Crate genco

GenCo

GenCo is an even simpler code generator for Rust, written for use in reproto.

The workhorse of GenCo is the quote! macro. While tokens can be constructed, manually, quote! makes this process much easier.

GenCo does not deal with language-specific syntax, instead it limits itself to do the following basic necessities through specialization:

• Handle and collapse import statements.
• Quote strings according to language convention.
• Indents and spaces your code according to generic indentation rules.

Examples

The following are language specific examples for GenCo using the quote! macro.

• Rust Example
• Java Example
• C# Example
• Dart Example (TODO)
• Go Example (TODO)
• JavaScript Example (TODO)
• Python Example (TODO)

The following is a simple example showcasing code generation for Rust.

#![feature(proc_macro_hygiene)]

use genco::rust::imported;
use genco::{quote, Rust, Tokens};

// Import the LittleEndian item, without referencing it through the last
// module component it is part of.
let little_endian = imported("byteorder", "LittleEndian").qualified();
let big_endian = imported("byteorder", "BigEndian");

// This is a trait, so only import it into the scope (unless we intent to
// implement it).
let write_bytes_ext = imported("byteorder", "WriteBytesExt").alias("_");

let tokens: Tokens<Rust> = quote! {
    @write_bytes_ext

    let mut wtr = vec![];
    wtr.write_u16::<#little_endian>(517).unwrap();
    wtr.write_u16::<#big_endian>(768).unwrap();
    assert_eq!(wtr, vec![5, 2, 3, 0]);
};

Indentation Rules

The quote! macro has the following rules for dealing with indentation and spacing.

Two tokens that are separated, are spaced. Regardless of how many spaces there are between them.

So:

#![feature(proc_macro_hygiene)]

let _: genco::Tokens<genco::Rust> = genco::quote!(fn   test() {});

Becomes:

fn test() {}

More that two line breaks are collapsed.

So:

#![feature(proc_macro_hygiene)]

let _: genco::Tokens<genco::Rust> = genco::quote! {
    fn test() {
        println!("Hello...");


        println!("... World!");
    }
};

Becomes:

fn test() {
    println!("Hello...");

    println!("... World!");
}

Indentation is determined on a row-by-row basis. If a column is further in than the one on the preceeding row, it is indented one level deeper.

Like wise if a column starts before the previous rows column, it is indended one level shallower.

So:

#![feature(proc_macro_hygiene)]

let _: genco::Tokens<genco::Rust> = genco::quote! {
  fn test() {
      println!("Hello...");
      println!("... World!");
    }
};

Becomes:

fn test() {
    println!("Hello...");
    println!("... World!");
}

Re-exports

pub use self::csharp::Csharp;

pub use self::dart::Dart;

pub use self::go::Go;

pub use self::java::Java;

pub use self::js::JavaScript;

pub use self::python::Python;

pub use self::rust::Rust;

Modules

csharp	Specialization for Csharp code generation.
dart	Specialization for Dart code generation.
go	Specialization for Go code generation.
java	Specialization for Java code generation.
js	Specialization for JavaScript code generation.
python	Specialization for Python code generation.
rust	Specialization for Rust code generation.
swift	Specialization for Swift code generation.

Macros

nested	Deprecated Helper macro to reduce boilerplate needed with nested token expressions.
push	Deprecated Helper macro to reduce boilerplate needed with pushed token expressions.
quote	Quotes the specified expression as a stream of tokens for use with genco.
toks	Deprecated Helper macro to reduce boilerplate needed with nested token expressions.

Structs

Formatter	Formatter implementation for write types.
IoFmt	Facade for writing formatted strings to io::Write types.
Tokens	A set of tokens.

Enums

Cons	A managed string that permits immutable borrowing.
Element	A single element in a set of tokens.
ErasedElement	A type-erased variant of element, useful for constructing elements which are not associated with any specific customization.

Traits

Config	A trait that must be implemented for all custom configurations.
Custom	Trait that must be implemented by custom elements.
IntoTokens	Helper trait to convert something into tokens.
Quoted	Trait to convert types to quoted elements.
WriteTokens	Helper trait to write tokens immediately to containers.