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)]
19 use syntax::codemap::Span;
20 use syntax::parse::token;
21 use syntax::ast::{TokenTree, TtToken};
22 use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacExpr};
23 use syntax::ext::build::AstBuilder; // trait for expr_usize
24 use rustc::plugin::Registry;
26 // WARNING WARNING WARNING WARNING WARNING
27 // =======================================
29 // This code also appears in src/doc/guide-plugin.md. Please keep
30 // the two copies in sync! FIXME: have rustdoc read this file
32 fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
33 -> Box<MacResult + 'static> {
35 static NUMERALS: &'static [(&'static str, uint)] = &[
36 ("M", 1000), ("CM", 900), ("D", 500), ("CD", 400),
37 ("C", 100), ("XC", 90), ("L", 50), ("XL", 40),
38 ("X", 10), ("IX", 9), ("V", 5), ("IV", 4),
41 let text = match args {
42 [TtToken(_, token::Ident(s, _))] => token::get_ident(s).to_string(),
44 cx.span_err(sp, "argument should be a single identifier");
45 return DummyResult::any(sp);
49 let mut text = text.as_slice();
51 while !text.is_empty() {
52 match NUMERALS.iter().find(|&&(rn, _)| text.starts_with(rn)) {
55 text = text.slice_from(rn.len());
58 cx.span_err(sp, "invalid Roman numeral");
59 return DummyResult::any(sp);
64 MacExpr::new(cx.expr_usize(sp, total))
68 pub fn plugin_registrar(reg: &mut Registry) {
69 reg.register_macro("rn", expand_rn);