From 13f079c5150d86bb87b71094e545e720e245658d Mon Sep 17 00:00:00 2001
From: Adrian Kummerländer
Date: Thu, 6 Feb 2014 20:26:45 +0100
Subject: Introduced simple result wrapper template * offers bool() operator
 for easy assignment checks inside conditional statements

---
 src/trie.h    | 34 ++++++++++++++++------------------
 src/utility.h | 29 +++++++++++++++++++++++++++++
 test.cc       | 30 +++++++++++++++---------------
 3 files changed, 60 insertions(+), 33 deletions(-)
 create mode 100644 src/utility.h

diff --git a/src/trie.h b/src/trie.h
index d4763ef..629e724 100644
--- a/src/trie.h
+++ b/src/trie.h
@@ -4,6 +4,8 @@
 #include <vector>
 #include <map>
 
+#include "utility.h"
+
 template <
 	typename Key,
 	typename Value = std::nullptr_t
@@ -34,29 +36,25 @@ class Trie {
 		}
 
 		inline bool check(key_list path) {
-			return this->resolve(path).first;
+			return this->resolve(path);
 		}
 
-		inline std::pair<bool, Value*> get(key_list path) {
-			std::pair<bool, Trie*> tmp(this->resolve(path));
-
-			if ( tmp.first ) {
-				if ( tmp.second->value_.first ) {
-					return std::make_pair(true, &tmp.second->value_.second);
+		inline detail::Result<Value*> get(key_list path) {
+			if ( auto tmp = this->resolve(path) ) {
+				if ( tmp.get()->value_.first ) {
+					return detail::Result<Value*>(&tmp.get()->value_.second);
 				} else {
-					return std::make_pair(false, nullptr);
+					return detail::Result<Value*>();
 				}
 			} else {
-				return std::make_pair(false, nullptr);
+				return detail::Result<Value*>();
 			}
 		}
 
 		inline bool set(key_list path, Value value) {
-			std::pair<bool, Trie*> tmp(this->resolve(path));
-
-			if ( tmp.first ) {
-				tmp.second->value_.first  = true;
-				tmp.second->value_.second = value;
+			if ( auto tmp = this->resolve(path) ) {
+				tmp.get()->value_.first  = true;
+				tmp.get()->value_.second = value;
 
 				return true;
 			} else {
@@ -107,11 +105,11 @@ class Trie {
 			}
 		}
 
-		inline std::pair<bool, Trie*> resolve(key_list path) {
+		inline detail::Result<Trie*> resolve(key_list path) {
 			return this->resolve(path, path.begin());
 		}
 
-		inline std::pair<bool, Trie*> resolve(
+		inline detail::Result<Trie*> resolve(
 			key_list& path,
 			typename key_list::const_iterator currStep
 		) {
@@ -125,12 +123,12 @@ class Trie {
 				);
 
 				if ( nextStep == path.end() ) {
-					return std::make_pair(true, &(*matchingTrie).second);
+					return detail::Result<Trie*>(&(*matchingTrie).second);
 				} else {
 					return (*matchingTrie).second.resolve(path, nextStep);
 				}
 			} else {
-				return std::make_pair(false, nullptr);
+				return detail::Result<Trie*>();
 			}
 		}
 
diff --git a/src/utility.h b/src/utility.h
new file mode 100644
index 0000000..6342420
--- /dev/null
+++ b/src/utility.h
@@ -0,0 +1,29 @@
+#ifndef TRIE_SRC_UTILITY_H_
+#define TRIE_SRC_UTILITY_H_
+
+namespace detail {
+
+template <
+	typename Value
+>
+struct Result {
+	Result():
+		value_(false, Value()) { }
+
+	Result(Value value):
+		value_(true, value) { }
+
+	inline operator bool() const {
+		return this->value_.first;
+	}
+
+	inline Value get() const {
+		return this->value_.second;
+	}
+
+	const std::pair<bool, Value> value_;
+};
+
+}
+
+#endif  // TRIE_SRC_UTILITY_H_
diff --git a/test.cc b/test.cc
index 2a99619..46ed5cd 100644
--- a/test.cc
+++ b/test.cc
@@ -50,25 +50,25 @@ TEST_F(TrieTest, Value) {
 	trie.add({2, 3, 4, 5}, 44);
 	trie.add({2, 3, 1, 2}, 45);
 
-	EXPECT_EQ(trie.get({1, 1, 1, 1}).first,  true);
-	EXPECT_EQ(*trie.get({1, 1, 1, 1}).second, 42);
-	EXPECT_EQ(trie.get({1, 2, 1, 2}).first,  true);
-	EXPECT_EQ(*trie.get({1, 2, 1, 2}).second, 43);
-	EXPECT_EQ(trie.get({2, 3, 4, 5}).first,  true);
-	EXPECT_EQ(*trie.get({2, 3, 4, 5}).second, 44);
-	EXPECT_EQ(trie.get({2, 3, 4, 5}).first,  true);
-	EXPECT_EQ(*trie.get({2, 3, 1, 2}).second, 45);
-
-	EXPECT_EQ(trie.get({1, 2}).first,        false);
-	EXPECT_EQ(trie.get({1, 2}).second,       nullptr);
+	EXPECT_EQ(trie.get({1, 1, 1, 1}),  true);
+	EXPECT_EQ(*trie.get({1, 1, 1, 1}).get(), 42);
+	EXPECT_EQ(trie.get({1, 2, 1, 2}),  true);
+	EXPECT_EQ(*trie.get({1, 2, 1, 2}).get(), 43);
+	EXPECT_EQ(trie.get({2, 3, 4, 5}),  true);
+	EXPECT_EQ(*trie.get({2, 3, 4, 5}).get(), 44);
+	EXPECT_EQ(trie.get({2, 3, 4, 5}),  true);
+	EXPECT_EQ(*trie.get({2, 3, 1, 2}).get(), 45);
+
+	EXPECT_EQ(trie.get({1, 2}),        false);
+	EXPECT_EQ(trie.get({1, 2}).get(),  nullptr);
 
 	trie.set({1, 2},       42);
 	trie.set({1, 1, 1, 1}, 255);
 
-	EXPECT_EQ(trie.get({1, 2}).first,         true);
-	EXPECT_EQ(*trie.get({1, 2}).second,       42);
-	EXPECT_EQ(trie.get({1, 1, 1, 1}).first,   true);
-	EXPECT_EQ(*trie.get({1, 1, 1, 1}).second, 255);
+	EXPECT_EQ(trie.get({1, 2}),         true);
+	EXPECT_EQ(*trie.get({1, 2}).get(),       42);
+	EXPECT_EQ(trie.get({1, 1, 1, 1}),   true);
+	EXPECT_EQ(*trie.get({1, 1, 1, 1}).get(), 255);
 }
 
 int main(int argc, char **argv) {
-- 
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