1 files changed, 57 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/lexer/comments.rs b/crates/ra_syntax/src/lexer/comments.rs
new file mode 100644
index 000000000..eb417c2dc
--- /dev/null
+++ b/crates/ra_syntax/src/lexer/comments.rs
@@ -0,0 +1,57 @@
+use lexer::ptr::Ptr;
+
+use SyntaxKind::{self, *};
+
+pub(crate) fn scan_shebang(ptr: &mut Ptr) -> bool {
+    if ptr.at_str("!/") {
+        ptr.bump();
+        ptr.bump();
+        bump_until_eol(ptr);
+        true
+    } else {
+        false
+    }
+}
+
+fn scan_block_comment(ptr: &mut Ptr) -> Option<SyntaxKind> {
+    if ptr.at('*') {
+        ptr.bump();
+        let mut depth: u32 = 1;
+        while depth > 0 {
+            if ptr.at_str("*/") {
+                depth -= 1;
+                ptr.bump();
+                ptr.bump();
+            } else if ptr.at_str("/*") {
+                depth += 1;
+                ptr.bump();
+                ptr.bump();
+            } else if ptr.bump().is_none() {
+                break;
+            }
+        }
+        Some(COMMENT)
+    } else {
+        None
+    }
+}
+
+pub(crate) fn scan_comment(ptr: &mut Ptr) -> Option<SyntaxKind> {
+    if ptr.at('/') {
+        bump_until_eol(ptr);
+        Some(COMMENT)
+    } else {
+        scan_block_comment(ptr)
+    }
+}
+
+fn bump_until_eol(ptr: &mut Ptr) {
+    loop {
+        if ptr.at('\n') || ptr.at_str("\r\n") {
+            return;
+        }
+        if ptr.bump().is_none() {
+            break;
+        }
+    }
+}