1 files changed, 26 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/algo.rs b/crates/ra_syntax/src/algo.rs
new file mode 100644
index 000000000..4b3548ea9
--- /dev/null
+++ b/crates/ra_syntax/src/algo.rs
@@ -0,0 +1,26 @@
+pub mod visit;
+
+use crate::{SyntaxNode, SyntaxNodeRef, TextRange, TextUnit};
+
+pub use rowan::LeafAtOffset;
+
+pub fn find_leaf_at_offset(node: SyntaxNodeRef, offset: TextUnit) -> LeafAtOffset<SyntaxNodeRef> {
+    match node.0.leaf_at_offset(offset) {
+        LeafAtOffset::None => LeafAtOffset::None,
+        LeafAtOffset::Single(n) => LeafAtOffset::Single(SyntaxNode(n)),
+        LeafAtOffset::Between(l, r) => LeafAtOffset::Between(SyntaxNode(l), SyntaxNode(r)),
+    }
+}
+
+pub fn find_covering_node(root: SyntaxNodeRef, range: TextRange) -> SyntaxNodeRef {
+    SyntaxNode(root.0.covering_node(range))
+}
+
+pub fn generate<T>(seed: Option<T>, step: impl Fn(&T) -> Option<T>) -> impl Iterator<Item = T> {
+    ::itertools::unfold(seed, move |slot| {
+        slot.take().map(|curr| {
+            *slot = step(&curr);
+            curr
+        })
+    })
+}