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 syntax::ast;
use syntax::codemap;
use syntax::ext::base;
use syntax::ext::build::AstBuilder;
use syntax::parse::token;
use std::string::String;
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pub fn expand_syntax_ext(cx: &mut base::ExtCtxt,
sp: codemap::Span,
tts: &[ast::TokenTree])
-> Box<base::MacResult+'static> {
let es = match base::get_exprs_from_tts(cx, sp, tts) {
Some(e) => e,
None => return base::DummyResult::expr(sp)
};
let mut accumulator = String::new();
for e in es {
match e.node {
ast::ExprKind::Lit(ref lit) => {
match lit.node {
ast::LitKind::Str(ref s, _) |
ast::LitKind::Float(ref s, _) |
ast::LitKind::FloatUnsuffixed(ref s) => {
accumulator.push_str(&s);
}
ast::LitKind::Char(c) => {
accumulator.push(c);
}
ast::LitKind::Int(i, ast::LitIntType::Unsigned(_)) |
ast::LitKind::Int(i, ast::LitIntType::Signed(_)) |
ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) => {
accumulator.push_str(&format!("{}", i));
}
ast::LitKind::Bool(b) => {
accumulator.push_str(&format!("{}", b));
}
ast::LitKind::Byte(..) |
ast::LitKind::ByteStr(..) => {
cx.span_err(e.span, "cannot concatenate a byte string literal");
}
}
}
_ => {
cx.span_err(e.span, "expected a literal");
}
}
}
base::MacEager::expr(cx.expr_str(
sp,
token::intern_and_get_ident(&accumulator[..])))
}