Syntex Code Generation Framework
================================
[](https://travis-ci.org/erickt/rust-syntex)
[](https://crates.io/crates/syntex)
`syntex` is a library that enables compile time syntax extension expansion.
This allows users to use libraries like [regex\_macros]() in a rust 1.0
compatible context.
Configuring with Cargo
======================
To create a package:
```toml
[package]
name = "hello_world_macros"
version = "0.2.0"
authors = [ "erick.tryzelaar@gmail.com" ]
[dependencies]
syntex = "*"
syntex_syntax = "*"
```
To use it:
Cargo.toml:
```toml
[package]
name = "hello_world"
version = "0.3.0"
authors = [ "erick.tryzelaar@gmail.com" ]
build = "build.rs"
[build-dependencies]
syntex = "*"
```
build.rs:
```rust
extern crate syntex;
extern crate hello_world_macros;
use std::env;
use std::path::Path;
fn main() {
let mut registry = syntex::Registry::new();
hello_world_macros::register(&mut registry);
let src = Path::new("src/main.rs.in");
let dst = Path::new(&env::var("OUT_DIR").unwrap()).join("main.rs");
registry.expand("hello_world", &src, &dst).unwrap();
}
```
src/main.rs:
```rust
// Include the real main
include!(concat!(env!("OUT_DIR"), "/main.rs"));
```
src/main.rs.in:
```rust
fn main() {
let s = hello_world!();
println!("{}", s);
}
```
Limitations
===========
Unfortunately because there is no stable plugin support in Rust yet, there are
some things that syntex cannot do:
* The code generated by syntex reports errors in the generated file, not the
source file.
* Syntex macros cannot be embedded in macros it doesn't know about, like the
builtin `vec![]`, `println!(...)`, and etc. This is because those macros
may override the `macro_name!(...)` to mean something different.