rocket_codegen 0.1.0

use {ROUTE_STRUCT_PREFIX, CATCH_STRUCT_PREFIX};
use utils::{sep_by_tok, ParserExt, IdentExt};

use syntax::codemap::Span;
use syntax::tokenstream::TokenTree;
use syntax::ast::{Path, Expr};
use syntax::ext::base::{DummyResult, ExtCtxt, MacResult, MacEager};
use syntax::parse::token::Token;
use syntax::ptr::P;

#[inline]
pub fn prefix_paths(prefix: &str, paths: &mut Vec<Path>) {
    for p in paths {
        let last = p.segments.len() - 1;
        let last_seg = &mut p.segments[last];
        last_seg.identifier = last_seg.identifier.prepend(prefix);
    }
}

pub fn prefixing_vec_macro<F>(prefix: &str,
                              mut to_expr: F,
                              ecx: &mut ExtCtxt,
                              sp: Span,
                              args: &[TokenTree])
                              -> Box<MacResult + 'static>
    where F: FnMut(&ExtCtxt, Path) -> P<Expr>
{
    let mut parser = ecx.new_parser_from_tts(args);
    let paths = parser.parse_paths();
    if let Ok(mut paths) = paths {
        // Prefix each path terminator and build up the P<Expr> for each path.
        prefix_paths(prefix, &mut paths);
        let path_exprs: Vec<P<Expr>> = paths.into_iter()
            .map(|path| to_expr(ecx, path))
            .collect();

        // Now put them all in one vector and return the thing.
        let path_list = sep_by_tok(ecx, &path_exprs, Token::Comma);
        let output = quote_expr!(ecx, vec![$path_list]).unwrap();
        MacEager::expr(P(output))
    } else {
        paths.unwrap_err().emit();
        DummyResult::expr(sp)
    }
}

#[rustfmt_skip]
pub fn routes(ecx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
        -> Box<MacResult + 'static> {
    prefixing_vec_macro(ROUTE_STRUCT_PREFIX, |ecx, path| {
        quote_expr!(ecx, ::rocket::Route::from(&$path))
    }, ecx, sp, args)
}

#[rustfmt_skip]
pub fn errors(ecx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
        -> Box<MacResult + 'static> {
    prefixing_vec_macro(CATCH_STRUCT_PREFIX, |ecx, path| {
        quote_expr!(ecx, rocket::Catcher::from(&$path))
    }, ecx, sp, args)
}