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- const { soliditySha3 } = require('web3-utils');
- const INTERFACE_ID_LENGTH = 4;
- function makeInterfaceId (interfaces = []) {
- const interfaceIdBuffer = interfaces
- .map(methodSignature => soliditySha3(methodSignature)) // keccak256
- .map(h =>
- Buffer
- .from(h.substring(2), 'hex')
- .slice(0, 4) // bytes4()
- )
- .reduce((memo, bytes) => {
- for (let i = 0; i < INTERFACE_ID_LENGTH; i++) {
- memo[i] = memo[i] ^ bytes[i]; // xor
- }
- return memo;
- }, Buffer.alloc(INTERFACE_ID_LENGTH));
- return `0x${interfaceIdBuffer.toString('hex')}`;
- }
- module.exports = {
- makeInterfaceId,
- };
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