bendns' repos / rust-fsm
Finite state machines in rust; bendns fork to add types.
Diffstat (limited to 'rust-fsm-dsl/src/lib.rs')
-rw-r--r--rust-fsm-dsl/src/lib.rs162
1 files changed, 162 insertions, 0 deletions
diff --git a/rust-fsm-dsl/src/lib.rs b/rust-fsm-dsl/src/lib.rs
new file mode 100644
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+++ b/rust-fsm-dsl/src/lib.rs
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+//! DSL implementation for defining finite state machines for `rust-fsm`. See
+//! more in the `rust-fsm` crate documentation.
+
+#![recursion_limit = "128"]
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use quote::quote;
+use std::collections::BTreeSet;
+use syn::{parse_macro_input, Ident};
+
+mod parser;
+
+/// The full information about a state transition. Used to unify the
+/// represantion of the simple and the compact forms.
+struct Transition<'a> {
+ initial_state: &'a Ident,
+ input_value: &'a Ident,
+ final_state: &'a Ident,
+ output: &'a Option<Ident>,
+}
+
+#[proc_macro]
+/// Produce a state machine definition from the provided `rust-fmt` DSL
+/// description.
+pub fn state_machine(tokens: TokenStream) -> TokenStream {
+ let input = parse_macro_input!(tokens as parser::StateMachineDef);
+
+ let derives = if let Some(derives) = input.derives {
+ quote! { #[derive(#(#derives,)*)] }
+ } else {
+ quote! {}
+ };
+
+ if input.transitions.is_empty() {
+ let output = quote! {
+ compile_error!("rust-fsm: at least one state transition must be provided");
+ };
+ return output.into();
+ }
+
+ let struct_name = input.name;
+ let visibility = input.visibility;
+
+ let transitions: Vec<_> = input
+ .transitions
+ .iter()
+ .flat_map(|def| {
+ def.transitions.iter().map(move |transition| Transition {
+ initial_state: &def.initial_state,
+ input_value: &transition.input_value,
+ final_state: &transition.final_state,
+ output: &transition.output,
+ })
+ })
+ .collect();
+
+ let mut states = BTreeSet::new();
+ let mut inputs = BTreeSet::new();
+ let mut outputs = BTreeSet::new();
+
+ states.insert(&input.initial_state);
+
+ for transition in transitions.iter() {
+ states.insert(&transition.initial_state);
+ states.insert(&transition.final_state);
+ inputs.insert(&transition.input_value);
+ if let Some(ref output) = transition.output {
+ outputs.insert(output);
+ }
+ }
+
+ let states_enum_name = Ident::new(&format!("{}State", struct_name), struct_name.span());
+ let initial_state_name = &input.initial_state;
+
+ let inputs_enum_name = Ident::new(&format!("{}Input", struct_name), struct_name.span());
+
+ let mut transition_cases = vec![];
+ for transition in transitions.iter() {
+ let initial_state = &transition.initial_state;
+ let input_value = &transition.input_value;
+ let final_state = &transition.final_state;
+ transition_cases.push(quote! {
+ (#states_enum_name::#initial_state, #inputs_enum_name::#input_value) => {
+ Some(#states_enum_name::#final_state)
+ }
+ });
+ }
+
+ let (outputs_repr, outputs_type, output_impl) = if !outputs.is_empty() {
+ let outputs_type_name = Ident::new(&format!("{}Output", struct_name), struct_name.span());
+ let outputs_repr = quote! {
+ #derives
+ #visibility enum #outputs_type_name {
+ #(#outputs),*
+ }
+ };
+
+ let outputs_type = quote! { #outputs_type_name };
+
+ let mut output_cases = vec![];
+ for transition in transitions.iter() {
+ if let Some(output_value) = &transition.output {
+ let initial_state = &transition.initial_state;
+ let input_value = &transition.input_value;
+ output_cases.push(quote! {
+ (#states_enum_name::#initial_state, #inputs_enum_name::#input_value) => {
+ Some(#outputs_type_name::#output_value)
+ }
+ });
+ }
+ }
+
+ let output_impl = quote! {
+ match (state, input) {
+ #(#output_cases)*
+ _ => None,
+ }
+ };
+
+ (outputs_repr, outputs_type, output_impl)
+ } else {
+ (quote! {}, quote! { () }, quote! {None})
+ };
+
+ let output = quote! {
+ #derives
+ #visibility struct #struct_name;
+
+ #derives
+ #visibility enum #states_enum_name {
+ #(#states),*
+ }
+
+ #derives
+ #visibility enum #inputs_enum_name {
+ #(#inputs),*
+ }
+
+ #outputs_repr
+
+ impl rust_fsm::StateMachineImpl for #struct_name {
+ type Input = #inputs_enum_name;
+ type State = #states_enum_name;
+ type Output = #outputs_type;
+ const INITIAL_STATE: Self::State = #states_enum_name::#initial_state_name;
+
+ fn transition(state: &Self::State, input: &Self::Input) -> Option<Self::State> {
+ match (state, input) {
+ #(#transition_cases)*
+ _ => None,
+ }
+ }
+
+ fn output(state: &Self::State, input: &Self::Input) -> Option<Self::Output> {
+ #output_impl
+ }
+ }
+ };
+
+ output.into()
+}