Add AST Passes and the #[toplevel] attribute. (#458)

* add toplevel attribute

* add "has" function for attributes

crates/ast/src/attribute.rs

@@ -9,12 +9,12 @@ pub enum NumAttr {}
 /// An flag attribute
 #[derive(Enum, Clone, Copy, PartialEq, EnumString)]
 pub enum BoolAttr {
+    /// This is a toplevel component
+    #[strum(serialize = "toplevel")]
+    TopLevel,
     /// Use a counter based FSM design
     #[strum(serialize = "counter_fsm")]
     CounterFSM,
-    /// Dummy attribute because the [Enum] trait derivation throws errors if there is only one varianat
-    #[strum(disabled)]
-    Dummy,
 }
 
 /// Represents a single attribute. This is a private enum that is used during
@@ -50,6 +50,11 @@ impl Attributes {
         }
     }
 
+    /// Check if an attribute is set
+    pub fn has(&self, attr: impl Into<Attr>) -> bool {
+        self.attrs[attr.into()].is_some()
+    }
+
     /// Get the value of an attribute.
     pub fn get(&self, attr: impl Into<Attr>) -> Option<u64> {
         self.attrs[attr.into()].map(|(v, _)| v)

crates/ast/src/component.rs

@@ -1,3 +1,5 @@
+use crate::BoolAttr;
+
 use super::{Command, Id, Signature};
 use fil_gen as gen;
 use gen::GenConfig;
@@ -44,30 +46,19 @@ impl Component {
     }
 }
 
+#[derive(Default)]
 pub struct Namespace {
     /// Imported files
     pub imports: Vec<String>,
     /// Define externals and their files
     pub externs: Vec<Extern>,
     /// Components defined in this file
     pub components: Vec<Component>,
-    /// Top-level component id
-    pub toplevel: String,
     /// Top level bindings
     pub bindings: Vec<u64>,
 }
 
 impl Namespace {
-    pub fn new(toplevel: String) -> Self {
-        Self {
-            imports: Vec::default(),
-            externs: Vec::default(),
-            components: Vec::default(),
-            bindings: Vec::default(),
-            toplevel,
-        }
-    }
-
     /// Returns true if the namespace declares at least one generative module
     pub fn requires_gen(&self) -> bool {
         self.externs.iter().any(|Extern { gen, .. }| gen.is_some())
@@ -103,8 +94,14 @@ impl Namespace {
     /// Get the index to the top-level component.
     /// Currently, this is the distinguished "main" component
     pub fn main_idx(&self) -> Option<usize> {
-        self.components.iter().position(|c| {
-            c.sig.name.inner() == &Id::from(self.toplevel.clone())
-        })
+        self.components
+            .iter()
+            .position(|c| c.sig.attributes.has(BoolAttr::TopLevel))
+    }
+
+    /// Get the toplevel component name
+    pub fn toplevel(&self) -> Option<&str> {
+        self.main_idx()
+            .map(|idx| self.components[idx].sig.name.inner().as_ref())
     }
 }

crates/ast/src/parser.rs

@@ -902,8 +902,11 @@ impl FilamentParser {
         Ok(match_nodes!(
             input.into_children();
             [imports(imps), comp_or_ext(mixed).., _EOI] => {
-                let mut namespace = ast::Namespace::new("main".to_string());
-                namespace.imports = imps;
+                let mut namespace = ast::Namespace {
+                    imports: imps,
+                    ..Default::default()
+                };
+
                 for m in mixed {
                     match m {
                         BodyEl::Ext(sig) => namespace.externs.push(sig),

crates/filament/src/ast_passes/mod.rs

@@ -0,0 +1,3 @@
+mod toplevel;
+
+pub use toplevel::TopLevel;

crates/filament/src/ast_passes/toplevel.rs

@@ -0,0 +1,84 @@
+use crate::ast_visitor::{Action, Visitor};
+use fil_ast as ast;
+use fil_utils::{Diagnostics, Error, GPosIdx};
+
+/// Sets the proper FSM Attributes for every component
+#[derive(Default)]
+pub struct TopLevel {
+    /// Set to true if we find a toplevel component
+    has_toplevel: Option<GPosIdx>,
+    /// Error reporting
+    diag: Diagnostics,
+}
+
+impl Visitor for TopLevel {
+    fn name() -> &'static str {
+        "fsm-attributes"
+    }
+
+    fn signature(&mut self, sig: &mut ast::Signature) -> Action {
+        if sig.attributes.get(ast::BoolAttr::TopLevel) == Some(1) {
+            if self.has_toplevel.is_some() {
+                let err = Error::malformed("Multiple top-level components")
+                    .add_note(self.diag.add_info(
+                        "first top-level component here",
+                        self.has_toplevel.unwrap(),
+                    ))
+                    .add_note(
+                        self.diag.add_info(
+                            "second top-level component here",
+                            sig.attributes
+                                .get_loc(ast::BoolAttr::TopLevel)
+                                .unwrap(),
+                        ),
+                    );
+
+                self.diag.add_error(err);
+            } else {
+                self.has_toplevel = Some(
+                    sig.attributes.get_loc(ast::BoolAttr::TopLevel).unwrap(),
+                );
+            }
+        }
+
+        // Stop traversal into component body
+        Action::Stop
+    }
+
+    fn external(&mut self, ext: &mut ast::Extern) {
+        for sig in &mut ext.comps {
+            if sig.attributes.get(ast::BoolAttr::TopLevel) == Some(1) {
+                let err =
+                    Error::malformed("External components cannot be top-level")
+                        .add_note(
+                            self.diag.add_info(
+                                "toplevel attribute here",
+                                sig.attributes
+                                    .get_loc(ast::BoolAttr::TopLevel)
+                                    .unwrap(),
+                            ),
+                        );
+
+                self.diag.add_error(err);
+            }
+        }
+    }
+
+    fn after_traversal(mut self) -> Option<u64> {
+        self.diag.report_all()
+    }
+
+    fn finish(&mut self, ast: &mut ast::Namespace) {
+        // If no toplevel component was found, find the component with the name "main"
+        if self.has_toplevel.is_none() {
+            for comp in ast.components.iter_mut() {
+                if comp.sig.name.as_ref() == "main" {
+                    // Add the toplevel attribute to the component
+                    comp.sig.attributes.set(ast::BoolAttr::TopLevel, 1);
+
+                    return;
+                }
+            }
+        }
+    }
+}

crates/filament/src/ast_visitor/mod.rs

@@ -0,0 +1,3 @@
+mod visitor;
+
+pub use visitor::{Action, Construct, Visitor};