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@PaulMaynard
Last active May 2, 2016 16:13
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Generator and Iterator manipulation
/**
* Eater.js version: 0.2.0
* Usage examples:
* // Even squares of numbers between 1-10
* _(_.filter( x => x % 2 === 0, _.map(x => x * x, _.range(1, 10))))
* // 10 coin flips
* _(_.take(10, _.map(n => n < 0.5, _.func(Math.random))))
* // first 100 Fibonacci numbers (assuming already defined generator)
* _(_.take(100, fibonacci()))
* // Convert pseudo-array to array
* _(_({ 0: 1, 1: 2, length: 2} ))
*/
window._ = window.eater = (function(){'use strict';
function eater(it) {
if(typeof it === 'function') {
return eater.func(it);
} else if(typeof it.length === 'number') {
return eater.loop(it);
} else if(it[Symbol.iterator]) {
return [...it];
} else if(it.next) {
return eater.take(it);
} else {
return eater.fill(it);
}
}
Object.assign(eater, {
/* Creators */
*range(start = Infinity, end = null) {
if(end == null) {
[start, end] = [1, start];
}
for(var i = start; i <= end; i++) {
yield i;
}
},
*fill(val) {
while(true) {
yield val;
}
},
*func(fn, ...args) {
while(true) {
yield fn(...args);
}
},
*loop(it) {
for(var i = 0; i < it.length; i++) {
yield it[i];
}
},
*join(...its) {
for(var it of its) {
yield* it;
}
},
/* Accessors */
*take(amt, iter) {
if(iter == null) {
iter = amt;
amt = Infinity
}
var it = iter[Symbol.iterator] ? iter[Symbol.iterator]() : iter
for(var i = 0, n; i < amt && !((n = it.next()).done); i++) {
yield n.value;
}
},
*each(fun, it) {
for(var i of it) {
fun(i);
yield i;
}
},
get(it) {
return it.next().value;
},
/* Manipulators */
*map(fun, it) {
for(var i of it) {
yield fun(i);
}
},
*filter(fun, it) {
for(var i of it) {
if(fun(i)) {
yield i;
}
}
}
});
return eater;
})();
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