Removed BufferedReaderAt

TODO.txt

@@ -1,4 +1,6 @@
 Write Repeat tests
+Clean up cursor tests
+Combine Cursor with State
 Think about not requiring so much Pos() when making messages
 Rename Seq2 to Seq
 Document Seq

bytes/regexp_test.go

@@ -4,6 +4,7 @@ package bytes_test
 
 import (
 	"bytes"
+	"strings"
 	"testing"
 
 	"git.codemonkeysoftware.net/b/gigaparsec"
@@ -28,7 +29,7 @@ func TestRegexp(t *testing.T) {
 
 	}))
 	t.Run("basically works", func(t *testing.T) {
-		result, err := pbytes.Regexp("a")(gigaparsec.MakeState(cursor.NewSlice([]byte("a"))))
+		result, err := pbytes.Regexp("a")(gigaparsec.MakeState(cursor.NewReaderAt(strings.NewReader("a"))))
 		must.NoError(t, err)
 		success, value, _ := result.Status()
 		test.True(t, success, test.Sprint(result.Message()))
@@ -38,8 +39,8 @@ func TestRegexp(t *testing.T) {
 }
 
 func TestRuneReader(t *testing.T) {
-	var s = []byte("abcdefghijklmnopqrstuvwxyz")
-	rr := pbytes.NewRuneReader(cursor.NewSlice(s))
+	var s = "abcdefghijklmnopqrstuvwxyz"
+	rr := pbytes.NewRuneReader(cursor.NewReaderAt(strings.NewReader(s)))
 	for i, b := range s {
 		r, n, err := rr.ReadRune()
 		test.NoError(t, err)
@@ -67,7 +68,7 @@ func TestMatchString(t *testing.T) {
 		notPrefix := func(b []byte) bool { return !bytes.HasPrefix(input, b) }
 		s := string(bgen.Filter(notPrefix).Draw(t, "s"))
 
-		result, err := pbytes.MatchString(s)(gigaparsec.MakeState(cursor.NewSlice(input)))
+		result, err := pbytes.MatchString(s)(gigaparsec.MakeState(cursor.NewReaderAt(bytes.NewReader(input))))
 		test.NoError(t, err)
 		success, _, _ := result.Status()
 		test.False(t, success)
@@ -77,7 +78,7 @@ func TestMatchString(t *testing.T) {
 		input := rapid.SliceOfN(rapid.Byte(), 1, 100).Draw(t, "input")
 		slen := rapid.IntRange(0, len(input)).Draw(t, "slen")
 		s := string(input[:slen])
-		result, err := pbytes.MatchString(s)(gigaparsec.MakeState(cursor.NewSlice(input)))
+		result, err := pbytes.MatchString(s)(gigaparsec.MakeState(cursor.NewReaderAt(bytes.NewReader(input))))
 		must.NoError(t, err)
 		success, value, next := result.Status()
 		must.True(t, success)

cursor/cursor.go

@@ -3,6 +3,7 @@
 package cursor
 
 import (
+	"errors"
 	"io"
 )
 
@@ -32,50 +33,36 @@ type Cursor[Datum any] interface {
 	At(pos uint64) Cursor[Datum]
 }
 
-type SliceCursor[Datum any] struct {
-	data   []Datum
-	offset uint64
+type ReaderAt[T any] interface {
+	ReadAt(p []T, off int64) (n int, err error)
 }
 
-func NewSlice[Datum any](data []Datum) SliceCursor[Datum] {
-	return SliceCursor[Datum]{
-		data:   data,
-		offset: 0,
-	}
-}
+type SliceReaderAt[T any] []T
 
-func (sc SliceCursor[Datum]) Read(dst []Datum) (n uint64, next Cursor[Datum], err error) {
-	if sc.offset == uint64(len(sc.data)) {
-		return 0, sc, io.EOF
+func (s SliceReaderAt[T]) ReadAt(dst []T, off int64) (n int, err error) {
+	if off < 0 {
+		return 0, errors.New("SliceReaderAt.ReadAt: negative offset")
 	}
-	copied := copy(dst, sc.data[sc.offset:])
-	if copied < len(dst) {
+	if off >= int64(len(s)) {
+		return 0, io.EOF
+	}
+	n = copy(dst, s[off:])
+	if n < len(dst) {
 		err = io.EOF
 	}
-	n = uint64(copied)
-	sc.offset += n
-	return n, sc, err
+	return n, err
 }
 
-func (sc SliceCursor[Datum]) Pos() uint64 {
-	return sc.offset
-}
-
-func (sc SliceCursor[Datum]) At(pos uint64) Cursor[Datum] {
-	sc.offset = pos
-	return sc
-}
-
-type ReaderAtCursor struct {
-	r   io.ReaderAt
+type ReaderAtCursor[T any] struct {
+	r   ReaderAt[T]
 	pos uint64
 }
 
-func NewReaderAt(r io.ReaderAt) ReaderAtCursor {
-	return ReaderAtCursor{r: r}
+func NewReaderAt[T any](r ReaderAt[T]) ReaderAtCursor[T] {
+	return ReaderAtCursor[T]{r: r}
 }
 
