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[](https://crates.io/crates/genco)
[](https://docs.rs/genco)
# genco
A whitespace-aware quasiquoter for beautiful code generation.
Central to genco are the [quote!] and [quote_in!] procedural macros which
ease the construction of [token streams].
This project solves the following language-specific concerns:
* **Imports** — Generates and groups [import statements] as they are used.
What you use is what you get with no redundancy and consistency. We also
do our best to [solve namespace conflicts] for you.
* **String Quoting** — genco knows how to [quote strings]. And can even
[interpolate] values *into* the quoted string if it's supported by the
language.
* **Structural Indentation** — The quoter relies on intuitive
[whitespace detection] to structurally sort out spacings and indentation.
Allowing genco to generate beautiful readable code with minimal effort.
This is also a requirement for generating correctly behaving code in
languages like Python where [indentation is meaningful].
* **Language Customization** — Building support for new languages is a
piece of cake with the help of the [impl_lang!] macro.
<br>
To do whitespace detection, we depend on the [`proc_macro_span` feature].
Until this is stabilized, you must build and run projects using genco with
the `nightly` compiler.
```bash
cargo +nightly run --example rust
```
[`proc_macro_span` feature]: https://github.com/rust-lang/rust/issues/54725
<br>
### Supported Languages
The following are languages which have built-in support in genco.
Is your favorite language missing? [Open an issue!]
* [Rust Example]
* [Java Example]
* [C# Example]
* [Go Example]
* [Dart Example]
* [JavaScript Example]
* [Python Example]
You can run one of the examples using:
```bash
cargo run --example go
```
<br>
### Rust Example
The following is a simple program producing Rust code to stdout with custom
configuration:
```rust
use genco::prelude::*;
use genco::fmt;
let map = rust::import("std::collections", "HashMap");
let tokens: rust::Tokens = quote! {
fn main() {
let mut m = #map::new();
m.insert(1u32, 2u32);
}
};
let stdout = std::io::stdout();
let mut w = fmt::IoWriter::new(stdout.lock());
let fmt = fmt::Config::from_lang::<Rust>()
.with_indentation(fmt::Indentation::Space(2));
let config = rust::Config::default();
tokens.format_file(&mut w.as_formatter(fmt), &config)?;
```
This would produce:
```rust
use std::collections::HashMap;
fn main() {
let mut m = HashMap::new();
m.insert(1u32, 2u32);
}
```
<br>
[solve namespace conflicts]: file:///home/udoprog/repo/genco/target/doc/genco/lang/csharp/fn.import.html
[indentation is meaningful]: https://docs.python.org/3/faq/design.html#why-does-python-use-indentation-for-grouping-of-statements
[token streams]: https://docs.rs/genco/0/genco/tokens/struct.Tokens.html
[import statements]: https://docs.rs/genco/0/genco/macro.quote.html#imports
[quote strings]: https://docs.rs/genco/0/genco/macro.quote.html#string-quoting
[interpolate]: https://docs.rs/genco/0/genco/macro.quote.html#quoted-string-interpolation
[whitespace detection]: https://docs.rs/genco/0/genco/macro.quote.html#whitespace-detection
[Rust Example]: https://github.com/udoprog/genco/blob/master/examples/rust.rs
[Java Example]: https://github.com/udoprog/genco/blob/master/examples/java.rs
[C# Example]: https://github.com/udoprog/genco/blob/master/examples/csharp.rs
[Go Example]: https://github.com/udoprog/genco/blob/master/examples/go.rs
[Dart Example]: https://github.com/udoprog/genco/blob/master/examples/dart.rs
[JavaScript Example]: https://github.com/udoprog/genco/blob/master/examples/js.rs
[Python Example]: https://github.com/udoprog/genco/blob/master/examples/python.rs
[quote!]: https://docs.rs/genco/0/genco/macro.quote.html
[quote_in!]: https://docs.rs/genco/0/genco/macro.quote_in.html
[impl_lang!]: https://docs.rs/genco/0/genco/macro.impl_lang.html
[quoted()]: https://docs.rs/genco/0/genco/tokens/fn.quoted.html
[Open an issue!]: https://github.com/udoprog/genco/issues/new