1 files changed, 68 insertions, 0 deletions

diff --git a/src/yellow/builder.rs b/src/yellow/builder.rs
new file mode 100644
index 000000000..346d561cd
--- /dev/null
+++ b/src/yellow/builder.rs
@@ -0,0 +1,68 @@
+use std::sync::Arc;
+use {
+    SyntaxKind, TextRange, TextUnit,
+    yellow::{SyntaxNode, GreenNode, SyntaxError},
+    parser::Sink
+};
+
+pub(crate) struct GreenBuilder {
+    text: String,
+    stack: Vec<GreenNode>,
+    pos: TextUnit,
+    root: Option<GreenNode>,
+    errors: Vec<SyntaxError>,
+}
+
+impl GreenBuilder {
+
+}
+
+impl Sink for GreenBuilder {
+    type Tree = SyntaxNode;
+
+    fn new(text: String) -> Self {
+        GreenBuilder {
+            text,
+            stack: Vec::new(),
+            pos: 0.into(),
+            root: None,
+            errors: Vec::new(),
+        }
+    }
+
+    fn leaf(&mut self, kind: SyntaxKind, len: TextUnit) {
+        let range = TextRange::offset_len(self.pos, len);
+        self.pos += len;
+        let text = self.text[range].to_owned();
+        let parent = self.stack.last_mut().unwrap();
+        if kind.is_trivia() {
+            parent.push_trivia(kind, text);
+        } else {
+            let node = GreenNode::new_leaf(kind, text);
+            parent.push_child(Arc::new(node));
+        }
+    }
+
+    fn start_internal(&mut self, kind: SyntaxKind) {
+        self.stack.push(GreenNode::new_branch(kind))
+    }
+
+    fn finish_internal(&mut self) {
+        let node = self.stack.pop().unwrap();
+        if let Some(parent) = self.stack.last_mut() {
+            parent.push_child(Arc::new(node))
+        } else {
+            self.root = Some(node);
+        }
+    }
+
+    fn error(&mut self, message: String) {
+        self.errors.push(SyntaxError { message, offset: self.pos })
+    }
+
+    fn finish(self) -> SyntaxNode {
+        SyntaxNode::new(Arc::new(self.root.unwrap()), self.errors)
+    }
+}
+
+