eth::abi¶

Classes¶

	Name
struct	eth::abi::AbiParam

Types¶

	Name
enum class uint8_t	AbiParamKind { kAddress, kUint, kInt, kBytes32, kBool, kBytes, kString} Identifies one parameter in an event/function signature.
using std::variant< codec::Address, intx::uint256, codec::Hash256, bool, codec::ByteBuffer, std::string >	AbiValue A decoded ABI value. Only the types needed for common ERC-20/ERC-721 events are included: address, uint256, bytes32, bool, bytes, string.

Functions¶

	Name
codec::Hash256	keccak256(const uint8_t * data, size_t len) Compute Keccak-256 of an arbitrary byte sequence.
codec::Hash256	keccak256(const std::string & text) Compute Keccak-256 of a string (e.g. an event signature).
codec::Hash256	event_signature_hash(const std::string & signature) Compute the event topic[0] hash from a human-readable signature.
rlp::Result< AbiValue >	decode_abi_word(const codec::Hash256 & word, AbiParamKind kind) Decode a single 32-byte ABI word from a topic or head slot.
rlp::Result< AbiValue >	decode_indexed_param(const codec::Hash256 & topic, const AbiParam & param) Decode an indexed event parameter from a topic hash.
rlp::Result< std::vector< AbiValue > >	decode_log_data(const codec::ByteBuffer & data, const std::vector< AbiParam > & params) Decode the ABI-encoded `data` field of a log entry.
rlp::Result< std::vector< AbiValue > >	decode_log(const codec::LogEntry & log, const std::string & signature, const std::vector< AbiParam > & params) Fully decode a log entry given its event descriptor.

Types Documentation¶

enum AbiParamKind¶

Enumerator	Value	Description
kAddress		address
kUint		uint — decoded as uint256
kInt		int — decoded as uint256 (sign handling left to caller)
kBytes32		bytesN where N == 32; also covers bytes1-bytes32 zero-padded
kBool		bool
kBytes		bytes (dynamic)
kString		string (dynamic)

Identifies one parameter in an event/function signature.

using AbiValue¶

using eth::abi::AbiValue =  std::variant<
    codec::Address,
    intx::uint256,
    codec::Hash256,
    bool,
    codec::ByteBuffer,
    std::string
>;

A decoded ABI value. Only the types needed for common ERC-20/ERC-721 events are included: address, uint256, bytes32, bool, bytes, string.

address (20 bytes) uint256 / uint widened to 256 bits bytes32 bool bytes (dynamic) string (dynamic)

Functions Documentation¶

function keccak256¶

codec::Hash256 keccak256(
    const uint8_t * data,
    size_t len
)

Compute Keccak-256 of an arbitrary byte sequence.

Parameters:

data Input bytes.

Return: 32-byte hash.

function keccak256¶

codec::Hash256 keccak256(
    const std::string & text
)

Compute Keccak-256 of a string (e.g. an event signature).

function event_signature_hash¶

codec::Hash256 event_signature_hash(
    const std::string & signature
)

Compute the event topic[0] hash from a human-readable signature.

Parameters:

signature e.g. "Transfer(address,address,uint256)"

Return: 32-byte Keccak-256 of the canonical signature string.

function decode_abi_word¶

rlp::Result< AbiValue > decode_abi_word(
    const codec::Hash256 & word,
    AbiParamKind kind
)

Decode a single 32-byte ABI word from a topic or head slot.

Parameters:

word Exactly 32 bytes (ABI head slot or topic).
kind Expected parameter type.

Return: Decoded value or error.

kAddress → reads rightmost 20 bytes
kUint → reads as big-endian uint256
kInt → reads as big-endian uint256 (raw bits, no sign extension)
kBytes32 → returns the 32 bytes directly
kBool → reads last byte, non-zero = true

function decode_indexed_param¶

rlp::Result< AbiValue > decode_indexed_param(
    const codec::Hash256 & topic,
    const AbiParam & param
)

Decode an indexed event parameter from a topic hash.

Parameters:

topic The 32-byte topic value.
param Parameter descriptor (kind, name).

For value types (address, uint, bool, bytes32) the topic IS the 32-byte ABI-encoded value. Dynamic types (bytes, string) are hashed and cannot be recovered — an empty ByteBuffer / string is returned.

function decode_log_data¶

rlp::Result< std::vector< AbiValue > > decode_log_data(
    const codec::ByteBuffer & data,
    const std::vector< AbiParam > & params
)

Decode the ABI-encoded data field of a log entry.

Parameters:

data Raw bytes from LogEntry::data.
params Ordered list of non-indexed parameters to decode.

Return: Vector of decoded values in the same order as params, or error.

Decodes the non-indexed parameters from the log's data field following the standard ABI head/tail encoding (EIP-838 / Solidity ABI spec).

function decode_log¶

rlp::Result< std::vector< AbiValue > > decode_log(
    const codec::LogEntry & log,
    const std::string & signature,
    const std::vector< AbiParam > & params
)

Fully decode a log entry given its event descriptor.

Parameters:

log The raw log entry.
signature Human-readable event signature, e.g. "Transfer(address,address,uint256)".
params Full ordered parameter list (indexed + non-indexed). topic[0] is implicitly the signature hash and is not listed here.

Return: Decoded values in declaration order (indexed first, then data), or error.

Combines topic decoding (indexed params) and data decoding (non-indexed).

Updated on 2026-04-13 at 23:22:46 -0700