webidl: move first pass logic to new module

I also updated it so that it is modeled in the same
extensible way as the WebidlParse trait.

crates/webidl/src/first_pass.rs

@@ -0,0 +1,150 @@
+use std::{
+    collections::{BTreeMap, BTreeSet}, mem,
+};
+
+use webidl;
+
+use super::Result;
+
+#[derive(Default)]
+pub(crate) struct FirstPassRecord<'a> {
+    pub(crate) interfaces: BTreeSet<String>,
+    pub(crate) dictionaries: BTreeSet<String>,
+    pub(crate) enums: BTreeSet<String>,
+    pub(crate) mixins: BTreeMap<String, MixinData<'a>>,
+}
+
+#[derive(Default)]
+pub(crate) struct MixinData<'a> {
+    pub(crate) non_partial: Option<&'a webidl::ast::NonPartialMixin>,
+    pub(crate) partials: Vec<&'a webidl::ast::PartialMixin>,
+}
+
+pub(crate) trait FirstPass {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()>;
+}
+
+impl FirstPass for [webidl::ast::Definition] {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        for def in self {
+            def.first_pass(record)?;
+        }
+
+        Ok(())
+    }
+}
+
+impl FirstPass for webidl::ast::Definition {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        use webidl::ast::Definition::*;
+
+        match self {
+            Dictionary(dictionary) => dictionary.first_pass(record),
+            Enum(enum_) => enum_.first_pass(record),
+            Interface(interface) => interface.first_pass(record),
+            Mixin(mixin) => mixin.first_pass(record),
+            _ => {
+                // Other definitions aren't currently used in the first pass
+                Ok(())
+            }
+        }
+    }
+}
+
+impl FirstPass for webidl::ast::Dictionary {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        use webidl::ast::Dictionary::*;
+
+        match self {
+            NonPartial(dictionary) => dictionary.first_pass(record),
+            _ => {
+                // Other dictionaries aren't currently used in the first pass
+                Ok(())
+            }
+        }
+    }
+}
+
+impl FirstPass for webidl::ast::NonPartialDictionary {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        if record.dictionaries.insert(self.name.clone()) {
+            warn!("Encountered multiple declarations of {}", self.name);
+        }
+
+        Ok(())
+    }
+}
+
+impl FirstPass for webidl::ast::Enum {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        if record.enums.insert(self.name.clone()) {
+            warn!("Encountered multiple declarations of {}", self.name);
+        }
+
+        Ok(())
+    }
+}
+
+impl FirstPass for webidl::ast::Interface {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        use webidl::ast::Interface::*;
+
+        match self {
+            NonPartial(interface) => interface.first_pass(record),
+            _ => {
+                // Other interfaces aren't currently used in the first pass
+                Ok(())
+            }
+        }
+    }
+}
+
+impl FirstPass for webidl::ast::NonPartialInterface {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        if record.interfaces.insert(self.name.clone()) {
+            warn!("Encountered multiple declarations of {}", self.name);
+        }
+
+        Ok(())
+    }
+}
+
+impl FirstPass for webidl::ast::Mixin {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        use webidl::ast::Mixin::*;
+
+        match self {
+            NonPartial(mixin) => mixin.first_pass(record),
+            Partial(mixin) => mixin.first_pass(record),
+        }
+    }
+}
+
+impl FirstPass for webidl::ast::NonPartialMixin {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        let entry = record
+            .mixins
+            .entry(self.name.clone())
+            .or_insert(Default::default());
+        if mem::replace(&mut entry.non_partial, Some(self)).is_some() {
+            warn!(
+                "Encounterd multiple declarations of {}, using last encountered",
+                self.name
+            );
+        }
+
+        Ok(())
+    }
+}
+
+impl FirstPass for webidl::ast::PartialMixin {
+    fn first_pass<'a>(&'a self, record: &mut FirstPassRecord<'a>) -> Result<()> {
+        let entry = record
+            .mixins
+            .entry(self.name.clone())
+            .or_insert(Default::default());
+        entry.partials.push(self);
+
+        Ok(())
+    }
+}