linq.js

demo 例子..  $ 在字符串中代表当前循环对象

 var arr = linq.from(this.list).select(function (v) {
                    var goodsList = v['goodsList'];
                    var res = linq.from(goodsList).where('$.checked==1').select(function (v) {
                        return {'id': v['id'], 'buy_number': v['buy_number']};
                    }).toArray();
                    if (res == undefined || res.length == 0) {
                        return null;
                    }
                    return res;
                }).where(' $!=null && $.length>0 ').toArray();

gitHub:

https://github.com/mihaifm/linq

var Enumerable = require('../linq');

/////////////////////////////////
//first step of Lambda Expression

console.log('\nfirst step of Lambda Expression\n');

// Anonymous function
Enumerable.range(1, 3).select(function(value, index) { return index + ':' + value }).log().toJoinedString();
// String like Lambda Expression (arguments => expression)
Enumerable.range(1, 3).select((value, index) => index + ':' + value).log().toJoinedString();

// If the number of arguments is one , can use default iterator variable '$'
Enumerable.range(1, 3).select(i => i * 2).log().toJoinedString();
Enumerable.range(1, 3).select("$*2").log().toJoinedString(); // same

// "" is shortcut of "x => x" (identity function)
Enumerable.range(4, 7).join(Enumerable.range(8, 5), "", "", (outer, inner) => outer * inner).log().toJoinedString();



/////////////////////////////
//Scope of lambda expression

console.log('\nScope of lambda expression\n');

var number = 3;
// Can't Find number | lambda expression can use only global variable
// Enumerable.range(1,10).where("$ == number").log().toJoinedString();

// use anonymous founction, can capture variable
Enumerable.range(1,10).where(function(i){return i == number}).log().toJoinedString();

//////////////////////////////////////////
//from(Object) -> convert to keyvaluePair

console.log('\nfrom(Object) -> convert to keyvaluePair\n');

var object = {foo:"a", "bar":100, "foobar":true};
Enumerable.from(object).forEach(function(obj)
{
    console.log(obj.key + ":" + obj.value);
});



//////////////////////////////
//forEach (continue and break)

console.log('\nforEach (continue and break)\n');

Enumerable.repeat("foo", 10).forEach(function(value, index)
{
    if (index % 2 == 0) return; // continue
    if (index > 6) return false; // break
    console.log(index + ":" + value);
});



/////////////////////////////////
//Grouping and ref/value compare

console.log('\nGrouping and ref/value comparen\n');

// ref compare
console.log((new Date(2000, 1, 1) == new Date(2000, 1, 1))); // false
console.log(({ a: 0} == { a: 0 })); // false

console.log("------");
var objects = [
    { Date: new Date(2000, 1, 1), Id: 1 },
    { Date: new Date(2010, 5, 5), Id: 2 },
    { Date: new Date(2000, 1, 1), Id: 3 }
]

// ref compare, can not grouping
Enumerable.from(objects)
    .groupBy("$.Date", "$.Id",
        function (key, group) { return { date: key, ids: group.toJoinedString(',')} })
    .log("$.date + ':' + $.ids").toJoinedString();

console.log("------");

// use fourth argument(compareSelector)
Enumerable.from(objects)
    .groupBy("$.Date", "$.Id",
        function (key, group) { return { date: key, ids: group.toJoinedString(',')} },
        function (key) { return key.toString() })
    .log("$.date + ':' + $.ids").toJoinedString();



//////////////////////////////
//Regular Expression matches

console.log('\nRegular Expression matches\n');

// Enumerable.matches return Enumerable<MatchObject>

var input = "abcdefgABzDefabgdg";
Enumerable.matches(input, "ab(.)d", "i").forEach(function(match)
{
    for (var prop in match)
    {
        console.log(prop + " : " + match[prop]);
    }
    console.log("toString() : " + match.toString());
    console.log("---");
});



//////////////////////////////////
//LazyEvaluation and InfinityList

console.log('\nLazyEvaluation and InfinityList\n');

// first radius of circle's area over 10000
var result = Enumerable.toInfinity(1).where(r => r * r * Math.PI > 10000).first();
console.log(result);



/////////////
//Dictionary

console.log('\nDictionary\n');

// sample class
var cls = function (a, b)
{
    this.a = a;
    this.b = b;
}
var instanceA = new cls("a", 100);
var instanceB = new cls("b", 2000);

// create blank dictionary
var dict = Enumerable.empty().toDictionary();
// create blank dictionary(use compareSelector)
var dict = Enumerable.empty().toDictionary("","",function (x) { return x.a + x.b });

dict.add(instanceA, "zzz");
dict.add(instanceB, "huga");
console.log(dict.get(instanceA)); // zzz
console.log(dict.get(instanceB)); // huga

// enumerable (to keyvaluePair)
dict.toEnumerable().forEach(function (kvp)
{
    console.log(kvp.key.a + ":" + kvp.value);
});



/////////////////////////////////////////////
//Nondeterministic Programs

console.log('\nNondeterministic Programs\n');

// from Structure and Interpretation of Computer Programs 4.3.2
var apart = Enumerable.range(1, 5);
var answers = apart
    .selectMany(function(baker){ return apart
    .selectMany(function(cooper){ return apart
    .selectMany(function(fletcher){ return apart
    .selectMany(function(miller){ return apart
    .select(function(smith){ return {
        baker: baker, cooper: cooper, fletcher: fletcher, miller: miller, smith: smith}})})})})})
    .where(function(x){ return Enumerable.from(x).distinct("$.value").count() == 5 })
    .where("$.baker != 5")
    .where("$.cooper != 1")
    .where("$.fletcher != 1 && $.fletcher != 5")
    .where("$.miller > $.cooper")
    .where("Math.abs($.smith - $.fletcher) != 1")
    .where("Math.abs($.fletcher - $.cooper) != 1");

answers.selectMany("").log("$.key + ':' + $.value").toJoinedString();