Separate parsing status from actual errors
This commit is contained in:
parent
c1eae9fa34
commit
d0460e71e3
@ -46,18 +46,18 @@ func Regexp(str string) gigaparsec.Parser[byte, []byte] {
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}
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re := regexp.MustCompile(str)
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expected := fmt.Sprintf("match `%s`", str)
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return func(input gigaparsec.State[byte]) (consumed bool, result gigaparsec.Result[byte, []byte], err error) {
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return func(input gigaparsec.State[byte]) (gigaparsec.Result[byte, []byte], error) {
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r := NewRuneReader(input.Cursor())
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idx := re.FindReaderIndex(r)
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// TODO Check error from r; this requires an Error() method on cursor.RuneReader.
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if idx == nil {
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return false, gigaparsec.Result[byte, []byte]{}, gigaparsec.ParseError{
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return gigaparsec.Fail[byte, []byte](false, gigaparsec.Message{
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Pos: input.Pos(),
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Expected: []string{expected},
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// TODO Not having a Got is unsatisfactory, but how do I extract useful information?
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// Maybe just read a fixed number of bytes or to the end, whichever comes first?
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// I could add extra methods to cursor.RuneReader to figure out how much it had read.
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}
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}), nil
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}
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// Alas, this is a little wasteful because a Regexp can only return indices
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// when searching a RuneReader.
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@ -65,13 +65,9 @@ func Regexp(str string) gigaparsec.Parser[byte, []byte] {
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n, _, err := input.Cursor().Read(dst)
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if err != nil {
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// If we can't access those same bytes again, something is wrong.
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return false, gigaparsec.Result[byte, []byte]{}, fmt.Errorf("Regex: unexpected error: %w", err)
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return gigaparsec.Result[byte, []byte]{}, fmt.Errorf("Regex: unexpected error: %w", err)
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}
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result = gigaparsec.Result[byte, []byte]{
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State: input.At(input.Pos() + n),
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Value: dst,
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Message: gigaparsec.MessageOK(input.Pos()),
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}
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return true, result, nil
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next := input.At(input.Pos() + n)
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return gigaparsec.Succeed(true, dst, next, gigaparsec.MessageOK(input.Pos())), nil
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}
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}
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208
gigaparsec.go
208
gigaparsec.go
@ -10,9 +10,57 @@ import (
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)
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type Result[In, Out any] struct {
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Value Out
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State[In]
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Message
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consumed, failed bool
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Value Out
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next State[In]
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Message Message
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}
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func Fail[In, Out any](consumed bool, msg Message) Result[In, Out] {
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return Result[In, Out]{
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consumed: consumed,
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failed: true,
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Message: msg,
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}
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}
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func (r Result[In, Out]) Failed() (ok, consumed bool, msg Message) {
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ok = r.failed
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if ok {
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consumed = r.consumed
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msg = r.Message
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}
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return
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}
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func Succeed[In, Out any](consumed bool, value Out, next State[In], msg Message) Result[In, Out] {
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return Result[In, Out]{
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failed: false,
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Value: value,
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consumed: consumed,
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next: next,
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Message: msg,
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}
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}
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func (r Result[In, Out]) Succeeded() (ok, consumed bool, value Out, next State[In], msg Message) {
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ok = !r.failed
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if ok {
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consumed = r.consumed
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value = r.Value
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next = r.next
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msg = r.Message
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}
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return
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}
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func (r Result[In, Out]) Consumed() bool {
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return r.consumed
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}
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func (r Result[In, Out]) Consume(consumed bool) Result[In, Out] {
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r.consumed = consumed
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return r
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}
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type Message struct {
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@ -30,11 +78,11 @@ func MessageOK(pos uint64) Message { return Message{Pos: pos} }
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func MessageEnd(pos uint64) Message { return Message{Pos: pos, Got: "end of input"} }
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type ParseError Message
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// type ParseError Message
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func (pe ParseError) Error() string {
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return fmt.Sprintf("parse error: %d: %s", pe.Pos, pe.Got)
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}
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// func (pe ParseError) Error() string {
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// return fmt.Sprintf("parse error: %d: %s", pe.Pos, pe.Got)
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// }
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func MakeState[In any](c cursor.Cursor[In]) State[In] {
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return State[In]{cursor: c}
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@ -61,125 +109,115 @@ func (s State[In]) At(pos uint64) State[In] {
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return State[In]{cursor: s.cursor.At(pos)}
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}
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type Parser[In, Out any] func(State[In]) (consumed bool, reply Result[In, Out], err error)
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type Parser[In, Out any] func(State[In]) (Result[In, Out], error)
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func Return[In, Out any](value Out) Parser[In, Out] {
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return func(state State[In]) (bool, Result[In, Out], error) {
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return false, Result[In, Out]{
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Value: value,
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State: state,
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Message: MessageOK(state.Pos()),
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}, nil
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return func(state State[In]) (Result[In, Out], error) {
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return Succeed(false, value, state, MessageOK(state.Pos())), nil
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}
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}
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func Satisfy[T any](pred func(T) bool) Parser[T, T] {
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return func(state State[T]) (bool, Result[T, T], error) {
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return func(state State[T]) (Result[T, T], error) {
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token := make([]T, 1)
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n, next, err := state.Read(token)
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if errors.Is(err, io.EOF) {
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return false, Result[T, T]{}, ParseError(MessageEnd(state.Pos()))
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return Fail[T, T](false, MessageEnd(state.Pos())), nil
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}
