https://github.com/onox/json-ada
An Ada 2012 library for parsing JSON
https://github.com/onox/json-ada
ada json json-ada
Last synced: 3 months ago
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An Ada 2012 library for parsing JSON
- Host: GitHub
- URL: https://github.com/onox/json-ada
- Owner: onox
- License: apache-2.0
- Created: 2016-07-30T22:59:37.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2024-07-28T16:06:01.000Z (11 months ago)
- Last Synced: 2024-07-31T20:42:48.002Z (11 months ago)
- Topics: ada, json, json-ada
- Language: Ada
- Homepage:
- Size: 273 KB
- Stars: 39
- Watchers: 8
- Forks: 3
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
- awesome-ada - json-ada - An Ada 2012 library for parsing JSON. (Libraries / Format Readers, Writers and Checkers)
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# json-ada
An Ada 2012 library for parsing JSON ([RFC 7159][url-rfc]). It supports
Ada 2012's iterator and indexing syntax. The RFC does not support
comments, thus this library does not support it either. If your JSON data
contains comments, you should minify the data so that comments are removed.
Escaped Unicode (`\u`) in strings is not supported yet.
## Usage
```ada
with Ada.Command_Line;
with Ada.Text_IO;
with JSON.Parsers;
with JSON.Types;
procedure Example is
package Types is new JSON.Types (Long_Integer, Long_Float);
package Parsers is new JSON.Parsers (Types);
Parser : Parsers.Parser := Parsers.Create_From_File (Ada.Command_Line.Argument (1));
Value : constant Types.JSON_Value := Parser.Parse;
use Types;
begin
-- The data type of a Value can be retrieved with `Value.Kind`. The value
-- can be one of:
--
-- Null_Kind, Boolean_Kind, Integer_Kind, Float_Kind, String_Kind,
-- Array_Kind, or Object_Kind.
case Value.Kind is
when Array_Kind | Object_Kind =>
-- Query the length of a JSON array or object with the function `Length`
Ada.Text_IO.Put_Line (Value.Length'Image);
-- A JSON object provides the function `Contains`
if Value.Kind = Object_Kind and then Value.Contains ("foo") then
-- To get an element of a JSON array or object write `Value.Get (Index_Or_Key)`
-- or use Ada 2012's indexing syntax `Value (Index_Or_Key)`.
--
-- If Value is a JSON object, you can call `Get_Array_Or_Empty`,
-- `Get_Object_Or_Empty`, or `Get` (with an additional parameter containing
-- the default value).
Ada.Text_IO.Put_Line (Value ("foo").Kind'Image);
end if;
-- Iterate over a JSON array or object by using the
-- Ada 2012 iterator syntax `for Element_Or_Key of Value`. The type is a
-- JSON_Value and represents an element of the array or the key of an object.
for Element of Value loop
-- To get the image of JSON_Value (to serialize it), use function `Image`:
Ada.Text_IO.Put_Line (Element.Image);
end loop;
when Float_Kind =>
declare
-- Get the value (String, generic Integer_Type or Float_Type, or Boolean)
-- of a Value by calling `Value.Value`. An Invalid_Type_Error
-- exception will be raised if Value has a different type than the type
-- of the variable in which you try to store the result.
Data : constant Long_Float := Value.Value;
begin
Ada.Text_IO.Put_Line (Data'Image);
end;
when others =>
null;
end case;
end Example;
```
Optional generic parameters of `JSON.Types`:
- `Maximum_Number_Length` (default is 30): Maximum length in characters of
numbers
Optional generic parameters of `JSON.Parsers`:
- `Default_Maximum_Depth` (default is 10)
- `Check_Duplicate_Keys` (default is False): Check for duplicate keys when
parsing. Parsing large JSON texts will be slower if enabled. If disabled
then the `Get` operation will return the value of the first key that matches.
A parser can be created by calling `Create_From_File` or `Create`.
The actual parameter of `Create` can be some text as a `String`
or an access to a `Ada.Streams.Stream_Element_Array` containing the text.
In case an access to a `Stream_Element_Array` is given, then the `Parser`
takes no ownership of the pointer and you must deallocate the array yourself.
The default maximum nesting depth can be overriden with
the optional second parameter `Maximum_Depth` of function `Create`.
After parsing, elements of arrays and objects are stored in the `Parser`
object, while strings remain stored in the `String` or `Stream_Element_Array`.
Therefore, the `Parser` object must not go out of scope before any `JSON_Value`
goes out of scope.
## Dependencies
In order to build the library, you need to have:
* An Ada 2012 compiler
* [Alire][url-alire]
Optional dependencies:
* `gcovr` to generate a coverage report for unit tests
* `make`
## Using the library
Use the library in your crates as follows:
```
$ alr with json
```
## Tools
The JSON pretty printer can be run as follows:
```
$ alr run -q --args=path/to/file.json
```
## Tests
The project contains a set of unit tests. Use `make tests` to build and
run the unit tests. A coverage report can be generated with `make coverage`:
```
$ make tests
$ make coverage
```
## Contributing
Read the [contributing guidelines][url-contributing] if you want to add
a bugfix or an improvement.
## License
The Ada code and unit tests are licensed under the [Apache License 2.0][url-apache].
The first line of each Ada file should contain an SPDX license identifier tag that
refers to this license:
SPDX-License-Identifier: Apache-2.0
[url-alire]: https://alire.ada.dev/
[url-rfc]: https://tools.ietf.org/html/rfc7159
[url-apache]: https://opensource.org/licenses/Apache-2.0
[url-contributing]: /CONTRIBUTING.md