dom-content-extraction 0.4.0

Rust implementation of Content extraction via text density paper
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dom-content-extraction

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A Rust library for extracting main content from web pages using text density analysis. This is an implementation of the Content Extraction via Text Density (CETD) algorithm described in the paper by Fei Sun, Dandan Song and Lejian Liao: Content Extraction via Text Density.

What Problem Does This Solve?

Web pages often contain a lot of peripheral content like navigation menus, advertisements, footers, and sidebars. This makes it challenging to extract just the main content programmatically. This library helps solve this problem by:

  • Analyzing the text density patterns in HTML documents
  • Identifying content-rich sections versus navigational/peripheral elements
  • Extracting the main content while filtering out noise
  • Handling various HTML layouts and structures

Key Features

  • Build a density tree representing text distribution in the HTML document
  • Calculate composite text density using multiple metrics
  • Extract main content blocks based on density patterns
  • Unicode Support
  • Support for nested HTML structures
  • Efficient processing of large documents
  • Error handling for malformed HTML
  • Markdown output (optional feature) - Extract content as structured markdown

Unicode Support

DOM Content Extraction includes Unicode support for handling multilingual content:

  • Proper character counting using Unicode grapheme clusters
  • Unicode normalization (NFC) for consistent text representation
  • Support for various writing systems including Latin, Cyrillic, and CJK scripts
  • Accurate text density calculations across different languages

This ensures accurate content extraction from web pages in any language, with proper handling of:

  • Combining characters (like accents in European languages)
  • Bidirectional text
  • Complex script rendering
  • Multi-code-point graphemes (like emojis)

Usage

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Basic usage example:

use scraper::Html;
use dom_content_extraction::get_content;

fn main() {
    let html = r#"<!DOCTYPE html><html><body>
        <nav>Home | About</nav>
        <main>
            <article>
                <h1>Main Article</h1>
                <p>This is the primary content that contains enough text to maintain proper density metrics. The paragraph needs sufficient length to establish text-to-link ratio.</p>
                <p>Second paragraph adds more textual density to ensure the content extraction algorithm works correctly.</p>
                <a href="\#">Related link</a>
            </article>
        </main>
        <footer>Copyright 2024</footer>
    </body></html>"#;

    let document = Html::parse_document(html);
    let content = get_content(&document).unwrap();
    println!("{}", content);
}

Installation

Add it it with:

cargo add dom-content-extraction

or add to you Cargo.toml

dom-content-extraction = "0.3"

Optional Features

To enable markdown output support:

dom-content-extraction = { version = "0.3", features = ["markdown"] }

Documentation

Read the docs!

dom-content-extraction documentation

Library Usage with Markdown

use dom_content_extraction::{DensityTree, extract_content_as_markdown, scraper::Html};

let html = "<html><body><article><h1>Title</h1><p>Content</p></article></body></html>";
let document = Html::parse_document(html);
let mut dtree = DensityTree::from_document(&document)?;
dtree.calculate_density_sum()?;

// Extract as markdown
let markdown = extract_content_as_markdown(&dtree, &document)?;
println!("{}", markdown);
# Ok::<(), dom_content_extraction::DomExtractionError>(())

Run examples

Check examples.

This one will extract content from generated "lorem ipsum" page

cargo run --example check -- lorem-ipsum

This one prints node with highest density:

cargo run --example check -- test4

Extract content as markdown from lorem ipsum (requires markdown feature):

cargo run --example check -- lorem-ipsum-markdown

There is scoring example i'm trying to implement scoring. You will need to download GoldenStandard and finalrun-input datasets from:

https://sigwac.org.uk/cleaneval/

and unpack archives into data/ directory.

cargo run --example ce_score

As far as i see there is problem opening some files:

Error processing file 730: Failed to read file: "data/finalrun-input/730.html"

Caused by:
    stream did not contain valid UTF-8

But overall extraction works pretty well:

Overall Performance:
  Files processed: 370
  Average Precision: 0.87
  Average Recall: 0.82
  Average F1 Score: 0.75

Read documentation on docs.rs

Binary Usage

The crate includes a command-line binary tool dce (DOM Content Extraction) for extracting main content from HTML documents. It supports both local files and remote URLs as input sources.

Installation

The binary is included by default. You can install it using cargo:

cargo install dom-content-extraction

Command-Line Options

dce [OPTIONS]

Options:
  -u, --url <URL>        URL to fetch HTML content from
  -f, --file <FILE>      Local HTML file to process
  -o, --output <FILE>    Output file (stdout if not specified)
      --format <FORMAT>  Output format [default: text] [possible values: text, markdown]
  -h, --help            Print help
  -V, --version         Print version

Note: Either --url or --file must be specified, but not both.

Markdown Output

To extract content as markdown format, use the --format markdown option:

# Extract as markdown from URL
cargo run --bin dce -- --url "https://example.com" --format markdown

# Extract as markdown from file and save to output
cargo run --bin dce -- --file input.html --format markdown --output content.md

Note: Markdown output requires the markdown feature to be enabled.

Features

  • URL Fetching: Automatically downloads HTML content from specified URLs
  • Timeout Control: 30-second timeout for URL fetching to prevent hangs
  • Error Handling: Comprehensive error messages for common failure cases
  • Flexible Output: Write to file or stdout
  • Temporary File Management: Automatic cleanup of downloaded content
  • Markdown Support: Extract content as structured markdown (requires markdown feature)

Examples

Extract content from a URL and print to stdout:

dce --url "https://example.com/article"

Process a local HTML file and save to output file:

dce --file input.html --output extracted.txt

Extract from URL and save directly to file:

dce --url "https://example.com/page" --output content.txt

Dependencies

The binary functionality requires the following additional dependencies:

  • clap: Command-line argument parsing
  • reqwest: HTTP client for URL fetching
  • tempfile: Temporary file management
  • url: URL parsing and validation
  • anyhow: Error handling
  • htmd: HTML to markdown conversion (for markdown feature)

These dependencies are only included when building with the default cli feature. The markdown feature requires the htmd dependency.