set-array/build/src/apply.js

Set array items declaratively

export const applyUpdates=(array,updates,{merge})=>{
const{array:arrayA,updates:updatesA}=applyAny(array,updates,merge);

const newArray=[];

let previousIndex=-1;


for(const update of updatesA){

previousIndex=applyUpdate({
update,
array:arrayA,
newArray,
previousIndex,
merge
})
}

pushValues(arrayA,newArray,previousIndex+1,arrayA.length);
return newArray
};


const applyAny=(array,updates,merge)=>{
if(updates.length===0||!updates[0].any){
return{array,updates}
}

const[{items},...updatesA]=updates;
const arrayA=array.flatMap((_,index)=>
applyMerge({items,array,index,merge})
);
return{array:arrayA,updates:updatesA}
};

const applyUpdate=({
update:{index,items},
array,
newArray,
previousIndex,
merge
})=>{
pushValues(array,newArray,previousIndex+1,Math.ceil(index));
const itemsA=applyMerge({items,array,index,merge});
pushValues(itemsA,newArray,0,itemsA.length);
return Math.floor(index)
};





const applyMerge=({items,array,index,merge})=>{
if(merge===undefined||!Number.isInteger(index)){
return items
}

const oldValue=array[index];
return items.map((newValue)=>merge(oldValue,newValue))
};


const pushValues=(array,newArray,from,to)=>{

for(let index=from;index<to;index+=1){

newArray.push(array[index])
}
};