2 files changed, 55 insertions, 0 deletions

diff --git a/src/bin/parse-rust.rs b/src/bin/parse-rust.rs
new file mode 100644
index 000000000..3c13e732e
--- /dev/null
+++ b/src/bin/parse-rust.rs
@@ -0,0 +1,20 @@
+extern crate libsyntax2;
+
+use std::io::Read;
+
+use libsyntax2::{tokenize, parse};
+use libsyntax2::utils::dump_tree;
+
+fn main() {
+    let text = read_input();
+    let tokens = tokenize(&text);
+    let file = parse(text, &tokens);
+    let tree = dump_tree(&file);
+    println!("{}", tree);
+}
+
+fn read_input() -> String {
+    let mut buff = String::new();
+    ::std::io::stdin().read_to_string(&mut buff).unwrap();
+    buff
+}
diff --git a/src/lib.rs b/src/lib.rs
index d95e26662..7fd9e547a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,3 +10,38 @@ pub use text::{TextUnit, TextRange};
 pub use tree::{SyntaxKind, Token, FileBuilder, Sink, File, Node};
 pub use lexer::{next_token, tokenize};
 pub use parser::parse;
+
+pub mod utils {
+    use std::fmt::Write;
+
+    use {File, Node};
+
+    pub fn dump_tree(file: &File) -> String {
+        let mut result = String::new();
+        go(file.root(), &mut result, 0);
+        return result;
+
+        fn go(node: Node, buff: &mut String, level: usize) {
+            buff.push_str(&String::from("  ").repeat(level));
+            write!(buff, "{:?}\n", node).unwrap();
+            let my_errors = node.errors().filter(|e| e.after_child().is_none());
+            let parent_errors = node.parent().into_iter()
+                .flat_map(|n| n.errors())
+                .filter(|e| e.after_child() == Some(node));
+
+            for err in my_errors {
+                buff.push_str(&String::from("  ").repeat(level));
+                write!(buff, "err: `{}`\n", err.message()).unwrap();
+            }
+
+            for child in node.children() {
+                go(child, buff, level + 1)
+            }
+
+            for err in parent_errors {
+                buff.push_str(&String::from("  ").repeat(level));
+                write!(buff, "err: `{}`\n", err.message()).unwrap();
+            }
+        }
+    }
+}