From: Alexandre Terrasa <alexandre@moz-code.org>
Date: Fri, 24 Apr 2015 02:00:03 +0000 (-0400)
Subject: lib/counter: introduce Counter::dec
X-Git-Tag: v0.7.4~5^2~2
X-Git-Url: http://nitlanguage.org

lib/counter: introduce Counter::dec

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>
---

diff --git a/lib/counter.nit b/lib/counter.nit
index 6545b73..6d5729d 100644
--- a/lib/counter.nit
+++ b/lib/counter.nit
@@ -93,6 +93,22 @@ class Counter[E]
 		for e in es do inc(e)
 	end
 
+	# Decrement the value of `e` by 1
+	fun dec(e: E) do
+		if not has_key(e) then
+			self.map[e] = 0
+		else
+			self.map[e] = self[e] - 1
+			sum += - 1
+		end
+	end
+
+	# Decrement the value for each element of `es`
+	fun dec_all(es: Collection[E])
+	do
+		for e in es do dec(e)
+	end
+
 	# A new Counter initialized with `inc_all`.
 	init from(es: Collection[E])
 	do