67 lines
2.4 KiB
Rust
67 lines
2.4 KiB
Rust
// Copyright 2013 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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use syntax::ast;
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use syntax::ext::base;
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use syntax::ext::build::AstBuilder;
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use syntax::symbol::Symbol;
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use syntax::tokenstream;
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use syntax_pos;
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use std::string::String;
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pub fn expand_syntax_ext(
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cx: &mut base::ExtCtxt,
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sp: syntax_pos::Span,
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tts: &[tokenstream::TokenTree],
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) -> Box<dyn base::MacResult + 'static> {
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let es = match base::get_exprs_from_tts(cx, sp, tts) {
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Some(e) => e,
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None => return base::DummyResult::expr(sp),
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};
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let mut accumulator = String::new();
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let mut missing_literal = vec![];
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for e in es {
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match e.node {
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ast::ExprKind::Lit(ref lit) => match lit.node {
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ast::LitKind::Str(ref s, _)
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| ast::LitKind::Float(ref s, _)
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| ast::LitKind::FloatUnsuffixed(ref s) => {
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accumulator.push_str(&s.as_str());
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}
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ast::LitKind::Char(c) => {
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accumulator.push(c);
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}
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ast::LitKind::Int(i, ast::LitIntType::Unsigned(_))
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| ast::LitKind::Int(i, ast::LitIntType::Signed(_))
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| ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) => {
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accumulator.push_str(&i.to_string());
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}
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ast::LitKind::Bool(b) => {
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accumulator.push_str(&b.to_string());
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}
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ast::LitKind::Byte(..) | ast::LitKind::ByteStr(..) => {
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cx.span_err(e.span, "cannot concatenate a byte string literal");
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}
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},
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_ => {
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missing_literal.push(e.span);
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}
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}
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}
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if missing_literal.len() > 0 {
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let mut err = cx.struct_span_err(missing_literal, "expected a literal");
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err.note("only literals (like `\"foo\"`, `42` and `3.14`) can be passed to `concat!()`");
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err.emit();
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}
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let sp = sp.apply_mark(cx.current_expansion.mark);
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base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&accumulator)))
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}
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