| // Copyright (c) 2017 Baidu, Inc. All Rights Reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions |
| // are met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above copyright |
| // notice, this list of conditions and the following disclaimer in |
| // the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Baidu, Inc., nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| |
| use quote::{Tokens, ToTokens}; |
| |
| pub enum Fragment { |
| /// Tokens that can be used as an expression. |
| Expr(Tokens), |
| /// Tokens that can be used inside a block. The surrounding curly braces are |
| /// not part of these tokens. |
| Block(Tokens), |
| } |
| |
| macro_rules! quote_expr { |
| ($($tt:tt)*) => { |
| $crate::fragment::Fragment::Expr(quote!($($tt)*)) |
| } |
| } |
| |
| macro_rules! quote_block { |
| ($($tt:tt)*) => { |
| $crate::fragment::Fragment::Block(quote!($($tt)*)) |
| } |
| } |
| |
| /// Interpolate a fragment in place of an expression. This involves surrounding |
| /// Block fragments in curly braces. |
| pub struct Expr(pub Fragment); |
| impl ToTokens for Expr { |
| fn to_tokens(&self, out: &mut Tokens) { |
| match self.0 { |
| Fragment::Expr(ref expr) => expr.to_tokens(out), |
| Fragment::Block(ref block) => { |
| out.append("{"); |
| block.to_tokens(out); |
| out.append("}"); |
| } |
| } |
| } |
| } |
| |
| /// Interpolate a fragment as the statements of a block. |
| pub struct Stmts(pub Fragment); |
| impl ToTokens for Stmts { |
| fn to_tokens(&self, out: &mut Tokens) { |
| match self.0 { |
| Fragment::Expr(ref expr) => expr.to_tokens(out), |
| Fragment::Block(ref block) => block.to_tokens(out), |
| } |
| } |
| } |
| |
| /// Interpolate a fragment as the value part of a `match` expression. This |
| /// involves putting a comma after expressions and curly braces around blocks. |
| pub struct Match(pub Fragment); |
| impl ToTokens for Match { |
| fn to_tokens(&self, out: &mut Tokens) { |
| match self.0 { |
| Fragment::Expr(ref expr) => { |
| expr.to_tokens(out); |
| out.append(","); |
| } |
| Fragment::Block(ref block) => { |
| out.append("{"); |
| block.to_tokens(out); |
| out.append("}"); |
| } |
| } |
| } |
| } |