feat: adds front and back methods to Value type (#1458)
Value::front and Value::back
diff --git a/include/json/value.h b/include/json/value.h
index 15c517e..9a302c1 100644
--- a/include/json/value.h
+++ b/include/json/value.h
@@ -585,6 +585,22 @@
iterator begin();
iterator end();
+ /// \brief Returns a reference to the first element in the `Value`.
+ /// Requires that this value holds an array or json object, with at least one element.
+ const Value& front() const;
+
+ /// \brief Returns a reference to the first element in the `Value`.
+ /// Requires that this value holds an array or json object, with at least one element.
+ Value& front();
+
+ /// \brief Returns a reference to the last element in the `Value`.
+ /// Requires that value holds an array or json object, with at least one element.
+ const Value& back() const;
+
+ /// \brief Returns a reference to the last element in the `Value`.
+ /// Requires that this value holds an array or json object, with at least one element.
+ Value& back();
+
// Accessors for the [start, limit) range of bytes within the JSON text from
// which this value was parsed, if any.
void setOffsetStart(ptrdiff_t start);
@@ -925,6 +941,14 @@
inline void swap(Value& a, Value& b) { a.swap(b); }
+inline const Value& Value::front() const { return *begin(); }
+
+inline Value& Value::front() { return *begin(); }
+
+inline const Value& Value::back() const { return *(--end()); }
+
+inline Value& Value::back() { return *(--end()); }
+
} // namespace Json
#pragma pack(pop)
diff --git a/src/test_lib_json/main.cpp b/src/test_lib_json/main.cpp
index d0f5364..a6f21c4 100644
--- a/src/test_lib_json/main.cpp
+++ b/src/test_lib_json/main.cpp
@@ -310,10 +310,14 @@
const Json::Value& constArray = array1_;
JSONTEST_ASSERT_EQUAL(Json::Value(1234), constArray[index0]);
JSONTEST_ASSERT_EQUAL(Json::Value(1234), constArray[0]);
+ JSONTEST_ASSERT_EQUAL(Json::Value(1234), constArray.front());
+ JSONTEST_ASSERT_EQUAL(Json::Value(1234), constArray.back());
// Access through non-const reference
JSONTEST_ASSERT_EQUAL(Json::Value(1234), array1_[index0]);
JSONTEST_ASSERT_EQUAL(Json::Value(1234), array1_[0]);
+ JSONTEST_ASSERT_EQUAL(Json::Value(1234), array1_.front());
+ JSONTEST_ASSERT_EQUAL(Json::Value(1234), array1_.back());
array1_[2] = Json::Value(17);
JSONTEST_ASSERT_EQUAL(Json::Value(), array1_[1]);
@@ -356,6 +360,8 @@
v.resize(n);
JSONTEST_ASSERT_EQUAL(n, v.size());
JSONTEST_ASSERT_EQUAL(n, std::distance(v.begin(), v.end()));
+ JSONTEST_ASSERT_EQUAL(v.front(), Json::Value{});
+ JSONTEST_ASSERT_EQUAL(v.back(), Json::Value{});
for (const Json::Value& e : v)
JSONTEST_ASSERT_EQUAL(e, Json::Value{});
}
@@ -406,6 +412,8 @@
JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array[0]); // check append
JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[1]);
JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[2]);
+ JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array.front());
+ JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array.back());
// insert lvalue at the head
JSONTEST_ASSERT(array.insert(0, str1));
@@ -413,6 +421,8 @@
JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array[1]);
JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[2]);
JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[3]);
+ JSONTEST_ASSERT_EQUAL(Json::Value("index3"), array.front());
+ JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array.back());
// checking address
for (Json::ArrayIndex i = 0; i < 3; i++) {
JSONTEST_ASSERT_EQUAL(vec[i], &array[i]);
@@ -425,6 +435,8 @@
JSONTEST_ASSERT_EQUAL(Json::Value("index4"), array[2]);
JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[3]);
JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[4]);
+ JSONTEST_ASSERT_EQUAL(Json::Value("index3"), array.front());
+ JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array.back());
// checking address
for (Json::ArrayIndex i = 0; i < 4; i++) {
JSONTEST_ASSERT_EQUAL(vec[i], &array[i]);
@@ -438,6 +450,8 @@
JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[3]);
JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[4]);
JSONTEST_ASSERT_EQUAL(Json::Value("index5"), array[5]);
+ JSONTEST_ASSERT_EQUAL(Json::Value("index3"), array.front());
+ JSONTEST_ASSERT_EQUAL(Json::Value("index5"), array.back());
// checking address
for (Json::ArrayIndex i = 0; i < 5; i++) {
JSONTEST_ASSERT_EQUAL(vec[i], &array[i]);
