More if-expr refactoring work

Think I finished all the parsing stuff, just need to fix the types
everywhere else

schala-lang/language/src/parsing.rs

@@ -126,8 +126,8 @@
 //! simple_pattern_match := pattern "then" simple_conditional
 //! else_case := "else" expr_or_block
 //!
-//! cond_block := "{" (cond_arm comma_or_delimiter)* ("else" expr_or_block) "}"
-//! cond_arm := condition guard "then" expr_or_block
+//! cond_block := "{" (cond_arm comma_or_delimiter)* "}"
+//! cond_arm := condition guard "then" expr_or_block | "else" expr_or_block
 //! condition := "is" pattern | operator precedence_expr | expression
 //! guard := "if" expression
 //! comma_or_delimiter := "," | delimiter
@@ -624,6 +624,7 @@ impl Parser {
       let next_tok = self.token_handler.next();
       let operation = match BinOp::from_sigil_token(&next_tok.kind) {
         Some(sigil) => sigil,
+        //TODO I think I can fix this unreachable
         None => unreachable!()
       };
       let rhs = self.precedence_expr(new_precedence)?;
@@ -860,68 +861,66 @@ impl Parser {
 
   #[recursive_descent_method]
   fn cond_block(&mut self) -> ParseResult<IfExpressionBody> {
-    //TODO - delimited! isn't sophisticated enough to do thisa
-    //let guards = delimited!(self, LCurlyBrace, guard_arm, Comma, RCurlyBrace);
     expect!(self, LCurlyBrace);
-
-    let mut guards = vec![];
+    let mut cond_arms = vec![];
     loop {
       match self.token_handler.peek_kind() {
         RCurlyBrace | EOF => break,
         Semicolon | Newline => { self.token_handler.next(); continue},
         _ => {
-          let guard_arm = self.guard_arm()?;
-          guards.push(guard_arm);
-          loop {
-            match self.token_handler.peek_kind() {
-              Semicolon | Newline => { self.token_handler.next(); continue; },
-              _ => break,
-            }
+          cond_arms.push(self.cond_arm()?);
+          match self.token_handler.peek_kind() {
+            Comma | Semicolon | Newline => { self.token_handler.next(); continue; },
+            _ => break,
           }
-          if let RCurlyBrace = self.token_handler.peek_kind() {
-            break;
-          }
-          expect!(self, Comma);
         }
       }
     }
     expect!(self, RCurlyBrace);
-    Ok(IfExpressionBody::GuardList(guards))
+    Ok(IfExpressionBody::CondList(cond_arms))
   }
 
   #[recursive_descent_method]
-  fn guard_arm(&mut self) -> ParseResult<GuardArm> {
-    if let Keyword(Kw::Else) = self.token_handler.peek_kind() {
+  fn cond_arm(&mut self) -> ParseResult<GuardArm> {
+    let (condition, guard) = if let Keyword(Kw::Else) = self.token_handler.peek_kind() {
       self.token_handler.next();
-      let body = self.expr_or_block()?;
-      Ok(GuardArm { guard: Guard::None, body })
+      (Condition:Else, None)
     } else {
+      let condition = self.condition()?;
       let guard = self.guard()?;
       expect!(self, Keyword(Kw::Then));
-      let body = self.expr_or_block()?;
-      Ok(GuardArm { guard, body })
-    }
+      (condition, guard)
+    };
+    let body = self.expr_or_block()?;
+    Ok(ConditionArm { condition, guard, body })
   }
 
   #[recursive_descent_method]
-  fn guard(&mut self) -> ParseResult<Guard> {
+  fn condition(&mut self) -> ParseResult<Condition> {
     Ok(match self.token_handler.peek_kind() {
       Keyword(Kw::Is) => {
         self.token_handler.next();
-        let pat = self.pattern()?;
-        Guard::Pat(pat)
+        Condition::Pattern(self.pattern()?)
       },
-      ref tok if BinOp::from_sigil_token(tok).is_some() => {
-        let op = BinOp::from_sigil_token(&self.token_handler.next().kind).unwrap();
-        let precedence = op.get_precedence();
-        let Expression { kind, .. } = self.precedence_expr(precedence)?;
-        Guard::HalfExpr(HalfExpr { op: Some(op), expr: kind })
+      Operator(ref op) if !PrefixOp::is_prefix(&*op) => {
+        let op = self.token_handler.next();
+        let expr = Box::new(self.expression()?);
+        Condition::TruncatedOp(op, expr)
       },
       _ => {
-        //TODO - I think there's a better way to do this involving the precedence of ->
-        let Expression { kind, .. } = self.prefix_expr()?;
-        Guard::HalfExpr(HalfExpr { op: None, expr: kind })
-      }
+        Condition::Expression(self.expression()?)
+      },
+    })
+  }
+
+  #[recursive_descent_method]
+  fn guard(&mut self) -> ParseResult<Option<Expression>> {
+    Ok(match self.token_handler.peek_kind() {
+      Keyword(Kw::If) => {
+        self.token_handler.next();
+        Some(self.expression()?)
+      },
+      _ => None
     })
   }