1 files changed, 77 insertions, 0 deletions

diff --git a/crates/syntax/src/syntax_node.rs b/crates/syntax/src/syntax_node.rs
new file mode 100644
index 000000000..b2abcbfbb
--- /dev/null
+++ b/crates/syntax/src/syntax_node.rs
@@ -0,0 +1,77 @@
+//! This module defines Concrete Syntax Tree (CST), used by rust-analyzer.
+//!
+//! The CST includes comments and whitespace, provides a single node type,
+//! `SyntaxNode`, and a basic traversal API (parent, children, siblings).
+//!
+//! The *real* implementation is in the (language-agnostic) `rowan` crate, this
+//! module just wraps its API.
+
+use rowan::{GreenNodeBuilder, Language};
+
+use crate::{Parse, SmolStr, SyntaxError, SyntaxKind, TextSize};
+
+pub use rowan::GreenNode;
+
+pub(crate) use rowan::GreenToken;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum RustLanguage {}
+impl Language for RustLanguage {
+    type Kind = SyntaxKind;
+
+    fn kind_from_raw(raw: rowan::SyntaxKind) -> SyntaxKind {
+        SyntaxKind::from(raw.0)
+    }
+
+    fn kind_to_raw(kind: SyntaxKind) -> rowan::SyntaxKind {
+        rowan::SyntaxKind(kind.into())
+    }
+}
+
+pub type SyntaxNode = rowan::SyntaxNode<RustLanguage>;
+pub type SyntaxToken = rowan::SyntaxToken<RustLanguage>;
+pub type SyntaxElement = rowan::SyntaxElement<RustLanguage>;
+pub type SyntaxNodeChildren = rowan::SyntaxNodeChildren<RustLanguage>;
+pub type SyntaxElementChildren = rowan::SyntaxElementChildren<RustLanguage>;
+
+pub use rowan::{Direction, NodeOrToken};
+
+#[derive(Default)]
+pub struct SyntaxTreeBuilder {
+    errors: Vec<SyntaxError>,
+    inner: GreenNodeBuilder<'static>,
+}
+
+impl SyntaxTreeBuilder {
+    pub(crate) fn finish_raw(self) -> (GreenNode, Vec<SyntaxError>) {
+        let green = self.inner.finish();
+        (green, self.errors)
+    }
+
+    pub fn finish(self) -> Parse<SyntaxNode> {
+        let (green, errors) = self.finish_raw();
+        if cfg!(debug_assertions) {
+            let node = SyntaxNode::new_root(green.clone());
+            crate::validation::validate_block_structure(&node);
+        }
+        Parse::new(green, errors)
+    }
+
+    pub fn token(&mut self, kind: SyntaxKind, text: SmolStr) {
+        let kind = RustLanguage::kind_to_raw(kind);
+        self.inner.token(kind, text)
+    }
+
+    pub fn start_node(&mut self, kind: SyntaxKind) {
+        let kind = RustLanguage::kind_to_raw(kind);
+        self.inner.start_node(kind)
+    }
+
+    pub fn finish_node(&mut self) {
+        self.inner.finish_node()
+    }
+
+    pub fn error(&mut self, error: parser::ParseError, text_pos: TextSize) {
+        self.errors.push(SyntaxError::new_at_offset(*error.0, text_pos))
+    }
+}