Checkpoint

An easy to use input validator.

Getting started

Download

Maven:

<dependency>
  <groupId>com.natigbabayev.checkpoint</groupId>
  <artifactId>core</artifactId>
  <version>x.y.z</version>
</dependency>

Gradle:

implementation 'com.natigbabayev.checkpoint:core:x.y.z'

(Please replace x, y and z with the latest version numbers: Maven Central
)

Snapshots of the development version are available in [Sonatype's snapshots repository][snap].

Usage

Checkpoint allows you to perform validation checks for given input. Checkpoint is generic collection of
rules with boolean output. You can create new instance of Checkpoint either by using builder or DSL:

Builder

fun main() {
    val pinCheckpoint = Checkpoint.Builder<String>()
        .addRule(
            DefaultRuleBuilder<String>()
                .isValid { it.length >= 4 }
                .whenInvalid { println("Must contain min. 4 characters") }
                .build()
        )
        .addRule(
            DefaultRuleBuilder<String>()
                .isValid { it.contains("@") || it.contains("!") }
                .whenInvalid { println("Must contain at least one of the @ or ! characters.") }
                .build()
        )
        .addRule(
            DefaultRuleBuilder<String>()
                .isValid { it.length <= 6 }
                .whenInvalid { println("Must contain max. 6 characters") }
                .build()
        )
        .build()

    pinCheckpoint.canPass("123") // returns false and invokes whenInvalid()
    pinCheckpoint.canPass("1234") // returns false and invokes whenInvalid()
    pinCheckpoint.canPass("[email protected]!") // returns false and invokes whenInvalid()
    pinCheckpoint.canPass("[email protected]") // returns true
}

DSL

fun main() {
    val pinCheckpoint = checkpoint<String> {
        addRule {
            isValid { it.length >= 4 }
            whenInvalid { println("Must contain min. 4 characters") }
        }

        addRule {
            isValid { it.contains("@") || it.contains("!") }
            whenInvalid { println("Must contain at least one of the @ or ! characters.") }
        }

        addRule {
            isValid { it.length <= 6 }
            whenInvalid { println("Must contain max. 6 characters") }
        }
    }

    pinCheckpoint.canPass("123") // returns false and invokes whenInvalid()
    pinCheckpoint.canPass("1234") // returns false and invokes whenInvalid()
    pinCheckpoint.canPass("[email protected]!") // returns false and invokes whenInvalid()
    pinCheckpoint.canPass("[email protected]") // returns true
}

Base classes

Checkpoint has several base classes which can be used for creating custom checkpoints and rules:

Creating new rule:

class NotEmpty(override val callback: Callback<String>) : DefaultRule<String>() {
    override fun isValid(input: String): Boolean {
        return input.isNotEmpty()
    }
}

fun main() {
    val rule = NotEmpty(
        Rule.Callback { println("Cannot be empty") }
    )
    
    val checkpoint = Checkpoint.Builder()
        .addRule(rule)
        .build()
}

GitHub