[parser, types] Clean up obj parsers

- Define ListParser, SymParser in their own separate modules
- Add some stuff to types to make working with them more ergonomic

parser/src/lib.rs

@@ -5,15 +5,18 @@
 extern crate sibillexer;
 extern crate sibiltypes;
 
+mod list_parser;
 mod node_parser;
+mod sym_parser;
 
 use std::iter::Peekable;
 use sibillexer::Result as LexerResult;
-use sibiltypes::Object;
-use node_parser::{NodeParser, IdParser, ListParser};
+use sibiltypes::Obj;
+use node_parser::NodeParser;
+use sym_parser::SymParser;
 
 /// The output of calling `parse()` on a Parser is one of these Result objects.
-pub type Result = std::result::Result<Object, ParseError>;
+pub type Result = std::result::Result<Obj, ParseError>;
 
 #[derive(Debug)]
 pub struct ParseError;

parser/src/list_parser.rs

@@ -0,0 +1,37 @@
+/* parser/src/list_parser.rs
+ * Eryn Wells <eryn@erynwells.me>
+ */
+
+use sibillexer::{Lex, Token};
+use sibiltypes::{Obj, Pair};
+use node_parser::{NodeParser, NodeParseResult};
+use sym_parser::SymParser;
+
+#[derive(Debug)]
+pub struct ListParser {
+    list: Obj
+}
+
+impl ListParser {
+    pub fn new() -> ListParser {
+        ListParser {
+            list: Obj::Null
+        }
+    }
+}
+
+impl NodeParser for ListParser {
+    fn parse(&mut self, lex: Lex) -> NodeParseResult {
+        match lex.token() {
+            Token::LeftParen => {
+                self.list = Obj::new(Pair::empty());
+                NodeParseResult::Continue
+            },
+            Token::Id => {
+                let parser = SymParser{};
+                NodeParseResult::Push { next: Box::new(parser) }
+            }
+            _ => NodeParseResult::Error { msg: "womp".to_string() }
+        }
+    }
+}

parser/src/node_parser.rs

@@ -4,7 +4,7 @@
 
 use std::fmt::Debug;
 use sibillexer::{Lex, Token};
-use sibiltypes::{Object, ObjectPtr};
+use sibiltypes::Obj;
 
 #[derive(Debug)]
 pub enum NodeParseResult {
@@ -12,7 +12,7 @@ pub enum NodeParseResult {
     Continue,
     /// This NodeParser has completed its work and has produced the given Object
     /// as a result.
-    Complete { obj: ObjectPtr },
+    Complete { obj: Obj },
     /// Push a new NodeParser onto the parsing stack and let that parser proceed
     /// with the current Lex.
     Push { next: Box<NodeParser> },
@@ -20,6 +20,12 @@ pub enum NodeParseResult {
     Error { msg: String },
 }
 
+impl NodeParseResult {
+    pub fn error(msg: String) -> NodeParseResult {
+        NodeParseResult::Error { msg: msg }
+    }
+}
+
 /// A `NodeParser` is responsible for parsing one particular thing in the Scheme
 /// parse tree. Roughly, there should be one `XParser` for each variant of the
 /// `sibiltypes::Object` enum. As the top-level `Parser` object progresses
@@ -45,47 +51,4 @@ impl NodeParser for ProgramParser {
     }
 }
 
-#[derive(Debug)]
-pub struct IdParser {
-}
 
-impl IdParser {
-    pub fn new() -> IdParser {
-        IdParser { }
-    }
-}
-
-impl NodeParser for IdParser {
-    fn parse(&mut self, lex: Lex) -> NodeParseResult {
-        match lex.token() {
-            Token::Id => {
-                let value = String::from(lex.value());
-                let obj = ObjectPtr::new(Object::Symbol(value));
-                NodeParseResult::Complete { obj: obj }
-            }
-            _ => {
-                let msg = String::from(format!("Invalid token: {:?}", lex));
-                NodeParseResult::Error { msg: msg }
-            }
-        }
-    }
-}
-
-#[derive(Debug)]
-pub struct ListParser {
-    list: ObjectPtr
-}
-
-impl ListParser {
-    pub fn new() -> ListParser {
-        ListParser {
-            list: ObjectPtr::Null
-        }
-    }
-}
-
-impl NodeParser for ListParser {
-    fn parse(&mut self, lex: Lex) -> NodeParseResult {
-        NodeParseResult::Error { msg: "womp".to_string() }
-    }
-}

