Add startsWith and endsWith predicates to StringData.

3 files changed, 58 insertions, 1 deletions

diff --git a/src/mongo/base/string_data-inl.h b/src/mongo/base/string_data-inl.h
index 635def4bb18..a99a78d230e 100644
--- a/src/mongo/base/string_data-inl.h
+++ b/src/mongo/base/string_data-inl.h
@@ -97,4 +97,18 @@ namespace mongo {
         return StringData( _data + pos, n );
     }
 
-}
+    inline bool StringData::startsWith( const StringData& prefix ) const {
+        // TODO: Investigate an optimized implementation.
+        return substr(0, prefix.size()) == prefix;
+    }
+
+    inline bool StringData::endsWith( const StringData& suffix ) const {
+        // TODO: Investigate an optimized implementation.
+        const size_t thisSize = size();
+        const size_t suffixSize = suffix.size();
+        if (suffixSize > thisSize)
+            return false;
+        return substr(thisSize - suffixSize) == suffix;
+    }
+
+}  // namespace mongo
diff --git a/src/mongo/base/string_data.h b/src/mongo/base/string_data.h
index a30a7398efa..86f9fd3d672 100644
--- a/src/mongo/base/string_data.h
+++ b/src/mongo/base/string_data.h
@@ -99,6 +99,16 @@ namespace mongo {
         size_t find( char c ) const;
         size_t find( const StringData& needle ) const;
 
+        /**
+         * Returns true if 'prefix' is a substring of this instance, anchored at position 0.
+         */
+        bool startsWith( const StringData& prefix ) const;
+
+        /**
+         * Returns true if 'suffix' is a substring of this instance, anchored at the end.
+         */
+        bool endsWith( const StringData& suffix ) const;
+
         //
         // accessors
         //
diff --git a/src/mongo/base/string_data_test.cpp b/src/mongo/base/string_data_test.cpp
index 14b5ac5e471..eecda842c25 100644
--- a/src/mongo/base/string_data_test.cpp
+++ b/src/mongo/base/string_data_test.cpp
@@ -148,4 +148,37 @@ namespace {
         ASSERT( !StringData( "ABC" ).equalCaseInsensitive( "AdC" ) );
     }
 
+    TEST(StartsWith, Simple) {
+        ASSERT(StringData("").startsWith(""));
+        ASSERT(!StringData("").startsWith("x"));
+        ASSERT(StringData("abcde").startsWith(""));
+        ASSERT(StringData("abcde").startsWith("a"));
+        ASSERT(StringData("abcde").startsWith("ab"));
+        ASSERT(StringData("abcde").startsWith("abc"));
+        ASSERT(StringData("abcde").startsWith("abcd"));
+        ASSERT(StringData("abcde").startsWith("abcde"));
+        ASSERT(!StringData("abcde").startsWith("abcdef"));
+        ASSERT(!StringData("abcde").startsWith("abdce"));
+        ASSERT(StringData("abcde").startsWith(StringData("abcdeXXXX").substr(0, 4)));
+        ASSERT(!StringData("abcde").startsWith(StringData("abdef").substr(0, 4)));
+        ASSERT(!StringData("abcde").substr(0, 3).startsWith("abcd"));
+    }
+
+    TEST(EndsWith, Simple) {
+        //ASSERT(StringData("").endsWith(""));
+        ASSERT(!StringData("").endsWith("x"));
+        //ASSERT(StringData("abcde").endsWith(""));
+        ASSERT(StringData("abcde").endsWith(StringData("e", 0)));
+        ASSERT(StringData("abcde").endsWith("e"));
+        ASSERT(StringData("abcde").endsWith("de"));
+        ASSERT(StringData("abcde").endsWith("cde"));
+        ASSERT(StringData("abcde").endsWith("bcde"));
+        ASSERT(StringData("abcde").endsWith("abcde"));
+        ASSERT(!StringData("abcde").endsWith("0abcde"));
+        ASSERT(!StringData("abcde").endsWith("abdce"));
+        ASSERT(StringData("abcde").endsWith(StringData("bcdef").substr(0, 4)));
+        ASSERT(!StringData("abcde").endsWith(StringData("bcde", 3)));
+        ASSERT(!StringData("abcde").substr(0, 3).endsWith("cde"));
+    }
+
 } // unnamed namespace