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.rs177
1 files changed, 177 insertions, 0 deletions
diff --git a/rust_fsm_dsl/src/lib.rs b/rust_fsm_dsl/src/lib.rs
index e69de29..479e119 100644
--- a/rust_fsm_dsl/src/lib.rs
+++ b/rust_fsm_dsl/src/lib.rs
@@ -0,0 +1,177 @@
+#![recursion_limit = "128"]
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use quote::quote;
+use std::collections::HashSet;
+use syn::{
+ bracketed, parenthesized,
+ parse::{Parse, ParseStream, Result},
+ parse_macro_input,
+ punctuated::Punctuated,
+ token::Bracket,
+ Ident, Token,
+};
+
+struct TransitionDef {
+ initial_state: Ident,
+ input_value: Ident,
+ final_state: Ident,
+ output: Option<Ident>,
+}
+
+impl Parse for TransitionDef {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let initial_state = input.parse()?;
+ let input_content;
+ parenthesized!(input_content in input);
+ let input_value = input_content.parse()?;
+ input.parse::<Token![=>]>()?;
+ let final_state = input.parse()?;
+ let output = if input.lookahead1().peek(Bracket) {
+ let output_content;
+ bracketed!(output_content in input);
+ Some(output_content.parse()?)
+ } else {
+ None
+ };
+ Ok(Self {
+ initial_state,
+ input_value,
+ final_state,
+ output,
+ })
+ }
+}
+
+struct StateMachineDef {
+ name: Ident,
+ initial_state: Ident,
+ transitions: Punctuated<TransitionDef, Token![,]>,
+}
+
+impl Parse for StateMachineDef {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let name = input.parse()?;
+ let initial_state_content;
+ parenthesized!(initial_state_content in input);
+ let initial_state = initial_state_content.parse()?;
+ let transitions = input.parse_terminated(TransitionDef::parse)?;
+ Ok(Self {
+ name,
+ initial_state,
+ transitions,
+ })
+ }
+}
+
+#[proc_macro]
+pub fn state_machine(tokens: TokenStream) -> TokenStream {
+ let input = parse_macro_input!(tokens as StateMachineDef);
+
+ let struct_name = input.name;
+
+ let mut states = HashSet::new();
+ let mut inputs = HashSet::new();
+ let mut outputs = HashSet::new();
+
+ states.insert(&input.initial_state);
+
+ for transition in input.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 input.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! {
+ #[derive(Debug, PartialEq)]
+ enum #outputs_type_name {
+ #(#outputs),*
+ }
+ };
+
+ let outputs_type = quote! { #outputs_type_name };
+
+ let mut output_cases = vec![];
+ for transition in input.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! {
+ struct #struct_name;
+
+ #[derive(Debug, PartialEq)]
+ enum #states_enum_name {
+ #(#states),*
+ }
+
+ #[derive(Debug, PartialEq)]
+ enum #inputs_enum_name {
+ #(#inputs),*
+ }
+
+ #outputs_repr
+
+ impl rust_fsm::StateMachine 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()
+}