[parser] Handle None from input

parser/src/lib.rs

@@ -44,6 +44,11 @@ impl<T> Parser<T> where T: Iterator<Item=LexerResult> {
         let parser = self.parsers.last_mut().expect("couldn't get a parser -- this is unexpected");
         parser.parse(lex)
     }
+
+    fn parse_none(&mut self) -> NodeParseResult {
+        let parser = self.parsers.last_mut().expect("couldn't get a parser -- this is unexpected");
+        parser.none()
+    }
 }
 
 impl<T> Iterator for Parser<T> where T: Iterator<Item=LexerResult> {
@@ -59,7 +64,11 @@ impl<T> Iterator for Parser<T> where T: Iterator<Item=LexerResult> {
                 Some(NodeParseResult::Continue) => self.input.next(),
                 Some(NodeParseResult::Complete{ obj }) => {
                     self.parsers.pop();
-                    // TODO: Handle obj
+                    if self.parsers.len() == 0 && input_lex.is_none() {
+                        // We are done.
+                        out = Some(Ok(obj));
+                        break;
+                    }
                     self.input.next()
                 },
                 Some(NodeParseResult::Push{ next }) => {
@@ -87,7 +96,7 @@ impl<T> Iterator for Parser<T> where T: Iterator<Item=LexerResult> {
                     // TODO: We didn't get a Lex from the input, which means the
                     // input is done. If there's any parse result waiting
                     // around, clean it up and return it or return an error.
-                    break;
+                    result = Some(self.parse_none());
                 }
             }
         }

parser/src/list_parser.rs

@@ -46,4 +46,9 @@ impl NodeParser for ListParser {
             }
         }
     }
+
+    fn none(&mut self) -> NodeParseResult {
+        let msg = format!("Unmatched paren, found EOF");
+        NodeParseResult::Error { msg }
+    }
 }

parser/src/node_parser.rs

@@ -33,4 +33,6 @@ impl NodeParseResult {
 /// nodes it encounters.
 pub trait NodeParser: Debug {
     fn parse(&mut self, lex: &Lex) -> NodeParseResult;
+    /// Called on a NodeParser when None is encountered in the input.
+    fn none(&mut self) -> NodeParseResult;
 }

parser/src/program_parser.rs

@@ -3,6 +3,7 @@
  */
 
 use sibillexer::{Lex, Token};
+use sibiltypes::Obj;
 use list_parser::ListParser;
 use node_parser::{NodeParser, NodeParseResult};
 use sym_parser::SymParser;
@@ -35,5 +36,9 @@ impl NodeParser for ProgramParser {
             }
         }
     }
+
+    fn none(&mut self) -> NodeParseResult {
+        NodeParseResult::Complete { obj: Obj::Null }
+    }
 }
 

parser/src/sym_parser.rs

@@ -19,9 +19,14 @@ impl NodeParser for SymParser {
                 NodeParseResult::Complete { obj: obj }
             }
             _ => {
-                let msg = format!("Expected symbol found {:?}", lex);
+                let msg = format!("Expected symbol, found {:?}", lex);
                 NodeParseResult::error(msg)
             }
         }
     }
+
+    fn none(&mut self) -> NodeParseResult {
+        let msg = format!("Expected symbol, found EOF");
+        NodeParseResult::Error { msg }
+    }
 }