From 203d3d71513fe316d97541dc3ef04bc8944b9f4a Mon Sep 17 00:00:00 2001
From: Sergey Pepyakin <sergei@parity.io>
Date: Thu, 18 Apr 2019 18:48:47 +0200
Subject: [PATCH] Keep::count

---
 src/isa.rs             | 10 ++++++++++
 src/prepare/compile.rs |  4 ++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/isa.rs b/src/isa.rs
index 01bc69c..fcb3905 100644
--- a/src/isa.rs
+++ b/src/isa.rs
@@ -82,6 +82,16 @@ pub enum Keep {
     Single,
 }
 
+impl Keep {
+    /// Reutrns a number of items that should be kept on the stack.
+    pub fn count(&self) -> u32 {
+        match *self {
+            Keep::None => 0,
+            Keep::Single => 1,
+        }
+    }
+}
+
 /// Specifies how many values we should keep and how many we should drop.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub struct DropKeep {
diff --git a/src/prepare/compile.rs b/src/prepare/compile.rs
index a79451e..83b3f6e 100644
--- a/src/prepare/compile.rs
+++ b/src/prepare/compile.rs
@@ -1012,14 +1012,14 @@ fn compute_drop_keep(
                 start_value_stack_height,
             )));
         }
-        if (actual_value_stack_height as u32 - start_value_stack_height as u32) < keep as u32 {
+        if (actual_value_stack_height as u32 - start_value_stack_height as u32) < keep.count() {
             return Err(Error(format!(
                 "Stack underflow detected: asked to keep {:?} values, but there are only {}",
                 keep,
                 actual_value_stack_height as u32 - start_value_stack_height as u32,
             )));
         }
-        (actual_value_stack_height as u32 - start_value_stack_height as u32) - keep as u32
+        (actual_value_stack_height as u32 - start_value_stack_height as u32) - keep.count()
     };
 
     Ok(isa::DropKeep { drop, keep })