Added MatchString

bytes/regexp.go

@@ -3,6 +3,7 @@
 package bytes
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"io"
@@ -87,3 +88,22 @@ func Regexp(pattern string) gigaparsec.Parser[byte, string] {
 		return gigaparsec.Succeed(true, string(dst), next, gigaparsec.MessageOK(input.Pos())), nil
 	}
 }
+
+func MatchString(s string) gigaparsec.Parser[byte, string] {
+	expected := fmt.Sprintf("%q", s)
+	b := []byte(s)
+	return func(input gigaparsec.State[byte]) (gigaparsec.Result[byte, string], error) {
+		dst := make([]byte, len(s))
+		_, next, err := input.Read(dst)
+		if errors.Is(err, io.EOF) {
+			return gigaparsec.Fail[byte, string](false, gigaparsec.MessageEnd(input.Pos(), expected)), nil
+		}
+		if err != nil {
+			return gigaparsec.Result[byte, string]{}, fmt.Errorf("MatchString: %w", err)
+		}
+		if !bytes.Equal(dst, b) {
+			return gigaparsec.Fail[byte, string](false, gigaparsec.MakeMessage(input.Pos(), string(dst), expected)), nil
+		}
+		return gigaparsec.Succeed(true, s, next, gigaparsec.MessageOK(input.Pos())), nil
+	}
+}