From f0de6395e84c665cd432dcda3c30a1d51b3eb485 Mon Sep 17 00:00:00 2001
From: Chris Smowton <chris@smowton.net>
Date: Mon, 15 Apr 2019 16:32:02 +0100
Subject: [PATCH] Add convenience method sharing_mapt::erase_if_exists

Just saves repeating the if-has-key-then-erase pattern
---
 src/util/sharing_map.h    | 13 +++++++++++++
 unit/util/sharing_map.cpp |  6 ++++++
 2 files changed, 19 insertions(+)

diff --git a/src/util/sharing_map.h b/src/util/sharing_map.h
index 0d9e307a6a..749776f0f8 100644
--- a/src/util/sharing_map.h
+++ b/src/util/sharing_map.h
@@ -222,6 +222,19 @@ public:
   /// \param k: The key of the element to erase
   void erase(const key_type &k);
 
+  /// Erase element if it exists
+  ///
+  /// Complexity:
+  /// - Worst case: O(H * S + M)
+  /// - Best case: O(H)
+  ///
+  /// \param k: The key of the element to erase
+  void erase_if_exists(const key_type &k)
+  {
+    if(has_key(k))
+      erase(k);
+  }
+
   /// Insert element, element must not exist in map
   ///
   /// Complexity:
diff --git a/unit/util/sharing_map.cpp b/unit/util/sharing_map.cpp
index b44a2e9b03..78b08cf222 100644
--- a/unit/util/sharing_map.cpp
+++ b/unit/util/sharing_map.cpp
@@ -201,6 +201,12 @@ TEST_CASE("Sharing map interface", "[core][util]")
     sm.erase("j");
     REQUIRE(!sm.has_key("j"));
 
+    sm.erase_if_exists("j");
+    REQUIRE(!sm.has_key("j"));
+    sm.insert("j", "1");
+    sm.erase_if_exists("j");
+    REQUIRE(!sm.has_key("j"));
+
     sm.insert("i", "0");
     sm.insert("j", "1");