Crate genco

genco

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

We depend on proc_macro_hygiene stabilizations. Until then, you must build with the nightly branch.

cargo +nightly run --example rust

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.

use genco::prelude::*;
use rand::Rng;

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 = rust::imported("byteorder", "LittleEndian");
    let big_endian = rust::imported("byteorder", "BigEndian").prefixed();

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

    let tokens = quote! {
        // Markup used for imports without an immediate use.
        #@(write_bytes_ext)
        #@(read_bytes_ext)

        fn test() {
            let mut wtr = vec![];
            wtr.write_u16::<#little_endian>(517).unwrap();
            wtr.write_u16::<#big_endian>(768).unwrap();
        }
    };

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

    tokens.to_io_writer_with(
        std::io::stdout().lock(),
        rust::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:

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

Becomes:

fn test() {}

More that two line breaks are collapsed.

So:

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:

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::ext::DisplayExt;

pub use self::ext::QuotedExt;

Modules

csharp	Specialization for Csharp code generation.
dart	Specialization for Dart code generation.
ext	Extension traits provided by GenCo.
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	Language neutral, whitespace sensitive quasi-quoting for GenCo.
quote_in	Same as [quote!], except that it allows for quoting directly to a token stream.
toks	Deprecated Helper macro to reduce boilerplate needed with nested token expressions.

Structs

Csharp	Language specialization for C#.
Dart	Language specialization for Dart.
Display	Struct containing a type that implements Display and can be tokenized into a stream.
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.
LangBox	A box containing a lang item.
Python	Language specialization for Python.
Quoted	Struct containing a type that is quoted.
Rust	Language specialization for Rust.
Swift	Swift token specialization.
Tokens	A stream of tokens.
VecWriter	Helper struct to write to an underlying writer.

Enums

Item	A single element in a set of tokens.
ItemStr	A managed string that permits immutable borrowing.

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.
RegisterTokens	Helper trait to convert something into a tokens registration.