Fix parsing bugs

1. empty key & value support
2. OnNull handling in test

saphyr/src/parser.rs

@@ -155,6 +155,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
     fn load_node<R: EventReceiver>(&mut self, first_ev: &Event, recv: &mut R)
         -> Result<(), ScanError> {
         match *first_ev {
+            Event::Alias => { unimplemented!() },
             Event::Scalar(ref v, style) => {
                 Ok(())
             },
@@ -164,8 +165,8 @@ impl<T: Iterator<Item=char>> Parser<T> {
             Event::MappingStart => {
                 self.load_mapping(first_ev, recv)
             },
-            // TODO more events
+            _ => { println!("UNREACHABLE EVENT: {:?}", first_ev);
-            _ => { unreachable!(); }
+                unreachable!(); }
         }
     }
 
@@ -379,7 +380,9 @@ impl<T: Iterator<Item=char>> Parser<T> {
                 self.skip();
                 let tok = try!(self.peek());
                 match tok.1 {
-                    TokenType::KeyToken | TokenType::ValueToken | TokenType::BlockEndToken
+                    TokenType::KeyToken
+                        | TokenType::ValueToken
+                        | TokenType::BlockEndToken
                         => {
                             self.state = State::BlockMappingValue;
                             // empty scalar
@@ -391,6 +394,11 @@ impl<T: Iterator<Item=char>> Parser<T> {
                     }
                 }
             },
+            // XXX(chenyh): libyaml failed to parse spec 1.2, ex8.18
+            TokenType::ValueToken => {
+                self.state = State::BlockMappingValue;
+                Ok(Event::empty_scalar())
+            },
             TokenType::BlockEndToken => {
                 self.pop_state();
                 self.skip();
@@ -411,7 +419,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
                     match tok.1 {
                         TokenType::KeyToken | TokenType::ValueToken | TokenType::BlockEndToken
                             => {
-                                self.state = State::BlockMappingValue;
+                                self.state = State::BlockMappingKey;
                                 // empty scalar
                                 Ok(Event::empty_scalar())
                             }

saphyr/tests/spec_test.rs

@@ -2,6 +2,7 @@
 extern crate yaml_rust;
 
 use yaml_rust::parser::{Parser, EventReceiver, Event};
+use yaml_rust::scanner::TScalarStyle;
 use yaml_rust::yaml::Yaml;
 
 #[derive(Clone, PartialEq, PartialOrd, Debug)]
@@ -31,7 +32,7 @@ impl EventReceiver for YamlChecker {
             Event::MappingStart => TestEvent::OnMapStart,
             Event::MappingEnd => TestEvent::OnMapEnd,
             Event::Scalar(ref v, style) => {
-                if v == "~" {
+                if v == "~" && style == TScalarStyle::Plain {
                     TestEvent::OnNull
                 } else {
                     TestEvent::OnScalar

saphyr/tests/specexamples.rs.inc

@@ -320,6 +320,7 @@ const EX8_16 : &'static str =
 const EX8_17 : &'static str =
     "? explicit key # Empty value\n? |\n  block key\n: - one # Explicit compact\n  - two # block value\n";
 
+// XXX libyaml failed this test
 const EX8_18 : &'static str =
     "plain key: in-line value\n:  # Both empty\n\"quoted key\":\n- entry\n";