-func (rac ReaderAtCursor) Read(dst []byte) (uint64, Cursor[byte], error) {
+func (rac ReaderAtCursor[T]) Read(dst []T) (uint64, Cursor[T], error) {
 	n, err := rac.r.ReadAt(dst, int64(rac.pos))
 	if n > 0 {
 		rac.pos += uint64(n)
@@ -83,11 +70,11 @@ func (rac ReaderAtCursor) Read(dst []byte) (uint64, Cursor[byte], error) {
 	return uint64(n), rac, err
 }
 
-func (rac ReaderAtCursor) Pos() uint64 {
+func (rac ReaderAtCursor[T]) Pos() uint64 {
 	return rac.pos
 }
 
-func (rac ReaderAtCursor) At(pos uint64) Cursor[byte] {
+func (rac ReaderAtCursor[T]) At(pos uint64) Cursor[T] {
 	rac.pos = pos
 	return rac
 }

cursor/cursor_test.go

@@ -100,12 +100,8 @@ func testCursor[C cursor.Cursor[byte]](t *testing.T, makeCursor func([]byte) C)
 	}))
 }
 
-func TestSliceCursor(t *testing.T) {
-	testCursor(t, cursor.NewSlice[byte])
-}
-
 func TestReaderAtCursor(t *testing.T) {
-	testCursor(t, func(b []byte) cursor.ReaderAtCursor {
+	testCursor(t, func(b []byte) cursor.ReaderAtCursor[byte] {
 		return cursor.NewReaderAt(bytes.NewReader(b))
 	})
 	t.Run("Read returns an error if the ReaderAt fails", rapid.MakeCheck(func(t *rapid.T) {

cursor/helper.go

@@ -1,26 +0,0 @@
-// SPDX-License-Identifier: Unlicense
-
-package cursor
-
-import (
-	"io"
-)
-
-// BufferedReaderAt uses a buffer to supplement an io.Reader
-// with limited backward seeking.
-type BufferedReaderAt struct{}
-
-func NewBufferedReaderAt(r io.Reader, minBuffer uint64) *BufferedReaderAt {
-	return nil
-}
-
-// ReadAt reads bytes from the underlying reader. If the offset is after
-// the end of the buffer, ReadAt will first read and ignore bytes from the
-// underlying reader until it reaches the offset. If the offset is
-// before the start of the buffer, ReadAt will return an error.
-//
-// If your parser needs unlimited lookahead, you should probably
-// just read the whole input into a slice and use BytesCursor.
-func (b *BufferedReaderAt) ReadAt(dst []byte, offset int64) (int, error) {
-	return 0, nil
-}

cursor/helper_test.go

@@ -1,9 +0,0 @@
-// SPDX-License-Identifier: Unlicense
-
-package cursor_test
-
-import "testing"
-
-func TestBufferedReader(t *testing.T) {
-	Todo(t)
-}

parser_test.go

@@ -30,7 +30,7 @@ func hasPrefix(prefix []byte) func([]byte) bool {
 func TestSlice(t *testing.T) {
 	assertParseFails := func(t rapid.TB, input []byte, p gigaparsec.Parser[byte, []byte]) {
 		t.Helper()
-		start := gigaparsec.MakeState(cursor.NewSlice(input))
+		start := gigaparsec.MakeState(cursor.NewReaderAt(bytes.NewReader(input)))
 		result, err := p(start)
 		must.NoError(t, err)
 		success, _, _ := result.Status()
@@ -66,7 +66,7 @@ func TestSlice(t *testing.T) {
 		input := rapid.SliceOfN(rapid.Byte(), 1, -1).Draw(t, "input")
 		sLen := rapid.IntRange(0, len(input)).Draw(t, "sLen")
 		s := input[:sLen]
-		start := gigaparsec.MakeState(cursor.NewSlice(input))
+		start := gigaparsec.MakeState(cursor.NewReaderAt(bytes.NewReader(input)))
 
 		result, err := gigaparsec.MatchSlice(s)(start)
 		must.NoError(t, err)
@@ -108,7 +108,7 @@ func TestBind(t *testing.T) {
 		p := makeParser(pConsume)
 		q := func(struct{}) gigaparsec.Parser[byte, struct{}] { return makeParser(qConsume) }
 
-		result, err := gigaparsec.Bind(p, q)(gigaparsec.MakeState(cursor.NewSlice([]byte{})))
+		result, err := gigaparsec.Bind(p, q)(gigaparsec.MakeState(cursor.NewReaderAt(bytes.NewReader(nil))))
 		must.NoError(t, err)
 		must.EqOp(t, pConsume || qConsume, result.Consumed())
 	}))
@@ -143,4 +143,6 @@ func TestRepeat(t *testing.T) {
 	t.Run("succeeds when number of successes is greater than minCount", Todo)
 	t.Run("consumes iff at least one application consumes", Todo)
 	t.Run("fails on error", Todo)
+	t.Run("position is unchanged on failure", Todo)
+	t.Run("position follows last success on overall success", Todo)
 }