https://github.com/wanseob/solidity-bloom-filter

256 bit bloom filter implementation written in Solidity
https://github.com/wanseob/solidity-bloom-filter

Last synced: 12 days ago
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256 bit bloom filter implementation written in Solidity

• Host: GitHub
• URL: https://github.com/wanseob/solidity-bloom-filter
• Owner: wanseob
• License: apache-2.0
• Created: 2019-03-19T18:57:13.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2019-03-30T02:38:30.000Z (over 5 years ago)
• Last Synced: 2024-11-21T04:31:01.856Z (21 days ago)
• Language: JavaScript
• Size: 84 KB
• Stars: 38
• Watchers: 4
• Forks: 6
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Solidity Bloom Filter

[![npm](https://img.shields.io/npm/v/solidity-bloom-filter/latest.svg)](https://www.npmjs.com/package/solidity-bloom-filter)

[![Build Status](https://travis-ci.org/wanseob/solidity-bloom-filter.svg?branch=master)](https://travis-ci.org/wanseob/solidity-bloom-filter)

Mainnet: [`0x9de80828ff54e961a41c3b31ca6e8eceadc8aef4`](https://etherscan.io/address/0x9de80828ff54e961a41c3b31ca6e8eceadc8aef4)

## Usage

#### With struct

```solidity

pragma solidity >=0.4.21 < 0.6.0;

import "truffle/Assert.sol";

import "../contracts/BloomFilter.sol";

contract TestBloomFilter {

    using BloomFilter for BloomFilter.Filter;

    BloomFilter.Filter filter;

    // Initialize the filter with the expected number of items to add into the bitmap

    function testInit() public {

        filter.init(10);

        Assert.equal(uint(filter.hashCount), uint(37), "Filter should have ");

    }

    // It updates the bitmap of the filter with the received item.

    function testAdd() public {

        filter.add('a'); // Calling add() method will update the bitmap of the filter

        uint256 bitmapA = filter.bitmap;

        filter.add('a');

        uint256 bitmapB = filter.bitmap;

        Assert.equal(bitmapB, bitmapA, "Adding same item should not update the bitmap");

        filter.add('c');

        uint256 bitmapC = filter.bitmap;

        Assert.notEqual(bitmapC, bitmapB, "Adding different item should update the bitmap");

    }

    // It returns the item's false positive value. If it returns true, then

    // the item may exist or not. Otherwise, it definitely does not exist.

    function testCheck() public {

        string[10] memory inclusion = ['a','b','c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'];

        string[10] memory nonInclusion = ['k','l','m', 'n', 'o', 'p', 'q', 'r', 's', 't'];

        for(uint i = 0; i < inclusion.length; i ++) {

            bytes32 key = keccak256(abi.encodePacked(inclusion[i]));

            filter.add(key);

        }

        for(uint j = 0; j < inclusion.length; j ++) {

            bytes32 key = keccak256(abi.encodePacked(inclusion[j])); 

            bool falsePositive = filter.check(key);

            // It may exist or not

            Assert.isTrue(falsePositive, "Should return false positive");

        }

        for(uint k = 0; k < nonInclusion.length; k ++) {

            bytes32 key = keccak256(abi.encodePacked(nonInclusion[k]));

            bool falsePositive = filter.check(key);

            // It definitely does not exist

            Assert.isFalse(falsePositive, "Should return definitely not exist");

        }

    }

}

```

## LICENSE

Apache-2.0