From c8992eb872adb96c1f1d87e56f8378a363de42c2 Mon Sep 17 00:00:00 2001
From: Dmitry Kokorin <dmitry@kokorin.org>
Date: Wed, 2 Mar 2016 00:36:23 +0300
Subject: [PATCH] nucleotide_count: iteration 2

---
 cpp/nucleotide-count/nucleotide_count.cpp | 28 ++++++++---------------
 cpp/nucleotide-count/nucleotide_count.h   |  7 ++++--
 2 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/cpp/nucleotide-count/nucleotide_count.cpp b/cpp/nucleotide-count/nucleotide_count.cpp
index fea82c4..e591522 100644
--- a/cpp/nucleotide-count/nucleotide_count.cpp
+++ b/cpp/nucleotide-count/nucleotide_count.cpp
@@ -1,7 +1,6 @@
 #include "nucleotide_count.h"
 
 #include <stdexcept>
-#include <unordered_set>
 
 
 namespace dna {
@@ -9,28 +8,19 @@ namespace dna {
 using namespace std;
 
 
-static const unordered_set<char> valid_nucleotides = {'A', 'T', 'C', 'G'};
-
-static inline bool is_valid_nucleotide(char c)
+counter::counter(const string &sequence)
+  : nucleotide_counts_{ {'A', 0}, {'T', 0}, {'C', 0}, {'G', 0}}
 {
-    return valid_nucleotides.find(c) != valid_nucleotides.cend();
-}
-
-counter::counter(const string &str)
-{
-    for (auto c : valid_nucleotides)
-        nucleotide_counts_[c] = 0;
-
-    for (auto c : str) {
-
-        if (!is_valid_nucleotide(c))
-            throw invalid_argument("invalid sequence");
-
+    for (auto c : sequence)
         ++nucleotide_counts_[c];
-    }
 }
 
-NucleotideCounts counter::nucleotide_counts() const
+bool counter::is_valid_nucleotide(char c) const
+{
+    return nucleotide_counts_.count(c);
+}
+
+const NucleotideCounts &counter::nucleotide_counts() const
 {
     return nucleotide_counts_;
 }
diff --git a/cpp/nucleotide-count/nucleotide_count.h b/cpp/nucleotide-count/nucleotide_count.h
index 9017300..e6244d0 100644
--- a/cpp/nucleotide-count/nucleotide_count.h
+++ b/cpp/nucleotide-count/nucleotide_count.h
@@ -14,10 +14,13 @@ class counter
 {
     NucleotideCounts nucleotide_counts_;
 
+    bool is_valid_nucleotide(char c) const;
+
 public:
 
-    counter(const std::string &str);
-    NucleotideCounts nucleotide_counts() const;
+    counter(const std::string &sequence);
+
+    const NucleotideCounts &nucleotide_counts() const;
     int count(char c) const;
 };