skeleton for codegen

cranelift/isle/src/codegen.rs

@@ -470,20 +470,48 @@ impl<'a> TermFunctionsBuilder<'a> {
             }
         }
     }
+
+    fn finalize(self) -> (HashMap<TermId, TrieNode>, HashMap<TermId, TrieNode>) {
+        let functions_by_input = self
+            .builders_by_input
+            .into_iter()
+            .map(|(term, builder)| (term, builder.trie))
+            .collect::<HashMap<_, _>>();
+        let functions_by_output = self
+            .builders_by_output
+            .into_iter()
+            .map(|(term, builder)| (term, builder.trie))
+            .collect::<HashMap<_, _>>();
+        (functions_by_input, functions_by_output)
+    }
 }
 
-#[derive(Clone, Debug, Default)]
-pub struct Automata {
-    pub automata_by_input: HashMap<TermId, ()>,
-    pub automata_by_output: HashMap<TermId, ()>,
+#[derive(Clone, Debug)]
+pub struct Codegen<'a> {
+    typeenv: &'a TypeEnv,
+    termenv: &'a TermEnv,
+    functions_by_input: HashMap<TermId, TrieNode>,
+    functions_by_output: HashMap<TermId, TrieNode>,
 }
 
-impl Automata {
-    pub fn compile(typeenv: &TypeEnv, termenv: &TermEnv) -> Result<Automata, Error> {
+impl<'a> Codegen<'a> {
+    pub fn compile(typeenv: &'a TypeEnv, termenv: &'a TermEnv) -> Result<Codegen<'a>, Error> {
         let mut builder = TermFunctionsBuilder::new(typeenv, termenv);
         builder.build();
         log::trace!("builder: {:?}", builder);
-        // TODO
-        Ok(Automata::default())
+        let (functions_by_input, functions_by_output) = builder.finalize();
+        Ok(Codegen {
+            typeenv,
+            termenv,
+            functions_by_input,
+            functions_by_output,
+        })
+    }
+
+    pub fn generate_rust(&self) -> Result<String, Error> {
+        use std::fmt::Write;
+        let mut code = String::new();
+        writeln!(&mut code, "// GENERATED BY ISLE. DO NOT EDIT!")?;
+        Ok(code)
     }
 }