)
    fmt.Println(html)

    // Or restore back to markdown
    restored := gomark.Restore(doc)
    fmt.Println(restored)
}

Advanced Usage

Custom Configuration

While gomark works great with zero configuration, you can customize it if needed:

import (
    "github.com/usememos/gomark"
    "github.com/usememos/gomark/config"
)

// Customize limits if needed
engine := gomark.NewEngine(gomark.WithConfig(
    config.DefaultConfig().WithMaxDepth(100).WithMaxFileSize(1024 * 1024), // 1MB limit
))

doc, err := engine.Parse(markdown)

Multiple Output Formats

import (
    "github.com/usememos/gomark/renderer"
    "github.com/usememos/gomark/renderer/html"
    "github.com/usememos/gomark/renderer/string"
)

// Parse once, render to multiple formats
doc, _ := gomark.Parse(markdown)

// Render to HTML
htmlRenderer := html.NewHTMLRenderer()
htmlOutput := htmlRenderer.RenderDocument(doc)

// Extract plain text
stringRenderer := string.NewStringRenderer()
textOutput := stringRenderer.RenderDocument(doc)

// Render back to markdown (roundtrip)
markdownOutput := gomark.Restore(doc)

Available Configurations

import "github.com/usememos/gomark/config"

// Default configuration: all features enabled with generous limits
cfg := config.DefaultConfig()

// Custom limits if needed
cfg := config.DefaultConfig().
    WithMaxDepth(50).                   // Limit nesting depth
    WithMaxFileSize(1024 * 1024)        // 1MB file size limit

Architecture

gomark follows a clean, modular architecture:

gomark/
├── ast/              # Abstract Syntax Tree definitions
├── config/           # Configuration management
├── parser/           # Parsing logic and tokenization
│   ├── internal/     # Parser implementations
│   ├── tokenizer/    # Tokenization engine
│   └── tests/        # Comprehensive parser tests
├── renderer/         # Output rendering
│   ├── html/         # HTML renderer
│   ├── markdown/     # Markdown renderer (roundtrip)
│   └── string/       # Plain text renderer
└── gomark.go         # Main engine and public API

Design Principles

1. Simplicity over Complexity: Clean, understandable code
2. Performance over Features: Fast parsing with minimal overhead
3. Extensibility: Easy to add new features without breaking existing code
4. Type Safety: Proper Go interfaces and error handling
5. Testing: Comprehensive test coverage for reliability

Performance

gomark is designed for performance:

• Token-based parsing: Efficient single-pass tokenization
• Minimal allocations: Reuses buffers and objects where possible
• Simple AST: Direct field access instead of complex tree operations
• Focused scope: Implements what's needed, not theoretical features

Extensions

All extensions can be configured via the config package:

cfg := config.DefaultConfig()

// Disable specific extensions
cfg = cfg.WithExtension("tables", false)
cfg = cfg.WithExtension("math", false)

// Enable strict parsing
cfg = cfg.WithStrictMode(true)

// Enable safe mode (sanitizes content)
cfg = cfg.WithSafeMode(true)

Available Extensions

Recent Improvements

• ✅ Phase 1 HTML Elements: Added support for <kbd>, <br>, <img>, <small>, <mark>
• ✅ Simplified Configuration: Zero-config usage with sensible defaults
• ✅ Enhanced HTML Parsing: Proper attribute handling and self-closing tag support
• ✅ Fixed blockquote blank lines (GitHub issue #19)
• ✅ Refactored to modular architecture
• ✅ Improved package organization with public APIs
• ✅ Enhanced test coverage with 26+ HTML element test cases

Contributing

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all tests pass: go test ./...
5. Submit a pull request

License

This project is part of the Memos ecosystem.

Inspiration

Designed for simplicity, performance, and ease of use. gomark focuses on practical markdown parsing with clean, maintainable code.