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mirror of https://github.com/nlohmann/json synced 2024-12-24 01:30:08 +00:00

allow push_back() and pop_back() calls on json_pointer

Putting pop_back() to public and creating a trivial push_back()
method allows users of nlohmann::json_pointer to manipulate an
existing json-pointer by adding or removing keys at the end.

This is useful for traversing a JSON-instance and keeping track
of its "absolute path" at any moment.

In my case for a schema-validator error-handler.
This commit is contained in:
Patrick Boettcher 2019-01-15 14:39:06 +01:00
parent e5753b14a8
commit 9225cf2f57
3 changed files with 74 additions and 2 deletions

View File

@ -97,7 +97,6 @@ class json_pointer
return res;
}
private:
/*!
@brief remove and return last reference pointer
@throw out_of_range.405 if JSON pointer has no parent
@ -114,6 +113,16 @@ class json_pointer
return last;
}
/*!
@brief remove and return last reference pointer
@throw out_of_range.405 if JSON pointer has no parent
*/
void push_back(const std::string& tok)
{
reference_tokens.push_back(tok);
}
private:
/// return whether pointer points to the root document
bool is_root() const noexcept
{

View File

@ -11885,7 +11885,6 @@ class json_pointer
return res;
}
private:
/*!
@brief remove and return last reference pointer
@throw out_of_range.405 if JSON pointer has no parent
@ -11902,6 +11901,16 @@ class json_pointer
return last;
}
/*!
@brief remove and return last reference pointer
@throw out_of_range.405 if JSON pointer has no parent
*/
void push_back(const std::string& tok)
{
reference_tokens.push_back(tok);
}
private:
/// return whether pointer points to the root document
bool is_root() const noexcept
{

View File

@ -459,4 +459,58 @@ TEST_CASE("JSON pointers")
CHECK(j.is_object());
}
}
SECTION("push and pop")
{
const json j =
{
{"", "Hello"},
{"pi", 3.141},
{"happy", true},
{"name", "Niels"},
{"nothing", nullptr},
{
"answer", {
{"everything", 42}
}
},
{"list", {1, 0, 2}},
{
"object", {
{"currency", "USD"},
{"value", 42.99},
{"", "empty string"},
{"/", "slash"},
{"~", "tilde"},
{"~1", "tilde1"}
}
}
};
// empty json_pointer returns the root JSON-object
auto ptr = ""_json_pointer;
CHECK(j[ptr] == j);
// simple field access
ptr.push_back("pi");
CHECK(j[ptr] == j["pi"]);
ptr.pop_back();
CHECK(j[ptr] == j);
// object and children access
ptr.push_back("answer");
ptr.push_back("everything");
CHECK(j[ptr] == j["answer"]["everything"]);
ptr.pop_back();
ptr.pop_back();
CHECK(j[ptr] == j);
// push key which has to be encoded
ptr.push_back("object");
ptr.push_back("/");
CHECK(j[ptr] == j["object"]["/"]);
CHECK(ptr.to_string() == "/object/~1");
}
}