Bloom filter in JavaScript using FNV hash.

LICENSE

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+Copyright (c) 2011, Jason Davies
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  * Redistributions of source code must retain the above copyright notice, this
+    list of conditions and the following disclaimer.
+
+  * Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+  * The name Jason Davies may not be used to endorse or promote products
+    derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL JASON DAVIES BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

bloomfilter.js

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+(function(exports) {
+  function BloomFilter(m, k) {
+    this.m = m;
+    this.k = k;
+    this.buckets = [];
+    var n = Math.ceil(m / k),
+        i = -1;
+    while (++i < n) this.buckets[i] = 0;
+  }
+
+  // See http://willwhim.wordpress.com/2011/09/03/producing-n-hash-functions-by-hashing-only-once/
+  BloomFilter.prototype.locations = function(v) {
+    var h = fnv64(v);
+        a = h & 0xffffffff,
+        b = (h & 0xffffffff00000000) >> 32,
+        k = this.k,
+        r = [],
+        i = -1;
+    while (++i < k) r[i] = (a + b * i) % this.m;
+    return r;
+  };
+
+  BloomFilter.prototype.add = function(v) {
+    var l = this.locations(v),
+        i = -1,
+        k = this.k;
+    while (++i < k) this.buckets[Math.floor(l[i] / k)] |= 1 << (l[i] % k)
+  };
+
+  BloomFilter.prototype.test = function(v) {
+    var l = this.locations(v),
+        n = l.length,
+        i = -1,
+        k = this.k,
+        b;
+    while (++i < n) {
+      b = l[i];
+      if ((this.buckets[Math.floor(b / k)] & (1 << (b % k))) === 0) {
+        return false;
+      }
+    }
+    return true;
+  };
+
+  // Fowler/Noll/Vo fast hash
+  function fnv64(d) {
+    var n = d.length,
+        h = 64,
+        i = -1,
+        c;
+    while (++i < n) {
+      c = d.charCodeAt(i);
+      h *= 1099511628211;
+      h ^= (c & 0xff00) >> 8;
+      h *= 1099511628211;
+      h ^= c & 0xff;
+    }
+    return h;
+  }
+
+  exports.BloomFilter = BloomFilter;
+})(typeof exports !== "undefined" ? exports : window);

test.js

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+var BloomFilter = require("./bloomfilter").BloomFilter;
+
+var f = new BloomFilter(100, 16);
+f.add("foo");
+
+var puts = require("util").puts;
+
+puts(f.test("foo"));
+puts(f.test("foop"));
+puts(f.test("bar"));