bendns' repos / rust-fsm
Finite state machines in rust; bendns fork to add types.
Diffstat (limited to 'rust-fsm-dsl/src/variant.rs')
-rw-r--r--rust-fsm-dsl/src/variant.rs73
1 files changed, 73 insertions, 0 deletions
diff --git a/rust-fsm-dsl/src/variant.rs b/rust-fsm-dsl/src/variant.rs
new file mode 100644
index 0000000..417476b
--- /dev/null
+++ b/rust-fsm-dsl/src/variant.rs
@@ -0,0 +1,73 @@
+use std::fmt::Display;
+
+use quote::ToTokens;
+use syn::{parse::Parse, *};
+/// Variant with no discriminator
+#[derive(Hash, Debug, PartialEq, Eq)]
+pub struct Variant {
+ // attrs: Vec<Attribute>,
+ ident: Ident,
+ field: Option<(Type, Expr)>,
+}
+
+impl Parse for Variant {
+ fn parse(input: parse::ParseStream) -> Result<Self> {
+ // let attrs = input.call(Attribute::parse_outer)?;
+ // let _visibility: Visibility = input.parse()?;
+ let ident: Ident = input.parse()?;
+ let field = if input.peek(token::Paren) {
+ let inp;
+ parenthesized!(inp in input);
+ let t = inp.parse()?;
+ inp.parse::<Token![=>]>()?;
+ Some((t, inp.parse()?))
+ } else {
+ None
+ };
+ Ok(Variant {
+ // attrs,
+ ident,
+ field,
+ })
+ }
+}
+
+impl PartialOrd for Variant {
+ fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+ self.ident.partial_cmp(&other.ident)
+ }
+}
+impl Ord for Variant {
+ fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+ self.ident.cmp(&other.ident)
+ }
+}
+
+impl ToTokens for Variant {
+ fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
+ self.ident.to_tokens(tokens);
+ if let Some((t, _)) = &self.field {
+ tokens.extend(quote::quote! { (#t) })
+ }
+ }
+}
+
+impl Variant {
+ pub fn match_on(&self) -> proc_macro2::TokenStream {
+ if let Self {
+ ident,
+ field: Some((_, p)),
+ } = self
+ {
+ quote::quote! { #ident(#p) }
+ } else {
+ self.ident.to_token_stream()
+ }
+ }
+}
+
+impl Display for Variant {
+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ write!(f, "{}", self.match_on())
+ }
+}