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This better documents invalidation. (#1625) 

* This better documents invalidation.

* Tweak.
This commit is contained in:
Daniel Lemire 2021-06-22 11:33:25 -04:00 committed by GitHub
parent ce38fe7bea
commit 1c01fc35eb
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2 changed files with 64 additions and 2 deletions
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9
include/simdjson/generic/ondemand/document.h
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@ -311,7 +311,8 @@ public:
/**
* Reset the iterator inside the document instance so we are pointing back at the
* beginning of the document, as if it had just been created.
* beginning of the document, as if it had just been created. It invalidates all
* values, objects and arrays that you have created so far (including unescaped strings).
*/
inline void rewind() noexcept;
/**
@ -335,7 +336,11 @@ public:
* auto doc = parser.iterate(json);
* doc.at_pointer("//a/1") == 20
*
* Note that at_pointer() automatically calls rewind between each call.
* Note that at_pointer() automatically calls rewind between each call. Thus
* all values, objects and arrays that you have created so far (including unescaped strings)
* are invalidated. After calling at_pointer, you need to consume the result: string values
* should be stored in your own variables, arrays should be decoded and stored in your own array-like
* structures and so forth.
* Also note that at_pointer() relies on find_field() which implies that we do not unescape keys when matching
*
* @return The value associated with the given JSON pointer, or:

57
tests/ondemand/ondemand_json_pointer_tests.cpp
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@ -124,8 +124,65 @@ namespace json_pointer_tests {
TEST_SUCCEED();
}
struct car_type {
std::string make;
std::string model;
uint64_t year;
std::vector<double> tire_pressure;
car_type(std::string_view _make, std::string_view _model, uint64_t _year,
std::vector<double>&& _tire_pressure) :
make{_make}, model{_model}, year(_year), tire_pressure(_tire_pressure) {}
};
bool json_pointer_invalidation() {
TEST_START();
auto cars_json = R"( [
{ "make": "Toyota", "model": "Camry", "year": 2018, "tire_pressure": [ 40.1, 39.9, 37.7, 40.4 ] },
{ "make": "Kia", "model": "Soul", "year": 2012, "tire_pressure": [ 30.1, 31.0, 28.6, 28.7 ] },
{ "make": "Toyota", "model": "Tercel", "year": 1999, "tire_pressure": [ 29.8, 30.0, 30.2, 30.5 ] }
] )"_padded;
ondemand::parser parser;
ondemand::document cars;
std::vector<double> measured;
ASSERT_SUCCESS(parser.iterate(cars_json).get(cars));
std::vector<car_type> content;
for (int i = 0; i < 3; i++) {
ondemand::object obj;
std::string json_pointer = "/" + std::to_string(i);
// Each successive at_pointer call invalidates
// previously parsed values, strings, objects and array.
ASSERT_SUCCESS(cars.at_pointer(json_pointer).get(obj));
// We materialize the object.
std::string_view make;
ASSERT_SUCCESS(obj["make"].get(make));
std::string_view model;
ASSERT_SUCCESS(obj["model"].get(model));
uint64_t year;
ASSERT_SUCCESS(obj["year"].get(year));
// We materialize the array.
ondemand::array arr;
ASSERT_SUCCESS(obj["tire_pressure"].get(arr));
std::vector<double> values;
for(auto x : arr) {
double value_double;
ASSERT_SUCCESS(x.get(value_double));
values.push_back(value_double);
}
content.emplace_back(make, model, year, std::move(values));
}
std::string expected[] = {"Toyota", "Kia", "Toyota"};
int i = 0;
for (car_type c : content) {
std::cout << c.make << " " << c.model << " " << c.year << "\n";
ASSERT_EQUAL(expected[i++], c.make);
}
TEST_SUCCEED();
}
bool run() {
return
json_pointer_invalidation() &&
demo_test() &&
demo_relative_path() &&
run_success_test(TEST_RFC_JSON,"",R"({"foo":["bar","baz"],"":0,"a/b":1,"c%d":2,"e^f":3,"g|h":4,"i\\j":5,"k\"l":6," ":7,"m~n":8})") &&