Handle .pushKV() and .checkObject() edge cases.

pushKV: Behave properly in the face of duplicate keys.

checkObject: return error, if not object.

Inspired-by: Charles Yin <yinyunqiao@gmail.com> in PR bitcoin#37

Author: jgarzik

include/univalue.h

@@ -111,6 +111,7 @@ class UniValue {
     }
     bool push_backV(const std::vector<UniValue>& vec);
 
+    void __pushKV(const std::string& key, const UniValue& val);
     bool pushKV(const std::string& key, const UniValue& val);
     bool pushKV(const std::string& key, const std::string& val_) {
         UniValue tmpVal(VSTR, val_);

lib/univalue.cpp

@@ -126,13 +126,22 @@ bool UniValue::push_backV(const std::vector<UniValue>& vec)
     return true;
 }
 
+void UniValue::__pushKV(const std::string& key, const UniValue& val_)
+{
+    keys.push_back(key);
+    values.push_back(val_);
+}
+
 bool UniValue::pushKV(const std::string& key, const UniValue& val_)
 {
     if (typ != VOBJ)
         return false;
 
-    keys.push_back(key);
-    values.push_back(val_);
+    size_t idx;
+    if (findKey(key, idx))
+        values[idx] = val_;
+    else
+        __pushKV(key, val_);
     return true;
 }
 
@@ -141,10 +150,8 @@ bool UniValue::pushKVs(const UniValue& obj)
     if (typ != VOBJ || obj.typ != VOBJ)
         return false;
 
-    for (unsigned int i = 0; i < obj.keys.size(); i++) {
-        keys.push_back(obj.keys[i]);
-        values.push_back(obj.values.at(i));
-    }
+    for (size_t i = 0; i < obj.keys.size(); i++)
+        __pushKV(obj.keys[i], obj.values.at(i));
 
     return true;
 }
@@ -163,6 +170,9 @@ bool UniValue::findKey(const std::string& key, size_t& retIdx) const
 
 bool UniValue::checkObject(const std::map<std::string,UniValue::VType>& t)
 {
+    if (typ != VOBJ)
+        return false;
+
     for (std::map<std::string,UniValue::VType>::const_iterator it = t.begin();
          it != t.end(); ++it) {
         size_t idx = 0;

test/object.cpp

@@ -311,6 +311,19 @@ BOOST_AUTO_TEST_CASE(univalue_object)
     obj.clear();
     BOOST_CHECK(obj.empty());
     BOOST_CHECK_EQUAL(obj.size(), 0);
+    BOOST_CHECK_EQUAL(obj.getType(), UniValue::VNULL);
+
+    BOOST_CHECK_EQUAL(obj.setObject(), true);
+    UniValue uv;
+    uv.setInt(42);
+    obj.__pushKV("age", uv);
+    BOOST_CHECK_EQUAL(obj.size(), 1);
+    BOOST_CHECK_EQUAL(obj["age"].getValStr(), "42");
+
+    uv.setInt(43);
+    obj.pushKV("age", uv);
+    BOOST_CHECK_EQUAL(obj.size(), 1);
+    BOOST_CHECK_EQUAL(obj["age"].getValStr(), "43");
 }
 
 static const char *json1 =