etl/DOCUMENTATION.md

Viewing the documentation locally

The documentation for this project is built using Hugo, a static site generator. This guide will walk you through installing Hugo and running the documentation site on your machine.

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Prerequisites

• You must have already cloned this repository, including its submodules (the Hugo themes are stored as submodules).
• If you cloned without submodules, run this first:

  git submodule update --init --recursive

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Step 1: Install Hugo Extended

This project requires the extended version of Hugo, which includes support for additional features such as SCSS/Sass processing.
Make sure you install the extended version, not the standard one.

Windows

1. The easiest way to install Hugo on Windows is via Chocolatey. If you have it installed, open a command prompt as Administrator and run:

   choco install hugo-extended -y

2. If you don't have Chocolatey, you can download Hugo Extended directly from the Hugo releases page.
   Download the file named hugo_extended_x.x.x_windows-amd64.zip, extract it, and add the folder to your system PATH.
3. Verify the installation by opening a new command prompt and running:

   hugo version

You should see the word extended in the output, for example: hugo v0.x.x+extended.

macOS

1. The easiest way to install Hugo Extended on macOS is via Homebrew. Homebrew installs the extended version by default. If you have it installed, open a terminal and run:

   brew install hugo

2. If you don't have Homebrew, you can install it first by following the instructions at brew.sh, then run the command above.
3. Verify the installation by running:

   hugo version

You should see the word extended in the output, for example: hugo v0.x.x+extended.

Linux

1. Package managers often provide an older or non-extended version of Hugo, so the recommended approach is to download the latest extended release directly from the Hugo releases page. Download the file named hugo_extended_x.x.x_linux-amd64.tar.gz, then run:

   tar -xzf hugo_extended_x.x.x_linux-amd64.tar.gz
   sudo mv hugo /usr/local/bin/

2. Verify the installation by running:

   hugo version

You should see the word extended in the output, for example: hugo v0.x.x+extended.

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Step 2: Run the documentation site

1. Open a terminal (or command prompt on Windows) and navigate to the hugo directory inside the project:

   cd hugo

2. Start the Hugo development server:

   hugo server

3. Hugo will start a local web server. You will see output similar to:

   Web Server is available at http://localhost:1313/

4. Open your browser and go to http://localhost:1313/ to view the documentation.

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Stopping the server

To stop the Hugo server, go back to your terminal and press Ctrl+C.

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Editing the Documentation

The documentation source files are located in the /docs directory at the root of the repository — not inside the hugo directory. Hugo is configured to mount this directory automatically via hugo.toml, so any changes you make to files in /docs will be picked up by the Hugo development server straight away.

Here is a quick overview of where things live:

hugo/
├── layouts/        # HTML templates (you probably won't need to touch these)
├── themes/         # The Hugo theme (managed as a git submodule)
└── hugo.toml       # Hugo configuration file (includes the /docs content mount)

docs/
└── section-name/   # Each subdirectory becomes a section in the documentation
    ├── _index.md   # The landing page for that section
    └── my-page.md  # Individual pages within the section

Adding or Editing a Page

All documentation pages are written in Markdown (.md files). To edit an existing page, open the relevant .md file in the /docs directory and make your changes.

The documentation is written in Goldmark markdown.

Hugo uses Goldmark as its default Markdown processor for versions 0.60.0 and newer.
It is built into Hugo, providing high-performance and fully CommonMark-compliant rendering, along with support for GitHub Markdown.

Documenting Algorithmic Complexity

When documenting the complexity of an operation, use the complexity shortcode instead of writing raw Big-O text. Place it on its own **Complexity** lines, right after the **Description** line/paragraph, for example:

**Description**  
Returns the number of linked items.

**Complexity**  
{{< complexity "constant" "1" >}}

The shortcode takes two arguments: a complexity class (used to color and label it) and the expression to show inside O(...). The supported classes are:

**Complexity**  
{{< complexity "constant" "1" >}}
**Complexity**  
{{< complexity "linear" "N" >}}, where N is number of items in the tree, and assuming comparator is {{< complexity "constant" "1" >}}.
**Complexity**  
{{< complexity "logarithmic" "log N" >}}, where N is number of items in the tree.
**Complexity**  
{{< complexity "linearithmic" "N log N" >}}, where N is number of items in the tree.
**Complexity**  
{{< complexity "polynomial" "N²" >}}, where N is number of items in the tree.
**Complexity**  
{{< complexity "constant" "1" >}} when something, or  
{{< complexity "exponential" "2ᴺ" >}} some alternative, where N is number of items in the tree.

Starting a New Page

A template file is provided at docs/page-template.md to use as a starting point. Copy it to the appropriate section directory, rename it, and edit the front matter, in particular, change the title and remove the draft: true line, otherwise Hugo will not include your page in the documentation.

Previewing Your Changes

If you have the Hugo development server running (see Step 2), your changes will appear in the browser automatically as soon as you save the file. There is no need to restart the server.

Images and Other Assets

If you need to include images in your documentation, place them in the hugo/static/ directory and reference them in your Markdown like so:

![Alt text](/my-image.png)

The site will automatically refresh in your browser whenever you save changes to the documentation files.