Example Extractor

Extract documentation examples from real source code

Overview

example-extractor is a command-line interface (CLI) tool designed to extract documentation examples directly from source files. This tool helps you automate the process of collecting code examples, making it easier to generate documentation or create educational material.

Do you want the examples in your documentation to be compiled and run as part of your regular tests, but don't want to include the whole file directly in your documentation? example-extractor is for you!

How it works

example-extractor will recursively scan your source, looking for examples in source files marked with special comments. These are extracted to markdown files in an output folder.

Marking Examples in Source Files

To mark an example in your source files, use the following comment format:

Start of the example:
// example-extract [example-name]
End of the example:
// end-example

(If you prefer, you can also use /** example extract [example-name] */)

Example

Here's an example of how to mark a code example in a TypeScript file:

// example-extract array-sum
function sumArray(arr: number[]): number {
  return arr.reduce((sum, current) => sum + current, 0);
}
// end-example

In this case, the tool will extract the code between the example-extract array-sum and end-example comments and save it under the name array-sum.mdx, complete with backticks and language hint for syntax highlighting:

```ts
function sumArray(arr: number[]): number {
  return arr.reduce((sum, current) => sum + current, 0);
}
```

By using example-extractor, you can easily maintain and manage code examples for documentation purposes, ensuring that your examples are always up-to-date with your source code.

Example Usage in Source Files

You can have multiple examples in your source files. Each example should have a unique name:

// example-extract array-sum
function sumArray(arr: number[]): number {
  return arr.reduce((sum, current) => sum + current, 0);
}
// end-example

// example-extract array-max
function maxArray(arr: number[]): number {
  return Math.max(...arr);
}
// end-example

Ignoring lines

Sometimes you want to exclude some code that needs to be there for your example to compile. If you'd like to exclude some lines in your examples, you can turn off extraction during an example with ignore-extract and end-ignore:

// example-extract general
function reduceNumbers(arr: number[]): number {
  return arr.reduce(
    /* your function goes here */
    // ignore-example
    (sum, current) => {
      return sum + current;
    },
    // end-ignore
    0,
  );
}
// end-example

This would result in the following extraction:

```ts
function reduceNumbers(arr: number[]): number {
  return arr.reduce(
    /* your function goes here */
    0,
  );
}
```

Clearing the examples directory

Since we want the examples to be fresh each time, example-extractor expects an empty directory. To help you remember this, it will fail if it tries to overwrite an example.

We recommend clearing out your examples directory each time using something like rimraf.

Usage

example-extractor [options]

Options

-i, --input <path>
Base path to recursively search source files.
Default: "."
-o, --output <path>
Base path where extracted examples will be written.
Default: "extracted-examples"
-e, --extensions [extension...]
Extensions for the files to read examples from.
Default: [".ts", ".java"]
-x, --exclude-endings [ending...]
Exclude source files that end with these extensions.
Default: [".d.ts"]
-l, --log-level <level>
Set log level to one of 'debug', 'warn', 'error', 'info', 'none'.
Default: "info"
-V, --version
Output the version number.
-h, --help
Display help for the command.

Examples

Basic usage with default settings:
```
example-extractor
```

Specify input and output paths:

example-extractor -i src -o docs/examples

Define file extensions to include and exclude:

example-extractor -e .js .jsx -x .test.js .spec.js

Set log level to debug:

# You can use this if you're not getting the output you expect
example-extractor -l debug

Future features

Currently, only markdown output is supported, and comments must be in // or /* */ or /** */ blocks. It would be easy to extend to other languages. Additionally, we'd like to release a docusaurus component making it easy to roll up these examples directly into your documentation.

License

This project is licensed under the BSD 3 Clause License. See the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to open an issue or submit a pull request if you have improvement suggestions.

Contact

For any questions or feedback, please open an issue

Developed by Timothy Jones, as part of making maintenance for the ContractCase test suite easier. If this is useful to you, please consider becoming a sponsor.

case-contract-testing/example-extractor