more enterprisey diagnostics setup

crates/ra_hir/src/diagnostics.rs

@@ -1,9 +1,9 @@
 use std::{fmt, any::Any};
 
 use ra_syntax::{SyntaxNodePtr, AstPtr, ast};
+use relative_path::RelativePathBuf;
 
 use crate::HirFileId;
-use relative_path::RelativePathBuf;
 
 /// Diagnostic defines hir API for errors and warnings.
 ///
@@ -21,7 +21,7 @@ pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
     fn message(&self) -> String;
     fn file(&self) -> HirFileId;
     fn syntax_node(&self) -> SyntaxNodePtr;
-    fn as_any(&self) -> &(Any + Send + 'static);
+    fn as_any(&self) -> &(dyn Any + Send + 'static);
 }
 
 impl dyn Diagnostic {
@@ -30,18 +30,37 @@ impl dyn Diagnostic {
     }
 }
 
-#[derive(Debug, Default)]
-pub struct DiagnosticSink {
-    data: Vec<Box<dyn Diagnostic>>,
+pub struct DiagnosticSink<'a> {
+    callbacks: Vec<Box<dyn FnMut(&dyn Diagnostic) -> Result<(), ()> + 'a>>,
+    default_callback: Box<dyn FnMut(&dyn Diagnostic) + 'a>,
 }
 
-impl DiagnosticSink {
-    pub fn push(&mut self, d: impl Diagnostic) {
-        self.data.push(Box::new(d))
+impl<'a> DiagnosticSink<'a> {
+    pub fn new(cb: impl FnMut(&dyn Diagnostic) + 'a) -> DiagnosticSink<'a> {
+        DiagnosticSink { callbacks: Vec::new(), default_callback: Box::new(cb) }
     }
 
-    pub fn into_diagnostics(self) -> Vec<Box<dyn Diagnostic>> {
-        self.data
+    pub fn on<D: Diagnostic, F: FnMut(&D) + 'a>(mut self, mut cb: F) -> DiagnosticSink<'a> {
+        let cb = move |diag: &dyn Diagnostic| match diag.downcast_ref::<D>() {
+            Some(d) => {
+                cb(d);
+                Ok(())
+            }
+            None => Err(()),
+        };
+        self.callbacks.push(Box::new(cb));
+        self
+    }
+
+    pub(crate) fn push(&mut self, d: impl Diagnostic) {
+        let d: &dyn Diagnostic = &d;
+        for cb in self.callbacks.iter_mut() {
+            match cb(d) {
+                Ok(()) => return,
+                Err(()) => (),
+            }
+        }
+        (self.default_callback)(d)
     }
 }