imp(erc20): types (evmos#1976)

* imp(erc20): types

* Apply suggestions from code review

Co-authored-by: stepit <48993133+0xstepit@users.noreply.github.com>
Co-authored-by: MalteHerrmann <42640438+MalteHerrmann@users.noreply.github.com>

---------

Co-authored-by: stepit <48993133+0xstepit@users.noreply.github.com>
Co-authored-by: MalteHerrmann <42640438+MalteHerrmann@users.noreply.github.com>

Author: 3 people

precompiles/erc20/types.go

@@ -0,0 +1,104 @@
+// Copyright Tharsis Labs Ltd.(Evmos)
+// SPDX-License-Identifier:ENCL-1.0(https://github.com/evmos/evmos/blob/main/LICENSE)
+
+package erc20
+
+import (
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+// ParseTransferArgs parses the arguments from the transfer method and returns
+// the destination address (to) and amount.
+func ParseTransferArgs(args []interface{}) (
+	to common.Address, amount *big.Int, err error,
+) {
+	if len(args) != 2 {
+		return common.Address{}, nil, fmt.Errorf("invalid number of arguments; expected 2; got: %d", len(args))
+	}
+
+	to, ok := args[0].(common.Address)
+	if !ok {
+		return common.Address{}, nil, fmt.Errorf("invalid to address: %v", args[0])
+	}
+
+	amount, ok = args[1].(*big.Int)
+	if !ok {
+		return common.Address{}, nil, fmt.Errorf("invalid amount: %v", args[1])
+	}
+
+	return to, amount, nil
+}
+
+// ParseTransferFromArgs parses the arguments from the transferFrom method and returns
+// the sender address (from), destination address (to) and amount.
+func ParseTransferFromArgs(args []interface{}) (
+	from, to common.Address, amount *big.Int, err error,
+) {
+	if len(args) != 3 {
+		return common.Address{}, common.Address{}, nil, fmt.Errorf("invalid number of arguments; expected 3; got: %d", len(args))
+	}
+
+	from, ok := args[0].(common.Address)
+	if !ok {
+		return common.Address{}, common.Address{}, nil, fmt.Errorf("invalid from address: %v", args[0])
+	}
+
+	to, ok = args[1].(common.Address)
+	if !ok {
+		return common.Address{}, common.Address{}, nil, fmt.Errorf("invalid to address: %v", args[1])
+	}
+
+	amount, ok = args[2].(*big.Int)
+	if !ok {
+		return common.Address{}, common.Address{}, nil, fmt.Errorf("invalid amount: %v", args[2])
+	}
+
+	return from, to, amount, nil
+}
+
+// ParseApproveArgs parses the approval arguments and returns the spender address
+// and amount.
+func ParseApproveArgs(args []interface{}) (
+	spender common.Address, amount *big.Int, err error,
+) {
+	if len(args) != 2 {
+		return common.Address{}, nil, fmt.Errorf("invalid number of arguments; expected 2; got: %d", len(args))
+	}
+
+	spender, ok := args[0].(common.Address)
+	if !ok {
+		return common.Address{}, nil, fmt.Errorf("invalid spender address: %v", args[0])
+	}
+
+	amount, ok = args[1].(*big.Int)
+	if !ok {
+		return common.Address{}, nil, fmt.Errorf("invalid amount: %v", args[1])
+	}
+
+	return spender, amount, nil
+}
+
+// ParseAllowanceArgs parses the allowance arguments and returns the owner and
+// the spender addresses.
+func ParseAllowanceArgs(args []interface{}) (
+	owner, spender common.Address, err error,
+) {
+	if len(args) != 2 {
+		return common.Address{}, common.Address{}, fmt.Errorf("invalid number of arguments; expected 2; got: %d", len(args))
+	}
+
+	owner, ok := args[0].(common.Address)
+	if !ok {
+		return common.Address{}, common.Address{}, fmt.Errorf("invalid owner address: %v", args[0])
+	}
+
+	spender, ok = args[1].(common.Address)
+	if !ok {
+		return common.Address{}, common.Address{}, fmt.Errorf("invalid spender address: %v", args[1])
+	}
+
+	return owner, spender, nil
+}