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LINQ

Linq for javascript

Version vom 28.12.2018. Aktuellste Version

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.org/scripts/376052/657567/LINQ.js 

// ==UserScript==
// @name         LINQ
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Linq for javascript
// @author       You
// @grant        none
// ==/UserScript==

class Enumerable{
    constructor(iterable,isClosure=true){
        this.iterable=isClosure?iterable():iterable;
        this.extends=[];
    }

    *[Symbol.iterator](){
        let cache=[];
        for(let x of this.iterable){
            cache.push(x);
            yield x;
        }
        for(let x of this.extends){
            cache.push(x);
            yield x;
        }
        this.iterable=cache;
    }

    where(predicate){
        let a=this;
        return new Enumerable(function*(){
            for (let x of a){
                if (predicate(a)){
                    yield x;
                }
            }
        });
    }

    count(predicate){
        predicate=predicate || function(){return true;};
        let count=0;
        for(let x of this){
            if (predicate(x)){
                count+=1;
            }
        }
        return count;
    }

    first(predicate){
        predicate=predicate || function(){return true;};
        for(let x of this){
            if (predicate(x)){
                return x;
            }
        }
        throw "Sequence least than 1";
    }

    firstOrDefault(predicate){
        try {
            return this.first();
        }
        catch(e){
            return null;
        }
    }

    elementAt(n){
        let id=0;
        for (let x of this){
            if (id==n){
                return x;
            }
            id++;
        }
        throw "Index of found";
    }

    select(selector){
        let a=this;
        return new Enumerable(function*(){
            for(let x of a){
                yield selector(x);
            }
        });
    }

    join(object,outerSelector,innerSelector,selector){
        let a=this;
        return new Enumerable(function*(){
            for(let x of a){
                for(let y of object){
                    if (outerSelector(x)==innerSelector(y)){
                        yield selector(x,y);
                    }
                }
            }
        });
    }

    groupBy(selector){
        let a=this.toArray();
        return new Enumerable(function*(){
            while (a.length!=0){
                let key=selector(a[0]);
                yield new Grouping(key,a.filter(function(x){return selector(x)==key;}));
                a=a.filter(function(x){return selector(x)!=key;});
            }
        });
    }

    toEnumerable(){
        return new Enumerable(this,false);
    }

    toArray(){
        let result=[];
        for(let x of this){
            result.push(x);
        }
        return result;
    }

    each(action){
        for (let x of this){
            action(x);
        }
    }

    aggregate(func,initValue=null){
        let isSetInit=false;
        let accu=null;
        if (initValue!=null){
            accu=initValue;
            isSetInit=false;
        }
        for (let x of this){
            if (!isSetInit && accu==null){
                accu=x;
                continue;
            }
            accu=func(accu,x);
        }
        if (accu==null){
            throw "Sequence less than 1";
        }
        return accu;
    }

    sum(selector){
        selector=selector || function(x){return x;};
        return this.select(selector).aggregate(function(accu,next){return accu+next;},0);
    }

    max(selector){
        selector=selector || function(x){return x;};
        return this.select(selector).aggregate(function(accu,next){return accu>next?accu:next;});
    }

    min(selector){
        selector=selector || function(x){return x;};
        return this.select(selector).aggregate(function(accu,next){return accu<next?accu:next;});
    }

    unique(selector){
        return this.groupBy(selector).select(function(x){return x.first();});
    }

    static from(iterable){
        return new Enumerable(iterable,false);
    }

    static range(from,to){
        return new Enumerable(function*(){
            for(let i=from;i<to;i++){
                yield i;
            }
        });
    }

    static repeat(object,count){
        return new Enumerable(function*(){
            for(let i=0;i<count;i++){
                yield object;
            }
        });
    }
}

class Grouping extends Enumerable {
    constructor(key, iterable) {
        super(iterable,false);
        this.key = key;
    }
}