rust/src/libsyntax/ext/concat.rs

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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use ast;
use codemap;
use ext::base;
use ext::build::AstBuilder;
use parse::token;
use std::strbuf::StrBuf;
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pub fn expand_syntax_ext(cx: &mut base::ExtCtxt,
sp: codemap::Span,
tts: &[ast::TokenTree])
-> Box<base::MacResult> {
let es = match base::get_exprs_from_tts(cx, sp, tts) {
Some(e) => e,
None => return base::DummyResult::expr(sp)
};
let mut accumulator = StrBuf::new();
for e in es.move_iter() {
match e.node {
ast::ExprLit(lit) => {
match lit.node {
ast::LitStr(ref s, _) |
ast::LitFloat(ref s, _) |
ast::LitFloatUnsuffixed(ref s) => {
accumulator.push_str(s.get());
}
ast::LitChar(c) => {
accumulator.push_char(c);
}
ast::LitInt(i, _) | ast::LitIntUnsuffixed(i) => {
accumulator.push_str(format!("{}", i).as_slice());
}
ast::LitUint(u, _) => {
accumulator.push_str(format!("{}", u).as_slice());
}
ast::LitNil => {}
ast::LitBool(b) => {
accumulator.push_str(format!("{}", b).as_slice());
}
ast::LitBinary(..) => {
cx.span_err(e.span, "cannot concatenate a binary literal");
}
}
}
_ => {
cx.span_err(e.span, "expected a literal");
}
}
}
base::MacExpr::new(cx.expr_str(
sp,
token::intern_and_get_ident(accumulator.into_owned())))
}