diff --git a/doc/examples/operatorjson_pointer.cpp b/doc/examples/operatorjson_pointer.cpp index 18e41c1f5..d7e8faff1 100644 --- a/doc/examples/operatorjson_pointer.cpp +++ b/doc/examples/operatorjson_pointer.cpp @@ -40,7 +40,7 @@ int main() // output the changed array std::cout << j["array"] << '\n'; - // "change" the arry element past the end + // "change" the array element past the end j["/array/-"_json_pointer] = 55; // output the changed array std::cout << j["array"] << '\n'; diff --git a/src/json.hpp b/src/json.hpp index 04c8573f4..1cbcedf6c 100644 --- a/src/json.hpp +++ b/src/json.hpp @@ -9436,6 +9436,12 @@ basic_json_parser_63: /*! @brief return a reference to the pointed to value + @note This version does not throw if a value is not present, but tries + to create nested values instead. For instance, calling this function + with pointer `"/this/that"` on a null value is equivalent to calling + `operator[]("this").operator[]("that")` on that value, effectively + changing the null value to an object. + @param[in] ptr a JSON value @return reference to the JSON value pointed to by the JSON pointer @@ -9450,6 +9456,12 @@ basic_json_parser_63: { for (const auto& reference_token : reference_tokens) { + // error condition (cf. RFC 6901, Sect. 4) + if (reference_token.size() > 1 and reference_token[0] == '0') + { + throw std::domain_error("array index must not begin with '0'"); + } + switch (ptr->m_type) { case value_t::object: @@ -9461,12 +9473,6 @@ basic_json_parser_63: case value_t::array: { - // error condition (cf. RFC 6901, Sect. 4) - if (reference_token.size() > 1 and reference_token[0] == '0') - { - throw std::domain_error("array index must not begin with '0'"); - } - if (reference_token == "-") { // explicityly treat "-" as index beyond the end @@ -9480,6 +9486,37 @@ basic_json_parser_63: break; } + // null values are converted to arrays or objects + case value_t::null: + { + // check if reference token is a number + const bool nums = std::all_of(reference_token.begin(), + reference_token.end(), + [](const char x) + { + return std::isdigit(x); + }); + + if (nums) + { + // if reference token consists solely of numbers + // use it as array index -> create array + ptr = &ptr->operator[](static_cast(std::stoi(reference_token))); + } + else if (reference_token == "-") + { + // explicityly treat "-" as index beyond the end + // which is 0 for an empty array -> create array + ptr = &ptr->operator[](0); + } + else + { + // treat reference token as key -> create object + ptr = &ptr->operator[](reference_token); + } + break; + } + default: { throw std::out_of_range("unresolved reference token '" + reference_token + "'"); diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c index 482248354..2dabc0310 100644 --- a/src/json.hpp.re2c +++ b/src/json.hpp.re2c @@ -8733,6 +8733,12 @@ class basic_json /*! @brief return a reference to the pointed to value + @note This version does not throw if a value is not present, but tries + to create nested values instead. For instance, calling this function + with pointer `"/this/that"` on a null value is equivalent to calling + `operator[]("this").operator[]("that")` on that value, effectively + changing the null value to an object. + @param[in] ptr a JSON value @return reference to the JSON value pointed to by the JSON pointer @@ -8747,6 +8753,12 @@ class basic_json { for (const auto& reference_token : reference_tokens) { + // error condition (cf. RFC 6901, Sect. 4) + if (reference_token.size() > 1 and reference_token[0] == '0') + { + throw std::domain_error("array index must not begin with '0'"); + } + switch (ptr->m_type) { case value_t::object: @@ -8758,12 +8770,6 @@ class basic_json case value_t::array: { - // error condition (cf. RFC 6901, Sect. 4) - if (reference_token.size() > 1 and reference_token[0] == '0') - { - throw std::domain_error("array index must not begin with '0'"); - } - if (reference_token == "-") { // explicityly treat "-" as index beyond the end @@ -8777,6 +8783,37 @@ class basic_json break; } + // null values are converted to arrays or objects + case value_t::null: + { + // check if reference token is a number + const bool nums = std::all_of(reference_token.begin(), + reference_token.end(), + [](const char x) + { + return std::isdigit(x); + }); + + if (nums) + { + // if reference token consists solely of numbers + // use it as array index -> create array + ptr = &ptr->operator[](static_cast(std::stoi(reference_token))); + } + else if (reference_token == "-") + { + // explicityly treat "-" as index beyond the end + // which is 0 for an empty array -> create array + ptr = &ptr->operator[](0); + } + else + { + // treat reference token as key -> create object + ptr = &ptr->operator[](reference_token); + } + break; + } + default: { throw std::out_of_range("unresolved reference token '" + reference_token + "'"); diff --git a/test/src/unit-json_pointer.cpp b/test/src/unit-json_pointer.cpp index c7f1708c4..892a958ff 100644 --- a/test/src/unit-json_pointer.cpp +++ b/test/src/unit-json_pointer.cpp @@ -109,8 +109,13 @@ TEST_CASE("JSON pointers") CHECK(j[json::json_pointer("/m~0n")] == j["m~n"]); // unescaped access - CHECK_THROWS_AS(j[json::json_pointer("/a/b")], std::out_of_range); - CHECK_THROWS_WITH(j[json::json_pointer("/a/b")], "unresolved reference token 'b'"); + // access to nonexisting values yield object creation + CHECK_NOTHROW(j[json::json_pointer("/a/b")] = 42); + CHECK(j["a"]["b"] == json(42)); + CHECK_NOTHROW(j[json::json_pointer("/a/c/1")] = 42); + CHECK(j["a"]["c"] == json({nullptr, 42})); + CHECK_NOTHROW(j[json::json_pointer("/a/d/-")] = 42); + CHECK(j["a"]["d"] == json::array({42})); // "/a/b" works for JSON {"a": {"b": 42}} CHECK(json({{"a", {{"b", 42}}}})[json::json_pointer("/a/b")] == json(42)); diff --git a/test/src/unit-regression.cpp b/test/src/unit-regression.cpp index 34eb197f5..6d93e7440 100644 --- a/test/src/unit-regression.cpp +++ b/test/src/unit-regression.cpp @@ -482,4 +482,11 @@ TEST_CASE("regression tests") CHECK_NOTHROW(j << f); } } + + SECTION("issue #323 - add nested object capabilities to pointers") + { + json j; + j["/this/that"_json_pointer] = 27; + CHECK(j == json({{"this", {{"that", 27}}}})); + } }