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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. | |
4 | // | |
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. | |
10 | ||
11 | // force-host | |
12 | ||
13 | #![crate_type="dylib"] | |
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14 | #![feature(plugin_registrar, rustc_private)] |
15 | #![feature(slice_patterns)] | |
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16 | |
17 | extern crate syntax; | |
18 | extern crate rustc; | |
92a42be0 | 19 | extern crate rustc_plugin; |
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20 | |
21 | use syntax::codemap::Span; | |
92a42be0 | 22 | use syntax::ast::TokenTree; |
c1a9b12d | 23 | use syntax::parse::token; |
c34b1796 | 24 | use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager}; |
85aaf69f | 25 | use syntax::ext::build::AstBuilder; // trait for expr_usize |
92a42be0 | 26 | use rustc_plugin::Registry; |
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27 | |
28 | // WARNING WARNING WARNING WARNING WARNING | |
29 | // ======================================= | |
30 | // | |
31 | // This code also appears in src/doc/guide-plugin.md. Please keep | |
32 | // the two copies in sync! FIXME: have rustdoc read this file | |
33 | ||
34 | fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree]) | |
35 | -> Box<MacResult + 'static> { | |
36 | ||
c34b1796 | 37 | static NUMERALS: &'static [(&'static str, usize)] = &[ |
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38 | ("M", 1000), ("CM", 900), ("D", 500), ("CD", 400), |
39 | ("C", 100), ("XC", 90), ("L", 50), ("XL", 40), | |
40 | ("X", 10), ("IX", 9), ("V", 5), ("IV", 4), | |
41 | ("I", 1)]; | |
42 | ||
92a42be0 SL |
43 | if args.len() != 1 { |
44 | cx.span_err( | |
45 | sp, | |
46 | &format!("argument should be a single identifier, but got {} arguments", args.len())); | |
47 | return DummyResult::any(sp); | |
48 | } | |
49 | ||
50 | let text = match args[0] { | |
51 | TokenTree::Token(_, token::Ident(s, _)) => s.to_string(), | |
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52 | _ => { |
53 | cx.span_err(sp, "argument should be a single identifier"); | |
54 | return DummyResult::any(sp); | |
55 | } | |
56 | }; | |
57 | ||
85aaf69f | 58 | let mut text = &*text; |
c34b1796 | 59 | let mut total = 0; |
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60 | while !text.is_empty() { |
61 | match NUMERALS.iter().find(|&&(rn, _)| text.starts_with(rn)) { | |
62 | Some(&(rn, val)) => { | |
63 | total += val; | |
85aaf69f | 64 | text = &text[rn.len()..]; |
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65 | } |
66 | None => { | |
67 | cx.span_err(sp, "invalid Roman numeral"); | |
68 | return DummyResult::any(sp); | |
69 | } | |
70 | } | |
71 | } | |
72 | ||
c34b1796 | 73 | MacEager::expr(cx.expr_usize(sp, total)) |
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74 | } |
75 | ||
76 | #[plugin_registrar] | |
77 | pub fn plugin_registrar(reg: &mut Registry) { | |
78 | reg.register_macro("rn", expand_rn); | |
79 | } |