Compare Engine

Installation

• From npm: npm install @alkemist/compare-engine
• From yarn: yarn add @alkemist/compare-engine

Test

• From npm: npm test
• From yarn: yarn test

About

Compares 2 value, considering array object movement :

• Either with a signature (identical object)
• Or with a key defined by the method passed to the constructor
• The search is recursive: if an object has been moved within a moved object, it will be detected as moved
• Takes into consideration : value type/class, function name and signature (without parameter type)

Examples

With JSON

import {CompareEngine} from '@alkemist/compare-engine';

const jsonLeft = {
    objectArray: [
        {
            id: "movedIndex",
            property: "old property",
            otherObjectArray: [
                {id: "1"},
                {id: "2"},
            ],
            otherArray: [
                0, 1, 2
            ]
        },
        {
            id: "removedObject",
        },
        {
            id: "equal"
        }
    ]
};
const jsonright = {
    objectArray: [
        {
            id: "newObject",
        },
        {
            id: "movedIndex",
            property: "updated property",
            otherObjectArray: [
                {id: "2"},
                {id: "1"},
            ],
            otherArray: [
                2, 1, 3
            ]
        },
        {
            id: "equal"
        }
    ]
};

const compareEngine = new CompareEngine((paths: string[]) => {
  return "id";
});

compareEngine.updateLeft(jsonLeft);
compareEngine.updateRight(jsonRight);

compareEngine.updateCompareIndex();

compareEngine.getLeftState("") // return UPDATED CompareState
compareEngine.getLeftState("objectArray") // return UPDATED CompareState
compareEngine.getLeftState("objectArray[0]") // return UPDATED CompareState
compareEngine.getLeftState("objectArray[0].id") // return EQUAL CompareState
compareEngine.getLeftState("objectArray[0].property") // return UPDATED CompareState
compareEngine.getLeftState("objectArray[0].otherObjectArray") // return UPDATED CompareState
compareEngine.getLeftState("objectArray[0].otherObjectArray[0]") // return MOVED CompareState
compareEngine.getLeftState("objectArray[0].otherObjectArray[0].id") // return NONE CompareState
compareEngine.getLeftState("objectArray[0].otherObjectArray[1]") // return MOVED CompareState
compareEngine.getLeftState("objectArray[0].otherObjectArray[1].id") // return NONE CompareState
compareEngine.getLeftState("objectArray[0].otherArray") // return UPDATED CompareState
compareEngine.getLeftState("objectArray[0].otherArray[0]") // return REMOVED CompareState
compareEngine.getLeftState("objectArray[0].otherArray[1]") // return EQUAL CompareState
compareEngine.getLeftState("objectArray[0].otherArray[2]") // return MOVED CompareState
compareEngine.getLeftState("objectArray[1]") // return REMOVED CompareState
compareEngine.getLeftState("objectArray[1].id") // return NONE CompareState
compareEngine.getLeftState("objectArray[2]") // return EQUAL CompareState
compareEngine.getLeftState("objectArray[2].id") // return NONE CompareState

compareEngine.getRightState("") // return UPDATED CompareState
compareEngine.getRightState("objectArray") // return UPDATED CompareState
compareEngine.getRightState("objectArray[0]") // return ADDED CompareState
compareEngine.getRightState("objectArray[0].id") // return NONE CompareState
compareEngine.getRightState("objectArray[1]") // return UPDATED CompareState
compareEngine.getRightState("objectArray[1].id") // return EQUAL CompareState
compareEngine.getRightState("objectArray[1].property") // return UPDATED CompareState
compareEngine.getRightState("objectArray[1].otherObjectArray") // return UPDATED CompareState
compareEngine.getRightState("objectArray[1].otherObjectArray[0]") // return MOVED CompareState
compareEngine.getRightState("objectArray[1].otherObjectArray[0].id") // return NONE CompareState
compareEngine.getRightState("objectArray[1].otherObjectArray[1]") // return MOVED CompareState
compareEngine.getRightState("objectArray[1].otherObjectArray[1].id") // return NONE CompareState
compareEngine.getRightState("objectArray[1].otherArray") // return UPDATED CompareState
compareEngine.getRightState("objectArray[1].otherArray[0]") // return MOVED CompareState
compareEngine.getRightState("objectArray[1].otherArray[1]") // return EQUAL CompareState
compareEngine.getRightState("objectArray[1].otherArray[2]") // return ADDED CompareState
compareEngine.getRightState("objectArray[2]") // return EQUAL CompareState
compareEngine.getRightState("objectArray[2].id") // return NONE CompareState

With Objects

class Parent {
    constructor(protected property = "value") {
    }
}

class Child extends Parent {
    constructor(protected override property = "value") {
        super();
    }
}

const compareEngine = new CompareEngine((paths: string[]) => {
  return "id";
}, new Parent(), new Parent());
compareEngine.updateCompareIndex();
compareEngine.getLeftState("") // return EQUAL CompareState

const compareEngine = new CompareEngine((paths: string[]) => {
  return "id";
}, new Parent(), new Child());
compareEngine.updateCompareIndex();
compareEngine.getLeftState("") // return UPDATED CompareState

const compareEngine = new CompareEngine((paths: string[]) => {
  return "id";
}, new Child(), new Child("otherValue"));
compareEngine.updateCompareIndex();
compareEngine.getLeftState("") // return UPDATED CompareState

Exposed models, enums and utils

enum CompareStateEnum {
    NONE = "",
    ADDED = "added",
    MOVED = "moved",
    UPDATED = "updated",
    REMOVED = "removed",
    EQUAL = "equal",
}

class CompareEngine<DATA_TYPE> {
    constructor(
        protected determineArrayIndexFn?: (paths: ValueKey[]) => ValueKey
        leftValue?: DATA_TYPE = null,
        rightValue?: DATA_TYPE = null
    )

    get leftValue(): DATA_TYPE | undefined
    get rightValue(): DATA_TYPE | undefined

    getInLeft(paths: ValueKey[] | ValueKey): unknown
    getInRight(paths: ValueKey[] | ValueKey): unknown

    updateLeft(value: DATA_TYPE | undefined): void
    updateRight(value: DATA_TYPE | undefined): void

    updateInLeft(value: DATA_TYPE | undefined, paths: ValueKey[] | ValueKey): void
    updateInRight(value: DATA_TYPE | undefined, paths: ValueKey[] | ValueKey): void

    leftToRight(): void
    rightToLeft(): void

    updateCompareIndex(): void

    hasChange(): boolean

    getLeftState(paths: ValueKey[] | ValueKey): CompareState
    getRightState(paths: ValueKey[] | ValueKey): CompareState
}

class CompareState {
    value: CompareStateEnum

    isNone(): boolean
    isAdded(): boolean
    isMoved(): boolean
    isUpdated(): boolean
    isRemoved(): boolean
    isEqual(): boolean
    isChanged(): boolean

    toString(): string
}

License

Apache License, Version 2.0