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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use syntax::ast;
use syntax::codemap::Span;
use syntax::ext::base;
use syntax::ext::base::ExtCtxt;
use syntax::ext::build::AstBuilder;
use syntax::parse::token;
pub fn expand_lower<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
-> Box<base::MacResult + 'cx> {
expand_cased(cx, sp, tts, |s| { s.to_lowercase() })
}
pub fn expand_upper<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
-> Box<base::MacResult + 'cx> {
expand_cased(cx, sp, tts, |s| { s.to_uppercase() })
}
fn expand_cased<'cx, T>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree], transform: T)
-> Box<base::MacResult + 'cx>
where T: Fn(&str) -> String
{
let es = match base::get_exprs_from_tts(cx, sp, tts) {
Some(e) => e,
None => return base::DummyResult::expr(sp)
};
let mut it = es.iter();
let res = if let Some(expr) = it.next() {
if let ast::ExprLit(ref lit) = expr.node {
if let ast::LitStr(ref s, _) = lit.node {
Some((s, lit.span))
} else {
cx.span_err(expr.span, "expected a string literal");
None
}
} else {
cx.span_err(expr.span, "expected a string literal");
None
}
} else {
cx.span_err(sp, "expected 1 argument, found 0");
None
};
match (res, it.count()) {
(Some((s, span)), 0) => {
base::MacEager::expr(cx.expr_str(span, token::intern_and_get_ident(&transform(&s))))
}
(_, rest) => {
if rest > 0 {
cx.span_err(sp, &format!("expected 1 argument, found {}", rest + 1));
}
base::DummyResult::expr(sp)
}
}
}
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