71 lines
2.2 KiB
Rust
71 lines
2.2 KiB
Rust
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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// force-host
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#![crate_type="dylib"]
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#![feature(plugin_registrar)]
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extern crate syntax;
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extern crate rustc;
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use syntax::codemap::Span;
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use syntax::parse::token::{IDENT, get_ident};
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use syntax::ast::{TokenTree, TTTok};
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use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacExpr};
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use syntax::ext::build::AstBuilder; // trait for expr_uint
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use rustc::plugin::Registry;
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// WARNING WARNING WARNING WARNING WARNING
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// =======================================
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//
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// This code also appears in src/doc/guide-plugin.md. Please keep
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// the two copies in sync! FIXME: have rustdoc read this file
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fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
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-> Box<MacResult + 'static> {
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static NUMERALS: &'static [(&'static str, uint)] = &[
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("M", 1000), ("CM", 900), ("D", 500), ("CD", 400),
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("C", 100), ("XC", 90), ("L", 50), ("XL", 40),
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("X", 10), ("IX", 9), ("V", 5), ("IV", 4),
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("I", 1)];
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let text = match args {
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[TTTok(_, IDENT(s, _))] => get_ident(s).to_string(),
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_ => {
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cx.span_err(sp, "argument should be a single identifier");
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return DummyResult::any(sp);
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}
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};
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let mut text = text.as_slice();
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let mut total = 0u;
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while !text.is_empty() {
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match NUMERALS.iter().find(|&&(rn, _)| text.starts_with(rn)) {
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Some(&(rn, val)) => {
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total += val;
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text = text.slice_from(rn.len());
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}
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None => {
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cx.span_err(sp, "invalid Roman numeral");
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return DummyResult::any(sp);
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}
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}
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}
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MacExpr::new(cx.expr_uint(sp, total))
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}
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#[plugin_registrar]
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pub fn plugin_registrar(reg: &mut Registry) {
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reg.register_macro("rn", expand_rn);
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}
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