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// Copyright 2017 Serde Developers
//
// 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 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("}");
}
}
}
}