ABI (abi v0.1.19)
Documentation for ABI, the function interface language for Solidity. Generally, the ABI describes how to take binary Ethereum and transform it to or from types that Solidity understands.
Link to this section Summary
Functions
Decodes the given data based on the function or tuple signature.
Decodes an event, including indexed and non-indexed data.
Encodes the given data into the function signature or tuple signature.
Parses the given ABI specification document into an array of ABI.FunctionSelector
s.
Link to this section Functions
decode(function_signature, data)
Decodes the given data based on the function or tuple signature.
In place of a signature, you can also pass one of the ABI.FunctionSelector
structs returned from parse_specification/1
.
examples
Examples
iex> ABI.decode("baz(uint,address)", "00000000000000000000000000000000000000000000000000000000000000320000000000000000000000000000000000000000000000000000000000000001" |> Base.decode16!(case: :lower))
[50, <<1::160>>]
iex> ABI.decode("(address[])", "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000" |> Base.decode16!(case: :lower))
[[]]
iex> ABI.decode("(uint256)", "000000000000000000000000000000000000000000000000000000000000000a" |> Base.decode16!(case: :lower))
[10]
iex> ABI.decode("(string)", "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000b457468657220546f6b656e000000000000000000000000000000000000000000" |> Base.decode16!(case: :lower))
["Ether Token"]
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification
...> |> Enum.find(&(&1.function == "bark")) # bark(address,bool)
...> |> ABI.decode("00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000001" |> Base.decode16!(case: :lower))
[<<1::160>>, true]
decode_event(function_signature, data, topics)
Decodes an event, including indexed and non-indexed data.
examples
Examples
iex> ABI.decode_event(
...> "Transfer(address indexed from, address indexed to, uint256 amount)",
...> "00000000000000000000000000000000000000000000000000000004a817c800" |> Base.decode16!(case: :lower),
...> [
...> "ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef" |> Base.decode16!(case: :lower),
...> "000000000000000000000000b2b7c1795f19fbc28fda77a95e59edbb8b3709c8" |> Base.decode16!(case: :lower),
...> "0000000000000000000000007795126b3ae468f44c901287de98594198ce38ea" |> Base.decode16!(case: :lower)
...> ]
...> )
{"Transfer",
%{
"amount" => 20_000_000_000,
"from" => [
<<252, 55, 141, 170, 149, 43, 167, 241, 99, 196, 161, 22, 40, 245, 90, 77, 245, 35, 179, 239>>
],
"to" => [
<<178, 183, 193, 121, 95, 25, 251, 194, 143, 218, 119, 169, 94, 89, 237, 187, 139, 55, 9, 200>>
]
}}
encode(function_signature, data)
Encodes the given data into the function signature or tuple signature.
In place of a signature, you can also pass one of the ABI.FunctionSelector
structs returned from parse_specification/1
.
examples
Examples
iex> ABI.encode("(uint256)", [{10}])
...> |> Base.encode16(case: :lower)
"000000000000000000000000000000000000000000000000000000000000000a"
iex> ABI.encode("baz(uint,address)", [50, <<1::160>>])
...> |> Base.encode16(case: :lower)
"a291add600000000000000000000000000000000000000000000000000000000000000320000000000000000000000000000000000000000000000000000000000000001"
iex> ABI.encode("price(string)", ["BAT"])
...> |> Base.encode16(case: :lower)
"fe2c6198000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000034241540000000000000000000000000000000000000000000000000000000000"
iex> ABI.encode("baz(uint8)", [9999])
** (RuntimeError) Data overflow encoding uint, data `9999` cannot fit in 8 bits
iex> ABI.encode("(uint,address)", [{50, <<1::160>>}])
...> |> Base.encode16(case: :lower)
"00000000000000000000000000000000000000000000000000000000000000320000000000000000000000000000000000000000000000000000000000000001"
iex> ABI.encode("(string)", [{"Ether Token"}])
...> |> Base.encode16(case: :lower)
"0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000b457468657220546f6b656e000000000000000000000000000000000000000000"
iex> ABI.encode("(string)", [{String.duplicate("1234567890", 10)}])
...> |> Base.encode16(case: :lower)
"000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000643132333435363738393031323334353637383930313233343536373839303132333435363738393031323334353637383930313233343536373839303132333435363738393031323334353637383930313233343536373839303132333435363738393000000000000000000000000000000000000000000000000000000000"
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification
...> |> Enum.find(&(&1.function == "bark")) # bark(address,bool)
...> |> ABI.encode([<<1::160>>, true])
...> |> Base.encode16(case: :lower)
"b85d0bd200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000001"
parse_specification(doc)
Parses the given ABI specification document into an array of ABI.FunctionSelector
s.
Non-function entries (e.g. constructors) in the ABI specification are skipped. Fallback function entries are accepted.
This function can be used in combination with a JSON parser, e.g. Jason
, to parse ABI specification JSON files.
examples
Examples
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification
[%ABI.FunctionSelector{function: "bark", returns: nil, types: [%{name: "at", type: :address}, %{name: "loudly", type: :bool}]},
%ABI.FunctionSelector{function: "rollover", returns: %{name: "is_a_good_boy", type: :bool}, types: []}]
iex> [%{
...> "constant" => true,
...> "inputs" => [
...> %{"name" => "at", "type" => "address"},
...> %{"name" => "loudly", "type" => "bool"}
...> ],
...> "name" => "bark",
...> "outputs" => [],
...> "payable" => false,
...> "stateMutability" => "nonpayable",
...> "type" => "function"
...> }]
...> |> ABI.parse_specification
[
%ABI.FunctionSelector{function: "bark", returns: nil, types: [
%{type: :address, name: "at"},
%{type: :bool, name: "loudly"}
]}
]
iex> [%{
...> "inputs" => [
...> %{"name" => "_numProposals", "type" => "uint8"}
...> ],
...> "payable" => false,
...> "stateMutability" => "nonpayable",
...> "type" => "constructor"
...> }]
...> |> ABI.parse_specification
[]
iex> ABI.decode("(string)", "000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000643132333435363738393031323334353637383930313233343536373839303132333435363738393031323334353637383930313233343536373839303132333435363738393031323334353637383930313233343536373839303132333435363738393000000000000000000000000000000000000000000000000000000000" |> Base.decode16!(case: :lower))
[String.duplicate("1234567890", 10)]
iex> [%{
...> "payable" => false,
...> "stateMutability" => "nonpayable",
...> "type" => "fallback"
...> }]
...> |> ABI.parse_specification
[%ABI.FunctionSelector{function: nil, returns: nil, types: []}]