Merge pull request #172 from cdunn2001/master

Fix bug in ValueIteratorBase::operator- 

Fixes #169.

Author: cdunn2001

Diff for: include/json/value.h

@@ -946,7 +946,7 @@ class JSON_API ValueIteratorBase {
   bool operator!=(const SelfType& other) const { return !isEqual(other); }
 
   difference_type operator-(const SelfType& other) const {
-    return computeDistance(other);
+    return other.computeDistance(*this);
   }
 
   /// Return either the index or the member name of the referenced value as a

Diff for: src/lib_json/json_valueiterator.inl

@@ -77,7 +77,7 @@ ValueIteratorBase::difference_type
 ValueIteratorBase::computeDistance(const SelfType& other) const {
 #ifndef JSON_VALUE_USE_INTERNAL_MAP
 #ifdef JSON_USE_CPPTL_SMALLMAP
-  return current_ - other.current_;
+  return other.current_ - current_;
 #else
   // Iterator for null value are initialized using the default
   // constructor, which initialize current_ to the default

Diff for: src/test_lib_json/main.cpp

@@ -1861,6 +1861,23 @@ JSONTEST_FIXTURE(CharReaderFailIfExtraTest, commentAfterBool) {
   JSONTEST_ASSERT_EQUAL(true, root.asBool());
   delete reader;
 }
+
+struct IteratorTest : JsonTest::TestCase {};
+
+JSONTEST_FIXTURE(IteratorTest, distance) {
+  Json::Value json;
+  json["k1"] = "a";
+  json["k2"] = "b";
+  int dist;
+  std::string str;
+  for (Json::ValueIterator it = json.begin(); it != json.end(); ++it) {
+    dist = it - json.begin();
+    str = it->asString().c_str();
+  }
+  JSONTEST_ASSERT_EQUAL(1, dist);
+  JSONTEST_ASSERT_STRING_EQUAL("b", str);
+}
+
 int main(int argc, const char* argv[]) {
   JsonTest::Runner runner;
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, checkNormalizeFloatingPointStr);
@@ -1905,6 +1922,8 @@ int main(int argc, const char* argv[]) {
   JSONTEST_REGISTER_FIXTURE(runner, CharReaderFailIfExtraTest, commentAfterArray);
   JSONTEST_REGISTER_FIXTURE(runner, CharReaderFailIfExtraTest, commentAfterBool);
 
+  JSONTEST_REGISTER_FIXTURE(runner, IteratorTest, distance);
+
   JSONTEST_REGISTER_FIXTURE(runner, WriterTest, dropNullPlaceholders);
   JSONTEST_REGISTER_FIXTURE(runner, StreamWriterTest, dropNullPlaceholders);