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if err != nil {
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return false, Result[T, T]{}, err
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return Result[T, T]{}, err
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}
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if n != 1 {
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panic(fmt.Sprintf("expected 1 element from Read, but got %d", n))
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}
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if pred(token[0]) {
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return true, Result[T, T]{
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Value: token[0],
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State: next,
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Message: MessageOK(state.Pos()),
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}, nil
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return Succeed(true, token[0], next, MessageOK(state.Pos())), nil
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}
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return false, Result[T, T]{}, ParseError{
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return Fail[T, T](false, Message{
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Pos: state.Pos(),
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Got: fmt.Sprint(token),
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}
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}), nil
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}
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}
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func Slice[T comparable](s []T) Parser[T, []T] {
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expected := fmt.Sprint(s)
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return func(state State[T]) (consumed bool, reply Result[T, []T], err error) {
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return func(state State[T]) (reply Result[T, []T], err error) {
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token := make([]T, len(s))
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_, next, err := state.Read(token)
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if errors.Is(err, io.EOF) {
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return false, Result[T, []T]{}, ParseError(MessageEnd(state.Pos()))
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return Fail[T, []T](false, MessageEnd(state.Pos())), nil
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}
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if err != nil {
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return false, Result[T, []T]{}, err
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return Result[T, []T]{}, err
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}
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if !slices.Equal(s, token) {
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return false, Result[T, []T]{}, ParseError{
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return Fail[T, []T](false, Message{
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Pos: state.Pos(),
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Got: fmt.Sprint(token),
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Expected: []string{expected},
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}
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}), nil
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}
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return true, Result[T, []T]{
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Value: token,
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State: next,
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Message: MessageOK(state.Pos()),
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}, nil
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return Succeed(true, token, next, MessageOK(state.Pos())), nil
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}
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}
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func Bind[In, A, B any](p Parser[In, A], f func(A) Parser[In, B]) Parser[In, B] {
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return func(input State[In]) (bool, Result[In, B], error) {
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consumed, resultA, err := p(input)
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return func(input State[In]) (Result[In, B], error) {
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resultA, err := p(input)
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if err != nil {
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return false, Result[In, B]{}, err
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return Result[In, B]{}, err
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}
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consumed2, replyB, err := f(resultA.Value)(resultA.State)
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return consumed || consumed2, replyB, err
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if ok, consumed, msg := resultA.Failed(); ok {
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return Fail[In, B](consumed, msg), nil
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}
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_, consumedA, valueA, next, _ := resultA.Succeeded()
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resultB, err := f(valueA)(next)
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if err != nil {
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return Result[In, B]{}, err
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}
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return resultB.Consume(consumedA || resultB.Consumed()), nil
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}
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}
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func Choose[In, Out any](p Parser[In, Out], ps ...Parser[In, Out]) Parser[In, Out] {
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// TODO Check this against the Parsec paper again, and simplify it.
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all := append([]Parser[In, Out]{p}, ps...)
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return func(input State[In]) (bool, Result[In, Out], error) {
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return func(input State[In]) (Result[In, Out], error) {
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expecteds := make([][]string, 0, len(all))
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var value Out
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var got string
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var gotGot bool
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var failed bool
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for _, q := range all {
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consumed, result, err := q(input)
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if consumed {
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return consumed, result, err
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result, err := q(input)
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if err != nil {
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return Result[In, Out]{}, err
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}
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if result.Consumed() {
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return result, nil
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}
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var qMsg Message
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if err != nil {
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var parseErr ParseError
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if !errors.As(err, &parseErr) {
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// It broke. Give up.
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return consumed, result, err
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}
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failed = failed && true
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qMsg = Message(parseErr)
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if isFailure, _, msg := result.Failed(); isFailure {
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qMsg = msg
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failed = true
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} else {
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_, _, qValue, _, msg := result.Succeeded()
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if failed {
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value = result.Value
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value = qValue
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failed = false
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}
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qMsg = result.Message
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qMsg = msg
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}
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if !gotGot {
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if got == "" {
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got = qMsg.Got
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gotGot = true
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}
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}
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msg := Message{Pos: input.Pos(), Got: got, Expected: slices.Concat(expecteds...)}
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if failed {
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return false, Result[In, Out]{}, ParseError(msg)
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return Fail[In, Out](false, msg), nil
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}
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return false, Result[In, Out]{
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Value: value,
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State: input,
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Message: msg,
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}, nil
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return Succeed(false, value, input, msg), nil
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}
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}
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@ -189,31 +227,29 @@ func Choose[In, Out any](p Parser[In, Out], ps ...Parser[In, Out]) Parser[In, Ou
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// parser consumed nothing, Try will allow backing out of a complex
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// parser that did partially succeeded.
