json/api/basic_json_document/source.md

nlohmann::basic_json_document::source

view_type::string_view_t source() const noexcept;

Returns the parsed text, whether it is borrowed from the caller or owned by the document.

Return value

A #!cpp string_view_t (#!cpp std::string_view on C++17 and newer) over the parsed text, or an empty one if the document is discarded.

Exception safety

No-throw guarantee: this function never throws exceptions.

Complexity

Constant.

Notes

For a borrowed document, source() points directly into the caller's buffer, so it is only valid while that buffer is; see owns_source.

Examples

??? example

```cpp
#include <iostream>
#include <string>
#include <nlohmann/json_view.hpp>

using json_document = nlohmann::json_document;

int main()
{
    std::cout << std::boolalpha;

    std::string text = R"({"a": 1})";
    json_document doc = json_document::parse(text);

    // source() is the parsed text, whether borrowed or owned
    std::cout << (doc.source().size() == text.size()) << '\n';
    std::cout << std::string(doc.source().data(), doc.source().size()) << '\n';

    // for a borrowed document, source() points right into the caller's buffer
    std::cout << (doc.source().data() == text.data()) << '\n';
}

```

Output:

```json
true
{"a": 1}
true

```

See also

• owns_source - return whether the document holds its own copy of the text
• source_offset - byte offset of a value in the source text

Version history

• Added in version 3.13.0.