1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 #![crate_type="dylib"]
14 #![feature(plugin_registrar, rustc_private)]
15 #![feature(slice_patterns)]
20 use syntax::codemap::Span;
21 use syntax::ast::{TokenTree, TtToken};
22 use syntax::parse::token;
23 use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager};
24 use syntax::ext::build::AstBuilder; // trait for expr_usize
25 use rustc::plugin::Registry;
27 // WARNING WARNING WARNING WARNING WARNING
28 // =======================================
30 // This code also appears in src/doc/guide-plugin.md. Please keep
31 // the two copies in sync! FIXME: have rustdoc read this file
33 fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
34 -> Box<MacResult + 'static> {
36 static NUMERALS: &'static [(&'static str, usize)] = &[
37 ("M", 1000), ("CM", 900), ("D", 500), ("CD", 400),
38 ("C", 100), ("XC", 90), ("L", 50), ("XL", 40),
39 ("X", 10), ("IX", 9), ("V", 5), ("IV", 4),
42 let text = match args {
43 [TtToken(_, token::Ident(s, _))] => s.to_string(),
45 cx.span_err(sp, "argument should be a single identifier");
46 return DummyResult::any(sp);
50 let mut text = &*text;
52 while !text.is_empty() {
53 match NUMERALS.iter().find(|&&(rn, _)| text.starts_with(rn)) {
56 text = &text[rn.len()..];
59 cx.span_err(sp, "invalid Roman numeral");
60 return DummyResult::any(sp);
65 MacEager::expr(cx.expr_usize(sp, total))
69 pub fn plugin_registrar(reg: &mut Registry) {
70 reg.register_macro("rn", expand_rn);