Faster and simpler filter implementation

.gitignore

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+node_modules
+*.log
+coverage
+.nyc_output

bench/bench.js

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+'use strict';
+
+var VectorTile = require('vector-tile').VectorTile;
+var Pbf = require('pbf');
+var fs = require('fs');
+var createFilter = require('../');
+var filters = require('./filters.json');
+var path = require('path');
+
+var tile = new VectorTile(new Pbf(fs.readFileSync(path.join(__dirname, './785.vector.pbf'))));
+
+var layers = [];
+for (var name in tile.layers) {
+    var layer = tile.layers[name];
+    if (!layer.length) continue;
+
+    var features = [];
+    for (var j = 0; j < layer.length; j++) {
+        features.push(layer.feature(j));
+    }
+
+    var layerFilters = [];
+    for (j = 0; j < filters.length; j++) {
+        if (filters[j].layer === name) layerFilters.push(filters[j].filter);
+    }
+
+    layers.push({
+        name: name,
+        features: features,
+        rawFilters: layerFilters
+    });
+}
+
+console.time('create filters');
+for (var m = 0; m < 100; m++) {
+    for (var i = 0; i < layers.length; i++) {
+        var layer = layers[i];
+        layer.filters = [];
+        for (j = 0; j < layer.rawFilters.length; j++) {
+            layer.filters.push(createFilter(layer.rawFilters[j]));
+        }
+    }
+}
+console.timeEnd('create filters');
+
+console.time('apply filters');
+for (var m = 0; m < 100; m++) {
+    for (var i = 0; i < layers.length; i++) {
+        var layer = layers[i];
+        for (j = 0; j < layer.features.length; j++) {
+            var feature = layer.features[j];
+            for (var k = 0; k < layer.filters.length; k++) {
+                var filter = layer.filters[k];
+                filter(feature);
+            }
+        }
+    }
+}
+console.timeEnd('apply filters');

bench/big.js

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+'use strict';
+
+var filter = require('../');
+
+var N = 64000;
+
+var arr = ['in', 'foo'];
+for (var i = 0; i < N; i++) arr.push(i);
+
+console.time('create ' + N + '-item filter');
+var f = filter(arr);
+console.timeEnd('create ' + N + '-item filter');
+
+var feature = {properties: {foo: 0}};
+
+console.time('filter 1 million times');
+for (var i = 0; i < 1000000; i++) {
+    feature.properties.foo = Math.floor(Math.random() * N * 2);
+    f(feature);
+}
+console.timeEnd('filter 1 million times');