// (c) 2019-2020, Lux Partners Limited.
//
// This file is a derived work, based on the go-ethereum library whose original
// notices appear below.
//
// It is distributed under a license compatible with the licensing terms of the
// original code from which it is derived.
//
// Much love to the original authors for their work.
// **********
// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package vm

import (
	"errors"
	"fmt"
)

// List evm execution errors
var (
	// errStopToken is an internal token indicating interpreter loop termination,
	// never returned to outside callers.
	errStopToken = errors.New("stop token")
)

// ErrStackUnderflow wraps an evm error when the items on the stack less
// than the minimal requirement.
type ErrStackUnderflow struct {
	stackLen int
	required int
}

func (e *ErrStackUnderflow) Error() string {
	return fmt.Sprintf("stack underflow (%d <=> %d)", e.stackLen, e.required)
}

// ErrStackOverflow wraps an evm error when the items on the stack exceeds
// the maximum allowance.
type ErrStackOverflow struct {
	stackLen int
	limit    int
}

func (e *ErrStackOverflow) Error() string {
	return fmt.Sprintf("stack limit reached %d (%d)", e.stackLen, e.limit)
}

// ErrInvalidOpCode wraps an evm error when an invalid opcode is encountered.
type ErrInvalidOpCode struct {
	opcode OpCode
}

func (e *ErrInvalidOpCode) Error() string { return fmt.Sprintf("invalid opcode: %s", e.opcode) }