add slicing/indexing for bytes kind

pkg/policy/selector/parsing_test.go

@@ -413,42 +413,6 @@ func TestParse(t *testing.T) {
 		fmt.Println(err)
 	})
 
-	t.Run("index out of range", func(t *testing.T) {
-		sel, err := Parse(".[1000]")
-		require.NoError(t, err)
-		require.Equal(t, 2, len(sel))
-		require.True(t, sel[0].Identity())
-		require.False(t, sel[0].Optional())
-		require.False(t, sel[0].Iterator())
-		require.Empty(t, sel[0].Slice())
-		require.Empty(t, sel[0].Field())
-		require.Empty(t, sel[0].Index())
-		require.False(t, sel[1].Identity())
-		require.False(t, sel[1].Optional())
-		require.False(t, sel[1].Iterator())
-		require.Empty(t, sel[1].Slice())
-		require.Empty(t, sel[1].Field())
-		require.Equal(t, sel[1].Index(), 1000)
-	})
-
-	t.Run("negative index out of range", func(t *testing.T) {
-		sel, err := Parse(".[-1000]")
-		require.NoError(t, err)
-		require.Equal(t, 2, len(sel))
-		require.True(t, sel[0].Identity())
-		require.False(t, sel[0].Optional())
-		require.False(t, sel[0].Iterator())
-		require.Empty(t, sel[0].Slice())
-		require.Empty(t, sel[0].Field())
-		require.Empty(t, sel[0].Index())
-		require.False(t, sel[1].Identity())
-		require.False(t, sel[1].Optional())
-		require.False(t, sel[1].Iterator())
-		require.Empty(t, sel[1].Slice())
-		require.Empty(t, sel[1].Field())
-		require.Equal(t, sel[1].Index(), -1000)
-	})
-
 	t.Run("slice with negative start and positive end", func(t *testing.T) {
 		sel, err := Parse(".[0:-2]")
 		require.NoError(t, err)

pkg/policy/selector/selector.go

@@ -3,7 +3,6 @@ package selector
 import (
 	"errors"
 	"fmt"
-	"math"
 	"strconv"
 	"strings"
 
@@ -229,7 +228,7 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, error) {
 					idx = len(b) + idx
 				}
 				if idx < 0 || idx >= len(b) {
-					err := newResolutionError(fmt.Sprintf("index out of bounds: %d", seg.Index()), at)
+					err := newResolutionError(fmt.Sprintf("index %d out of bounds for bytes of length %d", seg.Index(), len(b)), at)
 					return nil, errIfNotOptional(seg, err)
 				}
 				cur = basicnode.NewInt(int64(b[idx]))
@@ -263,32 +262,33 @@ func resolveSliceIndices(slice []int64, length int64) (start int64, end int64) {
 
 	start, end = slice[0], slice[1]
 
-	// adjust boundaries
-	switch {
-	case slice[0] == math.MinInt:
-		start = 0
-	case slice[0] < 0:
-		start = length + slice[0]
+	// clamp start index
+	if start < 0 {
+		start = length + start
+		if start < 0 {
+			start = 0
+		}
 	}
-	switch {
-	case slice[1] == math.MaxInt:
-		end = length
-	case slice[1] < 0:
-		end = length + slice[1]
+	if start > length {
+		start = length
 	}
 
-	// backward iteration is not allowed, shortcut to an empty result
-	if start >= end {
-		start, end = 0, 0
-	}
-	// clamp out of bound
-	if start < 0 {
-		start = 0
+	// clamp end index
+	if end < 0 {
+		end = length + end
+		if end < 0 {
+			end = 0
+		}
 	}
 	if end > length {
 		end = length
 	}
 
+	// handle backward slicing
+	if start > end {
+		start, end = 0, 0
+	}
+
 	return start, end
 }
 

pkg/policy/selector/selector_test.go

@@ -246,6 +246,58 @@ func TestSelect(t *testing.T) {
 		require.NoError(t, err)
 		require.Equal(t, 2, int(must.Int(val))) // Assert sliced value at index 1
 	})
+
+	t.Run("slice on bytes", func(t *testing.T) {
+		sel, err := Parse(`.[1:3]`)
+		require.NoError(t, err)
+
+		node := basicnode.NewBytes([]byte{0x01, 0x02, 0x03, 0x04, 0x05})
+		res, err := sel.Select(node)
+		require.NoError(t, err)
+		require.NotEmpty(t, res)
+
+		bytes, err := res.AsBytes()
+		require.NoError(t, err)
+		require.Equal(t, []byte{0x02, 0x03}, bytes) // assert sliced bytes
+	})
+
+	t.Run("index on bytes", func(t *testing.T) {
+		sel, err := Parse(`.[2]`)
+		require.NoError(t, err)
+
+		node := basicnode.NewBytes([]byte{0x01, 0x02, 0x03, 0x04, 0x05})
+		res, err := sel.Select(node)
+		require.NoError(t, err)
+		require.NotEmpty(t, res)
+
+		val, err := res.AsInt()
+		require.NoError(t, err)
+		require.Equal(t, int64(0x03), val) // assert indexed byte value
+	})
+
+	t.Run("out of bounds slicing on bytes", func(t *testing.T) {
+		sel, err := Parse(`.[10:20]`)
+		require.NoError(t, err)
+
+		node := basicnode.NewBytes([]byte{0x01, 0x02, 0x03})
+		res, err := sel.Select(node)
+		require.NoError(t, err)
+		require.NotNil(t, res)
+
+		bytes, err := res.AsBytes()
+		require.NoError(t, err)
+		require.Empty(t, bytes) // assert empty result for out of bounds slice
+	})
+
+	t.Run("out of bounds indexing on bytes", func(t *testing.T) {
+		sel, err := Parse(`.[10]`)
+		require.NoError(t, err)
+
+		node := basicnode.NewBytes([]byte{0x01, 0x02, 0x03})
+		_, err = sel.Select(node)
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "can not resolve path: .10") // assert error for out of bounds index
+	})
 }
 
 func FuzzParse(f *testing.F) {