Added Slice parser

gigaparsec.go

@@ -9,8 +9,6 @@ import (
 	"git.codemonkeysoftware.net/b/gigaparsec/cursor"
 )
 
-var ErrNoParse = errors.New("no parse")
-
 type Result[In, Out any] struct {
 	Value Out
 	State[In]
@@ -33,7 +31,22 @@ func (pe ParseError) Error() string {
 	return fmt.Sprintf("parse error: %d: %s", pe.Pos, pe.Got)
 }
 
-type State[T any] cursor.Cursor[T]
+type State[T any] struct {
+	cursor cursor.Cursor[T]
+}
+
+func (s State[T]) Cursor() cursor.Cursor[T] {
+	return s.cursor
+}
+
+func (s State[T]) Read(dst []T) (n uint64, next State[T], err error) {
+	n, c, err := s.cursor.Read(dst)
+	return n, State[T]{cursor: c}, err
+}
+
+func (s State[T]) Pos() uint64 {
+	return s.cursor.Pos()
+}
 
 type Parser[In, Out any] func(State[In]) (consumed bool, reply Result[In, Out], err error)
 
@@ -54,6 +67,9 @@ func Satisfy[T any](pred func(T) bool) Parser[T, T] {
 		if errors.Is(err, io.EOF) {
 			return false, Result[T, T]{}, ParseError(MessageEnd(state.Pos()))
 		}
+		if err != nil {
+			return false, Result[T, T]{}, err
+		}
 		if n != 1 {
 			panic(fmt.Sprintf("expected 1 element from Read, but got %d", n))
 		}
@@ -71,6 +87,32 @@ func Satisfy[T any](pred func(T) bool) Parser[T, T] {
 	}
 }
 
+func Slice[T comparable](s []T) Parser[T, []T] {
+	expected := fmt.Sprint(s)
+	return func(state State[T]) (consumed bool, reply Result[T, []T], err error) {
+		token := make([]T, len(s))
+		_, next, err := state.Read(token)
+		if errors.Is(err, io.EOF) {
+			return false, Result[T, []T]{}, ParseError(MessageEnd(state.Pos()))
+		}
+		if err != nil {
+			return false, Result[T, []T]{}, err
+		}
+		if !slices.Equal(s, token) {
+			return false, Result[T, []T]{}, ParseError{
+				Pos:      state.Pos(),
+				Got:      fmt.Sprint(token),
+				Expected: []string{expected},
+			}
+		}
+		return true, Result[T, []T]{
+			Value:   token,
+			State:   next,
+			Message: MessageOK(state.Pos()),
+		}, nil
+	}
+}
+
 func Bind[In, A, B any](p Parser[In, A], f func(A) Parser[In, B]) Parser[In, B] {
 	return func(input State[In]) (bool, Result[In, B], error) {
 		consumed, resultA, err := p(input)