README.md

expression-utils-java

Java utility library (with static methods) to parse array-based nested expressions.

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Installation

• In the Packages section, select the package expression-utils-java.lib
• Follow the installation instructions
• Or, download the library jar file and include in your Java project

Usage

• See the Javadoc for detailed documentation.
• See the test cases for detailed usage examples.

Example

import in.eko.exprutils.ExpressionParser;

// Single expression example: 2 + 3
(int)ExpressionParser.parseExpression("['+', 2, 3]");  // returns 5

// Nested expression example: 2 + (3 * 4)
(int)ExpressionParser.parseExpression("['+', 2, ['*', 3, 4]]");  // returns 14

Available functions:

Class	Method	Inputs	Output	Desc
ExpressionParser	parseExpression()	expression (string encoded Json array)	parsed value (Object)	returns parses an expression
	isValidOperator()	String operator	boolean	Checks if the provided operator is supported by the expressionParser
	interpolate()	String expr, Map<String, String> data	interpolated string	Interpolate/replace values of dollar-curly-brace-wrapped variables into a string
Hash	getHash()	String input, String type	hash	Generate hash of a string using the type algorithm (MD5, SHA-256, etc)
	sha256()	String input	sha-256 hash	Generate SHA-256 hash of a string
	sha512()	String input	sha-512 hash	Generate SHA-512 hash of a string
	md5()	String input	md5 hash	Generate md5 hash of a string
JsonObj	get()	String/JSONObject obj, String key, String default_value	value (Object)	Retrieve deep/nested value from a JSON Object
	set()	String obj, String key, Object value	object (String)	Set a key-value pair deep within a JSON Object
JWT	generate()	...	generated token	Generate JWT (token) with the given configuration
	parse()	...	claim map	Validates & parses a JWT (token)

Operators supported by the parseExpression() function:

Operator	Purpose	Expression Example	Result
+	Add	['+', 2, 3]	5
-	Subtract	['-', 3, 2]	1
*	Multiply	['*', 2, 3]	6
/	Divide	['/', 4, 2]	2
CONCAT	Concatenate string	['CONCAT', 'Hello', 'World']	HelloWorld
GET	Get nested-value from object	['GET', {'b':{'d':{'e':3}}}, 'b.d.e']	3
SET	Set nested-value into object	['SET', {'b':{'d':{}}}, 'b.d.e', 4]	{'b':{'d':{'e':4}}}
SHA256	Get sha-256 hash	['SHA256', 'hello world']	b94d27...cde9
SHA512	Get sha-512 hash	['SHA512', 'hello world']	309ecc48...cd76f
MD5	Get MD5 hash	['MD5', 'hello world']	5eb63...5acdc3
JWT	Generate JWT	['JWT', '<secret-key>', 'HS256', '{"issuer":...}']	generated token

Contribution Guide

Local Test

• ./gradlew test --info

Local Build

• ./gradlew build

Publish New Release

• Make sure to update the version number in the lib/build.gradle file
• Merge changes into the main branch
• Goto the Releases section and create a new release
• A new build will automatically be created and published to Github Packages