From 531b7b72a0b50e96a65b4b9206b4f239f4339647 Mon Sep 17 00:00:00 2001
From: Sebastian Schmidt <isibboi@gmail.com>
Date: Sat, 13 Apr 2019 19:11:09 +0200
Subject: [PATCH] Make `Operator::max_argument_amount` optional

Relates to #44
---
 src/operator/mod.rs | 14 +++++++-------
 src/tree/mod.rs     |  2 +-
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/operator/mod.rs b/src/operator/mod.rs
index a86eb53..a94dc9c 100644
--- a/src/operator/mod.rs
+++ b/src/operator/mod.rs
@@ -94,20 +94,20 @@ impl Operator {
     /// True if this operator is a leaf, meaning it accepts no arguments.
     // Make this a const fn once #57563 is resolved
     pub(crate) fn is_leaf(&self) -> bool {
-        self.max_argument_amount() == 0
+        self.max_argument_amount() == Some(0)
     }
 
     /// Returns the maximum amount of arguments required by this operator.
     // Make this a const fn once #57563 is resolved
-    pub(crate) fn max_argument_amount(&self) -> usize {
+    pub(crate) fn max_argument_amount(&self) -> Option<usize> {
         use crate::operator::Operator::*;
         match self {
             Add | Sub | Mul | Div | Mod | Exp | Eq | Neq | Gt | Lt | Geq | Leq | And | Or
-            | Tuple | Assign | Chain => 2,
-            Not | Neg | RootNode => 1,
-            Const { value: _ } => 0,
-            VariableIdentifier { identifier: _ } => 0,
-            FunctionIdentifier { identifier: _ } => 1,
+            | Tuple | Assign | Chain => Some(2),
+            Not | Neg | RootNode => Some(1),
+            Const { value: _ } => Some(0),
+            VariableIdentifier { identifier: _ } => Some(0),
+            FunctionIdentifier { identifier: _ } => Some(1),
         }
     }
 
diff --git a/src/tree/mod.rs b/src/tree/mod.rs
index 0d728d2..7e9f8b8 100644
--- a/src/tree/mod.rs
+++ b/src/tree/mod.rs
@@ -362,7 +362,7 @@ impl Node {
     }
 
     fn has_enough_children(&self) -> bool {
-        self.children().len() == self.operator().max_argument_amount()
+        Some(self.children().len()) == self.operator().max_argument_amount()
     }
 
     fn insert_back_prioritized(&mut self, node: Node, is_root_node: bool) -> EvalexprResult<()> {