73 lines
1.3 KiB
JavaScript
73 lines
1.3 KiB
JavaScript
return {
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compare: compare,
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compose: compose,
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defined: defined,
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id: id,
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insert: insert,
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map: map,
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mapFilter: mapFilter,
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of: of,
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proj: proj
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};
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function compare(on) {
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on = on || id;
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return function(a, b) {
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var va = on(a), vb = on(b);
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return va < vb ? -1 : (va > vb ? 1 : 0)
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};
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}
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function compose(f, g) {
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return function() {
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return f(g.apply(null, arguments));
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};
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}
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function defined(x) {
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return x != undefined;
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}
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function id(x) {
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return x;
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}
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function insert(obj, t, comparer, min, max) {
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min = defined(min) ? min : 0;
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max = defined(max) ? max : t.length;
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comparer = comparer || compare();
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if(max - min < 1) {
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return min;
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}
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var avg = Math.floor((max + min) / 2);
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if (compare(obj, t[avg]) < 0) {
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return insert(obj, t, compare, min, avg);
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} else {
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return insert(obj, t, compare, avg+1, max);
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}
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}
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function map(mapper, f) {
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return function() {
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var args = Array.prototype.map.call(arguments, mapper);
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return f.apply(null, args);
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}
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}
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function mapFilter(mapper, predicate) {
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return function(array) {
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return array.reduce(function(accumulator, elem) {
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var v = mapper(elem);
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return predicate(v) ? accumulator.concat(v) : accumulator;
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}, []);
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};
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}
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function of(o) {
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return function(key) {return o[key];};
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}
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function proj(key) {
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return function(o) {return o[key];};
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}
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