json_view: exceptions name the path and the bytes of the value (#5974)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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Niels Lohmann authored and GitHub committed 2026-11-01 17:25:26 +01:00
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@@ -81,6 +81,112 @@ std::string range(const json& j)
{
return j.start_pos() == npos && j.end_pos() == npos ? "none" : std::to_string(j.start_pos()) + "-" + std::to_string(j.end_pos());
}
#if !defined(JSON_NOEXCEPTION)
using json_view_test::exception_of_call;
// the exceptions about every value of v are those about the value at the same
// place in j, a value of the whole document from parse() or materialize() (so
// that its parents and positions are set); members whose key repeats are
// skipped (the view finds the first one, j holds the last)
template<typename View>
void check_exceptions(const View& v, const json& j)
{
CAPTURE(j.dump())
if (!v.is_number())
{
CHECK(exception_of_call([&] { static_cast<void>(v.template get<int>()); }) == exception_of_call([&] { static_cast<void>(j.get<int>()); }));
}
if (!v.is_string())
{
CHECK(exception_of_call([&] { static_cast<void>(v.template get<std::string>()); }) == exception_of_call([&] { static_cast<void>(j.get<std::string>()); }));
}
if (!v.is_array())
{
CHECK(exception_of_call([&] { static_cast<void>(v.template get<std::vector<int>>()); }) == exception_of_call([&] { static_cast<void>(j.get<std::vector<int>>()); }));
}
CHECK(exception_of_call([&] { static_cast<void>(v.at("missing")); }) == exception_of_call([&] { static_cast<void>(j.at("missing")); }));
CHECK(exception_of_call([&] { static_cast<void>(v.at(1000)); }) == exception_of_call([&] { static_cast<void>(j.at(1000)); }));
CHECK(exception_of_call([&] { static_cast<void>(v.at(json::json_pointer("/missing"))); }) == exception_of_call([&] { static_cast<void>(j.at(json::json_pointer("/missing"))); }));
CHECK(exception_of_call([&] { static_cast<void>(v.at(json::json_pointer("/-"))); }) == exception_of_call([&] { static_cast<void>(j.at(json::json_pointer("/-"))); }));
CHECK(exception_of_call([&] { static_cast<void>(v.value("k", 0)); }) == exception_of_call([&] { static_cast<void>(j.value("k", 0)); }));
if (!v.is_object())
{
CHECK(exception_of_call([&] { static_cast<void>(v["k"]); }) == exception_of_call([&] { static_cast<void>(j["k"]); }));
// (without the context of basic_json: view iterators do not know the value they iterate over)
CHECK(exception_of_call([&] { static_cast<void>(v.begin().key()); }) == "[json.exception.invalid_iterator.207] cannot use key() for non-object iterators");
}
if (!v.is_array())
{
CHECK(exception_of_call([&] { static_cast<void>(v[0]); }) == exception_of_call([&] { static_cast<void>(j[0]); }));
}
if (v.is_null())
{
CHECK(exception_of_call([&] { static_cast<void>(v.front()); }) == exception_of_call([&] { static_cast<void>(j.front()); }));
}
if (v.is_object())
{
for (auto it = v.begin(); it != v.end(); ++it)
{
const std::string key(it.key().data(), it.key().size());
if (v.count(key) == 1)
{
check_exceptions(it.value(), j.at(key));
}
}
}
else if (v.is_array())
{
for (std::size_t i = 0; i < v.size(); ++i)
{
check_exceptions(v[i], j[i]);
}
}
}
// as check_exceptions, for edits that fail (they change neither d nor j)
void check_edit_exceptions(json_editable_document& d, const json_editable_document::view_type& v, json& j)
{
CAPTURE(j.dump())
if (!v.is_object() && !v.is_null())
{
CHECK(exception_of_call([&] { d.set(v, "k", 1); }) == exception_of_call([&] { j["k"] = 1; }));
CHECK(exception_of_call([&] { d.erase(v, "k"); }) == exception_of_call([&] { j.erase("k"); }));
}
if (!v.is_array() && !v.is_null())
{
CHECK(exception_of_call([&] { d.set(v, 0, 1); }) == exception_of_call([&] { j[0] = 1; }));
CHECK(exception_of_call([&] { d.push_back(v, 1); }) == exception_of_call([&] { j.push_back(1); }));
}
if (!v.is_array())
{
CHECK(exception_of_call([&] { d.insert(v, 0, 1); }) == exception_of_call([&] { j.insert(j.cbegin(), 1); }));
CHECK(exception_of_call([&] { d.erase(v, 0); }) == exception_of_call([&] { j.erase(0); }));
}
else
{
CHECK(exception_of_call([&] { d.erase(v, 1000); }) == exception_of_call([&] { j.erase(1000); }));
}
if (v.is_object())
{
for (auto it = v.begin(); it != v.end(); ++it)
{
const std::string key(it.key().data(), it.key().size());
if (v.count(key) == 1)
{
check_edit_exceptions(d, it.value(), j.at(key));
}
}
}
else if (v.is_array())
{
