5 files changed, 44 insertions, 23 deletions

diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index 11e18a03d..b82d1bda0 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -5,7 +5,7 @@ mod input;
 use std::{panic, sync::Arc};
 
 use ra_prof::profile;
-use ra_syntax::{Parse, SourceFile, TextRange, TextUnit};
+use ra_syntax::{ast, Parse, SourceFile, TextRange, TextUnit};
 use relative_path::RelativePathBuf;
 
 pub use crate::{
@@ -74,7 +74,7 @@ pub trait SourceDatabase: CheckCanceled + std::fmt::Debug {
     fn file_text(&self, file_id: FileId) -> Arc<String>;
     // Parses the file into the syntax tree.
     #[salsa::invoke(parse_query)]
-    fn parse(&self, file_id: FileId) -> Parse;
+    fn parse(&self, file_id: FileId) -> Parse<ast::SourceFile>;
     /// Path to a file, relative to the root of its source root.
     #[salsa::input]
     fn file_relative_path(&self, file_id: FileId) -> RelativePathBuf;
@@ -98,7 +98,7 @@ fn source_root_crates(db: &impl SourceDatabase, id: SourceRootId) -> Arc<Vec<Cra
     Arc::new(res)
 }
 
-fn parse_query(db: &impl SourceDatabase, file_id: FileId) -> Parse {
+fn parse_query(db: &impl SourceDatabase, file_id: FileId) -> Parse<ast::SourceFile> {
     let _p = profile("parse_query");
     let text = db.file_text(file_id);
     SourceFile::parse(&*text)
diff --git a/crates/ra_ide_api/src/completion/completion_context.rs b/crates/ra_ide_api/src/completion/completion_context.rs
index f6584cdd6..4aa84751f 100644
--- a/crates/ra_ide_api/src/completion/completion_context.rs
+++ b/crates/ra_ide_api/src/completion/completion_context.rs
@@ -43,7 +43,7 @@ pub(crate) struct CompletionContext<'a> {
 impl<'a> CompletionContext<'a> {
     pub(super) fn new(
         db: &'a db::RootDatabase,
-        original_parse: &'a Parse,
+        original_parse: &'a Parse<ast::SourceFile>,
         position: FilePosition,
     ) -> Option<CompletionContext<'a>> {
         let module = source_binder::module_from_position(db, position);
@@ -83,7 +83,7 @@ impl<'a> CompletionContext<'a> {
         }
     }
 
-    fn fill(&mut self, original_parse: &'a Parse, offset: TextUnit) {
+    fn fill(&mut self, original_parse: &'a Parse<ast::SourceFile>, offset: TextUnit) {
         // Insert a fake ident to get a valid parse tree. We will use this file
         // to determine context, though the original_file will be used for
         // actual completion.
diff --git a/crates/ra_ide_api/src/status.rs b/crates/ra_ide_api/src/status.rs
index ce27f5ae2..d71c89b43 100644
--- a/crates/ra_ide_api/src/status.rs
+++ b/crates/ra_ide_api/src/status.rs
@@ -9,7 +9,7 @@ use ra_db::{
     FileTextQuery, SourceRootId,
 };
 use ra_prof::{memory_usage, Bytes};
-use ra_syntax::{AstNode, Parse, SyntaxNode, TreeArc};
+use ra_syntax::{ast, AstNode, Parse, SyntaxNode, TreeArc};
 
 use crate::{
     db::RootDatabase,
@@ -79,10 +79,10 @@ impl fmt::Display for SyntaxTreeStats {
     }
 }
 
-impl FromIterator<TableEntry<FileId, Parse>> for SyntaxTreeStats {
+impl FromIterator<TableEntry<FileId, Parse<ast::SourceFile>>> for SyntaxTreeStats {
     fn from_iter<T>(iter: T) -> SyntaxTreeStats
     where
-        T: IntoIterator<Item = TableEntry<FileId, Parse>>,
+        T: IntoIterator<Item = TableEntry<FileId, Parse<ast::SourceFile>>>,
     {
         let mut res = SyntaxTreeStats::default();
         for entry in iter {
diff --git a/crates/ra_ide_api/src/symbol_index.rs b/crates/ra_ide_api/src/symbol_index.rs
index 1f2ba954e..9b3a45319 100644
--- a/crates/ra_ide_api/src/symbol_index.rs
+++ b/crates/ra_ide_api/src/symbol_index.rs
@@ -169,7 +169,9 @@ impl SymbolIndex {
         self.map.as_fst().size() + self.symbols.len() * mem::size_of::<FileSymbol>()
     }
 
