Improve tree building

Cargo.toml

@@ -16,3 +16,6 @@ parking_lot = "0.6.0"
 
 [dev-dependencies]
 testutils = { path = "./tests/testutils" }
+
+[profile.release]
+debug = true

cli/src/main.rs

@@ -47,6 +47,7 @@ fn main() -> Result<()> {
                 println!("{}", file.syntax_tree());
             }
             eprintln!("parsing: {:?}", elapsed);
+            ::std::mem::forget(file);
         }
         ("symbols", _) => {
             let file = file()?;

src/yellow/builder.rs

@@ -1,14 +1,14 @@
 use {
     parser_impl::Sink,
-    yellow::{GreenNode, GreenNodeBuilder, SyntaxError, SyntaxNode, SyntaxRoot},
+    yellow::{GreenNode, SyntaxError, SyntaxNode, SyntaxRoot},
     SyntaxKind, TextRange, TextUnit,
 };
 
 pub(crate) struct GreenBuilder<'a> {
     text: &'a str,
-    stack: Vec<GreenNodeBuilder>,
+    parents: Vec<(SyntaxKind, usize)>,
+    children: Vec<GreenNode>,
     pos: TextUnit,
-    root: Option<GreenNode>,
     errors: Vec<SyntaxError>,
 }
 
@@ -18,9 +18,9 @@ impl<'a> Sink<'a> for GreenBuilder<'a> {
     fn new(text: &'a str) -> Self {
         GreenBuilder {
             text,
-            stack: Vec::new(),
+            parents: Vec::new(),
+            children: Vec::new(),
             pos: 0.into(),
-            root: None,
             errors: Vec::new(),
         }
     }
@@ -29,23 +29,24 @@ impl<'a> Sink<'a> for GreenBuilder<'a> {
         let range = TextRange::offset_len(self.pos, len);
         self.pos += len;
         let text = &self.text[range];
-        let leaf = GreenNodeBuilder::new_leaf(kind, text);
-        let parent = self.stack.last_mut().unwrap();
-        parent.push_child(leaf)
+        self.children.push(
+            GreenNode::new_leaf(kind, text)
+        );
     }
 
     fn start_internal(&mut self, kind: SyntaxKind) {
-        self.stack.push(GreenNodeBuilder::new_internal(kind))
+        let len = self.children.len();
+        self.parents.push((kind, len));
     }
 
     fn finish_internal(&mut self) {
-        let builder = self.stack.pop().unwrap();
-        let node = builder.build();
-        if let Some(parent) = self.stack.last_mut() {
-            parent.push_child(node);
-        } else {
-            self.root = Some(node);
-        }
+        let (kind, first_child) = self.parents.pop().unwrap();
+        let children = self.children
+            .drain(first_child..)
+            .collect();
+        self.children.push(
+            GreenNode::new_branch(kind, children)
+        );
     }
 
     fn error(&mut self, message: String) {
@@ -55,8 +56,10 @@ impl<'a> Sink<'a> for GreenBuilder<'a> {
         })
     }
 
-    fn finish(self) -> SyntaxNode {
-        let root = SyntaxRoot::new(self.root.unwrap(), self.errors);
+    fn finish(mut self) -> SyntaxNode {
+        assert_eq!(self.children.len(), 1);
+        let root = self.children.pop().unwrap();
+        let root = SyntaxRoot::new(root, self.errors);
         SyntaxNode::new_owned(root)
     }
 }

src/yellow/green.rs

@@ -12,6 +12,14 @@ pub(crate) enum GreenNode {
 }
 
 impl GreenNode {
+    pub(crate) fn new_leaf(kind: SyntaxKind, text: &str) -> GreenNode {
+        GreenNode::Leaf(GreenLeaf::new(kind, text))
+    }
+
+    pub(crate) fn new_branch(kind: SyntaxKind, children: Vec<GreenNode>) -> GreenNode {
+        GreenNode::Branch(Arc::new(GreenBranch::new(kind, children)))
+    }
+
     pub fn kind(&self) -> SyntaxKind {
         match self {
             GreenNode::Leaf(l) => l.kind(),
@@ -46,33 +54,6 @@ impl GreenNode {
     }
 }
 
-pub(crate) struct GreenNodeBuilder {
-    kind: SyntaxKind,
-    children: Vec<GreenNode>,
-}
-
-impl GreenNodeBuilder {
-    pub(crate) fn new_leaf(kind: SyntaxKind, text: &str) -> GreenNode {
-        GreenNode::Leaf(GreenLeaf::new(kind, text))
-    }
-
-    pub(crate) fn new_internal(kind: SyntaxKind) -> GreenNodeBuilder {
-        GreenNodeBuilder {
-            kind,
-            children: Vec::new(),
-        }
-    }
-
-    pub(crate) fn push_child(&mut self, node: GreenNode) {
-        self.children.push(node)
-    }
-
-    pub(crate) fn build(self) -> GreenNode {
-        let branch = GreenBranch::new(self.kind, self.children);
-        GreenNode::Branch(Arc::new(branch))
-    }
-}
-
 #[test]
 fn assert_send_sync() {
     fn f<T: Send + Sync>() {}

src/yellow/mod.rs

@@ -6,7 +6,7 @@ mod syntax;
 pub use self::syntax::{SyntaxNode, SyntaxNodeRef, SyntaxRoot, TreeRoot};
 pub(crate) use self::{
     builder::GreenBuilder,
-    green::{GreenNode, GreenNodeBuilder},
+    green::GreenNode,
     red::RedNode,
     syntax::SyntaxError,
 };