Skip to main content

​
FunctionSignature

A FunctionSignature represents a complete Ethereum function signature with metadata, including the 4-byte selector, function name, and parameter types.

​
Type Definition

type FunctionSignatureType = {
  readonly selector: SelectorType;
  readonly signature: string;
  readonly name: string;
  readonly inputs: readonly string[];
};

​
Creating Function Signatures

​
From Signature String

import * as FunctionSignature from '@tevm/primitives';

const sig = FunctionSignature.fromSignature('transfer(address,uint256)');

console.log(sig.name);                          // 'transfer'
console.log(sig.inputs);                        // ['address', 'uint256']
console.log(sig.signature);                     // 'transfer(address,uint256)'
console.log(FunctionSignature.toHex(sig));      // '0xa9059cbb'

​
From Selector

import * as Selector from '@tevm/primitives';

const selector = Selector.fromHex('0xa9059cbb');
const sig = FunctionSignature.from(selector);

console.log(sig.name);    // '' (unknown)
console.log(sig.inputs);  // [] (unknown)

​
Operations

​
Parse Signature

Extract function name and parameter types: 
const { name, inputs } = FunctionSignature.parseSignature(
  'swap(uint256,uint256,address,bytes)'
);

console.log(name);    // 'swap'
console.log(inputs);  // ['uint256', 'uint256', 'address', 'bytes']

​
Compare Signatures

Comparison is based on selector equality: 
const sig1 = FunctionSignature.fromSignature('transfer(address,uint256)');
const sig2 = FunctionSignature.fromSignature('transfer(address,uint256)');
const equal = FunctionSignature.equals(sig1, sig2); // true

​
Convert to Hex

const hex = FunctionSignature.toHex(sig);
// '0xa9059cbb'

​
Complex Type Support

​
Tuples

const sig = FunctionSignature.fromSignature(
  'execute((address,uint256,bytes)[])'
);

console.log(sig.name);    // 'execute'
console.log(sig.inputs);  // ['(address,uint256,bytes)[]']

​
Arrays

const sig = FunctionSignature.fromSignature(
  'batchTransfer(address[],uint256[])'
);

console.log(sig.inputs);  // ['address[]', 'uint256[]']

​
Nested Structures

const sig = FunctionSignature.fromSignature(
  'complexCall((address,(uint256,bytes)[])[])'
);

console.log(sig.inputs);  // ['(address,(uint256,bytes)[])[]']

​
Common Function Signatures

​
ERC-20

const transfer = FunctionSignature.fromSignature('transfer(address,uint256)');
const approve = FunctionSignature.fromSignature('approve(address,uint256)');
const balanceOf = FunctionSignature.fromSignature('balanceOf(address)');

​
ERC-721

const transferFrom = FunctionSignature.fromSignature(
  'transferFrom(address,address,uint256)'
);
const safeTransferFrom = FunctionSignature.fromSignature(
  'safeTransferFrom(address,address,uint256)'
);

​
Uniswap V2

const swap = FunctionSignature.fromSignature(
  'swap(uint256,uint256,address,bytes)'
);
// selector: 0x022c0d9f

​
Use Cases

​
ABI Encoding

Use with ABI encoding to construct function calls: 
const sig = FunctionSignature.fromSignature('transfer(address,uint256)');
const data = Abi.encodeFunctionData(sig, [recipient, amount]);

​
Function Routing

Build function dispatch tables: 
const handlers = new Map();
handlers.set(
  FunctionSignature.toHex(transferSig),
  handleTransfer
);
handlers.set(
  FunctionSignature.toHex(approveSig),
  handleApprove
);

​
Contract Introspection

Identify functions from transaction data: 
const selector = txData.slice(0, 4);
const sig = FunctionSignature.from(selector);
console.log(`Function: ${sig.name || 'unknown'}`);

​
API Reference

​
Constructors

  • from(value: FunctionSignatureLike): FunctionSignatureType - Create from various inputs
  • fromSignature(signature: string): FunctionSignatureType - Create from signature string

​
Operations

  • toHex(sig: FunctionSignatureType): string - Get selector as hex
  • equals(a: FunctionSignatureType, b: FunctionSignatureType): boolean - Compare signatures
  • parseSignature(signature: string): { name: string, inputs: string[] } - Parse signature string

​
See Also