Command-line utilty to print the parse tree

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
+}

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();
+            }
+        }
+    }
+}

tests/parser.rs

@@ -2,9 +2,8 @@ extern crate file;
 extern crate libsyntax2;
 extern crate testutils;
 
-use std::fmt::Write;
-
-use libsyntax2::{tokenize, parse, Node, File};
+use libsyntax2::{tokenize, parse};
+use libsyntax2::utils::dump_tree;
 use testutils::dir_tests;
 
 #[test]
@@ -18,32 +17,3 @@ fn parser_tests() {
         }
     )
 }
-
-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();
-        }
-    }
-}