/
generator.go
79 lines (64 loc) · 1.59 KB
/
generator.go
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package reggenerator
import (
"fmt"
"math/rand"
"strings"
"golang.org/x/sync/errgroup"
)
// RandFn is a pointer to a function that returns random generated number.
var RandFn func() int = rand.Int
// Generate generates N random strings based on supplied regex.
func Generate(regex string, count int) ([]string, error) {
tokens, err := tokenize(regex)
if err != nil {
return nil, fmt.Errorf("diagnosing: %w", err)
}
parsedTokens, err := parse(tokens)
if err != nil {
return nil, fmt.Errorf("parsing tokens: %w", err)
}
g := errgroup.Group{}
ch := make(chan string, count)
for i := 0; i < count; i++ {
g.Go(func() error {
s := strings.Builder{}
for _, t := range parsedTokens {
_, err := s.Write(generatePart(t.possibleCharacters, t.quantifier))
if err != nil {
return fmt.Errorf("writing to string builder: %w", err)
}
}
ch <- s.String()
return nil
})
}
go func() {
err = g.Wait()
close(ch)
}()
generated := make([]string, 0, count)
for {
s, ok := <-ch
if !ok {
break
}
generated = append(generated, s)
}
return generated, err
}
func generatePart(charList []byte, quantifier quantifier) []byte {
if quantifier.randomPossibility && RandFn()%2 == 0 {
return nil
}
count := quantifier.max // Fixed number of generations
if quantifier.max != quantifier.min {
// Generation range {1,3}
count = (RandFn() % (quantifier.max - quantifier.min + 1)) + quantifier.min
}
bytes := make([]byte, 0, count)
charListLen := len(charList)
for i := 0; i < count; i++ {
bytes = append(bytes, charList[RandFn()%charListLen])
}
return bytes
}