parser/src/sym_parser.rs

@@ -0,0 +1,27 @@
+/* parser/src/sym_parser.rs
+ * Eryn Wells <eryn@erynwells.me>
+ */
+
+use sibillexer::{Lex, Token};
+use sibiltypes::{Obj, Sym};
+use node_parser::{NodeParser, NodeParseResult};
+
+#[derive(Debug)]
+pub struct SymParser;
+
+impl NodeParser for SymParser {
+    fn parse(&mut self, lex: Lex) -> NodeParseResult {
+        match lex.token() {
+            Token::Id => {
+                let value = String::from(lex.value());
+                // Initializing with Sym(value) caused E0423. So use this isntead.
+                let obj = Obj::new(Sym::new(value));
+                NodeParseResult::Complete { obj: obj }
+            }
+            _ => {
+                let msg = format!("Invalid token: {:?}", lex);
+                NodeParseResult::error(msg)
+            }
+        }
+    }
+}

types/src/bool.rs

@@ -2,18 +2,28 @@
  * Eryn Wells <eryn@erynwells.me>
  */
 
-use object::Object;
-use predicates::IsBool;
+use std::fmt;
+use object::Obj;
+use preds;
 
-impl IsBool for Object {
-    fn is_bool(&self) -> bool {
-        match *self {
-            Object::Bool(_) => true,
-            _ => false,
+/// The Scheme boolean type. It can be `True` or `False`.
+pub enum Bool { True, False }
+
+impl Obj for Bool { }
+
+impl fmt::Display for Bool {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Bool::True => write!(f, "#t"),
+            Bool::False => write!(f, "#f")
         }
     }
 }
 
+impl preds::IsBool for Bool {
+    fn is_bool(&self) -> bool { true }
+}
+
 #[cfg(test)]
 mod tests {
     use object::Object;

types/src/object.rs

@@ -23,7 +23,8 @@ pub enum Obj {
 }
 
 pub trait Object:
-    fmt::Display 
+    fmt::Debug +
+    fmt::Display
 {
     fn as_any(&self) -> &Any;
     fn as_pair(&self) -> Option<&Pair>;
@@ -31,6 +32,10 @@ pub trait Object:
 }
 
 impl Obj {
+    pub fn new<T: 'static + Object>(obj: T) -> Obj {
+        Obj::Ptr(Box::new(obj))
+    }
+
     pub fn unbox_as<T: 'static + Object>(&self) -> Option<&T> {
         match self {
             Obj::Null => None,
@@ -48,6 +53,12 @@ impl fmt::Display for Obj {
     }
 }
 
+impl fmt::Debug for Obj {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self)
+    }
+}
+
 //#[derive(Debug, PartialEq)]
 //pub enum Object {
 //    ByteVector(Vec<u8>),

types/src/pair.rs

@@ -13,6 +13,10 @@ pub struct Pair {
 }
 
 impl Pair {
+    pub fn empty() -> Pair {
+        Pair { car: Obj::Null, cdr: Obj::Null }
+    }
+
     fn fmt_pair(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let r = write!(f, "{}", self.car);
         r.and_then(|r| match self.cdr {
@@ -39,3 +43,9 @@ impl fmt::Display for Pair {
                       .and_then(|_| write!(f, ")"))
     }
 }
+
+impl fmt::Debug for Pair {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self)
+    }
+}

types/src/sym.rs

@@ -9,6 +9,12 @@ use super::*;
 
 pub struct Sym(String);
 
+impl Sym {
+    pub fn new(value: String) -> Sym {
+        Sym(value)
+    }
+}
+
 impl Object for Sym {
     fn as_any(&self) -> &Any { self }
     fn as_pair(&self) -> Option<&Pair> { None }
@@ -20,3 +26,9 @@ impl fmt::Display for Sym {
         write!(f, "{}", self.0)
     }
 }
+
+impl fmt::Debug for Sym {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self)
+    }
+}