Move built-in syntax extensions to a separate crate

src/libsyntax_ext/concat.rs

@@ -0,0 +1,66 @@
+// 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;
+
+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::ExprLit(ref lit) => {
+                match lit.node {
+                    ast::LitStr(ref s, _) |
+                    ast::LitFloat(ref s, _) |
+                    ast::LitFloatUnsuffixed(ref s) => {
+                        accumulator.push_str(&s);
+                    }
+                    ast::LitChar(c) => {
+                        accumulator.push(c);
+                    }
+                    ast::LitInt(i, ast::UnsignedIntLit(_)) |
+                    ast::LitInt(i, ast::SignedIntLit(_, ast::Plus)) |
+                    ast::LitInt(i, ast::UnsuffixedIntLit(ast::Plus)) => {
+                        accumulator.push_str(&format!("{}", i));
+                    }
+                    ast::LitInt(i, ast::SignedIntLit(_, ast::Minus)) |
+                    ast::LitInt(i, ast::UnsuffixedIntLit(ast::Minus)) => {
+                        accumulator.push_str(&format!("-{}", i));
+                    }
+                    ast::LitBool(b) => {
+                        accumulator.push_str(&format!("{}", b));
+                    }
+                    ast::LitByte(..) |
+                    ast::LitByteStr(..) => {
+                        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[..])))
+}