Json

[عربي]

A JSON parser for Alusus Language. For now, this library supports only reading and extracting information from JSON, not creating JSONs.

Adding to the Project

You can add it to the project using APM:

import "Apm";
Apm.importFile("Alusus/Json");

Example

import "Srl/Console.alusus"
import "Apm";
Apm.importFile("Alusus/Json");

use Srl
func start {
    // define a variable with type Json to hold the information we want.
    def obj: Json = "{\n\t\"id\": 1,\n\t\"classes\": [\"c1\", \"c2\", \"c3\"],\n\t\"passed\": true\n}"

    // get the value stored under the key `id` as integer variable.
    def id: int = obj("id");
    Console.print("id is %d\n", id);

    // check if the value stored under the key `classes` is an array.
    def classesObj: Json = obj("classes");
    if (classesObj.isArray()) {
        Console.print("Array\n");
    }
    else {
        Console.print("Not array\n");
    }

    // get the value stored under the key `passed` as boolean variable
    def passed: Bool = obj("passed");
    // check if the student passed the exam or not.
    if (passed) {
        Console.print("passed\n");
    }
    else {
        Console.print("failed\n");
    }

}
start();

Json class

Member Variables

class Json {
    def keys: Array[String];
    def values: Array[Json];
    def rawValue: String;
}

keys: keys of the JSON if it's an object.

values: values of the JSON if it's an array or an object.

rawValue: raw value (unparsed) if the JSON is neither an object nor an array.

Initialization

We can initialize this class using many methods:

handler this~init()

default initialization without parameters.

handler this~init(str: ptr[array[Char]])

initialization from an array of char.

handler this~init(json: ref[Json])

initialization from another object of the class, copy initialization.

isObject

handler this.isObject(): bool;

Checks if the JSON is an object.

isArray

handler this.isArray(): bool;

Checks if the JSON is an array or not.

getLength

handler this.getLength(): Int;

Get the number of values in the JSON. This will return a positive number if the JSON is an object or an array.

getKey

handler this.getKey(index: Int): String;

Returns the key at at the specified index if the JSON is an object. Returns an empty string if the JSON is not an object or the index is out of range.

JsonStringBuilderMixin

The JsonStringBuilderMixin is a mixin that can be used with StringBuilder to provide JSON string formatting capabilities. It automatically escapes special characters in strings when building JSON output.

Usage

import "Srl/StringBuilder";
import "Apm";
Apm.importFile("Alusus/Json");
use Srl;

def stringBuilder: StringBuilder[JsonStringBuilderMixin](512, 512);

Format Specifiers

The mixin provides special format specifiers for the format method:

• %js - Format a String value with proper JSON escaping (escapes quotes, backslashes, etc.)
• %jpc - Format a CharsPtr value with proper JSON escaping

Example

import "Srl/Console";
import "Srl/StringBuilder";
import "Apm";
Apm.importFile("Alusus/Json");
use Srl;

func testJsonStringBuilderMixin {
    def stringBuilder: StringBuilder[JsonStringBuilderMixin](512, 512);
    def stringVal: String("test\"quotes'");
    def charsPtrVal: CharsPtr("test\"quotes'");
    stringBuilder.format("{ \"name\": %js, \"value\": %jpc }", stringVal, charsPtrVal);
    Console.print("%s\n", stringBuilder~cast[String].buf);
}
testJsonStringBuilderMixin();

Output:

{ "name": "test\"quotes'", "value": "test\"quotes'" }