-    pub(crate) fn for_files(files: impl ParallelIterator<Item = (FileId, Parse)>) -> SymbolIndex {
+    pub(crate) fn for_files(
+        files: impl ParallelIterator<Item = (FileId, Parse<ast::SourceFile>)>,
+    ) -> SymbolIndex {
         let symbols = files
             .flat_map(|(file_id, file)| source_file_to_file_symbols(file.tree(), file_id))
             .collect::<Vec<_>>();
diff --git a/crates/ra_syntax/src/lib.rs b/crates/ra_syntax/src/lib.rs
index 0fa2fe382..2eb3fcd57 100644
--- a/crates/ra_syntax/src/lib.rs
+++ b/crates/ra_syntax/src/lib.rs
@@ -35,7 +35,7 @@ use std::{fmt::Write, sync::Arc};
 
 use ra_text_edit::AtomTextEdit;
 
-use crate::syntax_node::GreenNode;
+use crate::syntax_node::{GreenNode, SyntaxNodeWrapper};
 
 pub use crate::{
     ast::{AstNode, AstToken},
@@ -57,14 +57,24 @@ pub use rowan::{SmolStr, TextRange, TextUnit};
 ///
 /// Note that we always produce a syntax tree, even for completely invalid
 /// files.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Parse {
-    tree: TreeArc<SourceFile>,
+#[derive(Debug, PartialEq, Eq)]
+pub struct Parse<T: SyntaxNodeWrapper> {
+    tree: TreeArc<T>,
     errors: Arc<Vec<SyntaxError>>,
 }
 
-impl Parse {
-    pub fn tree(&self) -> &SourceFile {
+impl<T: SyntaxNodeWrapper> Clone for Parse<T> {
+    fn clone(&self) -> Parse<T> {
+        Parse { tree: self.tree.clone(), errors: self.errors.clone() }
+    }
+}
+
+impl<T: SyntaxNodeWrapper> Parse<T> {
+    fn new(tree: TreeArc<T>, errors: Vec<SyntaxError>) -> Parse<T> {
+        Parse { tree, errors: Arc::new(errors) }
+    }
+
+    pub fn tree(&self) -> &T {
         &*self.tree
     }
 
@@ -72,18 +82,16 @@ impl Parse {
         &*self.errors
     }
 
-    pub fn ok(self) -> Result<TreeArc<SourceFile>, Arc<Vec<SyntaxError>>> {
+    pub fn ok(self) -> Result<TreeArc<T>, Arc<Vec<SyntaxError>>> {
         if self.errors.is_empty() {
             Ok(self.tree)
         } else {
             Err(self.errors)
         }
     }
+}
 
-    pub fn reparse(&self, edit: &AtomTextEdit) -> Parse {
-        self.incremental_reparse(edit).unwrap_or_else(|| self.full_reparse(edit))
-    }
-
+impl Parse<SourceFile> {
     pub fn debug_dump(&self) -> String {
         let mut buf = self.tree.syntax().debug_dump();
         for err in self.errors.iter() {
@@ -92,7 +100,11 @@ impl Parse {
         buf
     }
 
-    fn incremental_reparse(&self, edit: &AtomTextEdit) -> Option<Parse> {
+    pub fn reparse(&self, edit: &AtomTextEdit) -> Parse<SourceFile> {
+        self.incremental_reparse(edit).unwrap_or_else(|| self.full_reparse(edit))
+    }
+
+    fn incremental_reparse(&self, edit: &AtomTextEdit) -> Option<Parse<SourceFile>> {
         // FIXME: validation errors are not handled here
         parsing::incremental_reparse(self.tree.syntax(), edit, self.errors.to_vec()).map(
             |(green_node, errors, _reparsed_range)| Parse {
@@ -102,12 +114,19 @@ impl Parse {
         )
     }
 
-    fn full_reparse(&self, edit: &AtomTextEdit) -> Parse {
+    fn full_reparse(&self, edit: &AtomTextEdit) -> Parse<SourceFile> {
         let text = edit.apply(self.tree.syntax().text().to_string());
         SourceFile::parse(&text)
     }
 }
 
+impl Parse<SyntaxNode> {
+    pub fn cast<T: AstNode>(self) -> Option<Parse<T>> {
+        let node = T::cast(&self.tree)?;
+        Some(Parse { tree: node.to_owned(), errors: self.errors })
+    }
+}
+
 /// `SourceFile` represents a parse tree for a single Rust file.
 pub use crate::ast::SourceFile;
 
@@ -121,7 +140,7 @@ impl SourceFile {
         TreeArc::cast(root)
     }
 
-    pub fn parse(text: &str) -> Parse {
+    pub fn parse(text: &str) -> Parse<SourceFile> {
         let (green, mut errors) = parsing::parse_text(text);
         let tree = SourceFile::new(green);
         errors.extend(validation::validate(&tree));