strategy.go

package strategy

import (
	"fmt"
	"sort"

	"github.com/zimmski/tavor/rand"
	"github.com/zimmski/tavor/token"
)

// ErrorType the fuzzing strategy error type
type ErrorType int

const (
	// ErrEndlessLoopDetected the token graph has a cycle which is not allowed.
	ErrEndlessLoopDetected ErrorType = iota
	// ErrNilRandomGenerator the random generator is nil
	ErrNilRandomGenerator
)

// Error holds a fuzzing strategy error
type Error struct {
	Message string
	Type    ErrorType
}

func (err *Error) Error() string {
	return err.Message
}

// Strategy defines a fuzzing strategy.
// The function starts the first iteration of the fuzzing strategy returning a channel which controls the iteration flow. The channel returns a value if the iteration is complete and waits with calculating the next iteration until a value is put in. The channel is automatically closed when there are no more iterations. The error return argument is not nil if an error occurs during the setup of the fuzzing strategy.
type Strategy func(root token.Token, r rand.Rand) (chan struct{}, error)

var strategyLookup = make(map[string]Strategy)

// New returns a new fuzzing strategy instance given the registered name of the strategy.
// The error return argument is not nil, if the name does not exist in the registered fuzzing strategy list.
func New(name string) (Strategy, error) {
	strat, ok := strategyLookup[name]
	if !ok {
		return nil, fmt.Errorf("unknown fuzzing strategy %q", name)
	}

	return strat, nil
}

// List returns a list of all registered fuzzing strategy names.
func List() []string {
	keyStrategyLookup := make([]string, 0, len(strategyLookup))

	for key := range strategyLookup {
		keyStrategyLookup = append(keyStrategyLookup, key)
	}

	sort.Strings(keyStrategyLookup)

	return keyStrategyLookup
}

// Register registers a fuzzing strategy instance function with the given name.
func Register(name string, strat Strategy) {
	if strat == nil {
		panic("register fuzzing strategy is nil")
	}

	if _, ok := strategyLookup[name]; ok {
		panic("fuzzing strategy " + name + " already registered")
	}

	strategyLookup[name] = strat
}