File: basic_json_location.md

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### jsoncons::jsonpath::basic_json_location

```cpp
#include <jsoncons_ext/jsonpath/jsonpath.hpp>

template <typename CharT,typename Allocator = std::allocator<CharT>>     (since 0.172.0)
class basic_json_location
```

Two specializations for common character types are defined:

Type      |Definition
----------|------------------------------
json_location   |`basic_json_location<char>`
wjson_location  |`basic_json_location<wchar_t>`

Objects of type `basic_json_location` represents the location of a specific value in a JSON document.

#### Member types
Type        |Definition
------------|------------------------------
char_type   | `CharT`
allocator_type | Allocator
string_view_type | `jsoncons::basic_string_view<char_type>`
value_type  | basic_path_element<CharT,Allocator>
const_iterator | A constant [LegacyRandomAccessIterator](https://en.cppreference.com/w/cpp/named_req/RandomAccessIterator) with a `value_type` of [basic_path_element<char_type>](basic_path_element.md)
iterator    | An alias to `const_iterator`

#### Constructors

    basic_json_location(const allocator_type& alloc=Allocator());         (1)

    basic_json_location(const basic_path_node<char_type>& path, 
        const allocator_type& alloc=Allocator());                         (2)

    basic_json_location(const basic_json_location&);                      (3)

    basic_json_location(basic_json_location&&) noexcept;                  (4)

(1) Constructs an empty `basic_json_location`.

(2) Constructs a `basic_json_location` from a path node.

(3) Copy constructor

(4) Move constructor

#### operator=

    basic_json_location& operator=(const basic_json_location&);

    basic_json_location& operator=(basic_json_location&&);

#### Iterators

    iterator begin() const;
    iterator end() const;
Iterator access to the tokens in the pointer.

#### Accessors

    bool empty() const
Checks if the location is empty

    std::size_t size() const

    const path_element_type& operator[](std::size_t index) const

#### Modifiers

    void clear();    

    basic_json_location& append(const string_view_type& name)
Appends `name` to the location.

    template <typename IntegerType>
    basic_json_location& append(IntegerType index) 
Appends `index` to the location.
This overload only participates in overload resolution if `IntegerType` is an integer type.

    basic_json_location& append(const basic_json_location& relative_location)
Appends `relative_location` to the location.

#### Static member functions

   static parse(const string_view_type& str);
   static parse(const string_view_type& str, std::error_code& ec);
Constructs a `basic_json_location` from a normalized path, or an equivalent representation
using the dot notation.

#### Non-member functions

<table border="0">
  <tr>
    <td><a href="replace.md">replace</a></td>
    <td>Replace a value in a JSON document at a specified location with a new value</td> 
  </tr>
  <tr>
    <td><a href="get.md">get</a></td>
    <td>Returns a pointer to a JSON value in a JSON document at a specified location</td> 
  </tr>
  <tr>
    <td><a href="remove.md">remove</a></td>
    <td>Remove a JSON node from a JSON document at a specified location</td> 
  </tr>
</table>

    template <typename CharT,typename Allocator = std::allocator<CharT>>
    std::basic_string<CharT, std::char_traits<CharT>, Allocator> to_basic_string(const basic_json_location<CharT,Allocator>& location, 
        const Allocator& alloc = Allocator())
Returns a normalized path

    std::string to_string(const json_location& location)

    std::wstring to_wstring(const wjson_location& location)

### Examples

The examples below uses the sample data file `books.json`, 

```json
{
    "books":
    [
        {
            "category": "fiction",
            "title" : "A Wild Sheep Chase",
            "author" : "Haruki Murakami",
            "price" : 22.72
        },
        {
            "category": "fiction",
            "title" : "The Night Watch",
            "author" : "Sergei Lukyanenko",
            "price" : 23.58
        },
        {
            "category": "fiction",
            "title" : "The Comedians",
            "author" : "Graham Greene",
            "price" : 21.99
        },
        {
            "category": "memoir",
            "title" : "The Night Watch",
            "author" : "Phillips, David Atlee"
        }
    ]
}
```
                         
#### Get a pointer to the book at index 1

```
jsonpath::json_location loc;
loc.append("store").append("book").append(1);

auto result = jsonpath::get(doc, loc);   // since 0.175.0   
if (result.second)
{
    std::cout << *(result.first) << "\n";
}
```
                        
#### Convert a JSONPath normalized path into a JSONPointer                        
 
```cpp
#include <jsoncons/json.hpp>
#include <jsoncons_ext/jsonpath/jsonpath.hpp>
#include <fstream>

using jsoncons::json; 
namespace jsonpath = jsoncons::jsonpath;
namespace jsonpointer = jsoncons::jsonpointer;
#include <ifstream>

int main()
{
    std::ifstream is(/*path_to_books_file*/);
    json doc = json::parse(is);

    auto expr = jsonpath::make_expression<json>("$.books[?(@.category == 'fiction')]");
    std::vector<jsonpath::json_location> locations = expr.select_paths(doc, jsonpath::result_options::sort_descending);

    for (const auto& location : locations)
    {
        std::cout << jsonpath::to_string(location) << "\n";
    }
    std::cout << "\n";

    std::vector<jsoncons::jsonpointer::json_pointer> pointers;
    for (const auto& location : locations)
    {
        jsonpointer::json_pointer ptr;
        {
            for (const jsonpath::path_element& element : location)
            {
                if (element.has_name())
                {
                    ptr.append(element.name());
                }
                else
                {
                    ptr.append(element.index());
                }
            }
        }
        pointers.push_back(ptr);
    }

    for (const auto& ptr : pointers)
    {
        std::cout << jsonpointer::to_string(ptr) << "\n";
    }
    std::cout << "\n";
} 
```

Output:

```
$['books'][2]
$['books'][1]
$['books'][0]

/books/2
/books/1
/books/0
```