# DOT DSL

A [Domain Specific Language (DSL)](https://en.wikipedia.org/wiki/Domain-specific_language) is a
small language optimized for a specific domain. Since a DSL is
targeted, it can greatly impact productivity/understanding by allowing the
writer to declare *what* they want rather than *how*.

One problem area where they are applied are complex customizations/configurations.

For example the [DOT language](https://en.wikipedia.org/wiki/DOT_(graph_description_language)) allows
you to write a textual description of a graph which is then transformed into a picture by one of
the [Graphviz](http://graphviz.org/) tools (such as `dot`). A simple graph looks like this:

    graph {
        graph [bgcolor="yellow"]
        a [color="red"]
        b [color="blue"]
        a -- b [color="green"]
    }

Putting this in a file `example.dot` and running `dot example.dot -T png
-o example.png` creates an image `example.png` with red and blue circle
connected by a green line on a yellow background.

Write a Domain Specific Language similar to the Graphviz dot language.

Our DSL is similar to the Graphviz dot language in that our DSL will be used
to create graph data structures. However, unlike the DOT Language, our DSL will
be an internal DSL for use only in our language.

More information about the difference between internal and external DSLs can be
found [here](https://martinfowler.com/bliki/DomainSpecificLanguage.html).

## Builder pattern

This exercise expects you to build several structs using `builder pattern`.
In short, this pattern allows you to split the construction function of your struct, that contains a lot of arguments, into 
several separate functions. This approach gives you the means to make compact but highly-flexible struct construction and
configuration.
You can read more about it on the [following page](https://doc.rust-lang.org/1.0.0/style/ownership/builders.html).


## Rust Installation

Refer to the [exercism help page][help-page] for Rust installation and learning
resources.

## Writing the Code

Execute the tests with:

```bash
$ cargo test
```

All but the first test have been ignored. After you get the first test to
pass, open the tests source file which is located in the `tests` directory
and remove the `#[ignore]` flag from the next test and get the tests to pass
again. Each separate test is a function with `#[test]` flag above it.
Continue, until you pass every test.

If you wish to run all ignored tests without editing the tests source file, use:

```bash
$ cargo test -- --ignored
```

To run a specific test, for example `some_test`, you can use:

```bash
$ cargo test some_test
```

If the specific test is ignored use:

```bash
$ cargo test some_test -- --ignored
```

To learn more about Rust tests refer to the [online test documentation][rust-tests]

Make sure to read the [Modules][modules] chapter if you
haven't already, it will help you with organizing your files.

## Further improvements

After you have solved the exercise, please consider using the additional utilities, described in the [installation guide](https://exercism.io/tracks/rust/installation), to further refine your final solution.

To format your solution, inside the solution directory use

```bash
cargo fmt
```

To see, if your solution contains some common ineffective use cases, inside the solution directory use

```bash
cargo clippy --all-targets
```

## Submitting the solution

Generally you should submit all files in which you implemented your solution (`src/lib.rs` in most cases). If you are using any external crates, please consider submitting the `Cargo.toml` file. This will make the review process faster and clearer.

## Feedback, Issues, Pull Requests

The [exercism/rust](https://github.com/exercism/rust) repository on GitHub is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!

If you want to know more about Exercism, take a look at the [contribution guide](https://github.com/exercism/docs/blob/master/contributing-to-language-tracks/README.md).

[help-page]: https://exercism.io/tracks/rust/learning
[modules]: https://doc.rust-lang.org/book/ch07-02-defining-modules-to-control-scope-and-privacy.html
[cargo]: https://doc.rust-lang.org/book/ch14-00-more-about-cargo.html
[rust-tests]: https://doc.rust-lang.org/book/ch11-02-running-tests.html

## Source

Wikipedia [https://en.wikipedia.org/wiki/DOT_(graph_description_language)](https://en.wikipedia.org/wiki/DOT_(graph_description_language))

## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.