Add function call expressions

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/syn/ast.rs

@@ -22,9 +22,10 @@ impl Spanned for AssignStmt {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Expr {
-    Base(BaseExpr),
     Bin(Box<BinExpr>),
     Un(Box<UnExpr>),
+    FunCall(Box<FunCallExpr>),
+    Base(BaseExpr),
 }
 
 impl Spanned for Expr {
@@ -33,6 +34,7 @@ impl Spanned for Expr {
             Expr::Base(b) => b.span(),
             Expr::Bin(b) => b.span(),
             Expr::Un(u) => u.span(),
+            Expr::FunCall(f) => f.span(),
         }
     }
 }
@@ -86,6 +88,21 @@ impl Spanned for UnExpr {
     }
 }
 
+#[derive(Derivative, Clone, PartialEq, Eq)]
+#[derivative(Debug)]
+pub struct FunCallExpr {
+    pub expr: Expr,
+    pub args: Vec<Expr>,
+    #[derivative(Debug = "ignore")]
+    pub span: Span,
+}
+
+impl Spanned for FunCallExpr {
+    fn span(&self) -> Span {
+        self.span
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum BaseExprKind {
     Ident,