bdljsn_location

Detailed Description

Outline

• Purpose
• Classes
• Description
  • Attributes
  • Usage
    • Example 1: Basic Syntax

Purpose

Provide a value-semantic type for location in a JSON document.

Classes

• bdljsn::Location: position in a JSON document

See also

bdljsn_jsonutil, bdljsn_json

Description

This component provides a single, unconstrained (value-semantic) attribute class, bdljsn::Location, that is used to describe a location in a (JSON) document. Location is expressed by the offset (attrbute) in bytes from the start of the document. See {jsonutil} for utilities that may provide bdljsn::Location values when reporting error states.

Attributes

Name                Type           Default
------------------  -------------  -------
offset              bsl::uint64_t  0

• offset: the offset into the JSON document

Usage

This section illustrates intended use of this component.

Example 1: Basic Syntax

This example exercises each of the methods of the bdljsn::Location class.

First, create a bdljsn::Location object (having the default value):

bdljsn::Location locationA;
assert(0 == locationA.offset());

Then, set locationA to some other offset:

locationA.setOffset(1);
assert(1 == locationA.offset());

Next, use the value constructor to create a second location having the same offset as the first:

    bdljsn::Location locationB(1);
    assert(1         == locationB.offset());
    assert(locationA == locationB);

Then, set the second location to the maximum offset:

const bsl::uint64_t maxOffset = bsl::numeric_limits<bsl::uint64_t>::max();
 
locationB.setOffset(maxOffset);
assert(maxOffset == locationB.offset());

Next, create another Location that is a copy of the one at ‘maxOffset’:

bdljsn::Location locationC(locationB);
assert(locationB == locationC);

Then, set the first location back to the default state:

locationA.reset();
assert(0                  == locationA.offset());
assert(bdljsn::Location() == locationA);

Next, print the value of each:

bsl::cout << locationA << "\n"
          << locationB << bsl::endl;
 
bsl::cout << "\n";
 
locationC.print(bsl::cout, 2, 3);

and observe:

 0
 18446744073709551615
 
      [
         offset = 18446744073709551615
      ]

Finally, set each location equal to the first:

locationC = locationB = locationA;
assert(0 == locationA.offset());
assert(0 == locationB.offset());
assert(0 == locationC.offset());