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 only minimally deals with language-specific syntax, but primarily deals with solving the following:

• Generates and groups import statements.
• Quote (and escape) strings using <stmt>.quoted().
• Indents and spaces your code according to generic indentation rules that can be tweaked on a per-language basis.

Examples

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

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

You can run one of the examples above using:

cargo run --example go

The following is the included example Rust program.

#![feature(proc_macro_hygiene)]

use genco::rust::{imported, Config};
use genco::{quote, FormatterConfig, Rust};

use std::fmt;

fn main() -> fmt::Result {
    // 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 = quote! {
        @write_bytes_ext
        fn test() {
            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]);
        }
    };

    // Simpler printing with default indentation:
    // println!("{}", tokens.to_file_string()?);

    tokens.to_io_writer_with(
        std::io::stdout().lock(),
        Config::default(),
        FormatterConfig::from_lang::<Rust>().with_indentation(2),
    )?;

    Ok(())
}

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!");
}

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.
prelude	Prelude to import.
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

Csharp	Language specialization for C#.
Dart	Language specialization for Dart.
Formatter	Formatter implementation for write types.
FormatterConfig	Configuration to use for formatting output.
Go	Language specialization for Go.
Java	Language specialization for Java.
JavaScript	JavaScript language specialization.
Python	Language specialization for Python.
Rust	Language specialization for Rust.
Swift	Swift token specialization.
Tokens	A set of tokens.
VecWriter	Helper struct to write to an underlying writer.

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.
LangBox	A box containing a lang item.

Traits

FormatTokens	Helper trait to convert something into tokens.
Lang	Trait to implement for language specialization.
LangItem	A type-erased holder for language-specific items.
Quoted	Trait to provide string quoting through <stmt>.quoted().