1 files changed, 95 insertions, 0 deletions

diff --git a/crates/libsyntax2/src/yellow/green.rs b/crates/libsyntax2/src/yellow/green.rs
new file mode 100644
index 000000000..f505b26d7
--- /dev/null
+++ b/crates/libsyntax2/src/yellow/green.rs
@@ -0,0 +1,95 @@
+use std::sync::Arc;
+use {
+    SyntaxKind, TextUnit,
+    smol_str::SmolStr,
+};
+
+#[derive(Clone, Debug)]
+pub(crate) enum GreenNode {
+    Leaf {
+        kind: SyntaxKind,
+        text: SmolStr,
+    },
+    Branch(Arc<GreenBranch>),
+}
+
+impl GreenNode {
+    pub(crate) fn new_leaf(kind: SyntaxKind, text: &str) -> GreenNode {
+        GreenNode::Leaf { kind, text: SmolStr::new(text) }
+    }
+
+    pub(crate) fn new_branch(kind: SyntaxKind, children: Box<[GreenNode]>) -> GreenNode {
+        GreenNode::Branch(Arc::new(GreenBranch::new(kind, children)))
+    }
+
+    pub fn kind(&self) -> SyntaxKind {
+        match self {
+            GreenNode::Leaf { kind, .. } => *kind,
+            GreenNode::Branch(b) => b.kind(),
+        }
+    }
+
+    pub fn text_len(&self) -> TextUnit {
+        match self {
+            GreenNode::Leaf { text, ..} => TextUnit::of_str(text.as_str()),
+            GreenNode::Branch(b) => b.text_len(),
+        }
+    }
+
+    pub fn children(&self) -> &[GreenNode] {
+        match self {
+            GreenNode::Leaf { .. } => &[],
+            GreenNode::Branch(b) => b.children(),
+        }
+    }
+
+    pub fn text(&self) -> String {
+        let mut buff = String::new();
+        go(self, &mut buff);
+        return buff;
+        fn go(node: &GreenNode, buff: &mut String) {
+            match node {
+                GreenNode::Leaf { text, .. } => buff.push_str(text.as_str()),
+                GreenNode::Branch(b) => b.children().iter().for_each(|child| go(child, buff)),
+            }
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct GreenBranch {
+    text_len: TextUnit,
+    kind: SyntaxKind,
+    children: Box<[GreenNode]>,
+}
+
+impl GreenBranch {
+    fn new(kind: SyntaxKind, children: Box<[GreenNode]>) -> GreenBranch {
+        let text_len = children.iter().map(|x| x.text_len()).sum::<TextUnit>();
+        GreenBranch {
+            text_len,
+            kind,
+            children,
+        }
+    }
+
+    pub fn kind(&self) -> SyntaxKind {
+        self.kind
+    }
+
+    pub fn text_len(&self) -> TextUnit {
+        self.text_len
+    }
+
+    pub fn children(&self) -> &[GreenNode] {
+        &*self.children
+    }
+}
+
+#[test]
+fn test_sizes() {
+    use std::mem::size_of;
+    println!("GreenBranch = {}", size_of::<GreenBranch>());
+    println!("GreenNode   = {}", size_of::<GreenNode>());
+    println!("SmolStr     = {}", size_of::<SmolStr>());
+}