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lib/script/opcodes/stack/drop.ex
defmodule BitcoinLib.Script.Opcodes.Stack.Drop do
@moduledoc """
Based on https://en.bitcoin.it/wiki/Script
Word OP_DROP
Opcode 117
Hex 0x75
Input x
Output nothing
Removes the top stack item.
"""
@behaviour BitcoinLib.Script.Opcode
defstruct []
alias BitcoinLib.Script.Opcodes.Stack.Drop
@type t :: Drop
@value 0x75
@doc """
Returns 0x75
## Examples
iex> BitcoinLib.Script.Opcodes.Stack.Drop.v()
0x75
"""
@spec v() :: 0x75
def v do
@value
end
@doc """
Returns <<0x75>>
## Examples
iex> BitcoinLib.Script.Opcodes.Stack.Drop.encode()
<<0x75>>
"""
def encode() do
<<@value::8>>
end
@doc """
Removes the top stack item.
## Examples
iex> stack = [4, 3]
...> %BitcoinLib.Script.Opcodes.Stack.Drop{}
...> |> BitcoinLib.Script.Opcodes.Stack.Drop.execute(stack)
{:ok, [3]}
"""
@spec execute(Drop.t(), list()) :: {:ok, list()} | {:error, binary()}
def execute(_opcode, []), do: {:error, "trying to execute OP_DROP on an empty stack"}
def execute(_opcode, [_first_element | rest]) do
{:ok, rest}
end
end