Add Core::StringUtil::trim() to remove whitespace from strings

I thought I needed this, but it turns out I didn't. It's just dead code
now; I'm leaving it in as it may be useful later.

Core/StringUtil.cc

@@ -20,8 +20,11 @@
 
 #include <algorithm>
 #include <cassert>
+#include <cctype>
 #include <cstdarg>
 #include <cstring>
+#include <functional>
+#include <locale>
 #include <sstream>
 
 #include "Core/StringUtil.h"
@@ -160,6 +163,27 @@ endsWith(const std::string& haystack, const std::string& needle)
                              needle.length(), needle) == 0);
 }
 
+std::string
+trim(const std::string& original)
+{
+    // The black magic is from https://stackoverflow.com/a/217605
+    std::string s = original;
+
+    // trim whitespace at end of string
+    s.erase(std::find_if(s.rbegin(), s.rend(),
+                         std::not1(std::ptr_fun<int, int>(std::isspace)))
+                .base(),
+            s.end());
+
+    // trim whitespace at beginning of string
+    s.erase(s.begin(),
+            std::find_if(s.begin(), s.end(),
+                         std::not1(std::ptr_fun<int, int>(std::isspace))));
+
+    return s;
+}
+
+
 } // namespace LogCabin::Core::StringUtil
 } // namespace LogCabin::Core
 } // namespace LogCabin

Core/StringUtil.h

@@ -121,6 +121,12 @@ toString(const T& t)
     return ss.str();
 }
 
+/**
+ * Return a copy of the given string except with no leading or trailing
+ * whitespace.
+ */
+std::string trim(const std::string& s);
+
 } // namespace LogCabin::Core::StringUtil
 } // namespace LogCabin::Core
 } // namespace LogCabin

Core/StringUtilTest.cc

@@ -113,6 +113,13 @@ TEST(CoreStringUtilTest, toString) {
     EXPECT_EQ("3", toString(3));
 }
 
+TEST(CoreStringUtilTest, trim) {
+    EXPECT_EQ("abc", trim("abc"));
+    EXPECT_EQ("abc", trim(" abc "));
+    EXPECT_EQ("abc", trim("\tabc\n"));
+    EXPECT_EQ("", trim("  "));
+}
+
 } // namespace LogCabin::Core::StringUtil::<anonymous>
 } // namespace LogCabin::Core::StringUtil
 } // namespace LogCabin::Core