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func Try[In, Out any](p Parser[In, Out]) Parser[In, Out] {
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return func(input State[In]) (bool, Result[In, Out], error) {
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consumed, reply, err := p(input)
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return func(input State[In]) (Result[In, Out], error) {
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result, err := p(input)
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if err != nil {
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return false, Result[In, Out]{}, err
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return result, err
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}
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return consumed, reply, err
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if failed, _, msg := result.Failed(); failed {
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return Fail[In, Out](false, msg), nil
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}
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return result, nil
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}
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}
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func Label[In, Out any](p Parser[In, Out], l string) Parser[In, Out] {
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return func(input State[In]) (consumed bool, reply Result[In, Out], err error) {
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consumed, reply, err = p(input)
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if consumed {
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return
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return func(input State[In]) (reply Result[In, Out], err error) {
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result, err := p(input)
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if err != nil || result.Consumed() {
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return result, err
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}
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if err == nil {
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reply.Message = reply.Message.expect(l)
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return
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if succeeded, _, value, next, msg := result.Succeeded(); succeeded {
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return Succeed(false, value, next, msg.expect(l)), nil
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}
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var parseErr ParseError
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if errors.As(err, &parseErr) {
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err = ParseError(Message(parseErr).expect(l))
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return
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}
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return
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_, _, msg := result.Failed()
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return Fail[In, Out](false, msg.expect(l)), nil
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}
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}
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@ -223,21 +259,17 @@ func Map[In, Out1, Out2 any](p Parser[In, Out1], f func(Out1) Out2) Parser[In, O
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})
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}
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func End[In any](s State[In]) (consumed bool, reply Result[In, struct{}], err error) {
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func End[In any](s State[In]) (reply Result[In, struct{}], err error) {
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_, _, err = s.cursor.Read([]In{})
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if errors.Is(err, io.EOF) {
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reply := Result[In, struct{}]{
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State: s,
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Message: MessageOK(s.Pos()),
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}
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return true, reply, nil
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return Succeed(true, struct{}{}, s, MessageOK(s.Pos())), nil
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}
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if err != nil {
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return false, Result[In, struct{}]{}, fmt.Errorf("End: unexpected error: %w", err)
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return Result[In, struct{}]{}, fmt.Errorf("End: unexpected error: %w", err)
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}
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return false, Result[In, struct{}]{}, ParseError{
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return Fail[In, struct{}](false, Message{
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Pos: s.Pos(),
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Got: "",
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Expected: []string{"end of input"},
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}
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}), nil
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}
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@ -7,6 +7,7 @@ import (
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"git.codemonkeysoftware.net/b/gigaparsec"
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"git.codemonkeysoftware.net/b/gigaparsec/cursor"
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"github.com/shoenig/test"
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"github.com/shoenig/test/must"
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"pgregory.net/rapid"
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)
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@ -23,17 +24,17 @@ func hasPrefix(prefix []byte) func([]byte) bool {
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}
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func TestSlice(t *testing.T) {
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assertParseFails := func(t rapid.TB, input []byte, p gigaparsec.Parser[byte, []byte]) (parseErr gigaparsec.ParseError) {
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assertParseFails := func(t rapid.TB, input []byte, p gigaparsec.Parser[byte, []byte]) {
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t.Helper()
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start := gigaparsec.MakeState(cursor.NewSlice(input))
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consumed, result, err := p(start)
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test.ErrorAs(t, err, &parseErr, test.Sprint("expected ParseError"))
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test.False(t, consumed, test.Sprint("expected consumed to be false"))
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test.SliceEmpty(t, result.Value, test.Sprint("expected result value to be empty"))
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result, err := p(start)
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must.NoError(t, err)
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failed, consumed, _ := result.Failed()
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test.True(t, failed)
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test.False(t, consumed)
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if t.Failed() {
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t.FailNow()
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}
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return parseErr
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}
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t.Run("fails with wrong contents", rapid.MakeCheck(func(t *rapid.T) {
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@ -55,11 +56,13 @@ func TestSlice(t *testing.T) {
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s := input[:sLen]
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start := gigaparsec.MakeState(cursor.NewSlice(input))
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consumed, result, err := gigaparsec.Slice(s)(start)
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test.NoError(t, err)
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test.True(t, consumed, test.Sprint("expected consumed to be true"))
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test.SliceEqOp(t, s, result.Value)
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test.EqOp(t, uint64(len(s)), result.State.Pos())
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result, err := gigaparsec.Slice(s)(start)
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must.NoError(t, err)
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succeeded, consumed, value, next, _ := result.Succeeded()
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test.True(t, succeeded)
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test.True(t, consumed)
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test.SliceEqOp(t, s, value)
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test.EqOp(t, uint64(len(s)), next.Pos())
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}))
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}
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