for (std::size_t i = 0; i < v.size(); ++i)
{
check_edit_exceptions(d, v[i], j[i]);
}
}
}
#endif
} // namespace
TEST_CASE("json_view materialize() source positions")
@@ -345,3 +451,123 @@ TEST_CASE("json_view materialize() source positions")
}
#endif
}
#if !defined(JSON_NOEXCEPTION)
TEST_CASE("json_view exceptions name the path and the bytes of the value")
{
SECTION("as those of basic_json")
{
const std::vector<std::string> texts =
{
"null", "true", "42", "\"s\"", "[]", "{}", "[1, [2, [3, []]]]", R"({"a": {"b": [1, {"c": null}]}, "d": "e"})",
R"({"a/b": {"~": [1]}, "\u0041\n": {"x": "\t"}, "": [{}]})",
R"([1 /* ] */, {"a": [] // }
, "b": {} } , ])",
"\n\t[\r\n 1 ,\n {\n \"a\" : [ ]\n }\n]\n",
};
for (const auto& text : texts)
{
CAPTURE(text)
const json j = json::parse(text, nullptr, true, true, true);
const json_document d = json_document::parse(text, true, true, true);
check_exceptions(d.root(), j);
json_editable_document e = json_editable_document::parse(text, true, true, true);
check_exceptions(e.root(), j);
json m = e.root().materialize();
check_edit_exceptions(e, e.root(), m);
}
}
SECTION("generated documents")
{
json_view_test::generator gen;
for (int i = 0; i < 100; ++i)
{
std::string text;
gen.value(text, 0);
CAPTURE(text)
const json_document d = json_document::parse(text);
check_exceptions(d.root(), json::parse(text));
}
}
SECTION("edited documents: as those of materialize()")
{
const std::string text = R"({"a": [1, 2], "b": {"c": "\n", "d": true}, "e": [3, [4]], "f": "x"})";
json_editable_document d = json_editable_document::parse(text);
d.set(d.root()["f"], 5);
d.push_back(d.root()["a"], json::parse(R"({"n": [null]})"));
d.erase(d.root()["e"], 0);
d.set(d.root()["b"], "c2", d.root()["e"]);
d.insert(d.root()["e"], 0, "new");
json m = d.root().materialize();
check_exceptions(d.root(), m);
check_edit_exceptions(d, d.root(), m);
// (a value inside a new container: a path, but no bytes)
std::string expected = "[json.exception.type_error.302] ";
#if JSON_DIAGNOSTICS
expected += "(/a/2/n/0) ";
#endif
expected += "type must be number, but is null";
CHECK(exception_of_call([&] { static_cast<void>(d.root()["a"][2]["n"][0].get<int>()); }) == expected);
}
SECTION("deep documents with siblings after every nested container")
{
// the search for the path pushes and pops one frame per level (the
// stack reallocates while it grows, and shrinks again at every
// sibling): run under a sanitizer, a reference to a popped or moved
// frame would show here
std::string text = "7";
for (int level = 0; level < 40; ++level)
{
text = R"([[1, [2]], )" + text + R"(, {"k": [3, {"l": [4]}]}, [5, [6, [7]]]])";
}
CAPTURE(text)
const json j = json::parse(text);
const json_document d = json_document::parse(text);
check_exceptions(d.root(), j);
json_editable_document e = json_editable_document::parse(text);
e.set(e.root()[0][0], 9);
check_exceptions(e.root(), e.root().materialize());
}
SECTION("examples")
{
const std::string text = R"({"people": [{"name": "a", "age": 1}, {"name": "c", "age": "x"}], "o": {"k": 1}})";
const json_document d = json_document::parse(text);
std::string expected_age = "[json.exception.type_error.302] ";
#if JSON_DIAGNOSTICS
expected_age += "(/people/1/age) ";
#endif
expected_age += "(bytes 58-61) type must be number, but is string";
CHECK(exception_of_call([&] { static_cast<void>(d.root()["people"][1]["age"].get<int>()); }) == expected_age);
std::string expected_zz = "[json.exception.out_of_range.403] ";
#if JSON_DIAGNOSTICS
expected_zz += "(/people/0) ";
#endif
expected_zz += "(bytes 12-35) key 'zz' not found";
CHECK(exception_of_call([&] { static_cast<void>(d.root().at(json::json_pointer("/people/0/zz"))); }) == expected_zz);
// the root has no path, and with JSON_DIAGNOSTICS then no bytes either (as basic_json)
std::string expected_missing = "[json.exception.out_of_range.403] ";
#if !JSON_DIAGNOSTICS
expected_missing += "(bytes 0-79) ";
#endif
expected_missing += "key 'missing' not found";
CHECK(exception_of_call([&] { static_cast<void>(d.root().at("missing")); }) == expected_missing);
}
SECTION("duplicate keys: the value the view finds")
{
const json_document d = json_document::parse(R"({"x": "1", "x": "22"})");
std::string expected = "[json.exception.type_error.302] ";
#if JSON_DIAGNOSTICS
expected += "(/x) ";
#endif
expected += "(bytes 6-9) type must be number, but is string";
CHECK(exception_of_call([&] { static_cast<void>(d.root()["x"].get<int>()); }) == expected);
}
}
#endif