cffi-impl 0.1.6

Safe* C FFI interface generator - macro
Documentation 
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extern crate proc_macro;

use ctor::ctor;
use darling::FromMeta;
use proc_macro2::TokenStream;
use quote::quote;
use syn::AttributeArgs;

mod attr;
mod call_fn;
mod call_impl;
mod ext;
mod function;
mod ptr_type;
mod return_type;

use attr::invoke::InvokeParams;
use ext::*;

#[proc_macro_attribute]
pub fn marshal(
    params: proc_macro::TokenStream,
    function: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
    let params = syn::parse_macro_input!(params as AttributeArgs);

    let params = match InvokeParams::from_list(&params) {
        Ok(v) => v,
        Err(err) => return err.write_errors().into(),
    };

    match call_with(params, function.into()) {
        Ok(tokens) => tokens.into(),
        Err(err) => proc_macro::TokenStream::from(
            syn::Error::new(err.span(), err.to_string()).to_compile_error(),
        ),
    }
}

#[ctor]
fn init() {
    pretty_env_logger::init();
}

// fn json_output_path() -> PathBuf {
//     std::path::Path::new(&std::env::var("OUT_DIR").unwrap()).join("cthulhu.json")
// }

// fn is_exporting() -> bool {
//     let target = std::env::var("CTHULHU_PKG").ok();

//     if let Some(target) = target {
//         let name = match std::env::var("CARGO_PKG_NAME").ok() {
//             Some(v) => v,
//             None => return false,
//         };
//         let version = match std::env::var("CARGO_PKG_VERSION").ok() {
//             Some(v) => v,
//             None => return false,
//         };
//         format!("{}-{}", name, version) == target
//     } else {
//         false
//     }
// }

// pub(crate) struct Context {
//     pkg_name: String,
//     pkg_version: String,
//     cargo_manifest_dir: PathBuf,
// }

// impl Default for Context {
//     fn default() -> Context {
//         Context {
//             pkg_name:
//         }
//         std::env::var("CARGO_PKG_NAME")
//         std::env::var("CARGO_PKG_VERSION")
//         std::env::var("CARGO_MANIFEST_DIR")
//     }
// }

fn call_with(invoke_params: InvokeParams, item: TokenStream) -> Result<TokenStream, syn::Error> {
    // if let Some(value) = invoke_params.send_help.as_ref() {
    //     log::debug!("HELP REQUESTED: {}", value);
    //     return Ok(item);
    // }

    // log::debug!("{:?} {:?} {:?}", std::env::var("CARGO_PKG_NAME"), std::env::var("CARGO_PKG_VERSION"), std::env::var("CARGO_MANIFEST_DIR"));

    let item: syn::Item = syn::parse2(item.clone()).context("error parsing function body")?;
    let result = match item {
        syn::Item::Fn(item) => call_fn::call_with_function(
            invoke_params.return_marshaler,
            invoke_params.callback,
            item,
            None,
        ),
        syn::Item::Impl(item) => call_impl::call_with_impl(invoke_params.prefix, item),
        item => {
            log::error!("{:?}", &item);
            Err(syn::Error::new_spanned(
                &item,
                "Only supported on functions and impls",
            ))
        }
    };

    if result.is_err() {
        log::debug!("macro finished with error");
    } else {
        log::debug!("macro finished successfully");
    }

    result
}

include!(concat!(env!("OUT_DIR"), "/codegen.rs"));

pub(crate) fn default_marshaler(ty: &syn::Type) -> Option<syn::Path> {
    DEFAULT_MARSHALERS
        .get(&*quote! { #ty }.to_string())
        .and_then(|x| syn::parse_str(x).ok())
}

pub(crate) fn is_passthrough_type(ty: &syn::Type) -> bool {
    match ty {
        syn::Type::BareFn(bare_fn) => bare_fn.abi.is_some(),
        _ => PASSTHROUGH_TYPES.contains(&&*quote! { #ty }.to_string()),
    }
}