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Diffstat (limited to '')
-rw-r--r-- | vendor/serde_derive/src/fragment.rs | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/vendor/serde_derive/src/fragment.rs b/vendor/serde_derive/src/fragment.rs new file mode 100644 index 000000000..324504aa4 --- /dev/null +++ b/vendor/serde_derive/src/fragment.rs @@ -0,0 +1,74 @@ +use proc_macro2::TokenStream; +use quote::ToTokens; +use syn::token; + +pub enum Fragment { + /// Tokens that can be used as an expression. + Expr(TokenStream), + /// Tokens that can be used inside a block. The surrounding curly braces are + /// not part of these tokens. + Block(TokenStream), +} + +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 TokenStream) { + match &self.0 { + Fragment::Expr(expr) => expr.to_tokens(out), + Fragment::Block(block) => { + token::Brace::default().surround(out, |out| block.to_tokens(out)); + } + } + } +} + +/// Interpolate a fragment as the statements of a block. +pub struct Stmts(pub Fragment); +impl ToTokens for Stmts { + fn to_tokens(&self, out: &mut TokenStream) { + match &self.0 { + Fragment::Expr(expr) => expr.to_tokens(out), + Fragment::Block(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 TokenStream) { + match &self.0 { + Fragment::Expr(expr) => { + expr.to_tokens(out); + <Token![,]>::default().to_tokens(out); + } + Fragment::Block(block) => { + token::Brace::default().surround(out, |out| block.to_tokens(out)); + } + } + } +} + +impl AsRef<TokenStream> for Fragment { + fn as_ref(&self) -> &TokenStream { + match self { + Fragment::Expr(expr) => expr, + Fragment::Block(block) => block, + } + } +} |